Whatpm/CSS/Parser.pm

package Whatpm::CSS::Parser;
use strict;
use Whatpm::CSS::Tokenizer qw(:token);
require Whatpm::CSS::SelectorsParser;

sub new ($) {
  my $self = bless {onerror => sub { }, must_level => 'm',
                    message_level => 'w',
                    unsupported_level => 'unsupported'}, shift;
  # $self->{base_uri}
  # $self->{unitless_px} = 1/0
  # $self->{hashless_rgb} = 1/0

  ## Media-dependent RGB color range clipper
  $self->{clip_color} = sub {
    shift; #my $self = shift;
    my $value = shift;
    if (defined $value and $value->[0] eq 'RGBA') {
      my ($r, $g, $b) = @$value[1, 2, 3];
      $r = 0 if $r < 0;  $r = 255 if $r > 255;
      $g = 0 if $g < 0;  $g = 255 if $g > 255;
      $b = 0 if $b < 0;  $b = 255 if $b > 255;
      return ['RGBA', $r, $g, $b, $value->[4]];
    }
    return $value;
  };

  ## System dependent font expander
  $self->{get_system_font} = sub {
    #my ($self, $normalized_system_font_name, $font_properties) = @_;
    ## Modify $font_properties hash (except for 'font-family' property).
    return $_[2];
  };

  return $self;
} # new

sub BEFORE_STATEMENT_STATE () { 0 }
sub BEFORE_DECLARATION_STATE () { 1 }
sub IGNORED_STATEMENT_STATE () { 2 }
sub IGNORED_DECLARATION_STATE () { 3 }

our $Prop; ## By CSS property name
our $Attr; ## By CSSOM attribute name
our $Key; ## By internal key

sub parse_char_string ($$) {
  my $self = $_[0];

  my $s = $_[1];
  pos ($s) = 0;
  my $line = 1;
  my $column = 0;

  my $_onerror = $self->{onerror};
  my $onerror = sub {
    $_onerror->(@_, line => $line, column => $column);
  };
  
  my $tt = Whatpm::CSS::Tokenizer->new;
  $tt->{onerror} = $onerror;
  $tt->{get_char} = sub {
    if (pos $s < length $s) {
      my $c = ord substr $s, pos ($s)++, 1;
      if ($c == 0x000A) {
        $line++;
        $column = 0;
      } elsif ($c == 0x000D) {
        unless (substr ($s, pos ($s), 1) eq "\x0A") {
          $line++;
          $column = 0;
        } else {
          $column++;
        }
      } else {
        $column++;
      }
      return $c;
    } else {
      return -1;
    }
  }; # $tt->{get_char}
  $tt->init;

  my $sp = Whatpm::CSS::SelectorsParser->new;
  $sp->{onerror} = $onerror;
  $sp->{must_level} = $self->{must_level};
  $sp->{pseudo_element} = $self->{pseudo_element};
  $sp->{pseudo_class} = $self->{pseudo_class};

  my $nsmap = {prefix_to_uri => {}, uri_to_prefixes => {}};
  # $nsmap->{prefix_to_uri}->{p/""} = uri/undef
  # $nsmap->{uri_to_prefixes}->{uri} = ["p|"/"",...]/undef
  # $nsmap->{has_namespace} = 1/0
  $sp->{lookup_namespace_uri} = sub {
    return $nsmap->{prefix_to_uri}->{$_[0]}; # $_[0] is '' (default) or prefix
  }; # $sp->{lookup_namespace_uri}

  require Message::DOM::CSSStyleSheet;
  require Message::DOM::CSSRule;
  require Message::DOM::CSSStyleDeclaration;

  $self->{base_uri} = $self->{href} unless defined $self->{base_uri};

  my $state = BEFORE_STATEMENT_STATE;
  my $t = $tt->get_next_token;

  my $open_rules = [[]];
  my $current_rules = $open_rules->[-1];
  my $current_decls;
  my $closing_tokens = [];
  my $charset_allowed = 1;
  my $namespace_allowed = 1;

  S: {
    if ($state == BEFORE_STATEMENT_STATE) {
      $t = $tt->get_next_token
          while $t->{type} == S_TOKEN or
              $t->{type} == CDO_TOKEN or
              $t->{type} == CDC_TOKEN;

      if ($t->{type} == ATKEYWORD_TOKEN) {
        if (lc $t->{value} eq 'namespace') { ## TODO: case folding
          $t = $tt->get_next_token;
          $t = $tt->get_next_token while $t->{type} == S_TOKEN;

          my $prefix;
          if ($t->{type} == IDENT_TOKEN) {
            $prefix = lc $t->{value};
            ## TODO: case (Unicode lowercase)
            
            $t = $tt->get_next_token;
            $t = $tt->get_next_token while $t->{type} == S_TOKEN;
          }

          if ($t->{type} == STRING_TOKEN or $t->{type} == URI_TOKEN) {
            my $uri = $t->{value};
            
            $t = $tt->get_next_token;
            $t = $tt->get_next_token while $t->{type} == S_TOKEN;

            ## ISSUE: On handling of empty namespace URI, Firefox 2 and
            ## Opera 9 work differently (See SuikaWiki:namespace).
            ## TODO: We need to check what we do once it is specced.

            if ($t->{type} == SEMICOLON_TOKEN) {
              if ($namespace_allowed) {
                my $p = $prefix;
                $nsmap->{has_namespace} = 1;
                if (defined $prefix) {
                  $nsmap->{prefix_to_uri}->{$prefix} = $uri;
                  $p .= '|';
                } else {
                  $nsmap->{prefix_to_uri}->{''} = $uri;
                  $p = '';
                }
                for my $u (keys %{$nsmap->{uri_to_prefixes}}) {
                  next if $u eq $uri;
                  my $list = $nsmap->{uri_to_prefixes}->{$u};
                  next unless $list;
                  for (reverse 0..$#$list) {
                    splice @$list, $_, 1, () if $list->[$_] eq $p;
                  }
                }
                push @{$nsmap->{uri_to_prefixes}->{$uri} ||= []}, $p;
                push @$current_rules,
                    Message::DOM::CSSNamespaceRule->____new ($prefix, $uri);
                undef $charset_allowed;
              } else {
                $onerror->(type => 'at:namespace:not allowed',
                           level => $self->{must_level},
                           token => $t);
              }
              
              $t = $tt->get_next_token;
              ## Stay in the state.
              redo S;
            } else {
              #
            }
          } else {
            #
          }

          $onerror->(type => 'syntax error:at:namespace',
                     level => $self->{must_level},
                     token => $t);
          #
        } elsif (lc $t->{value} eq 'charset') { ## TODO: case folding
          $t = $tt->get_next_token;
          $t = $tt->get_next_token while $t->{type} == S_TOKEN;

          if ($t->{type} == STRING_TOKEN) {
            my $encoding = $t->{value};
            
            $t = $tt->get_next_token;
            $t = $tt->get_next_token while $t->{type} == S_TOKEN;
            
            if ($t->{type} == SEMICOLON_TOKEN) {
              if ($charset_allowed) {
                push @$current_rules,
                    Message::DOM::CSSCharsetRule->____new ($encoding);
                undef $charset_allowed;
              } else {
                 $onerror->(type => 'at:charset:not allowed',
                            level => $self->{must_level},
                            token => $t);
              }

              ## TODO: Detect the conformance errors for @charset...
              
              $t = $tt->get_next_token;
              ## Stay in the state.
              redo S;
            } else {
              #
            }
          } else {
            #
          }

          $onerror->(type => 'syntax error:at:charset',
                     level => $self->{must_level},
                     token => $t);
          #
        ## NOTE: When adding support for new at-rule, insert code
        ## "undef $charset_allowed" and "undef $namespace_token" as
        ## appropriate.
        } else {
          $onerror->(type => 'not supported:at:'.$t->{value},
                     level => $self->{unsupported_level},
                     token => $t);
        }

        $t = $tt->get_next_token;
        $state = IGNORED_STATEMENT_STATE;
        redo S;
      } elsif (@$open_rules > 1 and $t->{type} == RBRACE_TOKEN) {
        pop @$open_rules;
        ## Stay in the state.
        $t = $tt->get_next_token;
        redo S;
      } elsif ($t->{type} == EOF_TOKEN) {
        if (@$open_rules > 1) {
          $onerror->(type => 'syntax error:block not closed',
                     level => $self->{must_level},
                     token => $t);
        }

        last S;
      } else {
        undef $charset_allowed;
        undef $namespace_allowed;

        ($t, my $selectors) = $sp->_parse_selectors_with_tokenizer
            ($tt, LBRACE_TOKEN, $t);

        $t = $tt->get_next_token
            while $t->{type} != LBRACE_TOKEN and $t->{type} != EOF_TOKEN;

        if ($t->{type} == LBRACE_TOKEN) {
          $current_decls = Message::DOM::CSSStyleDeclaration->____new;
          my $rs = Message::DOM::CSSStyleRule->____new
              ($selectors, $current_decls);
          push @{$current_rules}, $rs if defined $selectors;

          $state = BEFORE_DECLARATION_STATE;
          $t = $tt->get_next_token;
          redo S;
        } else {
          $onerror->(type => 'syntax error:after selectors',
                     level => $self->{must_level},
                     token => $t);

          ## Stay in the state.
          $t = $tt->get_next_token;
          redo S;
        }
      }
    } elsif ($state == BEFORE_DECLARATION_STATE) {
      ## NOTE: DELIM? in declaration will be removed:
      ## <http://csswg.inkedblade.net/spec/css2.1?s=declaration%20delim#issue-2>.

      my $prop_def;
      my $prop_value;
      my $prop_flag = '';
      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      if ($t->{type} == IDENT_TOKEN) { # property
        my $prop_name = lc $t->{value}; ## TODO: case folding
        $t = $tt->get_next_token;
        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
        if ($t->{type} == COLON_TOKEN) {
          $t = $tt->get_next_token;
          $t = $tt->get_next_token while $t->{type} == S_TOKEN;

          $prop_def = $Prop->{$prop_name};
          if ($prop_def and $self->{prop}->{$prop_name}) {
            ($t, $prop_value)
                = $prop_def->{parse}->($self, $prop_name, $tt, $t, $onerror);
            if ($prop_value) {
              ## NOTE: {parse} don't have to consume trailing spaces.
              $t = $tt->get_next_token while $t->{type} == S_TOKEN;

              if ($t->{type} == EXCLAMATION_TOKEN) {
                $t = $tt->get_next_token;
                $t = $tt->get_next_token while $t->{type} == S_TOKEN;
                if ($t->{type} == IDENT_TOKEN and
                    lc $t->{value} eq 'important') { ## TODO: case folding
                  $prop_flag = 'important';
                  
                  $t = $tt->get_next_token;
                  $t = $tt->get_next_token while $t->{type} == S_TOKEN;

                  #
                } else {
                  $onerror->(type => 'syntax error:important',
                             level => $self->{must_level},
                             token => $t);
                  
                  ## Reprocess.
                  $state = IGNORED_DECLARATION_STATE;
                  redo S;
                }
              }

              #
            } else {
              ## Syntax error.
        
              ## Reprocess.
              $state = IGNORED_DECLARATION_STATE;
              redo S;
            }
          } else {
            $onerror->(type => 'not supported:property',
                       level => $self->{unsupported_level},
                       token => $t, value => $prop_name);

            #
            $state = IGNORED_DECLARATION_STATE;
            redo S;
          }
        } else {
          $onerror->(type => 'syntax error:property colon',
                     level => $self->{must_level},
                     token => $t);

          #
          $state = IGNORED_DECLARATION_STATE;
          redo S;
        }
      }

      if ($t->{type} == RBRACE_TOKEN) {
        $t = $tt->get_next_token;
        $state = BEFORE_STATEMENT_STATE;
        #redo S;
      } elsif ($t->{type} == SEMICOLON_TOKEN) {
        $t = $tt->get_next_token;
        ## Stay in the state.
        #redo S;
      } elsif ($t->{type} == EOF_TOKEN) {
        $onerror->(type => 'syntax error:ruleset not closed',
                   level => $self->{must_level},
                   token => $t);
        ## Reprocess.
        $state = BEFORE_STATEMENT_STATE;
        #redo S;
      } else {
        if ($prop_value) {
          $onerror->(type => 'syntax error:property semicolon',
                     level => $self->{must_level},
                     token => $t);
        } else {
          $onerror->(type => 'syntax error:property name',
                     level => $self->{must_level},
                     token => $t);
        }

        #
        $state = IGNORED_DECLARATION_STATE;
        redo S;
      }

      my $important = ($prop_flag eq 'important');
      for my $set_prop_name (keys %{$prop_value or {}}) {
        my $set_prop_def = $Prop->{$set_prop_name};
        $$current_decls->{$set_prop_def->{key}}
            = [$prop_value->{$set_prop_name}, $prop_flag]
            if $important or
                not $$current_decls->{$set_prop_def->{key}} or
                not defined $$current_decls->{$set_prop_def->{key}}->[1];
      }
      redo S;
    } elsif ($state == IGNORED_STATEMENT_STATE or
             $state == IGNORED_DECLARATION_STATE) {
      if (@$closing_tokens) { ## Something is yet in opening state.
        if ($t->{type} == EOF_TOKEN) {
          @$closing_tokens = ();
          ## Reprocess.
          $state = $state == IGNORED_STATEMENT_STATE
              ? BEFORE_STATEMENT_STATE : BEFORE_DECLARATION_STATE;
          redo S;
        } elsif ($t->{type} == $closing_tokens->[-1]) {
          pop @$closing_tokens;
          if (@$closing_tokens == 0 and
              $t->{type} == RBRACE_TOKEN and
              $state == IGNORED_STATEMENT_STATE) {
            $t = $tt->get_next_token;
            $state = BEFORE_STATEMENT_STATE;
            redo S;
          } else {
            $t = $tt->get_next_token;
            ## Stay in the state.
            redo S;
          }
        } elsif ({
          RBRACE_TOKEN, 1,
          #RBRACKET_TOKEN, 1,
          #RPAREN_TOKEN, 1,
          SEMICOLON_TOKEN, 1,
        }->{$t->{type}}) {
          $t = $tt->get_next_token;
          ## Stay in the state.
          #
        } else {
          #
        }
      } else {
        if ($t->{type} == SEMICOLON_TOKEN) {
          $t = $tt->get_next_token;
          $state = $state == IGNORED_STATEMENT_STATE
              ? BEFORE_STATEMENT_STATE : BEFORE_DECLARATION_STATE;
          redo S;
        } elsif ($t->{type} == RBRACE_TOKEN) {
          if ($state == IGNORED_DECLARATION_STATE) {
            $t = $tt->get_next_token;
            $state = BEFORE_STATEMENT_STATE;
            redo S;
          } else {
            ## NOTE: Maybe this state cannot be reached.
            $t = $tt->get_next_token;
            ## Stay in the state.
            redo S;
          }
        } elsif ($t->{type} == EOF_TOKEN) {
          ## Reprocess.
          $state = $state == IGNORED_STATEMENT_STATE
              ? BEFORE_STATEMENT_STATE : BEFORE_DECLARATION_STATE;
          redo S;
        #} elsif ($t->{type} == RBRACKET_TOKEN or $t->{type} == RPAREN_TOKEN) {
        #  $t = $tt->get_next_token;
        #  ## Stay in the state.
        #  #
        } else {
          #
        }
      }

      while (not {
        EOF_TOKEN, 1,
        RBRACE_TOKEN, 1,
        ## NOTE: ']' and ')' are disabled for browser compatibility.
        #RBRACKET_TOKEN, 1,
        #RPAREN_TOKEN, 1,
        SEMICOLON_TOKEN, 1,
      }->{$t->{type}}) {
        if ($t->{type} == LBRACE_TOKEN) {
          push @$closing_tokens, RBRACE_TOKEN;
        #} elsif ($t->{type} == LBRACKET_TOKEN) {
        #  push @$closing_tokens, RBRACKET_TOKEN;
        #} elsif ($t->{type} == LPAREN_TOKEN or $t->{type} == FUNCTION_TOKEN) {
        #  push @$closing_tokens, RPAREN_TOKEN;
        }

        $t = $tt->get_next_token;
      }

      #
      ## Stay in the state.
      redo S;
    } else {
      die "$0: parse_char_string: Unknown state: $state";
    }
  } # S

  my $ss = Message::DOM::CSSStyleSheet->____new
      (manakai_base_uri => $self->{base_uri},
       css_rules => $open_rules->[0],
       ## TODO: href
       ## TODO: owner_node
       ## TODO: media
       type => 'text/css', ## TODO: OK?
       _parser => $self, _nsmap => $nsmap);
  return $ss;
} # parse_char_string

my $compute_as_specified = sub ($$$$) {
  #my ($self, $element, $prop_name, $specified_value) = @_;
  return $_[3];
}; # $compute_as_specified

my $default_serializer = sub {
  my ($self, $prop_name, $value) = @_;
  if ($value->[0] eq 'NUMBER' or $value->[0] eq 'WEIGHT') {
    ## TODO: What we currently do for 'font-weight' is different from
    ## any browser for lighter/bolder cases.  We need to fix this, but
    ## how?
    return $value->[1]; ## TODO: big or small number cases?
  } elsif ($value->[0] eq 'DIMENSION') {
    return $value->[1] . $value->[2]; ## NOTE: This is what browsers do.
  } elsif ($value->[0] eq 'PERCENTAGE') {
    return $value->[1] . '%';
  } elsif ($value->[0] eq 'KEYWORD') {
    return $value->[1];
  } elsif ($value->[0] eq 'URI') {
    ## NOTE: This is what browsers do.
    return 'url('.$value->[1].')';
  } elsif ($value->[0] eq 'RGBA') {
    if ($value->[4] == 1) {
      return 'rgb('.$value->[1].', '.$value->[2].', '.$value->[3].')';
    } elsif ($value->[4] == 0) {
      ## TODO: check what browsers do...
      return 'transparent';
    } else {
      return 'rgba('.$value->[1].', '.$value->[2].', '.$value->[3].', '
          .$value->[4].')';
    }
  } elsif ($value->[0] eq 'INHERIT') {
    return 'inherit';
  } elsif ($value->[0] eq 'DECORATION') {
    my @v = ();
    push @v, 'underline' if $value->[1];
    push @v, 'overline' if $value->[2];
    push @v, 'line-through' if $value->[3];
    push @v, 'blink' if $value->[4];
    return 'none' unless @v;
    return join ' ', @v;
  } else {
    return '';
  }
}; # $default_serializer

