@@ 
[1] 
This is the work-in-progress
specification for the manakai's DOM binding for Perl.
This specification only scopes [[manakai]]'s DOM implementation;
it does not try to define what any other DOM implementation
should do.  However, other DOM implementation
that exposes interfaces to Perl scripts '''[[MAY]]''' use this binding.

@@ 
[2] TODO:
- Truck the draft for the ECMAScript binding authored by
W3C Web APIs WG
- Write comparison with SVGT 1.2's DOM Perl Language Binding
- [CITE@en-US[XML Binding Language (XBL) 2.0]] ([TIME[2007-03-16 13:20:16 +09:00]] 版) <http://www.w3.org/TR/xbl/#xbl-element-example>
- The global object ([CODE(DOMi)@en[[[Window]]]])


* Conformance

@@ 

[48] Statements about conformance in this specification
are only applied to implementations that support related
feature.  For example, [['''MUST''']]-level requirements
for treatement of the [CODE(DOMi)@en[[[EventHandler]]]] objects
do not apply to implementations that do not support
DOM Events module.


* Objects and interfaces

[3]
A DOM object, i.e. an object implementing one
or more DOM interfaces, '''[[MUST]]''' be represented
by a Perl object, i.e. a thingly referenced
by some Perl references and [CODE@en[bless]]ed in
a Perl class, unless otherwise specified.
The Perl class '''[[MUST]]''' implement 
the DOM interfaces implemented by the DOM object.

@@ better wording, getFeature consideration

[114] The class implementing a DOM interface [['''MAY''']] inherit non-DOM classes.

[EG[
[115] For example, the class implementing the [CODE(DOMi)@en[[[DOMException]]]] interface
might inherit a class that defines the exception mechanism the implementation is build on top of it.
Another example is that any class implementing DOM interfaces might inherit from the "object"
base class provided by the object-orient programming framework used by the implementation.
]EG]

[117] The implementation [['''MAY''']] provide ways to determine whether an object implements
a specific DOM interface or not.  However, this is not required.

[66] Specifications often requires that two objects be ''same''.  They don't have to be same object in Perl
sense, but they have to exhibit following characteristics:
- [67] Two objects [['''MUST''']] be equal according to [CODE(perl)@en[[[eq]]]] operation if and only if 
they are ''same''.  Operations [CODE(perl)@en[[[ne]]]] and [CODE(perl)@en[[[cmp]]]] [['''MUST''']] be 
consistent with the [CODE(perl)@en[[[eq]]]] operation.
- [68] If the stringifier is not defined for the object, its stringified value [['''MUST''']]
be different from the stringified value of any object without stringifier at the moment.
The stringified value [['''MUST NOT''']] change.

;; [69] >>68 ensures that following code works as intended:
[PRE(example perl code)[
@different_parents = grep { not $found{$node->parent_node}++ } @node;
]PRE]

* Methods and attributes

[5]
A [[DOM]] method [['''MUST''']] be implemented as a [[Perl]] method.

[6]
A read-only [[DOM]] attribute [['''MUST''']] be implemented as
a [[Perl]] method that returns the value contained in the [[DOM]] attribute.
The [[Perl]] method [['''MAY''']] throw an implementation
dependent exception if any argument is specified for the [[Perl]] method.

[7]
A read-write [[DOM]] attribute [['''MUST''']] be implemented as
a [[Perl]] method.  The [[Perl]] method [['''MUST''']] return
the value contained in the [[DOM]] attribute if no argument is
specified for the [[Perl]] method (i.e. the only argument to
the subroutine implementing the [[Perl]] method is the object itself).
Otherwise, the [[Perl]] method [['''MUST''']] try to set
the first argument specified for the method (i.e. the
second argument to the subroutine implementing the
[[Perl]] method) to the [[DOM]] attribute.

;; Note that specifying [CODE(perl)@en[[[undef]]]]
as the argument to the [[Perl]] method, which
set the [CODE(DOM)@en[[[null]]]] value
to the [[DOM]] attribute, is different from
specifying no argument, which returns the [[DOM]]
attribute value.

[8]
A [[DOM]] parameter to a method is [DFN@en[optional]] if
either [CODE(DOM)@en[[[null]]]] or [CODE(IDL)@en[[[boolean]]]]
[CODE(DOM)@en[[[false]]]] value is allowed to be specified
to that parameter and any following [[DOM]] parameter
is optional.

The [[Perl]] method [['''MUST''']] act as if an [CODE(perl)@en[[[undef]]]]
or a [[Perl]] false value, depending on the data type of the parameter,
is specified to each optional parameter if no argument
corresponding to that parameter is specified.

[98] If the return value of the operator is defined as [[void]], the method implementing the operation
[['''MUST''']] return an empty list.

[123] Since Perl objects can be overloaded such that stringification and similar operations can be
defined by the application, it is important to ensure the conversion from the Perl value to the WebIDL
value is performed in the right way.

