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;

  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 = {};
  $sp->{lookup_namespace_uri} = sub {
    return $nsmap->{$_[0]}; # $_[0] is '' (default namespace) or prefix
  }; # $sp->{lookup_namespace_uri}

  ## TODO: Supported pseudo classes and elements...

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

  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: 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) {
                $nsmap->{defined $prefix ? $prefix : ''} = $uri;
                push @$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 = $tt->get_next_token;
        if ($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 = (defined $prop_flag and $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 = $tt->get_next_token;
            ## Stay in the state.
            redo S;
          }
        } else {
          #
        }
      } else {
        if ($t->{type} == SEMICOLON_TOKEN) {
          $t = $tt->get_next_token;
          $state = $state == IGNORED_STATEMENT_STATE
              ? BEFORE_STATEMENT_STATE : BEFORE_DECLARATION_STATE;
          redo S;
        } elsif ($state == IGNORED_DECLARATION_STATE and
                 $t->{type} == RBRACE_TOKEN) {
          $t = $tt->get_next_token;
          $state = BEFORE_STATEMENT_STATE;
          redo S;
        } elsif ($t->{type} == EOF_TOKEN) {
          ## Reprocess.
          $state = $state == IGNORED_STATEMENT_STATE
              ? BEFORE_STATEMENT_STATE : BEFORE_DECLARATION_STATE;
          redo S;
        } else {
          #
        }
      }

      while (not {
        EOF_TOKEN, 1,
        RBRACE_TOKEN, 1,
        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
      (css_rules => $open_rules->[0],
       ## TODO: href
       ## TODO: owner_node
       ## TODO: media
       type => 'text/css', ## TODO: OK?
       _parser => $self);
  return $ss;
} # parse_char_string

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

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

    if ($t->{type} == IDENT_TOKEN) {
      if (lc $t->{value} eq 'blue') { ## TODO: case folding
        $t = $tt->get_next_token;
        return ($t, {$prop_name => ["RGBA", 0, 0, 255, 1]});
      } else {
        #
      }
    } else {
      #
    }

    $onerror->(type => 'syntax error:color',
               level => $self->{must_level},
               token => $t);
    
    return ($t, undef);
  },
  serialize => sub {
    my ($self, $prop_name, $value) = @_;
    if ($value->[0] eq 'RGBA') { ## TODO: %d? %f?
      return sprintf 'rgba(%d, %d, %d, %f)', @$value[1, 2, 3, 4];
    } else {
      return undef;
    }
  },
  initial => ["KEYWORD", "-manakai-initial-color"], ## NOTE: UA-dependent in CSS 2.1.
  inherited => 1,
  compute => $compute_as_specified,
};
$Attr->{color} = $Prop->{color};
$Key->{color} = $Prop->{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);
};

my $one_keyword_serializer = sub {
  my ($self, $prop_name, $value) = @_;
  if ($value->[0] eq 'KEYWORD') {
    return $value->[1];
  } elsif ($value->[0] eq 'INHERIT') {
    return 'inherit';
  } else {
    return undef;
  }
};

$Prop->{display} = {
  css => 'display',
  dom => 'display',
  key => 'display',
  parse => $one_keyword_parser,
  serialize => $one_keyword_serializer,
  keyword => {
    block => 1, inline => 1, 'inline-block' => 1, 'inline-table' => 1,
    'list-item' => 1, none => 1,
    table => 1, 'table-caption' => 1, 'table-cell' => 1, 'table-column' => 1,
    'table-column-group' => 1, 'table-header-group' => 1,
    'table-footer-group' => 1, 'table-row' => 1, 'table-row-group' => 1,
  },
  initial => ["KEYWORD", "inline"],
  #inherited => 0,
  compute => sub {
    my ($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 ($specified_value->[0] eq 'KEYWORD') {
      if ($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 => $one_keyword_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 => $one_keyword_serializer,
  keyword => {
    left => 1, right => 1, none => 1,
  },
  initial => ["KEYWORD", "none"],
  #inherited => 0,
  compute => sub {
    my ($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 ($specified_value->[0] eq 'KEYWORD') {
      if ($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 => $one_keyword_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 => $one_keyword_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 => $one_keyword_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'};

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 => $one_keyword_serializer,
  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 => $one_keyword_serializer,
  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 => $one_keyword_serializer,
  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 => $one_keyword_serializer,
  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'};

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

    my %prop_value;
    my $has_inherit;
    if ($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"];
        $has_inherit = 1;
      } 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 (not $has_inherit and
          $border_style_keyword->{$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 undef unless defined $v[-1];
    push @v, $self->border_right_style;
    return undef unless defined $v[-1];
    push @v, $self->border_bottom_style;
    return undef unless defined $v[-1];
    push @v, $self->border_bottom_style;
    return undef unless defined $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->{border_style} = $Prop->{'border-style'};

1;
## $Date: 2008/01/01 07:07:28 $