my $x11_colors = {
                  'aliceblue' =>        [0xf0, 0xf8, 0xff],
                  'antiquewhite' =>     [0xfa, 0xeb, 0xd7],
                  'aqua' =>     [0x00, 0xff, 0xff],
                  'aquamarine' =>       [0x7f, 0xff, 0xd4],
                  'azure' =>    [0xf0, 0xff, 0xff],
                  'beige' =>    [0xf5, 0xf5, 0xdc],
                  'bisque' =>   [0xff, 0xe4, 0xc4],
                  'black' =>    [0x00, 0x00, 0x00],
                  'blanchedalmond' =>   [0xff, 0xeb, 0xcd],
                  'blue' =>     [0x00, 0x00, 0xff],
                  'blueviolet' =>       [0x8a, 0x2b, 0xe2],
                  'brown' =>    [0xa5, 0x2a, 0x2a],
                  'burlywood' =>        [0xde, 0xb8, 0x87],
                  'cadetblue' =>        [0x5f, 0x9e, 0xa0],
                  'chartreuse' =>       [0x7f, 0xff, 0x00],
                  'chocolate' =>        [0xd2, 0x69, 0x1e],
                  'coral' =>    [0xff, 0x7f, 0x50],
                  'cornflowerblue' =>   [0x64, 0x95, 0xed],
                  'cornsilk' => [0xff, 0xf8, 0xdc],
                  'crimson' =>  [0xdc, 0x14, 0x3c],
                  'cyan' =>     [0x00, 0xff, 0xff],
                  'darkblue' => [0x00, 0x00, 0x8b],
                  'darkcyan' => [0x00, 0x8b, 0x8b],
                  'darkgoldenrod' =>    [0xb8, 0x86, 0x0b],
                  'darkgray' => [0xa9, 0xa9, 0xa9],
                  'darkgreen' =>        [0x00, 0x64, 0x00],
                  'darkgrey' => [0xa9, 0xa9, 0xa9],
                  'darkkhaki' =>        [0xbd, 0xb7, 0x6b],
                  'darkmagenta' =>      [0x8b, 0x00, 0x8b],
                  'darkolivegreen' =>   [0x55, 0x6b, 0x2f],
                  'darkorange' =>       [0xff, 0x8c, 0x00],
                  'darkorchid' =>       [0x99, 0x32, 0xcc],
                  'darkred' =>  [0x8b, 0x00, 0x00],
                  'darksalmon' =>       [0xe9, 0x96, 0x7a],
                  'darkseagreen' =>     [0x8f, 0xbc, 0x8f],
                  'darkslateblue' =>    [0x48, 0x3d, 0x8b],
                  'darkslategray' =>    [0x2f, 0x4f, 0x4f],
                  'darkslategrey' =>    [0x2f, 0x4f, 0x4f],
                  'darkturquoise' =>    [0x00, 0xce, 0xd1],
                  'darkviolet' =>       [0x94, 0x00, 0xd3],
                  'deeppink' => [0xff, 0x14, 0x93],
                  'deepskyblue' =>      [0x00, 0xbf, 0xff],
                  'dimgray' =>  [0x69, 0x69, 0x69],
                  'dimgrey' =>  [0x69, 0x69, 0x69],
                  'dodgerblue' =>       [0x1e, 0x90, 0xff],
                  'firebrick' =>        [0xb2, 0x22, 0x22],
                  'floralwhite' =>      [0xff, 0xfa, 0xf0],
                  'forestgreen' =>      [0x22, 0x8b, 0x22],
                  'fuchsia' =>  [0xff, 0x00, 0xff],
                  'gainsboro' =>        [0xdc, 0xdc, 0xdc],
                  'ghostwhite' =>       [0xf8, 0xf8, 0xff],
                  'gold' =>     [0xff, 0xd7, 0x00],
                  'goldenrod' =>        [0xda, 0xa5, 0x20],
                  'gray' =>     [0x80, 0x80, 0x80],
                  'green' =>    [0x00, 0x80, 0x00],
                  'greenyellow' =>      [0xad, 0xff, 0x2f],
                  'grey' =>     [0x80, 0x80, 0x80],
                  'honeydew' => [0xf0, 0xff, 0xf0],
                  'hotpink' =>  [0xff, 0x69, 0xb4],
                  'indianred' =>        [0xcd, 0x5c, 0x5c],
                  'indigo' =>   [0x4b, 0x00, 0x82],
                  'ivory' =>    [0xff, 0xff, 0xf0],
                  'khaki' =>    [0xf0, 0xe6, 0x8c],
                  'lavender' => [0xe6, 0xe6, 0xfa],
                  'lavenderblush' =>    [0xff, 0xf0, 0xf5],
                  'lawngreen' =>        [0x7c, 0xfc, 0x00],
                  'lemonchiffon' =>     [0xff, 0xfa, 0xcd],
                  'lightblue' =>        [0xad, 0xd8, 0xe6],
                  'lightcoral' =>       [0xf0, 0x80, 0x80],
                  'lightcyan' =>        [0xe0, 0xff, 0xff],
                  'lightgoldenrodyellow' =>     [0xfa, 0xfa, 0xd2],
                  'lightgray' =>        [0xd3, 0xd3, 0xd3],
                  'lightgreen' =>       [0x90, 0xee, 0x90],
                  'lightgrey' =>        [0xd3, 0xd3, 0xd3],
                  'lightpink' =>        [0xff, 0xb6, 0xc1],
                  'lightsalmon' =>      [0xff, 0xa0, 0x7a],
                  'lightseagreen' =>    [0x20, 0xb2, 0xaa],
                  'lightskyblue' =>     [0x87, 0xce, 0xfa],
                  'lightslategray' =>   [0x77, 0x88, 0x99],
                  'lightslategrey' =>   [0x77, 0x88, 0x99],
                  'lightsteelblue' =>   [0xb0, 0xc4, 0xde],
                  'lightyellow' =>      [0xff, 0xff, 0xe0],
                  'lime' =>     [0x00, 0xff, 0x00],
                  'limegreen' =>        [0x32, 0xcd, 0x32],
                  'linen' =>    [0xfa, 0xf0, 0xe6],
                  'magenta' =>  [0xff, 0x00, 0xff],
                  'maroon' =>   [0x80, 0x00, 0x00],
                  'mediumaquamarine' => [0x66, 0xcd, 0xaa],
                  'mediumblue' =>       [0x00, 0x00, 0xcd],
                  'mediumorchid' =>     [0xba, 0x55, 0xd3],
                  'mediumpurple' =>     [0x93, 0x70, 0xdb],
                  'mediumseagreen' =>   [0x3c, 0xb3, 0x71],
                  'mediumslateblue' =>  [0x7b, 0x68, 0xee],
                  'mediumspringgreen' =>        [0x00, 0xfa, 0x9a],
                  'mediumturquoise' =>  [0x48, 0xd1, 0xcc],
                  'mediumvioletred' =>  [0xc7, 0x15, 0x85],
                  'midnightblue' =>     [0x19, 0x19, 0x70],
                  'mintcream' =>        [0xf5, 0xff, 0xfa],
                  'mistyrose' =>        [0xff, 0xe4, 0xe1],
                  'moccasin' => [0xff, 0xe4, 0xb5],
                  'navajowhite' =>      [0xff, 0xde, 0xad],
                  'navy' =>     [0x00, 0x00, 0x80],
                  'oldlace' =>  [0xfd, 0xf5, 0xe6],
                  'olive' =>    [0x80, 0x80, 0x00],
                  'olivedrab' =>        [0x6b, 0x8e, 0x23],
                  'orange' =>   [0xff, 0xa5, 0x00],
                  'orangered' =>        [0xff, 0x45, 0x00],
                  'orchid' =>   [0xda, 0x70, 0xd6],
                  'palegoldenrod' =>    [0xee, 0xe8, 0xaa],
                  'palegreen' =>        [0x98, 0xfb, 0x98],
                  'paleturquoise' =>    [0xaf, 0xee, 0xee],
                  'palevioletred' =>    [0xdb, 0x70, 0x93],
                  'papayawhip' =>       [0xff, 0xef, 0xd5],
                  'peachpuff' =>        [0xff, 0xda, 0xb9],
                  'peru' =>     [0xcd, 0x85, 0x3f],
                  'pink' =>     [0xff, 0xc0, 0xcb],
                  'plum' =>     [0xdd, 0xa0, 0xdd],
                  'powderblue' =>       [0xb0, 0xe0, 0xe6],
                  'purple' =>   [0x80, 0x00, 0x80],
                  'red' =>      [0xff, 0x00, 0x00],
                  'rosybrown' =>        [0xbc, 0x8f, 0x8f],
                  'royalblue' =>        [0x41, 0x69, 0xe1],
                  'saddlebrown' =>      [0x8b, 0x45, 0x13],
                  'salmon' =>   [0xfa, 0x80, 0x72],
                  'sandybrown' =>       [0xf4, 0xa4, 0x60],
                  'seagreen' => [0x2e, 0x8b, 0x57],
                  'seashell' => [0xff, 0xf5, 0xee],
                  'sienna' =>   [0xa0, 0x52, 0x2d],
                  'silver' =>   [0xc0, 0xc0, 0xc0],
                  'skyblue' =>  [0x87, 0xce, 0xeb],
                  'slateblue' =>        [0x6a, 0x5a, 0xcd],
                  'slategray' =>        [0x70, 0x80, 0x90],
                  'slategrey' =>        [0x70, 0x80, 0x90],
                  'snow' =>     [0xff, 0xfa, 0xfa],
                  'springgreen' =>      [0x00, 0xff, 0x7f],
                  'steelblue' =>        [0x46, 0x82, 0xb4],
                  'tan' =>      [0xd2, 0xb4, 0x8c],
                  'teal' =>     [0x00, 0x80, 0x80],
                  'thistle' =>  [0xd8, 0xbf, 0xd8],
                  'tomato' =>   [0xff, 0x63, 0x47],
                  'turquoise' =>        [0x40, 0xe0, 0xd0],
                  'violet' =>   [0xee, 0x82, 0xee],
                  'wheat' =>    [0xf5, 0xde, 0xb3],
                  'white' =>    [0xff, 0xff, 0xff],
                  'whitesmoke' =>       [0xf5, 0xf5, 0xf5],
                  'yellow' =>   [0xff, 0xff, 0x00],
                  'yellowgreen' =>      [0x9a, 0xcd, 0x32],
}; # $x11_colors

my $system_colors = {
  activeborder => 1, activecaption => 1, appworkspace => 1, background => 1,
  buttonface => 1, buttonhighlight => 1, buttonshadow => 1, buttontext => 1,
  captiontext => 1, graytext => 1, highlight => 1, highlighttext => 1,
  inactiveborder => 1, inactivecaption => 1, inactivecaptiontext => 1,
  infobackground => 1, infotext => 1, menu => 1, menutext => 1, 
  scrollbar => 1, threeddarkshadow => 1, threedface => 1, threedhighlight => 1,
  threedlightshadow => 1, threedshadow => 1, window => 1, windowframe => 1,
  windowtext => 1,
}; # $system_colors

my $parse_color = sub {
  my ($self, $prop_name, $tt, $t, $onerror) = @_;

  ## See
  ## <http://suika.fam.cx/gate/2005/sw/%3Ccolor%3E>,
  ## <http://suika.fam.cx/gate/2005/sw/rgb>,
  ## <http://suika.fam.cx/gate/2005/sw/-moz-rgba>,
  ## <http://suika.fam.cx/gate/2005/sw/hsl>,
  ## <http://suika.fam.cx/gate/2005/sw/-moz-hsla>, and
  ## <http://suika.fam.cx/gate/2005/sw/color>
  ## for browser compatibility issue.

  ## NOTE: Implementing CSS3 Color CR (2003), except for attr(),
  ## rgba(), and hsla().
  ## NOTE: rgb(...{EOF} is not supported (only Opera does).

  if ($t->{type} == IDENT_TOKEN) {
    my $value = lc $t->{value}; ## TODO: case
    if ($x11_colors->{$value} or
        $system_colors->{$value}) {
      ## NOTE: "For systems that do not have a corresponding value, the
      ## specified value should be mapped to the nearest system value, or to
      ## a default color." [CSS 2.1].
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['KEYWORD', $value]});
    } elsif ({
      transparent => 1, ## For 'background-color' in CSS2.1, everywhre in CSS3.
      flavor => 1, ## CSS3.
      invert => 1, ## For 'outline-color' in CSS2.1.
      '-moz-use-text-color' => 1, ## For <border-color> in Gecko.
      '-manakai-default' => 1, ## CSS2.1 initial for 'color'
      '-manakai-invert-or-currentcolor' => 1, ## CSS2.1 initial4'outline-color'
    }->{$value} and $self->{prop_value}->{$prop_name}->{$value}) {
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['KEYWORD', $value]});
    } elsif ($value eq 'currentcolor' or $value eq '-moz-use-text-color') {
      $t = $tt->get_next_token;
      if ($prop_name eq 'color') {
        return ($t, {$prop_name => ['INHERIT']});
      } else {
        return ($t, {$prop_name => ['KEYWORD', $value]});
      }
    } elsif ($value eq 'inherit') {
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['INHERIT']});
    }
  }

  if ($t->{type} == HASH_TOKEN or
      ($self->{hashless_rgb} and {
        IDENT_TOKEN, 1,
        NUMBER_TOKEN, 1,
        DIMENSION_TOKEN, 1,
      }->{$t->{type}})) {
    my $v = lc (defined $t->{number} ? $t->{number} : '' . $t->{value}); ## TODO: case
    if ($v =~ /\A([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})\z/) {
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['RGBA', hex $1, hex $2, hex $3, 1]});
    } elsif ($v =~ /\A([0-9a-f])([0-9a-f])([0-9a-f])\z/) {
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['RGBA', hex $1.$1, hex $2.$2,
                                  hex $3.$3, 1]});
    }
  }

  if ($t->{type} == FUNCTION_TOKEN) {
    my $func = lc $t->{value}; ## TODO: case
    if ($func eq 'rgb') {
      $t = $tt->get_next_token;
      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      my $sign = 1;
      if ($t->{type} == MINUS_TOKEN) {
        $sign = -1;
        $t = $tt->get_next_token;
      }
      if ($t->{type} == NUMBER_TOKEN) {
        my $r = $t->{number} * $sign;
        $t = $tt->get_next_token;
        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
        if ($t->{type} == COMMA_TOKEN) {
          $t = $tt->get_next_token;
          $t = $tt->get_next_token while $t->{type} == S_TOKEN;
          $sign = 1;
          if ($t->{type} == MINUS_TOKEN) {
            $sign = -1;
            $t = $tt->get_next_token;
          } 
          if ($t->{type} == NUMBER_TOKEN) {
            my $g = $t->{number} * $sign;
            $t = $tt->get_next_token;
            $t = $tt->get_next_token while $t->{type} == S_TOKEN;
            if ($t->{type} == COMMA_TOKEN) {
              $t = $tt->get_next_token;
              $t = $tt->get_next_token while $t->{type} == S_TOKEN;
              $sign = 1;
              if ($t->{type} == MINUS_TOKEN) {
                $sign = -1;
                $t = $tt->get_next_token;
              } 
              if ($t->{type} == NUMBER_TOKEN) {
                my $b = $t->{number} * $sign;
                $t = $tt->get_next_token;
                $t = $tt->get_next_token while $t->{type} == S_TOKEN;
                if ($t->{type} == RPAREN_TOKEN) {
                  $t = $tt->get_next_token;
                  return ($t,
                          {$prop_name =>
                           $self->{clip_color}->($self,
                                                 ['RGBA', $r, $g, $b, 1])});
                }
              }
            }
          }
        }
      } elsif ($t->{type} == PERCENTAGE_TOKEN) {
        my $r = $t->{number} * 255 / 100 * $sign;
        $t = $tt->get_next_token;
        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
        if ($t->{type} == COMMA_TOKEN) {
          $t = $tt->get_next_token;
          $t = $tt->get_next_token while $t->{type} == S_TOKEN;
          $sign = 1;
          if ($t->{type} == MINUS_TOKEN) {
            $sign = -1;
            $t = $tt->get_next_token;
          }           
          if ($t->{type} == PERCENTAGE_TOKEN) {
            my $g = $t->{number} * 255 / 100 * $sign;
            $t = $tt->get_next_token;
            $t = $tt->get_next_token while $t->{type} == S_TOKEN;
            if ($t->{type} == COMMA_TOKEN) {
              $t = $tt->get_next_token;
              $t = $tt->get_next_token while $t->{type} == S_TOKEN;
              $sign = 1;
              if ($t->{type} == MINUS_TOKEN) {
                $sign = -1;
                $t = $tt->get_next_token;
              } 
              if ($t->{type} == PERCENTAGE_TOKEN) {
                my $b = $t->{number} * 255 / 100 * $sign;
                $t = $tt->get_next_token;
                $t = $tt->get_next_token while $t->{type} == S_TOKEN;
                if ($t->{type} == RPAREN_TOKEN) {
                  $t = $tt->get_next_token;
                  return ($t,
                          {$prop_name =>
                           $self->{clip_color}->($self,
                                                 ['RGBA', $r, $g, $b, 1])});
                }
              }
            }
          }
        }
      }
    } elsif ($func eq 'hsl') {
      $t = $tt->get_next_token;
      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      my $sign = 1;
      if ($t->{type} == MINUS_TOKEN) {
        $sign = -1;
        $t = $tt->get_next_token;
      }
      if ($t->{type} == NUMBER_TOKEN) {
        my $h = (((($t->{number} * $sign) % 360) + 360) % 360) / 360;
        $t = $tt->get_next_token;
        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
        if ($t->{type} == COMMA_TOKEN) {
          $t = $tt->get_next_token;
          $t = $tt->get_next_token while $t->{type} == S_TOKEN;
          $sign = 1;
          if ($t->{type} == MINUS_TOKEN) {
            $sign = -1;
            $t = $tt->get_next_token;
          } 
          if ($t->{type} == PERCENTAGE_TOKEN) {
            my $s = $t->{number} * $sign / 100;
            $s = 0 if $s < 0;
            $s = 1 if $s > 1;
            $t = $tt->get_next_token;
            $t = $tt->get_next_token while $t->{type} == S_TOKEN;
            if ($t->{type} == COMMA_TOKEN) {
              $t = $tt->get_next_token;
              $t = $tt->get_next_token while $t->{type} == S_TOKEN;
              $sign = 1;
              if ($t->{type} == MINUS_TOKEN) {
                $sign = -1;
                $t = $tt->get_next_token;
              } 
              if ($t->{type} == PERCENTAGE_TOKEN) {
                my $l = $t->{number} * $sign / 100;
                $l = 0 if $l < 0;
                $l = 1 if $l > 1;
                $t = $tt->get_next_token;
                $t = $tt->get_next_token while $t->{type} == S_TOKEN;
                if ($t->{type} == RPAREN_TOKEN) {
                  my $m2 = $l <= 0.5 ? $l * ($s + 1) : $l + $s - $l * $s;
                  my $m1 = $l * 2 - $m2;
                  my $hue2rgb = sub ($$$) {
                    my ($m1, $m2, $h) = @_;
                    $h++ if $h < 0;
                    $h-- if $h > 1;
                    return $m1 + ($m2 - $m1) * $h * 6 if $h * 6 < 1;
                    return $m2 if $h * 2 < 1;
                    return $m1 + ($m2 - $m1) * (2/3 - $h) * 6 if $h * 3 < 2;
                    return $m1;
                  };
                  $t = $tt->get_next_token;
                  return ($t,
                          {$prop_name =>
                           $self->{clip_color}
                               ->($self,
                                  ['RGBA',
                                   $hue2rgb->($m1, $m2, $h + 1/3),
                                   $hue2rgb->($m1, $m2, $h),
                                   $hue2rgb->($m1, $m2, $h - 1/3), 1])});
                }
              }
            }
          }
        }
      }
    }
  }
  