[EG[
[124] Following pairs of code fragments can make different side effects:
[PRE(perl code)[
## Evaluation order is significant.
$v1 = [SPAN[']]'.$_[1];
$v2 = [SPAN[']]'.$_[2];

$v2 = [SPAN[']]'.$_[2];
$v1 = [SPAN[']]'.$_[1];


## Three serializations can be different.
$v1 = [SPAN[']]'.$_[1];

$v1 = 0+$_[1];

$v1 = !!$_[1];


## Whether the overloaded operation has been invoked or not is observable.
$v1 = [SPAN[']]'.$_[1];
$v2 = [SPAN[']]'.$_[2];
return;

$v1 = [SPAN[']]'.$_[1];
return if $v1; # or throw an exception
$v2 = [SPAN[']]'.$_[2];
return;


## How many times overloaded operation has been invoked is observable.
$v1 = [SPAN[']]'.$_[1];
$v1 = [SPAN[']]'.$_[1];

$v1 = [SPAN[']]'.$_[1];
]PRE]
]EG]

* Constants

[62] Any constant [SRC[WebIDL]] defined by the interface [['''MUST''']] be implemented by a constant subroutine
in the class implementing the interface.  That is, there must be the subroutine in the class,
whose name is the name of the constant, which returns the value of the constant.

[63] Any constant [['''MUST''']] be exported from the class.  In other word, invoking the [CODE(perl)@en[[[import]]]]
method of the class with the argument equal to the name of the constant result in the constant subroutine
exported to the caller's package.

;; [64] Whether the constants are exported by default or not is implementation dependent.
This is not defined in this specification since operations such as [CODE(perl)@en[[[use]]]]ing modules and
invoking class methods cannot be interoperable across different implementations by nature.

;; [65] Since constant subroutines belong to the class for the interface of the constant, the constant
can also be accessible as the class or instance method of the class, e.g.:
[PRE(perl example code)[
is $node->ELEMENT_NODE, 1;
is +MyDOM::Node->ELEMENT_NODE, 1;
]PRE]


* Exceptions and errors

[9]
Throwing an exception [['''MUST''']] be implemented by [[Perl]]
[CODE(perl)@en[[[die]]]] function.  If the exception is one
defined in DOM specification, the argument to the
[CODE(perl)@en[[[die]]]] function [['''MUST''']]
be an object implementing the associated exception interface.

[DEL[
;; [53] Implementations are encouraged to employ the
[CODE(perl)@en[[[Error]]]] module as a basis
to construct their own exception mechanism.
]DEL]

[54] The [CODE(DOMi)@en[[[Error]]]] object and the [CODE(DOMi)@en[[[TypeError]]]] object
as defined in the [[WebIDL]] specification [['''MUST''']] be implemented as if they were
defined by following [[WebIDL]] fragment:
[FIG[
[PRE(IDL code)[
// XXX constructor
interface Error {
  readonly attribute DOMString name;
  readonly attribute DOMString message;
  readonly attribute DOMString fileName;
  readonly attribute long lineNumber;
  stringifier DOMString ();
  // XXX readonly attribute DOMString stack;
};

[Constructor(optional DOMString message)]
interface TypeError : Error {
  
};
]PRE]
]FIG]

[55] The [DFN[[CODE(DOMa)@en[[[name]]]]]] attribute [['''MUST''']] return the name [SRC[WebIDL]]
of the exception.

[56] The [DFN[[CODE(DOMa)@en[[[message]]]]]] attribute [['''MUST''']] return the message [SRC[WebIDL]]
of the exception.

[57] The [DFN[[CODE(DOMa)@en[[[fileName]]]]]] attribute [['''MUST''']] return the string identifying
the file where the method or attribute that throws the exception is invoked.
The [DFN[[CODE(DOMa)@en[[[lineNumber]]]]]] attribute [['''MUST''']]
return the line number in the file, where the method or attribute that throws the exception is invoked.
How to determine the these values are implementation dependent.

[58] The stringifier [SRC[WebIDL]] method [['''MUST''']] return the message [SRC[WebIDL]]
followed by string [CODE[ at ]] followed by the [CODE(DOMa)@en[[[fileName]]]] followed by string
[CODE[ line ]] followed by stringified [SRC[XXXref]] representation of [CODE(DOMa)@en[[[lineNumber]]]] followed
by [CODE[.]] followed by the value equal to Perl expression [CODE(perl)["\n"]].

[76] The [[constructor]] of the [CODE(DOMi)@en[[[TypeError]]]] interface [['''MUST'''']] follow
these steps:
[FIG[
= [77] Let [VAR@en[error]] be a new [CODE(DOMi)@en[[[TypeError]]]] object.
= [78] If [VAR[message]] is specified but is not [CODE@en[[[null]]]],
let [[message]] of the [VAR@en[error]] be the stringified value of [VAR[message]].
= [79] Return [VAR@en[error]].
]FIG]

[59] Any exception [['''MUST''']] inherit the class for the [CODE(DOMi)@en[[[Error]]]] interface.

@@ Constructor

[116] The [CODE(DOMi)@en[[[DOMError]]]] object's [CODE(perl)[[[""]]]] operation [['''MUST''']]
return the implementation-specific value that describes the error.

* Events


* Naming Rule

[15]
Names of DOM methods and attributes [['''MUST''']]
be mapped to Perl method (subroutine) name
by following algorithm:
= Let [VAR@en[n]] as the name of a DOM method or attribute.
= If the first column of the table >>14 contains
[VAR@en[n]], then return the name contained
in the cell in the second column of the same row.
= Otherwise, replace a sequence of one or more uppercase
letters at the end of [VAR@en[n]], if any, by the lowercase
variant of the sequence.
= Replace any sequence of two or more uppercase letters
in [VAR@en[n]] by a sequence of a 
[CODE(charname)@en[[[LOW LINE]]]] character, 
the lowercase variant of the sequence except the last letter, 
a [CODE(charname)@en[[[LOW LINE]]]] character,
and the lowercase variant of the last letter of the sequence.
= Replace any uppercase letter 
by a [CODE(charname)@en[[[LOW LINE]]]] character
followed by the lowercase variant of the letter.
= Then, return [VAR@en[n]].