  $onerror->(type => 'syntax error:'.$prop_name,
             level => $self->{must_level},
             token => $t);
  
  return ($t, undef);
}; # $parse_color

$Prop->{color} = {
  css => 'color',
  dom => 'color',
  key => 'color',
  parse => $parse_color,
  serialize => $default_serializer,
  initial => ['KEYWORD', '-manakai-default'],
  inherited => 1,
  compute => sub ($$$$) {
    my ($self, $element, $prop_name, $specified_value) = @_;

    if (defined $specified_value) {
      if ($specified_value->[0] eq 'KEYWORD') {
        if ($x11_colors->{$specified_value->[1]}) {
          return ['RGBA', @{$x11_colors->{$specified_value->[1]}}, 1];
        } elsif ($specified_value->[1] eq 'transparent') {
          return ['RGBA', 0, 0, 0, 0];
        } elsif ($specified_value->[1] eq 'currentcolor' or
                 $specified_value->[1] eq '-moz-use-text-color' or
                 ($specified_value->[1] eq '-manakai-invert-or-currentcolor'and
                  not $self->{has_invert})) {
          unless ($prop_name eq 'color') {
            return $self->get_computed_value ($element, 'color');
          } else {
            ## NOTE: This is an error, since it should have been
            ## converted to 'inherit' at parse time.
            return ['KEYWORD', '-manakai-default'];
          }
        } elsif ($specified_value->[1] eq '-manakai-invert-or-currentcolor') {
          return ['KEYWORD', 'invert'];
        }
      }
    }
    
    return $specified_value;
  },
};
$Attr->{color} = $Prop->{color};
$Key->{color} = $Prop->{color};

$Prop->{'background-color'} = {
  css => 'background-color',
  dom => 'background_color',
  key => 'background_color',
  parse => $parse_color,
  serialize => $default_serializer,
  serialize_multiple => sub {
    my $self = shift;

    ## TODO: !important handling is incorrect.

    my $r = {};
    my $has_all;
    
    local $Error::Depth = $Error::Depth + 1;
    my $x = $self->background_position_x;
    my $y = $self->background_position_y;
    my $xi = $self->get_property_priority ('background-position-x');
    my $yi = $self->get_property_priority ('background-position-y');
    $xi = ' !' . $xi if length $xi;
    $yi = ' !' . $yi if length $yi;
    if (length $x) {
      if (length $y) {
        if ($xi eq $yi) {
          $r->{'background-position'} = $x . ' ' . $y . $xi;
          $has_all = 1;
        } else {
          $r->{'background-position-x'} = $x . $xi;
          $r->{'background-position-y'} = $y . $yi;
        }
      } else {
        $r->{'background-position-x'} = $x . $xi;
      }
    } else {
      if (length $y) {
        $r->{'background-position-y'} = $y . $yi;
      } else {
        #
      }
    }
    
    for my $prop (qw/color image repeat attachment/) {
      my $prop_name = 'background_'.$prop;
      my $value = $self->$prop_name;
      if (length $value) {
        $r->{'background-'.$prop} = $value;
        my $i = $self->get_property_priority ('background-'.$prop);
        $r->{'background-'.$prop} .= ' !'.$i if length $i;
      } else {
        undef $has_all;
      }
    }

    if ($has_all) {
      my @v;
      push @v, $r->{'background-color'}
          unless $r->{'background-color'} eq 'transparent';
      push @v, $r->{'background-image'}
          unless $r->{'background-image'} eq 'none';
      push @v, $r->{'background-repeat'}
          unless $r->{'background-repeat'} eq 'repeat';
      push @v, $r->{'background-attachment'}
          unless $r->{'background-attachment'} eq 'scroll';
      push @v, $r->{'background-position'}
          unless $r->{'background-position'} eq '0% 0%';
      if (@v) {
        return {background => join ' ', @v};
      } else {
        return {background => 'transparent none repeat scroll 0% 0%'};
      }
    } else {
      return $r;
    }
  },
  initial => ['KEYWORD', 'transparent'],
  #inherited => 0,
  compute => $Prop->{color}->{compute},
};
$Attr->{background_color} = $Prop->{'background-color'};
$Key->{background_color} = $Prop->{'background-color'};

$Prop->{'border-top-color'} = {
  css => 'border-top-color',
  dom => 'border_top_color',
  key => 'border_top_color',
  parse => $parse_color,
  serialize => $default_serializer,
  serialize_multiple => sub {
    my $self = shift;
    ## NOTE: This algorithm returns the same result as that of Firefox 2
    ## in many case, but not always.
    my $r = {
      'border-top-color' => $self->border_top_color,
      'border-top-style' => $self->border_top_style,
      'border-top-width' => $self->border_top_width,
      'border-right-color' => $self->border_right_color,
      'border-right-style' => $self->border_right_style,
      'border-right-width' => $self->border_right_width,
      'border-bottom-color' => $self->border_bottom_color,
      'border-bottom-style' => $self->border_bottom_style,
      'border-bottom-width' => $self->border_bottom_width,
      'border-left-color' => $self->border_left_color,
      'border-left-style' => $self->border_left_style,
      'border-left-width' => $self->border_left_width,
    };
    my $i = 0;
    for my $prop (qw/border-top border-right border-bottom border-left/) {
      if (defined $r->{$prop.'-color'} and
          defined $r->{$prop.'-style'} and
          defined $r->{$prop.'-width'}) {
        $r->{$prop} = $r->{$prop.'-width'} . ' ' .
              $r->{$prop.'-style'} . ' ' .
              $r->{$prop.'-color'};
        delete $r->{$prop.'-width'};
        delete $r->{$prop.'-style'};
        delete $r->{$prop.'-color'};
        $i++;
      }
    }
    if ($i == 4 and $r->{'border-top'} eq $r->{'border-right'} and
        $r->{'border-right'} eq $r->{'border-bottom'} and
        $r->{'border-bottom'} eq $r->{'border-left'}) {
      return {border => $r->{'border-top'}};
    }

    unless ($i) {
      for my $prop (qw/color style width/) {
        if (defined $r->{'border-top-'.$prop} and
            defined $r->{'border-bottom-'.$prop} and
            defined $r->{'border-right-'.$prop} and
            defined $r->{'border-left-'.$prop}) {
          my @v = ($r->{'border-top-'.$prop},
                   $r->{'border-right-'.$prop},
                   $r->{'border-bottom-'.$prop},
                   $r->{'border-left-'.$prop});
          pop @v if $r->{'border-right-'.$prop} eq $r->{'border-left-'.$prop};
          pop @v if $r->{'border-bottom-'.$prop} eq $r->{'border-top-'.$prop};
          pop @v if $r->{'border-right-'.$prop} eq $r->{'border-top-'.$prop};
          $r->{'border-'.$prop} = join ' ', @v;
          delete $r->{'border-top-'.$prop};
          delete $r->{'border-bottom-'.$prop};
          delete $r->{'border-right-'.$prop};
          delete $r->{'border-left-'.$prop};
        }
      }
    }

    delete $r->{$_} for grep {not defined $r->{$_}} keys %$r;
    return $r;
  },
  initial => ['KEYWORD', 'currentcolor'],
  #inherited => 0,
  compute => $Prop->{color}->{compute},
};
$Attr->{border_top_color} = $Prop->{'border-top-color'};
$Key->{border_top_color} = $Prop->{'border-top-color'};

$Prop->{'border-right-color'} = {
  css => 'border-right-color',
  dom => 'border_right_color',
  key => 'border_right_color',
  parse => $parse_color,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  initial => ['KEYWORD', 'currentcolor'],
  #inherited => 0,
  compute => $Prop->{color}->{compute},
};
$Attr->{border_right_color} = $Prop->{'border-right-color'};
$Key->{border_right_color} = $Prop->{'border-right-color'};

$Prop->{'border-bottom-color'} = {
  css => 'border-bottom-color',
  dom => 'border_bottom_color',
  key => 'border_bottom_color',
  parse => $parse_color,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  initial => ['KEYWORD', 'currentcolor'],
  #inherited => 0,
  compute => $Prop->{color}->{compute},
};
$Attr->{border_bottom_color} = $Prop->{'border-bottom-color'};
$Key->{border_bottom_color} = $Prop->{'border-bottom-color'};

$Prop->{'border-left-color'} = {
  css => 'border-left-color',
  dom => 'border_left_color',
  key => 'border_left_color',
  parse => $parse_color,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  initial => ['KEYWORD', 'currentcolor'],
  #inherited => 0,
  compute => $Prop->{color}->{compute},
};
$Attr->{border_left_color} = $Prop->{'border-left-color'};
$Key->{border_left_color} = $Prop->{'border-left-color'};

$Prop->{'outline-color'} = {
  css => 'outline-color',
  dom => 'outline_color',
  key => 'outline_color',
  parse => $parse_color,
  serialize => $default_serializer,
  serialize_multiple => sub {
    my $self = shift;
    my $oc = $self->outline_color;
    my $os = $self->outline_style;
    my $ow = $self->outline_width;
    my $r = {};
    if (length $oc and length $os and length $ow) {
      $r->{outline} = $ow . ' ' . $os . ' ' . $oc;
    } else {
      $r->{'outline-color'} = $oc if length $oc;
      $r->{'outline-style'} = $os if length $os;
      $r->{'outline-width'} = $ow if length $ow;
    }
    return $r;
  },
  initial => ['KEYWORD', '-manakai-invert-or-currentcolor'],
  #inherited => 0,
  compute => $Prop->{color}->{compute},
};
$Attr->{outline_color} = $Prop->{'outline-color'};
$Key->{outline_color} = $Prop->{'outline-color'};

my $one_keyword_parser = sub {
  my ($self, $prop_name, $tt, $t, $onerror) = @_;

  if ($t->{type} == IDENT_TOKEN) {
    my $prop_value = lc $t->{value}; ## TODO: case folding
    $t = $tt->get_next_token;
    if ($Prop->{$prop_name}->{keyword}->{$prop_value} and
        $self->{prop_value}->{$prop_name}->{$prop_value}) {
      return ($t, {$prop_name => ["KEYWORD", $prop_value]});
    } elsif ($prop_value eq 'inherit') {
      return ($t, {$prop_name => ['INHERIT']});
    }
  }
  
  $onerror->(type => 'syntax error:keyword:'.$prop_name,
             level => $self->{must_level},
             token => $t);
  return ($t, undef);
};

$Prop->{display} = {
  css => 'display',
  dom => 'display',
  key => 'display',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    block => 1, inline => 1, 'inline-block' => 1, 'inline-table' => 1,
    'list-item' => 1, none => 1,
    table => 1, 'table-caption' => 1, 'table-cell' => 1, 'table-column' => 1,
    'table-column-group' => 1, 'table-header-group' => 1,
    'table-footer-group' => 1, 'table-row' => 1, 'table-row-group' => 1,
  },
  initial => ["KEYWORD", "inline"],
  #inherited => 0,
  compute => sub {
    my ($self, $element, $prop_name, $specified_value) = @_;
    ## NOTE: CSS 2.1 Section 9.7.

    ## WARNING: |compute| for 'float' property invoke this CODE
    ## in some case.  Careless modification might cause a infinite loop.

    if (defined $specified_value and $specified_value->[0] eq 'KEYWORD') {
      if ($specified_value->[1] eq 'none') {
        ## Case 1 [CSS 2.1]
        return $specified_value;
      } else {
        my $position = $self->get_computed_value ($element, 'position');
        if ($position->[0] eq 'KEYWORD' and 
            ($position->[1] eq 'absolute' or 
             $position->[1] eq 'fixed')) {
          ## Case 2 [CSS 2.1]
          #
        } else {
          my $float = $self->get_computed_value ($element, 'float');
          if ($float->[0] eq 'KEYWORD' and $float->[1] ne 'none') {
            ## Caes 3 [CSS 2.1]
            #
          } elsif (not defined $element->manakai_parent_element) {
            ## Case 4 [CSS 2.1]
            #
          } else {
            ## Case 5 [CSS 2.1]
            return $specified_value;
          }
        }
        
        return ["KEYWORD",
                {
                 'inline-table' => 'table',
                 inline => 'block',
                 'run-in' => 'block',
                 'table-row-group' => 'block',
                 'table-column' => 'block',
                 'table-column-group' => 'block',
                 'table-header-group' => 'block',
                 'table-footer-group' => 'block',
                 'table-row' => 'block',
                 'table-cell' => 'block',
                 'table-caption' => 'block',
                 'inline-block' => 'block',
                }->{$specified_value->[1]} || $specified_value->[1]];
      }
    } else {
      return $specified_value; ## Maybe an error of the implementation.
    }
  },
};
$Attr->{display} = $Prop->{display};
$Key->{display} = $Prop->{display};

$Prop->{position} = {
  css => 'position',
  dom => 'position',
  key => 'position',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    static => 1, relative => 1, absolute => 1, fixed => 1,
  },
  initial => ["KEYWORD", "static"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{position} = $Prop->{position};
$Key->{position} = $Prop->{position};

$Prop->{float} = {
  css => 'float',
  dom => 'css_float',
  key => 'float',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    left => 1, right => 1, none => 1,
  },
  initial => ["KEYWORD", "none"],
  #inherited => 0,
  compute => sub {
    my ($self, $element, $prop_name, $specified_value) = @_;
    ## NOTE: CSS 2.1 Section 9.7.

    ## WARNING: |compute| for 'display' property invoke this CODE
    ## in some case.  Careless modification might cause a infinite loop.
    
    if (defined $specified_value and $specified_value->[0] eq 'KEYWORD') {
      if ($specified_value->[1] eq 'none') {
        ## Case 1 [CSS 2.1]
        return $specified_value;
      } else {
        my $position = $self->get_computed_value ($element, 'position');
        if ($position->[0] eq 'KEYWORD' and 
            ($position->[1] eq 'absolute' or 
             $position->[1] eq 'fixed')) {
          ## Case 2 [CSS 2.1]
          return ["KEYWORD", "none"];
        }
      }
    }

    ## ISSUE: CSS 2.1 section 9.7 and 9.5.1 ('float' definition) disagree
    ## on computed value of 'float' property.
    
    ## Case 3, 4, and 5 [CSS 2.1]
    return $specified_value;
  },
};
$Attr->{css_float} = $Prop->{float};
$Attr->{style_float} = $Prop->{float}; ## NOTE: IEism
$Key->{float} = $Prop->{float};

$Prop->{clear} = {
  css => 'clear',
  dom => 'clear',
  key => 'clear',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    left => 1, right => 1, none => 1, both => 1,
  },
  initial => ["KEYWORD", "none"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{clear} = $Prop->{clear};
$Key->{clear} = $Prop->{clear};

$Prop->{direction} = {
  css => 'direction',
  dom => 'direction',
  key => 'direction',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    ltr => 1, rtl => 1,
  },
  initial => ["KEYWORD", "ltr"],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{direction} = $Prop->{direction};
$Key->{direction} = $Prop->{direction};

$Prop->{'unicode-bidi'} = {
  css => 'unicode-bidi',
  dom => 'unicode_bidi',
  key => 'unicode_bidi',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    normal => 1, embed => 1, 'bidi-override' => 1,
  },
  initial => ["KEYWORD", "normal"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{unicode_bidi} = $Prop->{'unicode-bidi'};
$Key->{unicode_bidi} = $Prop->{'unicode-bidi'};

$Prop->{overflow} = {
  css => 'overflow',
  dom => 'overflow',
  key => 'overflow',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    visible => 1, hidden => 1, scroll => 1, auto => 1,
  },
  initial => ["KEYWORD", "visible"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{overflow} = $Prop->{overflow};
$Key->{overflow} = $Prop->{overflow};

$Prop->{visibility} = {
  css => 'visibility',
  dom => 'visibility',
  key => 'visibility',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    visible => 1, hidden => 1, collapse => 1,
  },
  initial => ["KEYWORD", "visible"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{visibility} = $Prop->{visibility};
$Key->{visibility} = $Prop->{visibility};

$Prop->{'list-style-type'} = {
  css => 'list-style-type',
  dom => 'list_style_type',
  key => 'list_style_type',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    qw/
      disc 1 circle 1 square 1 decimal 1 decimal-leading-zero 1 
      lower-roman 1 upper-roman 1 lower-greek 1 lower-latin 1
      upper-latin 1 armenian 1 georgian 1 lower-alpha 1 upper-alpha 1
      none 1
    /,
  },
  initial => ["KEYWORD", 'disc'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{list_style_type} = $Prop->{'list-style-type'};
$Key->{list_style_type} = $Prop->{'list-style-type'};

$Prop->{'list-style-position'} = {
  css => 'list-style-position',
  dom => 'list_style_position',
  key => 'list_style_position',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    inside => 1, outside => 1,
  },
  initial => ["KEYWORD", 'outside'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{list_style_position} = $Prop->{'list-style-position'};
$Key->{list_style_position} = $Prop->{'list-style-position'};

$Prop->{'page-break-before'} = {
  css => 'page-break-before',
  dom => 'page_break_before',
  key => 'page_break_before',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    auto => 1, always => 1, avoid => 1, left => 1, right => 1,
  },
  initial => ["KEYWORD", 'auto'],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{page_break_before} = $Prop->{'page-break-before'};
$Key->{page_break_before} = $Prop->{'page-break-before'};

$Prop->{'page-break-after'} = {
  css => 'page-break-after',
  dom => 'page_break_after',
  key => 'page_break_after',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    auto => 1, always => 1, avoid => 1, left => 1, right => 1,
  },
  initial => ["KEYWORD", 'auto'],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{page_break_after} = $Prop->{'page-break-after'};
$Key->{page_break_after} = $Prop->{'page-break-after'};

$Prop->{'page-break-inside'} = {
  css => 'page-break-inside',
  dom => 'page_break_inside',
  key => 'page_break_inside',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    auto => 1, avoid => 1,
  },
  initial => ["KEYWORD", 'auto'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{page_break_inside} = $Prop->{'page-break-inside'};
$Key->{page_break_inside} = $Prop->{'page-break-inside'};

$Prop->{'background-repeat'} = {
  css => 'background-repeat',
  dom => 'background_repeat',
  key => 'background_repeat',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'background-color'}->{serialize_multiple},
  keyword => {
    repeat => 1, 'repeat-x' => 1, 'repeat-y' => 1, 'no-repeat' => 1,
  },
  initial => ["KEYWORD", 'repeat'],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{background_repeat} = $Prop->{'background-repeat'};
$Key->{backgroud_repeat} = $Prop->{'background-repeat'};

$Prop->{'background-attachment'} = {
  css => 'background-attachment',
  dom => 'background_attachment',
  key => 'background_attachment',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'background-color'}->{serialize_multiple},
  keyword => {
    scroll => 1, fixed => 1,
  },
  initial => ["KEYWORD", 'scroll'],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{background_attachment} = $Prop->{'background-attachment'};
$Key->{backgroud_attachment} = $Prop->{'background-attachment'};

$Prop->{'font-style'} = {
  css => 'font-style',
  dom => 'font_style',
  key => 'font_style',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    normal => 1, italic => 1, oblique => 1,
  },
  initial => ["KEYWORD", 'normal'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{font_style} = $Prop->{'font-style'};
$Key->{font_style} = $Prop->{'font-style'};

$Prop->{'font-variant'} = {
  css => 'font-variant',
  dom => 'font_variant',
  key => 'font_variant',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    normal => 1, 'small-caps' => 1,
  },
  initial => ["KEYWORD", 'normal'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{font_variant} = $Prop->{'font-variant'};
$Key->{font_variant} = $Prop->{'font-variant'};

$Prop->{'text-align'} = {
  css => 'text-align',
  dom => 'text_align',
  key => 'text_align',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    left => 1, right => 1, center => 1, justify => 1, ## CSS 2
    begin => 1, end => 1, ## CSS 3
  },
  initial => ["KEYWORD", 'begin'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{text_align} = $Prop->{'text-align'};
$Key->{text_align} = $Prop->{'text-align'};