;; For example, [CODE(DOMa)@en[[[localName]]]]
is mapped to [CODE(perl)@en[[[local_name]]]],
[CODE(DOMm)@en[[[setAttributeNS]]]] to
[CODE(perl)@en[[[set_attribute_ns]]]],
[CODE(DOMm)@en[[[createLSInput]]]] to
[CODE(perl)@en[[[create_ls_input]]]], and
[CODE(DOMa)@en[[[MozBoxSizing]]]] to
[CODE(perl)@en[[[_moz_box_sizing]]]].

[14]
'''Exceptions'''.
,[[DOM]]	,[[DOM Perl Binding]]	,Note
,[CODE(DOMa)@en[[[accessKey]]]]	,[CODE(perl)@en[[[accesskey]]]]	,"[CODE(DOMi)@en[[[HTMLInputElement]]]], [CODE(DOMi)@en[[[HTMLTextAreaElement]]]], [CODE(DOMi)@en[[[HTMLButtonElement]]]], [CODE(DOMi)@en[[[HTMLLabelElement]]]], [CODE(DOMi)@en[[[HTMLLegendElement]]]], [CODE(DOMi)@en[[[HTMLAnchorElement]]]], [CODE(DOMi)@en[[[HTMLAreaElement]]]] ([[DOM HTML]])"
,[CODE(DOMa)@en[[[aLink]]]]	,[CODE(perl)@en[[[alink]]]]	,[CODE(DOMi)@en[[[HTMLBodyElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[bgColor]]]]	,[CODE(perl)@en[[[bgcolor]]]]	,"[CODE(DOMi)@en[[[HTMLDocument]]]], [CODE(DOMi)@en[[[HTMLBodyElement]]]], [CODE(DOMi)@en[[[HTMLTableElement]]]], [CODE(DOMi)@en[[[HTMLTableRowElement]]]], [CODE(DOMi)@en[[[HTMLTableCellElement]]]] ([[DOM HTML]])"
,[CODE(DOMa)@en[[[cellPadding]]]]	,[CODE(perl)@en[[[cellpadding]]]]	,[CODE(DOMi)@en[[[HTMLTableElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[cellSpacing]]]]	,[CODE(perl)@en[[[cellspacing]]]]	,[CODE(DOMi)@en[[[HTMLTableElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[codeBase]]]]	,[CODE(perl)@en[[[codebase]]]]	,"[CODE(DOMi)@en[[[HTMLObjectElement]]]], [CODE(DOMi)@en[[[HTMLAppletElement]]]] ([[DOM HTML]])"
,[CODE(DOMa)@en[[[codeType]]]]	,[CODE(perl)@en[[[codetype]]]]	,[CODE(DOMi)@en[[[HTMLObjectElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[colSpan]]]]	,[CODE(perl)@en[[[colspan]]]]	,[CODE(DOMi)@en[[[HTMLTableCellElement]]]] ([[DOM HTML]])
,[CODE(DOMm)@en[[[createTFoot]]]]	,[CODE(perl)@en[[[create_tfoot]]]]	,[CODE(DOMi)@en[[[HTMLTableElement]]]] ([[DOM HTML]])
,[CODE(DOMm)@en[[[createTHead]]]]	,[CODE(perl)@en[[[create_thead]]]]	,[CODE(DOMi)@en[[[HTMLTableElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[dateTime]]]]	,[CODE(perl)@en[[[datetime]]]]	,[CODE(DOMi)@en[[[HTMLModElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[dateTime]]]]	,[CODE(perl)@en[[[datetime]]]]	,[CODE(DOMi)@en[[[HTMLTimeElement]]]] ([[DOM HTML]])
,[CODE(DOMm)@en[[[deleteTFoot]]]]	,[CODE(perl)@en[[[delete_tfoot]]]]	,[CODE(DOMi)@en[[[HTMLTableElement]]]] ([[DOM HTML]])
,[CODE(DOMm)@en[[[deleteTHead]]]]	,[CODE(perl)@en[[[delete_thead]]]]	,[CODE(DOMi)@en[[[HTMLTableElement]]]] ([[DOM HTML]])
,[CODE(DOMm)@en[[[findOffset16]]]]	,[CODE(perl)@en[[[find_offset_16]]]]	,[CODE(DOMi)@en[[[StringExtended]]]] ([[DOM Core]] informative)
,[CODE(DOMm)@en[[[findOffset32]]]]	,[CODE(perl)@en[[[find_offset_32]]]]	,[CODE(DOMi)@en[[[StringExtended]]]] ([[DOM Core]] informative)
,[CODE(DOMa)@en[[[frameBorder]]]]	,[CODE(perl)@en[[[frameborder]]]]	,"[CODE(DOMi)@en[[[HTMLFrameElement]]]], [CODE(DOMi)@en[[[HTMLIFrameElement]]]] ([[DOM HTML]])"
,[CODE(DOMm)@en[[[getAbsoluteReference3986]]]]	,[CODE(perl)@en[[[get_absolute_reference_3986]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMm)@en[[[getAbsoluteReference3987]]]]	,[CODE(perl)@en[[[get_absolute_reference_3987]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMm)@en[[[getIRIReference3987]]]]	,[CODE(perl)@en[[[get_iri_reference_3987]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMm)@en[[[getURIReference3986]]]]	,[CODE(perl)@en[[[get_uri_reference_3986]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMa)@en[[[isAbsoluteIRI3987]]]]	,[CODE(perl)@en[[[is_absolute_iri_3987]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMa)@en[[[isAbsoluteURI3986]]]]	,[CODE(perl)@en[[[is_absolute_uri_3986]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMa)@en[[[isIRI3987]]]]	,[CODE(perl)@en[[[is_iri_3987]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMa)@en[[[isIRIReference3987]]]]	,[CODE(perl)@en[[[is_iri_reference_3987]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMa)@en[[[isMap]]]]	,[CODE(perl)@en[[[ismap]]]]	,[CODE(DOMi)@en[[[HTMLImageElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[isRelativeIRIReference3987]]]]	