$Prop->{'text-transform'} = {
  css => 'text-transform',
  dom => 'text_transform',
  key => 'text_transform',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    capitalize => 1, uppercase => 1, lowercase => 1, none => 1,
  },
  initial => ["KEYWORD", 'none'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{text_transform} = $Prop->{'text-transform'};
$Key->{text_transform} = $Prop->{'text-transform'};

$Prop->{'white-space'} = {
  css => 'white-space',
  dom => 'white_space',
  key => 'white_space',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    normal => 1, pre => 1, nowrap => 1, 'pre-wrap' => 1, 'pre-line' => 1,
  },
  initial => ["KEYWORD", 'normal'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{white_space} = $Prop->{'white-space'};
$Key->{white_space} = $Prop->{'white-space'};

$Prop->{'caption-side'} = {
  css => 'caption-side',
  dom => 'caption_side',
  key => 'caption_side',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    top => 1, bottom => 1,
  },
  initial => ['KEYWORD', 'top'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{caption_side} = $Prop->{'caption-side'};
$Key->{caption_side} = $Prop->{'caption-side'};

$Prop->{'table-layout'} = {
  css => 'table-layout',
  dom => 'table_layout',
  key => 'table_layout',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    auto => 1, fixed => 1,
  },
  initial => ['KEYWORD', 'auto'],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{table_layout} = $Prop->{'table-layout'};
$Key->{table_layout} = $Prop->{'table-layout'};

$Prop->{'border-collapse'} = {
  css => 'border-collapse',
  dom => 'border_collapse',
  key => 'border_collapse',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    collapse => 1, separate => 1,
  },
  initial => ['KEYWORD', 'separate'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{border_collapse} = $Prop->{'border-collapse'};
$Key->{border_collapse} = $Prop->{'border-collapse'};

$Prop->{'empty-cells'} = {
  css => 'empty-cells',
  dom => 'empty_cells',
  key => 'empty_cells',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  keyword => {
    show => 1, hide => 1,
  },
  initial => ['KEYWORD', 'show'],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{empty_cells} = $Prop->{'empty-cells'};
$Key->{empty_cells} = $Prop->{'empty-cells'};

$Prop->{'z-index'} = {
  css => 'z-index',
  dom => 'z_index',
  key => 'z_index',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $sign = -1;
      $t = $tt->get_next_token;
    }

    if ($t->{type} == NUMBER_TOKEN) {
      ## ISSUE: See <http://suika.fam.cx/gate/2005/sw/z-index> for
      ## browser compatibility issue.
      my $value = $t->{number};
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ["NUMBER", $sign * int ($value / 1)]});
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($value eq 'auto') {
        ## NOTE: |z-index| is the default value and therefore it must be
        ## supported anyway.
        return ($t, {$prop_name => ["KEYWORD", 'auto']});
      } elsif ($value eq 'inherit') {
        return ($t, {$prop_name => ['INHERIT']});
      }
    }
    
    $onerror->(type => 'syntax error:'.$prop_name,
               level => $self->{must_level},
               token => $t);
    return ($t, undef);
  },
  serialize => $default_serializer,
  initial => ['KEYWORD', 'auto'],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{z_index} = $Prop->{'z-index'};
$Key->{z_index} = $Prop->{'z-index'};

$Prop->{orphans} = {
  css => 'orphans',
  dom => 'orphans',
  key => 'orphans',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == NUMBER_TOKEN) {
      ## ISSUE: See <http://suika.fam.cx/gate/2005/sw/orphans> and
      ## <http://suika.fam.cx/gate/2005/sw/widows> for
      ## browser compatibility issue.
      my $value = $t->{number};
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ["NUMBER", $sign * int ($value / 1)]});
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($value eq 'inherit') {
        return ($t, {$prop_name => ['INHERIT']});
      }
    }
    
    $onerror->(type => 'syntax error:'.$prop_name,
               level => $self->{must_level},
               token => $t);
    return ($t, undef);
  },
  serialize => $default_serializer,
  initial => ['NUMBER', 2],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{orphans} = $Prop->{orphans};
$Key->{orphans} = $Prop->{orphans};

$Prop->{widows} = {
  css => 'widows',
  dom => 'widows',
  key => 'widows',
  parse => $Prop->{orphans}->{parse},
  serialize => $default_serializer,
  initial => ['NUMBER', 2],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{widows} = $Prop->{widows};
$Key->{widows} = $Prop->{widows};

$Prop->{opacity} = {
  css => 'opacity',
  dom => 'opacity',
  key => 'opacity',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == NUMBER_TOKEN) {
      ## ISSUE: See <http://suika.fam.cx/gate/2005/sw/opacity> for
      ## browser compatibility issue.
      my $value = $t->{number};
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ["NUMBER", $sign * $value]});
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($value eq 'inherit') {
        return ($t, {$prop_name => ['INHERIT']});
      }
    }
    
    $onerror->(type => 'syntax error:'.$prop_name,
               level => $self->{must_level},
               token => $t);
    return ($t, undef);
  },
  serialize => $default_serializer,
  initial => ['NUMBER', 2],
  inherited => 1,
  compute => sub {
    my ($self, $element, $prop_name, $specified_value) = @_;

    if (defined $specified_value) {
      if ($specified_value->[0] eq 'NUMBER') {
        if ($specified_value->[1] < 0) {
          return ['NUMBER', 0];
        } elsif ($specified_value->[1] > 1) {
          return ['NUMBER', 1];
        }
      }
    }

    return $specified_value;
  },
  serialize_multiple => sub {
    ## NOTE: This CODE is necessary to avoid two 'opacity' properties
    ## are outputed in |cssText| (for 'opacity' and for '-moz-opacity').
    return {opacity => shift->opacity},
  },
};
$Attr->{opacity} = $Prop->{opacity};
$Key->{opacity} = $Prop->{opacity};

$Prop->{'-moz-opacity'} = $Prop->{opacity};
$Attr->{MozOpacity} = $Attr->{opacity};

my $length_unit = {
  em => 1, ex => 1, px => 1,
  in => 1, cm => 1, mm => 1, pt => 1, pc => 1,
};

$Prop->{'font-size'} = {
  css => 'font-size',
  dom => 'font_size',
  key => 'font_size',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        return ($t, {$prop_name => ['DIMENSION', $value, $unit]});
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['PERCENTAGE', $value]}) if $value >= 0;
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['DIMENSION', $value, 'px']}) if $value >= 0;
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ({
           'xx-small' => 1, 'x-small' => 1, small => 1, medium => 1,
           large => 1, 'x-large' => 1, 'xx-large' => 1, 
           '-manakai-xxx-large' => 1, # -webkit-xxx-large
           larger => 1, smaller => 1,
          }->{$value}) {
        return ($t, {$prop_name => ['KEYWORD', $value]});        
      } elsif ($value eq 'inherit') {
        return ($t, {$prop_name => ['INHERIT']});
      }
    }
    
    $onerror->(type => 'syntax error:'.$prop_name,
               level => $self->{must_level},
               token => $t);
    return ($t, undef);
  },
  serialize => $default_serializer,
  initial => ['KEYWORD', 'medium'],
  inherited => 1,
  compute => sub {
    my ($self, $element, $prop_name, $specified_value) = @_;
    
    if (defined $specified_value) {
      if ($specified_value->[0] eq 'DIMENSION') {
        my $unit = $specified_value->[2];
        my $value = $specified_value->[1];

        if ($unit eq 'em' or $unit eq 'ex') {
          $value *= 0.5 if $unit eq 'ex';
          ## TODO: Preferred way to determine the |ex| size is defined
          ## in CSS 2.1.

          my $parent_element = $element->manakai_parent_element;
          if (defined $parent_element) {
            $value *= $self->get_computed_value ($parent_element, $prop_name)
                ->[1];
          } else {
            $value *= $self->{font_size}->[3]; # medium
          }
          $unit = 'px';
        } elsif ({in => 1, cm => 1, mm => 1, pt => 1, pc => 1}->{$unit}) {
          ($value *= 12, $unit = 'pc') if $unit eq 'pc';
          ($value /= 72, $unit = 'in') if $unit eq 'pt';
          ($value *= 2.54, $unit = 'cm') if $unit eq 'in';
          ($value *= 10, $unit = 'mm') if $unit eq 'cm';
          ($value /= 0.26, $unit = 'px') if $unit eq 'mm';
        }
        ## else: consistency error

        return ['DIMENSION', $value, $unit];
      } elsif ($specified_value->[0] eq 'PERCENTAGE') {
        my $parent_element = $element->manakai_parent_element;
        my $parent_cv;
        if (defined $parent_element) {
          $parent_cv = $self->get_computed_value
              ($parent_element, $prop_name);
        } else {
          $parent_cv = [undef, $self->{font_size}->[3]];
        }
        return ['DIMENSION', $parent_cv->[1] * $specified_value->[1] / 100,
                'px'];
      } elsif ($specified_value->[0] eq 'KEYWORD') {
        if ($specified_value->[1] eq 'larger') {
          my $parent_element = $element->manakai_parent_element;
          if (defined $parent_element) {
            my $parent_cv = $self->get_computed_value
                ($parent_element, $prop_name);
            return ['DIMENSION',
                    $self->{get_larger_font_size}->($self, $parent_cv->[1]),
                    'px'];
          } else { ## 'larger' relative to 'medium', initial of 'font-size'
            return ['DIMENSION', $self->{font_size}->[4], 'px'];
          }
        } elsif ($specified_value->[1] eq 'smaller') {
          my $parent_element = $element->manakai_parent_element;
          if (defined $parent_element) {
            my $parent_cv = $self->get_computed_value
                ($parent_element, $prop_name);
            return ['DIMENSION',
                    $self->{get_smaller_font_size}->($self, $parent_cv->[1]),
                    'px'];
          } else { ## 'smaller' relative to 'medium', initial of 'font-size'
            return ['DIMENSION', $self->{font_size}->[2], 'px'];
          }
        } else {
          return ['DIMENSION', $self->{font_size}->[{
            'xx-small' => 0,
            'x-small' => 1,
            small => 2,
            medium => 3,
            large => 4,
            'x-large' => 5,
            'xx-large' => 6,
            '-manakai-xxx-large' => 7,
          }->{$specified_value->[1]}], 'px'];
        }
      }
    }
    
    return $specified_value;
  },
};
$Attr->{font_size} = $Prop->{'font-size'};
$Key->{font_size} = $Prop->{'font-size'};

my $compute_length = sub {
  my ($self, $element, $prop_name, $specified_value) = @_;
  
  if (defined $specified_value) {
    if ($specified_value->[0] eq 'DIMENSION') {
      my $unit = $specified_value->[2];
      my $value = $specified_value->[1];

      if ($unit eq 'em' or $unit eq 'ex') {
        $value *= 0.5 if $unit eq 'ex';
        ## TODO: Preferred way to determine the |ex| size is defined
        ## in CSS 2.1.

        $value *= $self->get_computed_value ($element, 'font-size')->[1];
        $unit = 'px';
      } elsif ({in => 1, cm => 1, mm => 1, pt => 1, pc => 1}->{$unit}) {
        ($value *= 12, $unit = 'pc') if $unit eq 'pc';
        ($value /= 72, $unit = 'in') if $unit eq 'pt';
        ($value *= 2.54, $unit = 'cm') if $unit eq 'in';
        ($value *= 10, $unit = 'mm') if $unit eq 'cm';
        ($value /= 0.26, $unit = 'px') if $unit eq 'mm';
      }

      return ['DIMENSION', $value, $unit];
    }
  }
  
  return $specified_value;
}; # $compute_length

$Prop->{'letter-spacing'} = {
  css => 'letter-spacing',
  dom => 'letter_spacing',
  key => 'letter_spacing',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    ## NOTE: Used also for 'word-spacing', '-manakai-border-spacing-x',
    ## and '-manakai-border-spacing-y'.

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }
    my $allow_negative = $Prop->{$prop_name}->{allow_negative};

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and ($allow_negative or $value >= 0)) {
        return ($t, {$prop_name => ['DIMENSION', $value, $unit]});
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['DIMENSION', $value, 'px']})
          if $allow_negative or $value >= 0;
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($Prop->{$prop_name}->{keyword}->{$value}) {
        return ($t, {$prop_name => ['KEYWORD', $value]});        
      } elsif ($value eq 'inherit') {
        return ($t, {$prop_name => ['INHERIT']});
      }
    }
    
    $onerror->(type => 'syntax error:'.$prop_name,
               level => $self->{must_level},
               token => $t);
    return ($t, undef);
  },
  allow_negative => 1,
  keyword => {normal => 1},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'normal'],
  inherited => 1,
  compute => $compute_length,
};
$Attr->{letter_spacing} = $Prop->{'letter-spacing'};
$Key->{letter_spacing} = $Prop->{'letter-spacing'};

$Prop->{'word-spacing'} = {
  css => 'word-spacing',
  dom => 'word_spacing',
  key => 'word_spacing',
  parse => $Prop->{'letter-spacing'}->{parse},
  allow_negative => 1,
  keyword => {normal => 1},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'normal'],
  inherited => 1,
  compute => $compute_length,
};
$Attr->{word_spacing} = $Prop->{'word-spacing'};
$Key->{word_spacing} = $Prop->{'word-spacing'};

$Prop->{'-manakai-border-spacing-x'} = {
  css => '-manakai-border-spacing-x',
  dom => '_manakai_border_spacing_x',
  key => 'border_spacing_x',
  parse => $Prop->{'letter-spacing'}->{parse},
  #allow_negative => 0,
  #keyword => {},
  serialize => $default_serializer,
  serialize_multiple => sub {
    my $self = shift;
    
    local $Error::Depth = $Error::Depth + 1;
    my $x = $self->_manakai_border_spacing_x;
    my $y = $self->_manakai_border_spacing_y;
    my $xi = $self->get_property_priority ('-manakai-border-spacing-x');
    my $yi = $self->get_property_priority ('-manakai-border-spacing-y');
    $xi = ' !' . $xi if length $xi;
    $yi = ' !' . $yi if length $yi;
    if (length $x) {
      if (length $y) {
        if ($xi eq $yi) {
          if ($x eq $y) {
            return {'border-spacing' => $x . $xi};
          } else {
            return {'border-spacing' => $x . ' ' . $y . $xi};
          }
        } else {
          return {'-manakai-border-spacing-x' => $x . $xi,
                  '-manakai-border-spacing-y' => $y . $yi};
        }
      } else {
        return {'-manakai-border-spacing-x' => $x . $xi};
      }
    } else {
      if (length $y) {
        return {'-manakai-border-spacing-y' => $y . $yi};
      } else {
        return {};
      }
    }
  },
  initial => ['DIMENSION', 0, 'px'],
  inherited => 1,
  compute => $compute_length,
};
$Attr->{_manakai_border_spacing_x} = $Prop->{'-manakai-border-spacing-x'};
$Key->{border_spacing_x} = $Prop->{'-manakai-border-spacing-x'};

$Prop->{'-manakai-border-spacing-y'} = {
  css => '-manakai-border-spacing-y',
  dom => '_manakai_border_spacing_y',
  key => 'border_spacing_y',
  parse => $Prop->{'letter-spacing'}->{parse},
  #allow_negative => 0,
  #keyword => {},
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'-manakai-border-spacing-x'}
      ->{serialize_multiple},
  initial => ['DIMENSION', 0, 'px'],
  inherited => 1,
  compute => $compute_length,
};
$Attr->{_manakai_border_spacing_y} = $Prop->{'-manakai-border-spacing-y'};
$Key->{border_spacing_y} = $Prop->{'-manakai-border-spacing-y'};

$Prop->{'margin-top'} = {
  css => 'margin-top',
  dom => 'margin_top',
  key => 'margin_top',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    ## NOTE: Used for 'margin-top', 'margin-right', 'margin-bottom',
    ## 'margin-left', 'top', 'right', 'bottom', 'left', 'padding-top',
    ## 'padding-right', 'padding-bottom', 'padding-left',
    ## 'border-top-width', 'border-right-width', 'border-bottom-width',
    ## 'border-left-width', 'text-indent', 'background-position-x',
    ## and 'background-position-y'.

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }
    my $allow_negative = $Prop->{$prop_name}->{allow_negative};

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and ($allow_negative or $value >= 0)) {
        return ($t, {$prop_name => ['DIMENSION', $value, $unit]});
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['PERCENTAGE', $value]})
          if $allow_negative or $value >= 0;
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['DIMENSION', $value, 'px']})
          if $allow_negative or $value >= 0;
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      if ($Prop->{$prop_name}->{keyword}->{$value}) {
        $t = $tt->get_next_token;
        return ($t, {$prop_name => ['KEYWORD', $value]});        
      } elsif ($value eq 'inherit') {
        $t = $tt->get_next_token;
        return ($t, {$prop_name => ['INHERIT']});
      }
      ## NOTE: In the "else" case, don't procede the |$t| pointer
      ## for the support of 'border-top' property (and similar ones).
    }
    
    $onerror->(type => 'syntax error:'.$prop_name,
               level => $self->{must_level},
               token => $t);
    return ($t, undef);
  },
  allow_negative => 1,
  keyword => {auto => 1},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{margin_top} = $Prop->{'margin-top'};
$Key->{margin_top} = $Prop->{'margin-top'};

$Prop->{'margin-bottom'} = {
  css => 'margin-bottom',
  dom => 'margin_bottom',
  key => 'margin_bottom',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {auto => 1},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{margin_bottom} = $Prop->{'margin-bottom'};
$Key->{margin_bottom} = $Prop->{'margin-bottom'};

$Prop->{'margin-right'} = {
  css => 'margin-right',
  dom => 'margin_right',
  key => 'margin_right',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {auto => 1},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{margin_right} = $Prop->{'margin-right'};
$Key->{margin_right} = $Prop->{'margin-right'};

$Prop->{'margin-left'} = {
  css => 'margin-left',
  dom => 'margin_left',
  key => 'margin_left',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {auto => 1},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{margin_left} = $Prop->{'margin-left'};
$Key->{margin_left} = $Prop->{'margin-left'};

$Prop->{top} = {
  css => 'top',
  dom => 'top',
  key => 'top',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {auto => 1},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'auto'],
  #inherited => 0,
  compute_multiple => sub {
    my ($self, $element, $eid, $prop_name) = @_;

    my $pos_value = $self->get_computed_value ($element, 'position');
    if (defined $pos_value and $pos_value->[0] eq 'KEYWORD') {
      if ($pos_value->[1] eq 'static') {
        $self->{computed_value}->{$eid}->{top} = ['KEYWORD', 'auto'];
        $self->{computed_value}->{$eid}->{bottom} = ['KEYWORD', 'auto'];
        return;
      } elsif ($pos_value->[1] eq 'relative') {
        my $top_specified = $self->get_specified_value_no_inherit
          ($element, 'top');
        if (defined $top_specified and
            ($top_specified->[0] eq 'DIMENSION' or
             $top_specified->[0] eq 'PERCENTAGE')) {
          my $tv = $self->{computed_value}->{$eid}->{top}
              = $compute_length->($self, $element, 'top', $top_specified);
          $self->{computed_value}->{$eid}->{bottom}
              = [$tv->[0], -$tv->[1], $tv->[2]];
        } else { # top: auto
          my $bottom_specified = $self->get_specified_value_no_inherit
              ($element, 'bottom');
          if (defined $bottom_specified and
              ($bottom_specified->[0] eq 'DIMENSION' or
               $bottom_specified->[0] eq 'PERCENTAGE')) {
            my $tv = $self->{computed_value}->{$eid}->{bottom}
                = $compute_length->($self, $element, 'bottom',
                                    $bottom_specified);
            $self->{computed_value}->{$eid}->{top}
                = [$tv->[0], -$tv->[1], $tv->[2]];
          } else { # bottom: auto
            $self->{computed_value}->{$eid}->{top} = ['DIMENSION', 0, 'px'];
            $self->{computed_value}->{$eid}->{bottom} = ['DIMENSION', 0, 'px'];
          }
        }
        return;
      }
    }

    my $top_specified = $self->get_specified_value_no_inherit
        ($element, 'top');
    $self->{computed_value}->{$eid}->{top}
        = $compute_length->($self, $element, 'top', $top_specified);
    my $bottom_specified = $self->get_specified_value_no_inherit
        ($element, 'bottom');
    $self->{computed_value}->{$eid}->{bottom}
        = $compute_length->($self, $element, 'bottom', $bottom_specified);
  },
};
$Attr->{top} = $Prop->{top};
$Key->{top} = $Prop->{top};

$Prop->{bottom} = {
  css => 'bottom',
  dom => 'bottom',
  key => 'bottom',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {auto => 1},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'auto'],
  #inherited => 0,
  compute_multiple => $Prop->{top}->{compute_multiple},
};
$Attr->{bottom} = $Prop->{bottom};
$Key->{bottom} = $Prop->{bottom};

$Prop->{left} = {
  css => 'left',
  dom => 'left',
  key => 'left',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {auto => 1},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'auto'],
  #inherited => 0,
  compute_multiple => sub {
    my ($self, $element, $eid, $prop_name) = @_;

    my $pos_value = $self->get_computed_value ($element, 'position');
    if (defined $pos_value and $pos_value->[0] eq 'KEYWORD') {
      if ($pos_value->[1] eq 'static') {
        $self->{computed_value}->{$eid}->{left} = ['KEYWORD', 'auto'];
        $self->{computed_value}->{$eid}->{right} = ['KEYWORD', 'auto'];
        return;
      } elsif ($pos_value->[1] eq 'relative') {
        my $left_specified = $self->get_specified_value_no_inherit
            ($element, 'left');
        if (defined $left_specified and
            ($left_specified->[0] eq 'DIMENSION' or
             $left_specified->[0] eq 'PERCENTAGE')) {
          my $right_specified = $self->get_specified_value_no_inherit
              ($element, 'right');
          if (defined $right_specified and
              ($right_specified->[0] eq 'DIMENSION' or
               $right_specified->[0] eq 'PERCENTAGE')) {
            my $direction = $self->get_computed_value ($element, 'direction');
            if (defined $direction and $direction->[0] eq 'KEYWORD' and
                $direction->[0] eq 'ltr') {
              my $tv = $self->{computed_value}->{$eid}->{left}
                  = $compute_length->($self, $element, 'left',
                                      $left_specified);
              $self->{computed_value}->{$eid}->{right}
                  = [$tv->[0], -$tv->[1], $tv->[2]];
            } else {
              my $tv = $self->{computed_value}->{$eid}->{right}
                  = $compute_length->($self, $element, 'right',
                                      $right_specified);
              $self->{computed_value}->{$eid}->{left}
                  = [$tv->[0], -$tv->[1], $tv->[2]];
            }
          } else {
            my $tv = $self->{computed_value}->{$eid}->{left}
                = $compute_length->($self, $element, 'left', $left_specified);
            $self->{computed_value}->{$eid}->{right}
                = [$tv->[0], -$tv->[1], $tv->[2]];
          }
        } else { # left: auto
          my $right_specified = $self->get_specified_value_no_inherit
              ($element, 'right');
          if (defined $right_specified and
              ($right_specified->[0] eq 'DIMENSION' or
               $right_specified->[0] eq 'PERCENTAGE')) {
            my $tv = $self->{computed_value}->{$eid}->{right}
                = $compute_length->($self, $element, 'right',
                                    $right_specified);
            $self->{computed_value}->{$eid}->{left}
                = [$tv->[0], -$tv->[1], $tv->[2]];
          } else { # right: auto
            $self->{computed_value}->{$eid}->{left} = ['DIMENSION', 0, 'px'];
            $self->{computed_value}->{$eid}->{right} = ['DIMENSION', 0, 'px'];
          }
        }
        return;
      }
    }

    my $left_specified = $self->get_specified_value_no_inherit
        ($element, 'left');
    $self->{computed_value}->{$eid}->{left}
        = $compute_length->($self, $element, 'left', $left_specified);
    my $right_specified = $self->get_specified_value_no_inherit
        ($element, 'right');
    $self->{computed_value}->{$eid}->{right}
        = $compute_length->($self, $element, 'right', $right_specified);
  },
};
$Attr->{left} = $Prop->{left};
$Key->{left} = $Prop->{left};

$Prop->{right} = {
  css => 'right',
  dom => 'right',
  key => 'right',
  parse => $Prop->{'margin-top'}->{parse},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'auto'],
  #inherited => 0,
  compute_multiple => $Prop->{left}->{compute_multiple},
};
$Attr->{right} = $Prop->{right};
$Key->{right} = $Prop->{right};

$Prop->{width} = {
  css => 'width',
  dom => 'width',
  key => 'width',
  parse => $Prop->{'margin-top'}->{parse},
  #allow_negative => 0,
  keyword => {auto => 1},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'auto'],
  #inherited => 0,
  compute => $compute_length,
      ## NOTE: See <http://suika.fam.cx/gate/2005/sw/width> for
      ## browser compatibility issues.
};
$Attr->{width} = $Prop->{width};
$Key->{width} = $Prop->{width};

$Prop->{'min-width'} = {
  css => 'min-width',
  dom => 'min_width',
  key => 'min_width',
  parse => $Prop->{'margin-top'}->{parse},
  #allow_negative => 0,
  #keyword => {},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{min_width} = $Prop->{'min-width'};
$Key->{min_width} = $Prop->{'min-width'};

$Prop->{'max-width'} = {
  css => 'max-width',
  dom => 'max_width',
  key => 'max_width',
  parse => $Prop->{'margin-top'}->{parse},
  #allow_negative => 0,
  keyword => {none => 1},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'none'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{max_width} = $Prop->{'max-width'};
$Key->{max_width} = $Prop->{'max-width'};

$Prop->{height} = {
  css => 'height',
  dom => 'height',
  key => 'height',
  parse => $Prop->{'margin-top'}->{parse},
  #allow_negative => 0,
  keyword => {auto => 1},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'auto'],
  #inherited => 0,
  compute => $compute_length,
      ## NOTE: See <http://suika.fam.cx/gate/2005/sw/height> for
      ## browser compatibility issues.
};
$Attr->{height} = $Prop->{height};
$Key->{height} = $Prop->{height};

$Prop->{'min-height'} = {
  css => 'min-height',
  dom => 'min_height',
  key => 'min_height',
  parse => $Prop->{'margin-top'}->{parse},
  #allow_negative => 0,
  #keyword => {},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{min_height} = $Prop->{'min-height'};
$Key->{min_height} = $Prop->{'min-height'};

$Prop->{'max-height'} = {
  css => 'max-height',
  dom => 'max_height',
  key => 'max_height',
  parse => $Prop->{'margin-top'}->{parse},
  #allow_negative => 0,
  keyword => {none => 1},
  serialize => $default_serializer,
  initial => ['KEYWORD', 'none'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{max_height} = $Prop->{'max-height'};
$Key->{max_height} = $Prop->{'max-height'};

$Prop->{'line-height'} = {
  css => 'line-height',
  dom => 'line_height',
  key => 'line_height',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    ## NOTE: Similar to 'margin-top', but different handling
    ## for unitless numbers.

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }
    my $allow_negative = $Prop->{$prop_name}->{allow_negative};

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        return ($t, {$prop_name => ['DIMENSION', $value, $unit]});
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['PERCENTAGE', $value]})
          if $value >= 0;
    } elsif ($t->{type} == NUMBER_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['NUMBER', $value]}) if $value >= 0;
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($value eq 'normal') {
        return ($t, {$prop_name => ['KEYWORD', $value]});        
      } elsif ($value eq 'inherit') {
        return ($t, {$prop_name => ['INHERIT']});
      }
    }
    
    $onerror->(type => 'syntax error:'.$prop_name,
               level => $self->{must_level},
               token => $t);
    return ($t, undef);
  },
  serialize => $default_serializer,
  initial => ['KEYWORD', 'normal'],
  inherited => 1,
  compute => $compute_length,
};
$Attr->{line_height} = $Prop->{'line-height'};
$Key->{line_height} = $Prop->{'line-height'};

$Prop->{'vertical-align'} = {
  css => 'vertical-align',
  dom => 'vertical_align',
  key => 'vertical_align',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {
    baseline => 1, sub => 1, super => 1, top => 1, 'text-top' => 1,
    middle => 1, bottom => 1, 'text-bottom' => 1,
  },
  ## NOTE: Currently, we don't support option to select subset of keywords
  ## supported by application (i.e. 
  ## $parser->{prop_value}->{'line-height'->{$keyword}).  Should we support
  ## it?
  serialize => $default_serializer,
  initial => ['KEYWORD', 'baseline'],
  #inherited => 0,
  compute => $compute_length,
      ## NOTE: See <http://suika.fam.cx/gate/2005/sw/vertical-align> for
      ## browser compatibility issues.
};
$Attr->{vertical_align} = $Prop->{'vertical-align'};
$Key->{vertical_align} = $Prop->{'vertical-align'};

$Prop->{'text-indent'} = {
  css => 'text-indent',
  dom => 'text_indent',
  key => 'text_indent',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  inherited => 1,
  compute => $compute_length,
};
$Attr->{text_indent} = $Prop->{'text-indent'};
$Key->{text_indent} = $Prop->{'text-indent'};

$Prop->{'background-position-x'} = {
  css => 'background-position-x',
  dom => 'background_position_x',
  key => 'background_position_x',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {left => 1, center => 1, right => 1},
  serialize => $default_serializer,
  initial => ['PERCENTAGE', 0],
  #inherited => 0,
  compute => sub {
    my ($self, $element, $prop_name, $specified_value) = @_;

    if (defined $specified_value and $specified_value->[0] eq 'KEYWORD') {
      my $v = {
        left => 0, center => 50, right => 100, top => 0, bottom => 100,
      }->{$specified_value->[1]};
      if (defined $v) {
        return ['PERCENTAGE', $v];
      } else {
        return $specified_value;
      }
    } else {
      return $compute_length->(@_);
    }
  },
  serialize_multiple => $Prop->{'background-color'}->{serialize_multiple},
};
$Attr->{background_position_x} = $Prop->{'background-position-x'};
$Key->{background_position_x} = $Prop->{'background-position-x'};

$Prop->{'background-position-y'} = {
  css => 'background-position-y',
  dom => 'background_position_y',
  key => 'background_position_y',
  parse => $Prop->{'margin-top'}->{parse},
  allow_negative => 1,
  keyword => {top => 1, center => 1, bottom => 1},
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'background-color'}->{serialize_multiple},
  initial => ['PERCENTAGE', 0],
  #inherited => 0,
  compute => $Prop->{'background-position-x'}->{compute},
};
$Attr->{background_position_y} = $Prop->{'background-position-y'};
$Key->{background_position_y} = $Prop->{'background-position-y'};

$Prop->{'padding-top'} = {
  css => 'padding-top',
  dom => 'padding_top',
  key => 'padding_top',
  parse => $Prop->{'margin-top'}->{parse},
  #allow_negative => 0,
  #keyword => {},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{padding_top} = $Prop->{'padding-top'};
$Key->{padding_top} = $Prop->{'padding-top'};

$Prop->{'padding-bottom'} = {
  css => 'padding-bottom',
  dom => 'padding_bottom',
  key => 'padding_bottom',
  parse => $Prop->{'padding-top'}->{parse},
  #allow_negative => 0,
  #keyword => {},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{padding_bottom} = $Prop->{'padding-bottom'};
$Key->{padding_bottom} = $Prop->{'padding-bottom'};

$Prop->{'padding-right'} = {
  css => 'padding-right',
  dom => 'padding_right',
  key => 'padding_right',
  parse => $Prop->{'padding-top'}->{parse},
  #allow_negative => 0,
  #keyword => {},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{padding_right} = $Prop->{'padding-right'};
$Key->{padding_right} = $Prop->{'padding-right'};

$Prop->{'padding-left'} = {
  css => 'padding-left',
  dom => 'padding_left',
  key => 'padding_left',
  parse => $Prop->{'padding-top'}->{parse},
  #allow_negative => 0,
  #keyword => {},
  serialize => $default_serializer,
  initial => ['DIMENSION', 0, 'px'],
  #inherited => 0,
  compute => $compute_length,
};
$Attr->{padding_left} = $Prop->{'padding-left'};
$Key->{padding_left} = $Prop->{'padding-left'};

$Prop->{'border-top-width'} = {
  css => 'border-top-width',
  dom => 'border_top_width',
  key => 'border_top_width',
  parse => $Prop->{'margin-top'}->{parse},
  #allow_negative => 0,
  keyword => {thin => 1, medium => 1, thick => 1},
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  initial => ['KEYWORD', 'medium'],
  #inherited => 0,
  compute => sub {
    my ($self, $element, $prop_name, $specified_value) = @_;

    ## NOTE: Used for 'border-top-width', 'border-right-width',
    ## 'border-bottom-width', 'border-right-width', and
    ## 'outline-width'.

    my $style_prop = $prop_name;
    $style_prop =~ s/width/style/;
    my $style = $self->get_computed_value ($element, $style_prop);
    if (defined $style and $style->[0] eq 'KEYWORD' and
        ($style->[1] eq 'none' or $style->[1] eq 'hidden')) {
      return ['DIMENSION', 0, 'px'];
    }

    my $value = $compute_length->(@_);
    if (defined $value and $value->[0] eq 'KEYWORD') {
      if ($value->[1] eq 'thin') {
        return ['DIMENSION', 1, 'px']; ## Firefox/Opera
      } elsif ($value->[1] eq 'medium') {
        return ['DIMENSION', 3, 'px']; ## Firefox/Opera
      } elsif ($value->[1] eq 'thick') {
        return ['DIMENSION', 5, 'px']; ## Firefox
      }
    }
    return $value;
  },
  ## NOTE: CSS3 will allow <percentage> as an option in <border-width>.
  ## Opera 9 has already implemented it.
};
$Attr->{border_top_width} = $Prop->{'border-top-width'};
$Key->{border_top_width} = $Prop->{'border-top-width'};

$Prop->{'border-right-width'} = {
  css => 'border-right-width',
  dom => 'border_right_width',
  key => 'border_right_width',
  parse => $Prop->{'border-top-width'}->{parse},
  #allow_negative => 0,
  keyword => {thin => 1, medium => 1, thick => 1},
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  initial => ['KEYWORD', 'medium'],
  #inherited => 0,
  compute => $Prop->{'border-top-width'}->{compute},
};
$Attr->{border_right_width} = $Prop->{'border-right-width'};
$Key->{border_right_width} = $Prop->{'border-right-width'};

$Prop->{'border-bottom-width'} = {
  css => 'border-bottom-width',
  dom => 'border_bottom_width',
  key => 'border_bottom_width',
  parse => $Prop->{'border-top-width'}->{parse},
  #allow_negative => 0,
  keyword => {thin => 1, medium => 1, thick => 1},
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  initial => ['KEYWORD', 'medium'],
  #inherited => 0,
  compute => $Prop->{'border-top-width'}->{compute},
};
$Attr->{border_bottom_width} = $Prop->{'border-bottom-width'};
$Key->{border_bottom_width} = $Prop->{'border-bottom-width'};

$Prop->{'border-left-width'} = {
  css => 'border-left-width',
  dom => 'border_left_width',
  key => 'border_left_width',
  parse => $Prop->{'border-top-width'}->{parse},
  #allow_negative => 0,
  keyword => {thin => 1, medium => 1, thick => 1},
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  initial => ['KEYWORD', 'medium'],
  #inherited => 0,
  compute => $Prop->{'border-top-width'}->{compute},
};
$Attr->{border_left_width} = $Prop->{'border-left-width'};
$Key->{border_left_width} = $Prop->{'border-left-width'};

$Prop->{'outline-width'} = {
  css => 'outline-width',
  dom => 'outline_width',
  key => 'outline_width',
  parse => $Prop->{'border-top-width'}->{parse},
  #allow_negative => 0,
  keyword => {thin => 1, medium => 1, thick => 1},
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'outline-color'}->{serialize_multiple},
  initial => ['KEYWORD', 'medium'],
  #inherited => 0,
  compute => $Prop->{'border-top-width'}->{compute},
};
$Attr->{outline_width} = $Prop->{'outline-width'};
$Key->{outline_width} = $Prop->{'outline-width'};

$Prop->{'font-weight'} = {
  css => 'font-weight',
  dom => 'font_weight',
  key => 'font_weight',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    if ($t->{type} == NUMBER_TOKEN) {
      ## ISSUE: See <http://suika.fam.cx/gate/2005/sw/font-weight> for
      ## browser compatibility issue.
      my $value = $t->{number};
      $t = $tt->get_next_token;
      if ($value % 100 == 0 and 100 <= $value and $value <= 900) {
        return ($t, {$prop_name => ['WEIGHT', $value, 0]});
      }
    } elsif ($t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ({
           normal => 1, bold => 1, bolder => 1, lighter => 1,
          }->{$value}) {
        return ($t, {$prop_name => ['KEYWORD', $value]});
      } elsif ($value eq 'inherit') {
        return ($t, {$prop_name => ['INHERIT']});
      }
    }
    
    $onerror->(type => 'syntax error:'.$prop_name,
               level => $self->{must_level},
               token => $t);
    return ($t, undef);
  },
  serialize => $default_serializer,
  initial => ['KEYWORD', 'normal'],
  inherited => 1,
  compute => sub {
    my ($self, $element, $prop_name, $specified_value) = @_;

    if (defined $specified_value and $specified_value->[0] eq 'KEYWORD') {
      if ($specified_value->[1] eq 'normal') {
        return ['WEIGHT', 400, 0];
      } elsif ($specified_value->[1] eq 'bold') {
        return ['WEIGHT', 700, 0];
      } elsif ($specified_value->[1] eq 'bolder') {
        my $parent_element = $element->manakai_parent_element;
        if (defined $parent_element) {
          my $parent_value = $self->get_cascaded_value
              ($parent_element, $prop_name); ## NOTE: What Firefox does.
          return ['WEIGHT', $parent_value->[1], $parent_value->[2] + 1];
        } else {
          return ['WEIGHT', 400, 1];
        }
      } elsif ($specified_value->[1] eq 'lighter') {
        my $parent_element = $element->manakai_parent_element;
        if (defined $parent_element) {
          my $parent_value = $self->get_cascaded_value
              ($parent_element, $prop_name); ## NOTE: What Firefox does.
          return ['WEIGHT', $parent_value->[1], $parent_value->[2] - 1];
        } else {
          return ['WEIGHT', 400, 1];
        }
      }
    #} elsif (defined $specified_value and $specified_value->[0] eq 'WEIGHT') {
      #
    }

    return $specified_value;
  },
};
$Attr->{font_weight} = $Prop->{'font-weight'};
$Key->{font_weight} = $Prop->{'font-weight'};

my $uri_or_none_parser = sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    if ($t->{type} == URI_TOKEN) {
      my $value = $t->{value};
      $t = $tt->get_next_token;
      return ($t, {$prop_name => ['URI', $value, \($self->{base_uri})]});
    } elsif ($t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($value eq 'none') {
        ## NOTE: |none| is the default value and therefore it must be
        ## supported anyway.
        return ($t, {$prop_name => ["KEYWORD", 'none']});
      } elsif ($value eq 'inherit') {
        return ($t, {$prop_name => ['INHERIT']});
      }
    ## NOTE: None of Firefox2, WinIE6, and Opera9 support this case.
    #} elsif ($t->{type} == URI_INVALID_TOKEN) {
    #  my $value = $t->{value};
    #  $t = $tt->get_next_token;
    #  if ($t->{type} == EOF_TOKEN) {
    #    $onerror->(type => 'syntax error:eof:'.$prop_name,
    #               level => $self->{must_level},
    #               token => $t);
    #    
    #    return ($t, {$prop_name => ['URI', $value, \($self->{base_uri})]});
    #  }
    }
    