,[CODE(perl)@en[[[is_iri_reference_3987]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMa)@en[[[isRelativeReference3986]]]]	,[CODE(perl)@en[[[is_relative_reference_3986]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMm)@en[[[isSameDocumentReference3986]]]]	,[CODE(perl)@en[[[is_same_document_reference_3986]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMa)@en[[[isURI3986]]]]	,[CODE(perl)@en[[[is_uri_3986]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMa)@en[[[isURIReference3986]]]]	,[CODE(perl)@en[[[is_uri_reference_3986]]]]	,[CODE(DOMi)@en[[[URIReference]]]] ([[manakai]]'s extension)
,[CODE(DOMa)@en[[[longDesc]]]]	,[CODE(perl)@en[[[longdesc]]]]	,"[CODE(DOMi)@en[[[HTMLImageElement]]]], [CODE(DOMi)@en[[[HTMLFrameElement]]]], [CODE(DOMi)@en[[[HTMLIFrameElement]]]] ([[DOM HTML]])"
,[CODE(DOMa)@en[[[marginHeight]]]]	,[CODE(perl)@en[[[marginheight]]]]	,"[CODE(DOMi)@en[[[HTMLFrameElement]]]], [CODE(DOMi)@en[[[HTMLIFrameElement]]]] ([[DOM HTML]])"
,[CODE(DOMa)@en[[[marginWidth]]]]	,[CODE(perl)@en[[[marginwidth]]]]	,"[CODE(DOMi)@en[[[HTMLFrameElement]]]], [CODE(DOMi)@en[[[HTMLIFrameElement]]]] ([[DOM HTML]])"
,[CODE(DOMa)@en[[[maxLength]]]]	,[CODE(perl)@en[[[maxlength]]]]	,[CODE(DOMi)@en[[[HTMLInputElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[noHref]]]]	,[CODE(perl)@en[[[nohref]]]]	,[CODE(DOMi)@en[[[HTMLAreaElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[noResize]]]]	,[CODE(perl)@en[[[noresize]]]]	,[CODE(DOMi)@en[[[HTMLFrameElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[noShade]]]]	,[CODE(perl)@en[[[noshade]]]]	,[CODE(DOMi)@en[[[HTMLHRElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[noWrap]]]]	,[CODE(perl)@en[[[nowrap]]]]	,[CODE(DOMi)@en[[[HTMLTableCellElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[readOnly]]]]	,[CODE(perl)@en[[[readonly]]]]	,"[CODE(DOMi)@en[[[HTMLInputElement]]]], [CODE(DOMi)@en[[[HTMLTextAreaElement]]]]([[DOM HTML]])"
,[CODE(DOMa)@en[[[rowSpan]]]]	,[CODE(perl)@en[[[rowspan]]]]	,[CODE(DOMi)@en[[[HTMLTableCellElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[scrollbar3dLightShadowColor]]]]	,[CODE(perl)@en[[[scrollbar_3dlight_color]]]]	,[CODE(DOMi)@en[[[CSSStyleDeclarationProperties]]]] ([[CSSOM]])
,[CODE(DOMa)@en[[[scrollbarDarkShadowColor]]]]	,[CODE(perl)@en[[[scrollbar_darkshadow_color]]]]	,[CODE(DOMi)@en[[[CSSStyleDeclarationProperties]]]] ([[CSSOM]])
,[CODE(DOMa)@en[[[tabIndex]]]]	,[CODE(perl)@en[[[tabindex]]]]	,"[CODE(DOMi)@en[[[HTMLSelectElement]]]], [CODE(DOMi)@en[[[HTMLInputElement]]]], [CODE(DOMi)@en[[[HTMLTextAreaElement]]]], [CODE(DOMi)@en[[[HTMLButtonElement]]]], [CODE(DOMi)@en[[[HTMLAnchorElement]]]], [CODE(DOMi)@en[[[HTMLObjectElement]]]], [CODE(DOMi)@en[[[HTMLAreaElement]]]] ([[DOM HTML]])"
,[CODE(DOMa)@en[[[tBodies]]]]	,[CODE(perl)@en[[[tbodies]]]]	,[CODE(DOMi)@en[[[HTMLTableElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[tFoot]]]]	,[CODE(perl)@en[[[tfoot]]]]	,[CODE(DOMi)@en[[[HTMLTableElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[tHead]]]]	,[CODE(perl)@en[[[thead]]]]	,[CODE(DOMi)@en[[[HTMLTableElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[URL]]]]	,[CODE(perl)@en[[[url]]]]	,[CODE(DOMi)@en[[[HTMLDocument]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[useMap]]]]	,[CODE(perl)@en[[[usemap]]]]	,"[CODE(DOMi)@en[[[HTMLInputElement]]]] , [CODE(DOMi)@en[[[HTMLImageElement]]]], [CODE(DOMi)@en[[[HTMLObjectElement]]]] ([[DOM HTML]])"
,[CODE(DOMa)@en[[[utf16Offset]]]]	,[CODE(perl)@en[[[utf16_offset]]]]	,[CODE(DOMi)@en[[[DOMLocator]]]] ([[DOM Core]])
,[CODE(DOMa)@en[[[utf32Offset]]]]	,[CODE(perl)@en[[[utf32_offset]]]]	,[CODE(DOMi)@en[[[DOMLocator]]]] ([[DOM Core]])
,[CODE(DOMa)@en[[[vAlign]]]]	,[CODE(perl)@en[[[valign]]]]	,"[CODE(DOMi)@en[[[HTMLTableColElement]]]] , [CODE(DOMi)@en[[[HTMLTableSectionElement]]]], [CODE(DOMi)@en[[[HTMLTableRowElement]]]], [CODE(DOMi)@en[[[HTMLTableCellElement]]]] ([[DOM HTML]])"
,[CODE(DOMa)@en[[[valueType]]]]	,[CODE(perl)@en[[[valuetype]]]]	,[CODE(DOMi)@en[[[HTMLParamElement]]]] ([[DOM HTML]])
,[CODE(DOMa)@en[[[vLink]]]]	,[CODE(perl)@en[[[vlink]]]]	,[CODE(DOMi)@en[[[HTMLBodyElement]]]] ([[DOM HTML]])

;; Editor's note (informative): [[manakai//Issue//1//9]]


* Data types

[10] In this section, [DFN@en[number type]]s includes:
[CODE(IDL)@en[[[long]]]], [CODE(IDL)@en[[[unsigned long]]]],
[CODE(IDL)@en[[[unsigned long long]]]],
[CODE(IDL)@en[[[short]]]], 
and [CODE(IDL)@en[[[unsigned short]]]].

[11]
If the return value of the [[DOM]] method or the [[DOM]] attribute
is of number type and a [[Perl]] method return a value
in that type, jt [['''MUST''']] return a value
that can be evaluated as a number (by, e.g., [CODE(perl)@en[0+]]
operation).

[12]
If a [[DOM]] method parameter or the [[DOM]] attribute is 
of number type and it is necessary for a [[Perl]] method to
get the specified value, it [['''MAY''']] evaluate
the specified value as a value (by, e.g., [CODE(perl)@en[0+]]
operation).

@@ 
Similary, IDL type <TYPE^^DISCore|QName::idl|boolean>
[PRE[
    is expected to be evaluated in the Boolean context.
]PRE]

[PRE[
    IDL type <TYPE^^DISCore|QName::idl|any> is corresponding to any scalar valu\
e
    in Perl.  IDL type <TYPE^^DISCore|QName::idl|Object> is bound to object.
]PRE]

** Execution of algorithms defined for JavaScript

[84] When an algorithm for JavaScript is executed for a Perl value, the word "ECMAScript value" 
in the algorithm is read as "Perl value" instead.

[85] When the [CODE(JS)@en[[[ToNumber()]]]] function is invoked, the following steps [['''MUST''']]
be processed instead:
[FIG[
= Let [VAR@en[$x]] be the argument to the algorithm.
= Evaluate the Perl expression [CODE(perl)[0 + $x]] in scalar context and return the result.
]FIG]

** [CODE(IDL)@en[boolean]]

[120] If a [[WebIDL]] [[boolean]] value [[true]] or [[false]] is converted into a [[Perl]] value,
it [['''MUST''']] be converted to a [[Perl]] true or false value, respectively.
If the value is returned in context where both [[boolean]] and [[null]] can be returned,
the false value [['''MUST''']] be represented as non-[CODE(perl)@en[[[undef]]]] value in [[Perl]].

** [CODE(IDL)@en[unsigned long]]

[83] A [[Perl]] value is converted to an IDL [CODE(IDL)@en[[[unsigned long]]]] value by running the
algorithm for JavaScript <http://dev.w3.org/2006/webapi/WebIDL/#es-unsigned-long>.

** [CODE(IDL)@en[unsigned short]]

[118] A [[Perl]] value is converted to an IDL [CODE(IDL)@en[[[unsigned short]]]] value by running the
algorithm for JavaScript <http://dev.w3.org/2006/webapi/WebIDL/#es-unsigned-short>.

** [CODE(IDL)@en[null]]

[23]
The [CODE(IDL)@en[[[null]]]] value in [[DOM]] is bound to
[CODE(perl)@en[[[undef]]]] in [[Perl]].

[24]
If something is defined to return or set [CODE(IDL)@en[[[null]]]],
it [['''MUST''']] return or set [CODE(perl)@en[[[undef]]]]
unless otherwise specified.

[25]
Where [CODE(IDL)@en[[[null]]]] is allowed to
be specified, an implementation [['''MUST''']] behave as if a
[CODE(IDL)@en[[[null]]]] is specified when
a [CODE(perl)@en[[[undef]]]] is specified.