    $onerror->(type => 'syntax error:'.$prop_name,
               level => $self->{must_level},
               token => $t);
    return ($t, undef);
}; # $uri_or_none_parser

my $compute_uri_or_none = sub {
    my ($self, $element, $prop_name, $specified_value) = @_;
    
    if (defined $specified_value and
        $specified_value->[0] eq 'URI' and
        defined $specified_value->[2]) {
      require Message::DOM::DOMImplementation;
      return ['URI',
              Message::DOM::DOMImplementation->create_uri_reference
                  ($specified_value->[1])
                  ->get_absolute_reference (${$specified_value->[2]})
                  ->get_uri_reference,
              $specified_value->[2]];
    }

    return $specified_value;
}; # $compute_uri_or_none

$Prop->{'list-style-image'} = {
  css => 'list-style-image',
  dom => 'list_style_image',
  key => 'list_style_image',
  parse => $uri_or_none_parser,
  serialize => $default_serializer,
  initial => ['KEYWORD', 'none'],
  inherited => 1,
  compute => $compute_uri_or_none,
};
$Attr->{list_style_image} = $Prop->{'list-style-image'};
$Key->{list_style_image} = $Prop->{'list-style-image'};

$Prop->{'background-image'} = {
  css => 'background-image',
  dom => 'background_image',
  key => 'background_image',
  parse => $uri_or_none_parser,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'background-color'}->{serialize_multiple},
  initial => ['KEYWORD', 'none'],
  #inherited => 0,
  compute => $compute_uri_or_none,
};
$Attr->{background_image} = $Prop->{'background-image'};
$Key->{background_image} = $Prop->{'background-image'};

my $border_style_keyword = {
  none => 1, hidden => 1, dotted => 1, dashed => 1, solid => 1,
  double => 1, groove => 1, ridge => 1, inset => 1, outset => 1,
};

$Prop->{'border-top-style'} = {
  css => 'border-top-style',
  dom => 'border_top_style',
  key => 'border_top_style',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  keyword => $border_style_keyword,
  initial => ["KEYWORD", "none"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{border_top_style} = $Prop->{'border-top-style'};
$Key->{border_top_style} = $Prop->{'border-top-style'};

$Prop->{'border-right-style'} = {
  css => 'border-right-style',
  dom => 'border_right_style',
  key => 'border_right_style',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  keyword => $border_style_keyword,
  initial => ["KEYWORD", "none"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{border_right_style} = $Prop->{'border-right-style'};
$Key->{border_right_style} = $Prop->{'border-right-style'};

$Prop->{'border-bottom-style'} = {
  css => 'border-bottom-style',
  dom => 'border_bottom_style',
  key => 'border_bottom_style',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  keyword => $border_style_keyword,
  initial => ["KEYWORD", "none"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{border_bottom_style} = $Prop->{'border-bottom-style'};
$Key->{border_bottom_style} = $Prop->{'border-bottom-style'};

$Prop->{'border-left-style'} = {
  css => 'border-left-style',
  dom => 'border_left_style',
  key => 'border_left_style',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
  keyword => $border_style_keyword,
  initial => ["KEYWORD", "none"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{border_left_style} = $Prop->{'border-left-style'};
$Key->{border_left_style} = $Prop->{'border-left-style'};

$Prop->{'outline-style'} = {
  css => 'outline-style',
  dom => 'outline_style',
  key => 'outline_style',
  parse => $one_keyword_parser,
  serialize => $default_serializer,
  serialize_multiple => $Prop->{'outline-color'}->{serialize_multiple},
  keyword => {%$border_style_keyword},
  initial => ['KEYWORD', 'none'],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{outline_style} = $Prop->{'outline-style'};
$Key->{outline_style} = $Prop->{'outline-style'};
delete $Prop->{'outline-style'}->{keyword}->{hidden};

my $generic_font_keywords => {
  serif => 1, 'sans-serif' => 1, cursive => 1,
  fantasy => 1, monospace => 1, '-manakai-default' => 1,
  '-manakai-caption' => 1, '-manakai-icon' => 1,
  '-manakai-menu' => 1, '-manakai-message-box' => 1, 
  '-manakai-small-caption' => 1, '-manakai-status-bar' => 1,
};
## NOTE: "All five generic font families are defined to exist in all CSS
## implementations (they need not necessarily map to five distinct actual
## fonts)." [CSS 2.1].
## NOTE: "If no font with the indicated characteristics exists on a given
## platform, the user agent should either intelligently substitute (e.g., a
## smaller version of the 'caption' font might be used for the 'small-caption'
## font), or substitute a user agent default font." [CSS 2.1].

$Prop->{'font-family'} = {
  css => 'font-family',
  dom => 'font_family',
  key => 'font_family',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    ## NOTE: See <http://suika.fam.cx/gate/2005/sw/font-family> for
    ## how chaotic browsers are!

    my @prop_value;

    my $font_name = '';
    my $may_be_generic = 1;
    my $may_be_inherit = ($prop_name ne 'font');
    my $has_s = 0;
    F: {
      if ($t->{type} == IDENT_TOKEN) {
        undef $may_be_inherit if $has_s or length $font_name;
        undef $may_be_generic if $has_s or length $font_name;
        $font_name .= ' ' if $has_s;
        $font_name .= $t->{value};
        undef $has_s;
        $t = $tt->get_next_token;
      } elsif ($t->{type} == STRING_TOKEN) {
        $font_name .= ' ' if $has_s;
        $font_name .= $t->{value};
        undef $may_be_inherit;
        undef $may_be_generic;
        undef $has_s;
        $t = $tt->get_next_token;
      } elsif ($t->{type} == COMMA_TOKEN) { ## TODO: case
        if ($may_be_generic and $generic_font_keywords->{lc $font_name}) {
          push @prop_value, ['KEYWORD', $font_name];
        } elsif (not $may_be_generic or length $font_name) {
          push @prop_value, ["STRING", $font_name];
        }
        undef $may_be_inherit;
        $may_be_generic = 1;
        undef $has_s;
        $font_name = '';
        $t = $tt->get_next_token;
        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      } elsif ($t->{type} == S_TOKEN) {
        $has_s = 1;
        $t = $tt->get_next_token;
      } else {
        if ($may_be_generic and $generic_font_keywords->{lc $font_name}) {
          push @prop_value, ['KEYWORD', $font_name]; ## TODO: case
        } elsif (not $may_be_generic or length $font_name) {
          push @prop_value, ['STRING', $font_name];
        } else {
          $onerror->(type => 'syntax error:'.$prop_name,
                     level => $self->{must_level},
                     token => $t);
          return ($t, undef);
        }
        last F;
      }
      redo F;
    } # F

    if ($may_be_inherit and
        @prop_value == 1 and
        $prop_value[0]->[0] eq 'STRING' and
        lc $prop_value[0]->[1] eq 'inherit') { ## TODO: case
      return ($t, {$prop_name => ['INHERIT']});
    } else {
      unshift @prop_value, 'FONT';
      return ($t, {$prop_name => \@prop_value});
    }
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;

    if ($value->[0] eq 'FONT') {
      return join ', ', map {
        if ($_->[0] eq 'STRING') {
          '"'.$_->[1].'"'; ## NOTE: This is what Firefox does.
        } elsif ($_->[0] eq 'KEYWORD') {
          $_->[1]; ## NOTE: This is what Firefox does.
        } else {
          ## NOTE: This should be an error.
          '""';
        }
      } @$value[1..$#$value];
    } elsif ($value->[0] eq 'INHERIT') {
      return 'inherit';
    } else {
      return '';
    }
  },
  initial => ['FONT', ['KEYWORD', '-manakai-default']],
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{font_family} = $Prop->{'font-family'};
$Key->{font_family} = $Prop->{'font-family'};

$Prop->{cursor} = {
  css => 'cursor',
  dom => 'cursor',
  key => 'cursor',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    ## NOTE: See <http://suika.fam.cx/gate/2005/sw/cursor> for browser
    ## compatibility issues.

    my @prop_value = ('CURSOR');

    F: {
      if ($t->{type} == IDENT_TOKEN) {
        my $v = lc $t->{value}; ## TODO: case
        $t = $tt->get_next_token;
        if ($Prop->{$prop_name}->{keyword}->{$v}) {
          push @prop_value, ['KEYWORD', $v];
          last F;
        } elsif ($v eq 'inherit' and @prop_value == 1) {
          return ($t, {$prop_name => ['INHERIT']});
        } else {
          $onerror->(type => 'syntax error:'.$prop_name,
                     level => $self->{must_level},
                     token => $t);
          return ($t, undef);
        }
      } elsif ($t->{type} == URI_TOKEN) {
        push @prop_value, ['URI', $t->{value}, \($self->{base_uri})];
        $t = $tt->get_next_token;
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    
      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      if ($t->{type} == COMMA_TOKEN) {
        $t = $tt->get_next_token;
        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
        redo F;
      }
    } # F

    return ($t, {$prop_name => \@prop_value});
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;

    if ($value->[0] eq 'CURSOR') {
      return join ', ', map {
        if ($_->[0] eq 'URI') {
          'url('.$_->[1].')'; ## NOTE: This is what Firefox does.
        } elsif ($_->[0] eq 'KEYWORD') {
          $_->[1];
        } else {
          ## NOTE: This should be an error.
          '""';
        }
      } @$value[1..$#$value];
    } elsif ($value->[0] eq 'INHERIT') {
      return 'inherit';
    } else {
      return '';
    }
  },
  keyword => {
    auto => 1, crosshair => 1, default => 1, pointer => 1, move => 1,
    'e-resize' => 1, 'ne-resize' => 1, 'nw-resize' => 1, 'n-resize' => 1,
    'n-resize' => 1, 'se-resize' => 1, 'sw-resize' => 1, 's-resize' => 1,
    'w-resize' => 1, text => 1, wait => 1, help => 1, progress => 1,
  },
  initial => ['CURSOR', ['KEYWORD', 'auto']],
  inherited => 1,
  compute => sub {
    my ($self, $element, $prop_name, $specified_value) = @_;

    if (defined $specified_value and $specified_value->[0] eq 'CURSOR') {
      my @new_value = ('CURSOR');
      for my $value (@$specified_value[1..$#$specified_value]) {
        if ($value->[0] eq 'URI') {
          if (defined $value->[2]) {
            require Message::DOM::DOMImplementation;
            push @new_value, ['URI',
                              Message::DOM::DOMImplementation
                                  ->create_uri_reference ($value->[1])
                                  ->get_absolute_reference (${$value->[2]})
                                  ->get_uri_reference,
                              $value->[2]];
          } else {
            push @new_value, $value;
          }
        } else {
          push @new_value, $value;
        }
      }
      return \@new_value;
    }

    return $specified_value;
  },
};
$Attr->{cursor} = $Prop->{cursor};
$Key->{cursor} = $Prop->{cursor};

$Prop->{'border-style'} = {
  css => 'border-style',
  dom => 'border_style',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;
    if ($t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ($border_style_keyword->{$prop_value} and
          $self->{prop_value}->{'border-top-style'}->{$prop_value}) {
        $prop_value{'border-top-style'} = ["KEYWORD", $prop_value];
      } elsif ($prop_value eq 'inherit') {
        $prop_value{'border-top-style'} = ["INHERIT"];
        $prop_value{'border-right-style'} = $prop_value{'border-top-style'};
        $prop_value{'border-bottom-style'} = $prop_value{'border-top-style'};
        $prop_value{'border-left-style'} = $prop_value{'border-right-style'};
        return ($t, \%prop_value);
      } else {
        $onerror->(type => 'syntax error:keyword:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      $prop_value{'border-right-style'} = $prop_value{'border-top-style'};
      $prop_value{'border-bottom-style'} = $prop_value{'border-top-style'};
      $prop_value{'border-left-style'} = $prop_value{'border-right-style'};
    } else {
      $onerror->(type => 'syntax error:keyword:'.$prop_name,
                 level => $self->{must_level},
                 token => $t);
      return ($t, undef);
    }

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    if ($t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ($border_style_keyword->{$prop_value} and
          $self->{prop_value}->{'border-right-style'}->{$prop_value}) {
        $prop_value{'border-right-style'} = ["KEYWORD", $prop_value];
      } else {
        $onerror->(type => 'syntax error:keyword:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      $prop_value{'border-left-style'} = $prop_value{'border-right-style'};

      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      if ($t->{type} == IDENT_TOKEN) {
        my $prop_value = lc $t->{value}; ## TODO: case folding
        $t = $tt->get_next_token;
        if ($border_style_keyword->{$prop_value} and
            $self->{prop_value}->{'border-bottom-style'}->{$prop_value}) {
          $prop_value{'border-bottom-style'} = ["KEYWORD", $prop_value];
        } else {
          $onerror->(type => 'syntax error:keyword:'.$prop_name,
                     level => $self->{must_level},
                     token => $t);
          return ($t, undef);
        }
        
        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
        if ($t->{type} == IDENT_TOKEN) {
          my $prop_value = lc $t->{value}; ## TODO: case folding
          $t = $tt->get_next_token;
          if ($border_style_keyword->{$prop_value} and
              $self->{prop_value}->{'border-left-style'}->{$prop_value}) {
            $prop_value{'border-left-style'} = ["KEYWORD", $prop_value];
          } else {
            $onerror->(type => 'syntax error:keyword:'.$prop_name,
                       level => $self->{must_level},
                       token => $t);
            return ($t, undef);
          }
        }
      }
    }        

    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my @v;
    push @v, $self->border_top_style;
    return '' unless length $v[-1];
    push @v, $self->border_right_style;
    return '' unless length $v[-1];
    push @v, $self->border_bottom_style;
    return '' unless length $v[-1];
    push @v, $self->border_left_style;
    return '' unless length $v[-1];

    pop @v if $v[1] eq $v[3];
    pop @v if $v[0] eq $v[2];
    pop @v if $v[0] eq $v[1];
    return join ' ', @v;
  },
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
};
$Attr->{border_style} = $Prop->{'border-style'};

$Prop->{'border-color'} = {
  css => 'border-color',
  dom => 'border_color',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;
    ($t, my $pv) = $parse_color->($self, 'border-color', $tt, $t, $onerror);
    if (not defined $pv) {
      return ($t, undef);
    }
    $prop_value{'border-top-color'} = $pv->{'border-color'};
    $prop_value{'border-bottom-color'} = $prop_value{'border-top-color'};
    $prop_value{'border-right-color'} = $prop_value{'border-top-color'};
    $prop_value{'border-left-color'}= $prop_value{'border-right-color'};
    if ($prop_value{'border-top-color'}->[0] eq 'INHERIT') {
      return ($t, \%prop_value);
    }

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    if ({
         IDENT_TOKEN, 1,
         HASH_TOKEN, 1, NUMBER_TOKEN, 1, DIMENSION_TOKEN, 1,
         FUNCTION_TOKEN, 1,
        }->{$t->{type}}) {
      ($t, $pv) = $parse_color->($self, 'border-color', $tt, $t, $onerror);
      if (not defined $pv) {
        return ($t, undef);
      } elsif ($pv->{'border-color'}->[0] eq 'INHERIT') {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      $prop_value{'border-right-color'} = $pv->{'border-color'};
      $prop_value{'border-left-color'}= $prop_value{'border-right-color'};

      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      if ({
           IDENT_TOKEN, 1,
           HASH_TOKEN, 1, NUMBER_TOKEN, 1, DIMENSION_TOKEN, 1,
           FUNCTION_TOKEN, 1,
          }->{$t->{type}}) {
        ($t, $pv) = $parse_color->($self, 'border-color', $tt, $t, $onerror);
        if (not defined $pv) {
          return ($t, undef);
        } elsif ($pv->{'border-color'}->[0] eq 'INHERIT') {
          $onerror->(type => 'syntax error:'.$prop_name,
                     level => $self->{must_level},
                     token => $t);
          return ($t, undef);
        }
        $prop_value{'border-bottom-color'} = $pv->{'border-color'};

        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
        if ({
             IDENT_TOKEN, 1,
             HASH_TOKEN, 1, NUMBER_TOKEN, 1, DIMENSION_TOKEN, 1,
             FUNCTION_TOKEN, 1,
            }->{$t->{type}}) {
          ($t, $pv) = $parse_color->($self, 'border-color', $tt, $t, $onerror);
          if (not defined $pv) {
            return ($t, undef);
          } elsif ($pv->{'border-color'}->[0] eq 'INHERIT') {
            $onerror->(type => 'syntax error:'.$prop_name,
                       level => $self->{must_level},
                       token => $t);
            return ($t, undef);
          }
          $prop_value{'border-left-color'} = $pv->{'border-color'};
        }
      }
    }
    
    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my @v;
    push @v, $self->border_top_color;
    return '' unless length $v[-1];
    push @v, $self->border_right_color;
    return '' unless length $v[-1];
    push @v, $self->border_bottom_color;
    return '' unless length $v[-1];
    push @v, $self->border_left_color;
    return '' unless length $v[-1];

    pop @v if $v[1] eq $v[3];
    pop @v if $v[0] eq $v[2];
    pop @v if $v[0] eq $v[1];
    return join ' ', @v;
  },
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
};
$Attr->{border_color} = $Prop->{'border-color'};