[26]
Where [CODE(IDL)@en[[[null]]]] is ''not'' allowed to
be specified, how an implementation behaves when
a [CODE(perl)@en[[[undef]]]] depends on the 
expected data type.  An implementation [['''MAY''']]
cause zero or more [Q@en[uninitialized]] warnings
reported by Perl or [['''MAY''']] report its own
[Q@en[uninitialized]] warnings, when warnings
are enabled by e.g. [CODE(perl)@en[[[use]] [[warnings]]]]
pragma.

@@ TODO: Make relationship to [[JavaScript]]
[CODE(JS)@en[[[undefined]]]] and
[CODE(JS)@en[[[null]]]] clearer.


** [CODE(DOM)@en[DOMString]]

;; [70] In [[WebIDL]] and [[DOM]], strings are defined in terms of UTF-16 code units,
while in [[Perl]] they are represented in UTF-8 based encoding in most environments.

;; [75] This specification does not support any environment where Perl character strings are not
represented in [[utf8]] (e.g. [[EBCDIC]] environment).

[EG[
[96] Since some methods are defined in terms of [[UTF-16 code units]], if the index used by the method
identifies a location between surrogate code points, a character is broken into two surrogate code points.
If the string [CODE(perl)["a\x{10003}b"]] is split into two substrings with index two (2),
the first substring is [CODE(perl)["a\x{D800}"]] and the second substring is [CODE(perl)["\x{DC03}b"]].
]EG]

[71] When a string in [[WebIDL]] context is exposed to Perl, it [['''MUST''']] be represented
as the value that can be interpreted as a sequence of characters.  If no character in
the sequence is greater than U+00FF, it [['''MAY''']] be represented as the value 
that can be interpreted as a sequence of bytes encoded in [[Latin-1]].

;; [72] The [[Latin-1]] encoding in this context is different from the Web [CODE(charset)@en[[[iso-8859-1]]]]
encoding, which is equivalent to the [CODE(charset)@en[[[windows-1252]]]] encoding [SRC[[[Encoding]]]]. 

[73] When a value in Perl in interpreted in [[WebIDL]] context, it [['''MUST''']]
be first stringified by concatenated with the empty string and then interpreted as the
sequence of characters.  If the result of the stringification is the sequence of the bytes,
then it is interpreted as encoded in the [[Latin-1]] encoding.

[74] A [[Perl]] string can contain non-Unicode characters (i.e. code points greater than [[U+10FFFF]]).
Unless otherwise specified, such a character [['''MUST''']] be treated as if that were an unassigned
Unicode character.

;; [91] Therefore, the [[code-point length]] of the string consist of a character greater than [CODE(char)[[[U+10FFFF]]]]
is one (1).

[92] A [[Perl]] string can contain both surrogate code points and code points greater than [CODE(char)[[[U+FFFF]]]].
Since a [[Perl]] string is not encoded in [[UTF-16]], combination of surrogate code points does not represent
a character, but are barely interpreted as sequence of those code points as is.

[EG[
[93] For example, a string [CODE(perl)["\x{10003}"]] is different from [CODE(perl)["\x{D800}\x{DC03}"]].
]EG]

[DEL[
[94] When a string ending with a high surrogate code point is concatenated with a string starting by
a low surrogate code point by a [[DOM]] operation, these two code points [['''MUST''']] be replaced
by corresponding code point.

[EG[
[95] For example, if [CODE(perl)["a\x{D800}"]] is followed by [CODE(perl)["\x{DC03}b"]], then
the result is string [CODE(perl)["a\x{10003}b"]].
]EG]
]DEL]

[97] Even when strings beginning with or ending by surrogate pair code points are concatenated,
they are not automatically converted into a Unicode character.  Therefore, even if same sequence of operations are
performed, semantics of result strings could be different in the [[DOM Perl Binding]] and 
in the [[JavaScript]]-based Web browser environment.
However, this does not mean requirements in Web platform specifications apply differently
among these environments.

[EG[
[121] The number of [[Unicode code points]] in the string [CODE(perl)["a\x{D800}\x{DC03}b"]] is three
in both environments.
]EG]

[33]
Some methods are defined to accept a scalar reference
specified as a value of a parameter.  Such a method,
when a scalar reference is specified as a parameter value,
[['''MUST''']] dereference the parameter value as a
scalar reference (i.e. by operator [CODE(perl)[[[${}]]]])
before it is in use, if the [CODE(perl)@en[[[ref]]]] of the parameter
value is [CODE(perl)@en[[[SCALAR]]]].

[89] If the [CODE(IDL)@en['''['''[[TreatNullAs]]=[[EmptyString]]''']''']] [[extended attribute]] is specified,
when the value is [[undef]] it [['''MUST''']] be converted to the empty string before it is processed.

;; [90] The [CODE(IDL)@en['''['''[[TreatUndefinedAs]]''']''']] [[extended attribute]] is ignored
by the [[DOM Perl Binding]].

** [CODE(DOMi)@en[StringExtended]]

[99] The operations of the [CODE(DOMi)@en[[[StringExtended]]]] interface [SRC[DOM3CORE]]
[['''MUST''']] be implemented as functions, where the zeroth argument to the function
is treated as the [[context object]] (i.e. the string) and the first argument to the function
is treated as the argument to the operation.  The [CODE(IDL)[int]] data type [['''MUST''']] be
handled as [[WebIDL]] [CODE(IDL)@en[[[unsigned long]]]] data type.  The [CODE@en[StringIndexOutOfBoundsException]]
exception [['''MUST''']] be treated as the "[CODE[[[IndexSizeError]]]]" exception.

** [CODE(DOM)@en[DOMTimeStamp]]

[4] '''[CODE(DOM)@en[DOMTimeStamp]] for a Calendar Date-Time'''

A [CODE(DOM)@en[DOMTimeStamp]] value that is
an absolute date-time [['''MUST''']] be represented
by a scalar value of the number of the seconds
from [CODE[[[1970-01-01T00:00:00Z]]]].
The scalar value [['''MAY''']] contain fraction part,
which represents a fraction of a second.

;; For example, [CODE[[[1970-01-01T00:00:00Z]]]]
is mapped to a numeric value of [CODE(perl)[[[0]]]].

@@ Leap seconds, days before [CODE[[[1970-01-01T00:00:00Z]]]]

** Objects

@@ XXX this wording is a bit unclear

[80] If [[WebIDL]] definition for the method parameter is typed with an interface but the
value that is not an instance of the interface is specified as the argument, then
a [CODE(DOMi)@en[[[TypeError]]]] [['''MUST''']] be thrown and the processing of the method
[['''MUST''']] be aborted.  This type checking [['''MUST''']] be performed in the
order of parameters.

[81] Likewise, if [[WebIDL]] definition for the attribute is typed with an interface but the
value that is not an instance of the interface is specified as the new value of the attribute,
then a [CODE(DOMi)@en[[[TypeError]]]] [['''MUST''']] be thrown and the processing of the method
[['''MUST''']] be aborted.

[82] An implementation [['''MAY''']] treat an object from another DOM implementation
as implementing no DOM interface at all.

@@ XXX but it might be treated as user object (rather than platform object).

** [CODE(DOMi)@en[DOMUserData]]

[100] The [CODE(DOMi)@en[[[DOMUserData]]]] data type [SRC[DOM3CORE]]
corresponding to any scalar value in [[Perl]].

* Security


* Features


* [CODE(DOMi)@en[[[DOMImplementationRegistry]]]]

[16]
The variable
[CODE(perl)@en[$[[Message::DOM::DOMImplementationRegistry]]]]
[['''MUST''']] contain a value via which methods
provided by [CODE(DOMi)@en[[[DOMImplementationRegistry]]]]
object can be invoked.

;; For example,
[PRE(perl example code)[
$Message::DOM::DOMImplementationRegistry->get_dom_implementation
]PRE]

returns a DOM implementation.

;; The [CODE(DOMi)@en[[[DOMImplementationRegistry]]]]
[Q@en[object]] don't have to be an object in the Perl
context; it might be a string representing
the package name of the class implementing
the [CODE(DOMi)@en[[[DOMImplementationRegistry]]]]
[Q@en[interface]].

* Operator overloading


[127] The implementation [['''MUST NOT''']] overload the following operators (using the [CODE(perl)[[[overload]]]]
pragma) in a way that contradicts with this specification and any [[applicable specifications]]:
[FIG[
[CODE(perl)[[[""]]]], [CODE(perl)[[[0+]]]], [CODE(perl)[[[bool]]]],
[CODE(perl)[[[@{}]]]], [CODE(perl)[[[%{}]]]], [CODE(perl)[[[&{}]]]],
[CODE(perl)[[[cmp]]]], [CODE(perl)[[[eq]]]], [CODE(perl)[[[ne]]]],
[CODE(perl)[[[lt]]]], [CODE(perl)[[[le]]]], [CODE(perl)[[[gt]]]], and [CODE(perl)[[[ge]]]].
]FIG]

[18] Unless otherwise specified, an object implementing some DOM interface [['''SHOULD NOT''']] overload 
these operators.  If these operators are overloaded in implementation-specific ways, it [['''MUST''']]
behave as if it were not overloaded to the extent applications don't have to distinguish whether it is
overloaded or not.

[EG[
[128] For example, an implementation can choose to let the [CODE(perl)[[[""]]]] operator of the
[CODE(DOMi)@en[[[Element]]]] object to return the internal address of the object followed by the class name
of the implementation.  An application can use this string to distinguish element objects each other,
or element objects and non-DOM objects, as it does for non-DOM objects.  However, the implementation
cannot choose to let the operator to return the XML representation of the element.
]EG]

[28] In any way, when an operator is overloaded,
it [['''MUST''']] be consistent with other operators.

;; For example, if the [CODE(perl)@en[[[eq]]]]
operator is overloaded,
[PRE(perl example code)[
my $eq = $a eq $b;
my $ne = $a ne $b;
die unless ($eq and not $ne) or (not $eq and $ne);
]PRE]

... must not die.

@@ More details - 
- Even if "" is overloaded and results in false, bool must return true.
- eq, ne, and cmp must be consistent.
- ==, !=, and <=> must be consistent.

** Array-like and / or hash-like objects

[86] If an interface [[supports indexed properties]] <http://dev.w3.org/2006/webapi/WebIDL/#dfn-support-indexed-properties>,
the object implementing the interface [['''MUST''']] behave as if that were a blessed array reference,
at least to the extent allowed by defining the Perl [CODE(perl)@en[[[overload]]]] pragma's [CODE[[[@{}]]]] operator.

[87] If only the [[indexed property getter]] is defined for the interface, the object [['''MUST''']]
behave as if that were a read-only array reference.