$Prop->{'border-top'} = {
  css => 'border-top',
  dom => 'border_top',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;
    my $pv;
    ## NOTE: Since $onerror is disabled for three invocations below,
    ## some informative warning messages (if they are added someday) will not
    ## be reported.
    ($t, $pv) = $parse_color->($self, $prop_name.'-color', $tt, $t, sub {});
    if (defined $pv) {
      if ($pv->{$prop_name.'-color'}->[0] eq 'INHERIT') {
        return ($t, {$prop_name.'-color' => ['INHERIT'],
                     $prop_name.'-style' => ['INHERIT'],
                     $prop_name.'-width' => ['INHERIT']});
      } else {
        $prop_value{$prop_name.'-color'} = $pv->{$prop_name.'-color'};
      }
    } else {
      ($t, $pv) = $Prop->{'border-top-width'}->{parse}
          ->($self, $prop_name.'-width', $tt, $t, sub {});
      if (defined $pv) {
        $prop_value{$prop_name.'-width'} = $pv->{$prop_name.'-width'};
      } else {
        ($t, $pv) = $Prop->{'border-top-style'}->{parse}
            ->($self, $prop_name.'-style', $tt, $t, sub {});
        if (defined $pv) {
          $prop_value{$prop_name.'-style'} = $pv->{$prop_name.'-style'};
        } else {
          $onerror->(type => 'syntax error:'.$prop_name,
                     level => $self->{must_level},
                     token => $t);
          return ($t, undef);
        }
      }
    }

    for (1..2) {
      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      if ($t->{type} == IDENT_TOKEN) {
        my $prop_value = lc $t->{value}; ## TODO: case
        if ($border_style_keyword->{$prop_value} and
            $self->{prop_value}->{'border-top-style'}->{$prop_value} and
            not defined $prop_value{$prop_name.'-style'}) {
          $prop_value{$prop_name.'-style'} = ['KEYWORD', $prop_value];
          $t = $tt->get_next_token;
          next;
        } elsif ({thin => 1, medium => 1, thick => 1}->{$prop_value} and
                 not defined $prop_value{$prop_name.'-width'}) {
          $prop_value{$prop_name.'-width'} = ['KEYWORD', $prop_value];
          $t = $tt->get_next_token;
          next;
        }
      }

      undef $pv;
      ($t, $pv) = $parse_color->($self, $prop_name.'-color', $tt, $t, $onerror)
          if not defined $prop_value{$prop_name.'-color'} and
              {
                IDENT_TOKEN, 1,
                HASH_TOKEN, 1, NUMBER_TOKEN, 1, DIMENSION_TOKEN, 1,
                FUNCTION_TOKEN, 1,
              }->{$t->{type}};
      if (defined $pv) {
        if ($pv->{$prop_name.'-color'}->[0] eq 'INHERIT') {
          $onerror->(type => 'syntax error:'.$prop_name,
                     level => $self->{must_level},
                     token => $t);
        } else {
          $prop_value{$prop_name.'-color'} = $pv->{$prop_name.'-color'};
        }
      } else {
        undef $pv;
        ($t, $pv) = $Prop->{'border-top-width'}->{parse}
            ->($self, $prop_name.'-width',
               $tt, $t, $onerror)
            if not defined $prop_value{$prop_name.'-width'} and
                {
                  DIMENSION_TOKEN, 1,
                  NUMBER_TOKEN, 1,
                  IDENT_TOKEN, 1,
                  MINUS_TOKEN, 1,
                }->{$t->{type}};
        if (defined $pv) {
          if ($pv->{$prop_name.'-width'}->[0] eq 'INHERIT') {
            $onerror->(type => 'syntax error:'.$prop_name,
                       level => $self->{must_level},
                       token => $t);
          } else {
            $prop_value{$prop_name.'-width'} = $pv->{$prop_name.'-width'};
          }
        } else {
          last;
        }
      }    
    }

    $prop_value{$prop_name.'-color'}
        ||= $Prop->{$prop_name.'-color'}->{initial};
    $prop_value{$prop_name.'-width'}
        ||= $Prop->{$prop_name.'-width'}->{initial};
    $prop_value{$prop_name.'-style'}
        ||= $Prop->{$prop_name.'-style'}->{initial};
    
    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my $width_prop = $prop_name . '_width';  $width_prop =~ tr/-/_/;
    my $width_value = $self->$width_prop;
    return '' unless length $width_value;
    my $style_prop = $prop_name . '_style';  $style_prop =~ tr/-/_/;
    my $style_value = $self->$style_prop;
    return '' unless length $style_value;
    my $color_prop = $prop_name . '_color';  $color_prop =~ tr/-/_/;
    my $color_value = $self->$color_prop;
    return '' unless length $color_value;

    return $width_value . ' ' . $style_value . ' ' . $color_value;
  },
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
};
$Attr->{border_top} = $Prop->{'border-top'};

$Prop->{'border-right'} = {
  css => 'border-right',
  dom => 'border_right',
  parse => $Prop->{'border-top'}->{parse},
  serialize => $Prop->{'border-top'}->{serialize},
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
};
$Attr->{border_right} = $Prop->{'border-right'};

$Prop->{'border-bottom'} = {
  css => 'border-bottom',
  dom => 'border_bottom',
  parse => $Prop->{'border-top'}->{parse},
  serialize => $Prop->{'border-top'}->{serialize},
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
};
$Attr->{border_bottom} = $Prop->{'border-bottom'};

$Prop->{'border-left'} = {
  css => 'border-left',
  dom => 'border_left',
  parse => $Prop->{'border-top'}->{parse},
  serialize => $Prop->{'border-top'}->{serialize},
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
};
$Attr->{border_left} = $Prop->{'border-left'};

$Prop->{outline} = {
  css => 'outline',
  dom => 'outline',
  parse => $Prop->{'border-top'}->{parse},
  serialize => $Prop->{'border-top'}->{serialize},
  serialize_multiple => $Prop->{'outline-color'}->{serialize_multiple},
};
$Attr->{outline} = $Prop->{outline};

$Prop->{border} = {
  css => 'border',
  dom => 'border',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;
    my $prop_value;
    ($t, $prop_value) = $Prop->{'border-top'}->{parse}
        ->($self, 'border-top', $tt, $t, $onerror);
    return ($t, undef) unless defined $prop_value;
    
    for (qw/border-right border-bottom border-left/) {
      $prop_value->{$_.'-color'} = $prop_value->{'border-top-color'}
          if defined $prop_value->{'border-top-color'};
      $prop_value->{$_.'-style'} = $prop_value->{'border-top-style'}
          if defined $prop_value->{'border-top-style'};
      $prop_value->{$_.'-width'} = $prop_value->{'border-top-width'}
          if defined $prop_value->{'border-top-width'};
    }
    return ($t, $prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my $bt = $self->border_top;
    return '' unless length $bt;
    my $br = $self->border_right;
    return '' unless length $br;
    return '' unless $bt eq $br;
    my $bb = $self->border_bottom;
    return '' unless length $bb;
    return '' unless $bt eq $bb;
    my $bl = $self->border_left;
    return '' unless length $bl;
    return '' unless $bt eq $bl;

    return $bt;
  },
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
};
$Attr->{border} = $Prop->{border};

$Prop->{margin} = {
  css => 'margin',
  dom => 'margin',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit}) {
        $prop_value{'margin-top'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'margin-top'} = ['PERCENTAGE', $value];
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'margin-top'} = ['DIMENSION', $value, 'px'];
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ($prop_value eq 'auto') {
        $prop_value{'margin-top'} = ['KEYWORD', $prop_value];
      } elsif ($prop_value eq 'inherit') {
        $prop_value{'margin-top'} = ['INHERIT'];
        $prop_value{'margin-right'} = $prop_value{'margin-top'};
        $prop_value{'margin-bottom'} = $prop_value{'margin-top'};
        $prop_value{'margin-left'} = $prop_value{'margin-right'};
        return ($t, \%prop_value);
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      $onerror->(type => 'syntax error:'.$prop_name,
                 level => $self->{must_level},
                 token => $t);
      return ($t, undef);
    }
    $prop_value{'margin-right'} = $prop_value{'margin-top'};
    $prop_value{'margin-bottom'} = $prop_value{'margin-top'};
    $prop_value{'margin-left'} = $prop_value{'margin-right'};

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit}) {
        $prop_value{'margin-right'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'margin-right'} = ['PERCENTAGE', $value];
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'margin-right'} = ['DIMENSION', $value, 'px'];
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ($prop_value eq 'auto') {
        $prop_value{'margin-right'} = ['KEYWORD', $prop_value];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }
    $prop_value{'margin-left'} = $prop_value{'margin-right'};

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit}) {
        $prop_value{'margin-bottom'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'margin-bottom'} = ['PERCENTAGE', $value];
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'margin-bottom'} = ['DIMENSION', $value, 'px'];
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ($prop_value eq 'auto') {
        $prop_value{'margin-bottom'} = ['KEYWORD', $prop_value];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit}) {
        $prop_value{'margin-left'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'margin-left'} = ['PERCENTAGE', $value];
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'margin-left'} = ['DIMENSION', $value, 'px'];
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ($prop_value eq 'auto') {
        $prop_value{'margin-left'} = ['KEYWORD', $prop_value];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }

    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my @v;
    push @v, $self->margin_top;
    return '' unless length $v[-1];
    push @v, $self->margin_right;
    return '' unless length $v[-1];
    push @v, $self->margin_bottom;
    return '' unless length $v[-1];
    push @v, $self->margin_left;
    return '' unless length $v[-1];

    pop @v if $v[1] eq $v[3];
    pop @v if $v[0] eq $v[2];
    pop @v if $v[0] eq $v[1];
    return join ' ', @v;
  },
};
$Attr->{margin} = $Prop->{margin};

$Prop->{padding} = {
  css => 'padding',
  dom => 'padding',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'padding-top'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'padding-top'} = ['PERCENTAGE', $value];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'padding-top'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ($prop_value eq 'inherit') {
        $prop_value{'padding-top'} = ['INHERIT'];
        $prop_value{'padding-right'} = $prop_value{'padding-top'};
        $prop_value{'padding-bottom'} = $prop_value{'padding-top'};
        $prop_value{'padding-left'} = $prop_value{'padding-right'};
        return ($t, \%prop_value);
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      $onerror->(type => 'syntax error:'.$prop_name,
                 level => $self->{must_level},
                 token => $t);
      return ($t, undef);
    }
    $prop_value{'padding-right'} = $prop_value{'padding-top'};
    $prop_value{'padding-bottom'} = $prop_value{'padding-top'};
    $prop_value{'padding-left'} = $prop_value{'padding-right'};

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'padding-right'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'padding-right'} = ['PERCENTAGE', $value];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'padding-right'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }
    $prop_value{'padding-left'} = $prop_value{'padding-right'};

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'padding-bottom'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'padding-bottom'} = ['PERCENTAGE', $value];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'padding-bottom'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'padding-left'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'padding-left'} = ['PERCENTAGE', $value];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'padding-left'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }

    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my @v;
    push @v, $self->padding_top;
    return '' unless length $v[-1];
    push @v, $self->padding_right;
    return '' unless length $v[-1];
    push @v, $self->padding_bottom;
    return '' unless length $v[-1];
    push @v, $self->padding_left;
    return '' unless length $v[-1];

    pop @v if $v[1] eq $v[3];
    pop @v if $v[0] eq $v[2];
    pop @v if $v[0] eq $v[1];
    return join ' ', @v;
  },
};
$Attr->{padding} = $Prop->{padding};

$Prop->{'border-spacing'} = {
  css => 'border-spacing',
  dom => 'border_spacing',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'-manakai-border-spacing-x'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'-manakai-border-spacing-x'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ($prop_value eq 'inherit') {
        $prop_value{'-manakai-border-spacing-x'} = ['INHERIT'];
        $prop_value{'-manakai-border-spacing-y'}
            = $prop_value{'-manakai-border-spacing-x'};
        return ($t, \%prop_value);
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      $onerror->(type => 'syntax error:'.$prop_name,
                 level => $self->{must_level},
                 token => $t);
      return ($t, undef);
    }
    $prop_value{'-manakai-border-spacing-y'}
        = $prop_value{'-manakai-border-spacing-x'};

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'-manakai-border-spacing-y'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'-manakai-border-spacing-y'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }

    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my @v;
    push @v, $self->_manakai_border_spacing_x;
    return '' unless length $v[-1];
    push @v, $self->_manakai_border_spacing_y;
    return '' unless length $v[-1];

    pop @v if $v[0] eq $v[1];
    return join ' ', @v;
  },
  serialize_multiple => $Prop->{'-manakai-border-spacing-x'}
      ->{serialize_multiple},
};
$Attr->{border_spacing} = $Prop->{'border-spacing'};

## NOTE: See <http://suika.fam.cx/gate/2005/sw/background-position> for
## browser compatibility problems.
$Prop->{'background-position'} = {
  css => 'background-position',
  dom => 'background_position',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit}) {
        $prop_value{'background-position-x'} = ['DIMENSION', $value, $unit];
        $prop_value{'background-position-y'} = ['PERCENTAGE', 50];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'background-position-x'} = ['PERCENTAGE', $value];
      $prop_value{'background-position-y'} = ['PERCENTAGE', 50];
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'background-position-x'} = ['DIMENSION', $value, 'px'];
      $prop_value{'background-position-y'} = ['PERCENTAGE', 50];
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ({left => 1, center => 1, right => 1}->{$prop_value}) {
        $prop_value{'background-position-x'} = ['KEYWORD', $prop_value];
        $prop_value{'background-position-y'} = ['KEYWORD', 'center'];
      } elsif ($prop_value eq 'top' or $prop_value eq 'bottom') {
        $prop_value{'background-position-y'} = ['KEYWORD', $prop_value];

        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
        if ($t->{type} == IDENT_TOKEN) {
          my $prop_value = lc $t->{value}; ## TODO: case folding
          if ({left => 1, center => 1, right => 1}->{$prop_value}) {
            $prop_value{'background-position-x'} = ['KEYWORD', $prop_value];
            $t = $tt->get_next_token;
            return ($t, \%prop_value);
          }
        }
        $prop_value{'background-position-x'} = ['KEYWORD', 'center'];
        return ($t, \%prop_value);
      } elsif ($prop_value eq 'inherit') {
        $prop_value{'background-position-x'} = ['INHERIT'];
        $prop_value{'background-position-y'} = ['INHERIT'];
        return ($t, \%prop_value);
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      $onerror->(type => 'syntax error:'.$prop_name,
                 level => $self->{must_level},
                 token => $t);
      return ($t, undef);
    }

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit}) {
        $prop_value{'background-position-y'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == PERCENTAGE_TOKEN) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'background-position-y'} = ['PERCENTAGE', $value];
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'background-position-y'} = ['DIMENSION', $value, 'px'];
    } elsif ($t->{type} == IDENT_TOKEN) {
      my $value = lc $t->{value}; ## TODO: case
      if ({top => 1, center => 1, bottom => 1}->{$value}) {
        $prop_value{'background-position-y'} = ['KEYWORD', $value];
        $t = $tt->get_next_token;
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }

    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my $x = $self->background_position_x;
    my $y = $self->background_position_y;
    return $x . ' ' . $y if length $x and length $y;
    return '';
  },
  serialize_multiple => $Prop->{'background-color'}->{serialize_multiple},
};
$Attr->{background_position} = $Prop->{'background-position'};

$Prop->{background} = {
  css => 'background',
  dom => 'background',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;
    my %prop_value;
    B: for (1..5) {
      my $sign = 1;
      if ($t->{type} == MINUS_TOKEN) {
        $sign = -1;
        $t = $tt->get_next_token;
      }

      if ($sign > 0 and $t->{type} == IDENT_TOKEN) {
        my $value = lc $t->{value}; ## TODO: case
        if ($Prop->{'background-repeat'}->{keyword}->{$value} and
            $self->{prop_value}->{'background-repeat'}->{$value} and
            not defined $prop_value{'background-repeat'}) {
          $prop_value{'background-repeat'} = ['KEYWORD', $value];
          $t = $tt->get_next_token;
        } elsif ($Prop->{'background-attachment'}->{keyword}->{$value} and
                 $self->{prop_value}->{'background-attachment'}->{$value} and
                 not defined $prop_value{'background-attachment'}) {
          $prop_value{'background-attachment'} = ['KEYWORD', $value];
          $t = $tt->get_next_token;
        } elsif ($value eq 'none' and
                 not defined $prop_value{'background-image'}) {
          $prop_value{'background-image'} = ['KEYWORD', $value];
          $t = $tt->get_next_token;
        } elsif ({left => 1, center => 1, right => 1}->{$value} and
                 not defined $prop_value{'background-position-x'}) {
          $prop_value{'background-position-x'} = ['KEYWORD', $value];
          $t = $tt->get_next_token;
          $t = $tt->get_next_token while $t->{type} == S_TOKEN;
          my $sign = 1;
          if ($t->{type} == MINUS_TOKEN) {
            $sign = -1;
            $t = $tt->get_next_token;
          }
          if ($sign > 0 and $t->{type} == IDENT_TOKEN) {
            my $value = lc $t->{value}; ## TODO: case
            if ({top => 1, bottom => 1, center => 1}->{$value}) {
              $prop_value{'background-position-y'} = ['KEYWORD', $value];
              $t = $tt->get_next_token;
            } elsif ($prop_value{'background-position-x'}->[1] eq 'center' and
                     $value eq 'left' or $value eq 'right') {
              $prop_value{'background-position-y'} = ['KEYWORD', 'center'];
              $prop_value{'background-position-x'} = ['KEYWORD', $value];
              $t = $tt->get_next_token;
            } else {
              $prop_value{'background-position-y'} = ['KEYWORD', 'center'];
            }
          } elsif ($t->{type} == DIMENSION_TOKEN) {
            my $value = $t->{number} * $sign;
            my $unit = lc $t->{value}; ## TODO: case
            $t = $tt->get_next_token;
            if ($length_unit->{$unit}) {
              $prop_value{'background-position-y'}
                  = ['DIMENSION', $value, $unit];
            } else {
              $onerror->(type => 'syntax error:'.$prop_name,
                         level => $self->{must_level},
                         token => $t);
              last B;
            }
          } elsif ($t->{type} == PERCENTAGE_TOKEN) {
            my $value = $t->{number} * $sign;
            $t = $tt->get_next_token;
            $prop_value{'background-position-y'} = ['PERCENTAGE', $value];
          } elsif ($t->{type} == NUMBER_TOKEN and
                   ($self->{unitless_px} or $t->{number} == 0)) {
            my $value = $t->{number} * $sign;
            $t = $tt->get_next_token;
            $prop_value{'background-position-y'} = ['DIMENSION', $value, 'px'];
          } elsif ($sign < 0) {
            $onerror->(type => 'syntax error:'.$prop_name,
                       level => $self->{must_level},
                       token => $t);
            last B;
          }
        } elsif (($value eq 'top' or $value eq 'bottom') and
                 not defined $prop_value{'background-position-y'}) {
          $prop_value{'background-position-y'} = ['KEYWORD', $value];
          $t = $tt->get_next_token;
          $t = $tt->get_next_token while $t->{type} == S_TOKEN;
          if ($t->{type} == IDENT_TOKEN and ## TODO: case
              {left => 1, center => 1, right => 1}->{lc $t->{value}}) {
            $prop_value{'background-position-x'} = ['KEYWORD', $value];
            $t = $tt->get_next_token;
          } else {
            $prop_value{'background-position-x'} = ['KEYWORD', 'center'];
          }
        } elsif ($value eq 'inherit' and not keys %prop_value) {
          $prop_value{'background-color'} =
          $prop_value{'background-image'} =
          $prop_value{'background-repeat'} =
          $prop_value{'background-attachment'} = 
          $prop_value{'background-position-x'} =
          $prop_value{'background-position-y'} = ['INHERIT'];
          $t = $tt->get_next_token;
          return ($t, \%prop_value);
        } elsif (not defined $prop_value{'background-color'} or
                 not keys %prop_value) {
          ($t, my $pv) = $parse_color->($self, 'background', $tt, $t,
                                        $onerror);
          if (defined $pv) {
            $prop_value{'background-color'} = $pv->{background};
          } else {
            ## NOTE: An error should already be raiased.
            return ($t, undef);
          }
        }
      } elsif (($t->{type} == DIMENSION_TOKEN or
                $t->{type} == PERCENTAGE_TOKEN or
                ($t->{type} == NUMBER_TOKEN and
                 $t->{unitless_px} or $t->{number} == 0)) and
               not defined $prop_value{'background-position-x'}) {
        if ($t->{type} == DIMENSION_TOKEN) {
          my $value = $t->{number} * $sign;
          my $unit = lc $t->{value}; ## TODO: case
          $t = $tt->get_next_token;
          if ($length_unit->{$unit}) {
            $prop_value{'background-position-x'}
                = ['DIMENSION', $value, $unit];
          } else {
            $onerror->(type => 'syntax error:'.$prop_name,
                       level => $self->{must_level},
                       token => $t);
            last B;
          }
        } elsif ($t->{type} == PERCENTAGE_TOKEN) {
          my $value = $t->{number} * $sign;
          $t = $tt->get_next_token;
          $prop_value{'background-position-x'} = ['PERCENTAGE', $value];
        } elsif ($t->{type} == NUMBER_TOKEN and
                 ($self->{unitless_px} or $t->{number} == 0)) {
          my $value = $t->{number} * $sign;
          $t = $tt->get_next_token;
          $prop_value{'background-position-x'} = ['DIMENSION', $value, 'px'];
        } else {
          ## NOTE: Should not be happened.
          last B;
        }
        
        $t = $tt->get_next_token while $t->{type} == S_TOKEN;
        if ($t->{type} == MINUS_TOKEN) {
          $sign = -1;
          $t = $tt->get_next_token;
        } else {
          $sign = 1;
        }

        if ($t->{type} == DIMENSION_TOKEN) {
          my $value = $t->{number} * $sign;
          my $unit = lc $t->{value}; ## TODO: case
          $t = $tt->get_next_token;
          if ($length_unit->{$unit}) {
            $prop_value{'background-position-y'}
                = ['DIMENSION', $value, $unit];
          } else {
            $onerror->(type => 'syntax error:'.$prop_name,
                       level => $self->{must_level},
                       token => $t);
            last B;
          }
        } elsif ($t->{type} == PERCENTAGE_TOKEN) {
          my $value = $t->{number} * $sign;
          $t = $tt->get_next_token;
          $prop_value{'background-position-y'} = ['PERCENTAGE', $value];
        } elsif ($t->{type} == NUMBER_TOKEN and
                 ($self->{unitless_px} or $t->{number} == 0)) {
          my $value = $t->{number} * $sign;
          $t = $tt->get_next_token;
          $prop_value{'background-position-y'} = ['DIMENSION', $value, 'px'];
        } elsif ($t->{type} == IDENT_TOKEN) {
          my $value = lc $t->{value}; ## TODO: case
          if ({top => 1, center => 1, bottom => 1}->{$value}) {
            $prop_value{'background-position-y'} = ['KEYWORD', $value];
            $t = $tt->get_next_token;
          } else {
            $prop_value{'background-position-y'} = ['PERCENTAGE', 50];
          }
        } else {
          if ($sign > 0) {
            $prop_value{'background-position-y'} = ['PERCENTAGE', 50];
          } else {
            $onerror->(type => 'syntax error:'.$prop_name,
                       level => $self->{must_level},
                       token => $t);
          }
        }
      } elsif ($t->{type} == URI_TOKEN and
               not defined $prop_value{'background-image'}) {
        $prop_value{'background-image'} = ['URI', $t->{value}];
        $t = $tt->get_next_token;
      } else {
        if (keys %prop_value and $sign > 0) {
          last B;
        } else {
          $onerror->(type => 'syntax error:'.$prop_name,
                     level => $self->{must_level},
                     token => $t);
        }
      }

      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    } # B

    $prop_value{$_} ||= $Prop->{$_}->{initial}
        for qw/background-image background-attachment background-repeat
               background-color background-position-x background-position-y/;

    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my $color = $self->background_color;
    return '' unless length $color;
    my $image = $self->background_image;
    return '' unless length $image;
    my $repeat = $self->background_repeat;
    return '' unless length $repeat;
    my $attachment = $self->background_attachment;
    return '' unless length $attachment;
    my $position = $self->background_position;
    return '' unless length $position;

    my @v;
    push @v, $color unless $color eq 'transparent';
    push @v, $image unless $image eq 'none';
    push @v, $repeat unless $repeat eq 'repeat';
    push @v, $attachment unless $attachment eq 'scroll';
    push @v, $position unless $position eq '0% 0%';
    if (@v) {
      return join ' ', @v;
    } else {
      return 'transparent none repeat scroll 0% 0%';
    }
  },
  serialize_multiple => $Prop->{'background-color'}->{serialize_multiple},
};
$Attr->{background} = $Prop->{background};

$Prop->{font} = {
  css => 'font',
  dom => 'font',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;

    A: for (1..3) {
      if ($t->{type} == IDENT_TOKEN) {
        my $value = lc $t->{value}; ## TODO: case
        if ($value eq 'normal') {
          $t = $tt->get_next_token;
        } elsif ($Prop->{'font-style'}->{keyword}->{$value} and
                 $self->{prop_value}->{'font-style'}->{$value} and
                 not defined $prop_value{'font-style'}) {
          $prop_value{'font-style'} = ['KEYWORD', $value];
          $t = $tt->get_next_token;
        } elsif ($Prop->{'font-variant'}->{keyword}->{$value} and
                 $self->{prop_value}->{'font-variant'}->{$value} and
                 not defined $prop_value{'font-variant'}) {
          $prop_value{'font-variant'} = ['KEYWORD', $value];
          $t = $tt->get_next_token;
        } elsif ({normal => 1, bold => 1,
                  bolder => 1, lighter => 1}->{$value} and
                 not defined $prop_value{'font-weight'}) {
          $prop_value{'font-weight'} = ['KEYWORD', $value];
          $t = $tt->get_next_token;
        } elsif ($value eq 'inherit' and 0 == keys %prop_value) {
          $t = $tt->get_next_token;
          return ($t, {'font-style' => ['INHERIT'],
                       'font-variant' => ['INHERIT'],
                       'font-weight' => ['INHERIT'],
                       'font-size' => ['INHERIT'],
                       'line-height' => ['INHERIT'],
                       'font-family' => ['INHERIT']});
        } elsif ({
                  caption => 1, icon => 1, menu => 1, 
                  'message-box' => 1, 'small-caption' => 1, 'status-bar' => 1,
                 }->{$value} and 0 == keys %prop_value) {
          $t = $tt->get_next_token;
          return ($t, $self->{get_system_font}->($self, $value, {
            'font-style' => $Prop->{'font-style'}->{initial},
            'font-variant' => $Prop->{'font-variant'}->{initial},
            'font-weight' => $Prop->{'font-weight'}->{initial},
            'font-size' => $Prop->{'font-size'}->{initial},
            'line-height' => $Prop->{'line-height'}->{initial},
            'font-family' => ['FONT', ['KEYWORD', '-manakai-'.$value]],
          }));
        } else {
          if (keys %prop_value) {
            last A;
          } else {
            $onerror->(type => 'syntax error:'.$prop_name,
                       level => $self->{must_level},
                       token => $t);
            return ($t, undef);
          }
        }
      } elsif ($t->{type} == NUMBER_TOKEN) {
        if ({100 => 1, 200 => 1, 300 => 1, 400 => 1, 500 => 1,
             600 => 1, 700 => 1, 800 => 1, 900 => 1}->{$t->{value}}) {
          $prop_value{'font-weight'} = ['NUMBER', $t->{value}];
          $t = $tt->get_next_token;
        } else {
          last A;
        }
      }

      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    } # A
    
    for (qw/font-style font-variant font-weight/) {
      $prop_value{$_} = $Prop->{$_}->{initial} unless defined $prop_value{$_};
    }
      
    ($t, my $pv) = $Prop->{'font-size'}->{parse}
        ->($self, 'font', $tt, $t, $onerror);
    return ($t, undef) unless defined $pv;
    if ($pv->{font}->[0] eq 'INHERIT') {
      $onerror->(type => 'syntax error:'.$prop_name,
                 level => $self->{must_level},
                 token => $t);
      return ($t, undef);
    }
    $prop_value{'font-size'} = $pv->{font};

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    if ($t->{type} == DELIM_TOKEN and $t->{value} eq '/') {
      $t = $tt->get_next_token;
      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      ($t, my $pv) = $Prop->{'line-height'}->{parse}
          ->($self, 'font', $tt, $t, $onerror);
      return ($t, undef) unless defined $pv;
      if ($pv->{font}->[0] eq 'INHERIT') {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      $prop_value{'line-height'} = $pv->{font};
      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    } else {
      $prop_value{'line-height'} = $Prop->{'line-height'}->{initial};
    }

    undef $pv;
    ($t, $pv) = $Prop->{'font-family'}->{parse}
        ->($self, 'font', $tt, $t, $onerror);
    return ($t, undef) unless defined $pv;
    $prop_value{'font-family'} = $pv->{font};

    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my $style = $self->font_style;
    my $i = $self->get_property_priority ('font-style');
    return '' unless length $style;
    my $variant = $self->font_variant;
    return '' unless length $variant;
    return '' if $i ne $self->get_property_priority ('font-variant');
    my $weight = $self->font_weight;
    return '' unless length $weight;
    return '' if $i ne $self->get_property_priority ('font-weight');
    my $size = $self->font_size;
    return '' unless length $size;
    return '' if $i ne $self->get_property_priority ('font-size');
    my $height = $self->line_height;
    return '' unless length $height;
    return '' if $i ne $self->get_property_priority ('line-height');
    my $family = $self->font_family;
    return '' unless length $family;
    return '' if $i ne $self->get_property_priority ('font-family');
    
    my @v;
    push @v, $style unless $style eq 'normal';
    push @v, $variant unless $variant eq 'normal';
    push @v, $weight unless $weight eq 'normal';
    push @v, $size.($height eq 'normal' ? '' : '/'.$height);
    push @v, $family;
    push @v, '! '.$i if length $i;
    return join ' ', @v;
  },
};
$Attr->{font} = $Prop->{font};

$Prop->{'border-width'} = {
  css => 'border-width',
  dom => 'border_width',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;

    my $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'border-top-width'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'border-top-width'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case folding
      $t = $tt->get_next_token;
      if ({thin => 1, medium => 1, thick => 1}->{$prop_value}) {
        $prop_value{'border-top-width'} = ['KEYWORD', $prop_value];
      } elsif ($prop_value eq 'inherit') {
        $prop_value{'border-top-width'} = ['INHERIT'];
        $prop_value{'border-right-width'} = $prop_value{'border-top-width'};
        $prop_value{'border-bottom-width'} = $prop_value{'border-top-width'};
        $prop_value{'border-left-width'} = $prop_value{'border-right-width'};
        return ($t, \%prop_value);
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } else {
      $onerror->(type => 'syntax error:'.$prop_name,
                 level => $self->{must_level},
                 token => $t);
      return ($t, undef);
    }
    $prop_value{'border-right-width'} = $prop_value{'border-top-width'};
    $prop_value{'border-bottom-width'} = $prop_value{'border-top-width'};
    $prop_value{'border-left-width'} = $prop_value{'border-right-width'};

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'border-right-width'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'border-right-width'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case
      if ({thin => 1, medium => 1, thick => 1}->{$prop_value}) {
        $prop_value{'border-right-width'} = ['KEYWORD', $prop_value];
        $t = $tt->get_next_token;
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }
    $prop_value{'border-left-width'} = $prop_value{'border-right-width'};

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'border-bottom-width'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'border-bottom-width'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case
      if ({thin => 1, medium => 1, thick => 1}->{$prop_value}) {
        $prop_value{'border-bottom-width'} = ['KEYWORD', $prop_value];
        $t = $tt->get_next_token;
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }

    $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    $sign = 1;
    if ($t->{type} == MINUS_TOKEN) {
      $t = $tt->get_next_token;
      $sign = -1;
    }

    if ($t->{type} == DIMENSION_TOKEN) {
      my $value = $t->{number} * $sign;
      my $unit = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($length_unit->{$unit} and $value >= 0) {
        $prop_value{'border-left-width'} = ['DIMENSION', $value, $unit];
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($t->{type} == NUMBER_TOKEN and
             ($self->{unitless_px} or $t->{number} == 0)) {
      my $value = $t->{number} * $sign;
      $t = $tt->get_next_token;
      $prop_value{'border-left-width'} = ['DIMENSION', $value, 'px'];
      unless ($value >= 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    } elsif ($sign > 0 and $t->{type} == IDENT_TOKEN) {
      my $prop_value = lc $t->{value}; ## TODO: case
      if ({thin => 1, medium => 1, thick => 1}->{$prop_value}) {
        $prop_value{'border-left-width'} = ['KEYWORD', $prop_value];
        $t = $tt->get_next_token;
      }
    } else {
      if ($sign < 0) {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      return ($t, \%prop_value);
    }

    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    my @v;
    push @v, $self->border_top_width;
    return '' unless length $v[-1];
    push @v, $self->border_right_width;
    return '' unless length $v[-1];
    push @v, $self->border_bottom_width;
    return '' unless length $v[-1];
    push @v, $self->border_left_width;
    return '' unless length $v[-1];

    pop @v if $v[1] eq $v[3];
    pop @v if $v[0] eq $v[2];
    pop @v if $v[0] eq $v[1];
    return join ' ', @v;
  },
  serialize_multiple => $Prop->{'border-top-color'}->{serialize_multiple},
};
$Attr->{border_width} = $Prop->{'border-width'};

$Prop->{'list-style'} = {
  css => 'list-style',
  dom => 'list_style',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my %prop_value;
    my $none = 0;

    F: for my $f (1..3) {
      if ($t->{type} == IDENT_TOKEN) {
        my $prop_value = lc $t->{value}; ## TODO: case folding
        $t = $tt->get_next_token;

        if ($prop_value eq 'none') {
          $none++;
        } elsif ($Prop->{'list-style-type'}->{keyword}->{$prop_value}) {
          if (exists $prop_value{'list-style-type'}) {
            $onerror->(type => q[syntax error:duplicate:'list-style-type':].
                           $prop_name,
                       level => $self->{must_level},
                       token => $t);
            return ($t, undef);
          } else {
            $prop_value{'list-style-type'} = ['KEYWORD', $prop_value];
          }
        } elsif ($Prop->{'list-style-position'}->{keyword}->{$prop_value}) {
          if (exists $prop_value{'list-style-position'}) {
            $onerror->(type => q[syntax error:duplicate:'list-style-position':].
                           $prop_name,
                       level => $self->{must_level},
                       token => $t);
            return ($t, undef);
          }

          $prop_value{'list-style-position'} = ['KEYWORD', $prop_value];
        } elsif ($f == 1 and $prop_value eq 'inherit') {
          $prop_value{'list-style-type'} = ["INHERIT"];
          $prop_value{'list-style-position'} = ["INHERIT"];
          $prop_value{'list-style-image'} = ["INHERIT"];
          last F;
        } else {
          if ($f == 1) {
            $onerror->(type => 'syntax error:'.$prop_name,
                       level => $self->{must_level},
                       token => $t);
            return ($t, undef);
          } else {
            last F;
          }
        }
      } elsif ($t->{type} == URI_TOKEN) {
        if (exists $prop_value{'list-style-image'}) {
          $onerror->(type => q[syntax error:duplicate:'list-style-image':].
                         $prop_name,
                     level => $self->{must_level},
                     token => $t);
          return ($t, undef);
        }
        
        $prop_value{'list-style-image'}
            = ['URI', $t->{value}, \($self->{base_uri})];
        $t = $tt->get_next_token;
      } else {
        if ($f == 1) {
          $onerror->(type => 'syntax error:keyword:'.$prop_name,
                     level => $self->{must_level},
                     token => $t);
          return ($t, undef);
        } else {
          last F;
        }
      }

      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
    } # F
    ## NOTE: No browser support |list-style: url(xxx|{EOF}.

    if ($none == 1) {
      if (exists $prop_value{'list-style-type'}) {
        if (exists $prop_value{'list-style-image'}) {
          $onerror->(type => q[syntax error:duplicate:'list-style-image':].
                         $prop_name,
                     level => $self->{must_level},
                     token => $t);
          return ($t, undef);
        } else {
          $prop_value{'list-style-image'} = ['KEYWORD', 'none'];
        }
      } else {
        $prop_value{'list-style-type'} = ['KEYWORD', 'none'];
        $prop_value{'list-style-image'} = ['KEYWORD', 'none']
            unless exists $prop_value{'list-style-image'};
      }
    } elsif ($none == 2) {
      if (exists $prop_value{'list-style-type'}) {
        $onerror->(type => q[syntax error:duplicate:'list-style-type':].
                       $prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      if (exists $prop_value{'list-style-image'}) {
        $onerror->(type => q[syntax error:duplicate:'list-style-image':].
                       $prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
      
      $prop_value{'list-style-type'} = ['KEYWORD', 'none'];
      $prop_value{'list-style-image'} = ['KEYWORD', 'none'];
    } elsif ($none == 3) {
      $onerror->(type => q[syntax error:duplicate:'list-style-type':].
                     $prop_name,
                 level => $self->{must_level},
                 token => $t);
      return ($t, undef);
    }

    for (qw/list-style-type list-style-position list-style-image/) {
      $prop_value{$_} = $Prop->{$_}->{initial} unless exists $prop_value{$_};
    }

    return ($t, \%prop_value);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    
    local $Error::Depth = $Error::Depth + 1;
    return $self->list_style_type . ' ' . $self->list_style_position .
        ' ' . $self->list_style_image;
  },
};
$Attr->{list_style} = $Prop->{'list-style'};

## NOTE: Future version of the implementation will change the way to
## store the parsed value to support CSS 3 properties.
$Prop->{'text-decoration'} = {
  css => 'text-decoration',
  dom => 'text_decoration',
  key => 'text_decoration',
  parse => sub {
    my ($self, $prop_name, $tt, $t, $onerror) = @_;

    my $value = ['DECORATION']; # , underline, overline, line-through, blink

    if ($t->{type} == IDENT_TOKEN) {
      my $v = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($v eq 'inherit') {
        return ($t, {$prop_name => ['INHERIT']});
      } elsif ($v eq 'none') {
        return ($t, {$prop_name => $value});
      } elsif ($v eq 'underline' and
               $self->{prop_value}->{$prop_name}->{$v}) {
        $value->[1] = 1;
      } elsif ($v eq 'overline' and
               $self->{prop_value}->{$prop_name}->{$v}) {
        $value->[2] = 1;
      } elsif ($v eq 'line-through' and
               $self->{prop_value}->{$prop_name}->{$v}) {
        $value->[3] = 1;
      } elsif ($v eq 'blink' and
               $self->{prop_value}->{$prop_name}->{$v}) {
        $value->[4] = 1;
      } else {
        $onerror->(type => 'syntax error:'.$prop_name,
                   level => $self->{must_level},
                   token => $t);
        return ($t, undef);
      }
    }

    F: {
      $t = $tt->get_next_token while $t->{type} == S_TOKEN;
      last F unless $t->{type} == IDENT_TOKEN;

      my $v = lc $t->{value}; ## TODO: case
      $t = $tt->get_next_token;
      if ($v eq 'underline' and
          $self->{prop_value}->{$prop_name}->{$v}) {
        $value->[1] = 1;
      } elsif ($v eq 'overline' and
               $self->{prop_value}->{$prop_name}->{$v}) {
        $value->[1] = 2;
      } elsif ($v eq 'line-through' and
               $self->{prop_value}->{$prop_name}->{$v}) {
        $value->[1] = 3;
      } elsif ($v eq 'blink' and
               $self->{prop_value}->{$prop_name}->{$v}) {
        $value->[1] = 4;
      } else {
        last F;
      }

      redo F;
    } # F

    return ($t, {$prop_name => $value});
  },
  serialize => $default_serializer,
  initial => ["KEYWORD", "none"],
  #inherited => 0,
  compute => $compute_as_specified,
};
$Attr->{text_decoration} = $Prop->{'text-decoration'};
$Key->{text_decoration} = $Prop->{'text-decoration'};

1;
## $Date: 2008/01/14 10:02:46 $