[EG[
[88] Following code fragment illustrates how the [CODE(DOMi)@en[[[NodeList]]]] object behave:
[PRE(perl example code)[
my $node_list = $node->child_nodes;
warn scalar @$node_list;      # Number of child nodes
warn $node_list->[1];         # Child node with index 1 (= second node in the children list)
warn $node_list->[-1];        # Last child node
$node_list->[2] = $new_node;  # Error because setter is not defined for NodeList
]PRE]

Please note that index [CODE(perl)[-1]] is converted by Perl to the index of the last element in the
array before WebIDL processing (i.e. [CODE(IDL)@en[[[unsigned long]]]] conversion), it would return
different item in the list from the corresponding normal method;
[PRE(perl example code)[
warn $node_list->[-1];        # last item in the list
warn $node_list->item (-1);   # (-1 % 2^32 == 4294967295)th item (undef in most cases)
]PRE]
]EG]

@@ better wording

[17]
For following interfaces, dereferencing an object
as array acts as if it is an array:
- [CODE(DOMi)@en[[[DOMImplementationList]]]]
- [CODE(DOMi)@en[[[DOMStringList]]]]
- [CODE(DOMi)@en[[[TextTrackCueList]]]]

That is, 
[CODE(perl)@en[[VAR@en[$obj]]->'''['''[VAR@en[$n]]''']''']]
[['''MUST''']] return the same value as
[CODE(perl)@en[[VAR@en[$obj]]->item ([VAR@en[$n]])]]
if [VAR@en[$obj]] is an object implementing 
any of interfaces listed above and [VAR@en[$n]]
is a non-negative integer less than
[CODE(perl)@en[[VAR@en[$obj]]->length]].

@@ If [VAR@en[$n]] is negative, then 
length - $n.
If length is zero, greater than $n, smaller than -length,
non-number, then?

@@ [CODE(DOMi)@en[[[NameList]]]]

[50] The [CODE(perl)@en[[[to_a]]]] method and the [CODE(perl)[[[as_list]]]] of an
array-like object [['''MUST''']] return a reference to a new array that contains
the items in the array-like object, in order.

;; [51] The [CODE(perl)[[[as_list]]]] method is provided for compatibility with 
[CODE(perl)[[[Template::Iterator]]]] module.  It should not be used for other purposes.

[52] The [CODE(perl)@en[[[to_list]]]] method of an array-like object [['''MUST''']]
return a Perl list that contains the items in the array-like object, in order.

[113] If an interface [[supports named properties]], they [['''MUST''']] be accessible by
dereferencing the object by the [CODE(perl)[[[%{}]]]] operator.

@@ Need to define it much more strictly...

@@ [126] [VAR[T]][] (e.g. DOMString[]) - tied array; obj.domstringlist = ["str1", "str2"]

*** Read-only array-like or hash-like objects

[DEL[
[29]
If an array-like or hash-like object is read-only,
[CODE(perl)@en[[[STORE]]]], [CODE(perl)@en[[[STORESIZE]]]],
[CODE(perl)@en[[[DELETE]]]], and any other operations
that implies these operations [['''MUST''']]
throw an [CODE(DOMc)@en[[[NO_MODIFICATION_ALLOWED_ERR]]]]
[CODE(DOMi)@en[[[DOMException]]]].
]DEL]

[112] When an array or hash is read-only, any attempt to modify it or its values [['''MAY''']] throw
an exception.  Whether an exception is thrown or not, any attempt to modify them [['''MUST''']]
be ignored.

;; [129] Whether that exception is a string or an object, what the stringified representation of the
exception is, or whether the exception is actually thrown or not, is implementation dependent.
This is a quality of implementation issue, as what is the behavior of the "native" Perl read-only array or hash
is somewhat unclear or unstable.

*** The [CODE(DOMi)@en[DOMConfiguration]] interface

[105] The [DFN[Perl parameter name]] of a parameter is the value returned by the following steps:
[FIG[
= Let [VAR@en[name]] be the parameter name.
= If [VAR@en[name]] starts with [CODE[http://]], return [[null]] and abort these steps.
= Replace any [CODE(char)[[[-]]]] character in [VAR@en[name]] by a [CODE(char)[[[_]]]] character.
= Return [VAR@en[name]].
]FIG]

[106] The [[supported property names]] of a [CODE(DOMi)@en[[[DOMConfiguration]]]] object is the
values returned by the following steps:
[FIG[
= Let [VAR@en[values]] be the array of the string containing the values in the
[CODE(DOMa)@en[[[parameterNames]]]] attribute of the object.
= For each item [VAR@en[value]] in the array, in order:
== Let [VAR@en[perl value]] be the [[Perl parameter name]] of the parameter whose name is [VAR@en[name]].
== If [VAR@en[perl value]] is [[null]], delete [VAR@en[value]] from [VAR@en[values]].
== Otherwise, replace [VAR@en[value]] in [VAR@en[values]] by [VAR@en[perl value]].
= Return [VAR@en[values]].
]FIG]

[107] To [[determine the value of a named property]] of a [CODE(DOMi)@en[[[DOMConfiguration]]]] object,
the following steps [['''MUST''']] be run:
[FIG[
= Let [VAR@en[name]] be the property name.
= If [VAR@en[name]] is one of the [[supported property names]], return the value
that would be returned if the [CODE(DOMm)@en[[[getParameter]]]] method is invoked with
the parameter name whose [[Perl parameter name]] is [VAR@en[name]].
= Otherwise, return [CODE(perl)@en[[[undef]]]].
]FIG]

[108] To [[set the value of an existing named property]] or [[set the value of a new named property]]
of a [CODE(DOMi)@en[[[DOMConfiguration]]]] object, the following steps [['''MUST''']] be run:
[FIG[
= Let [VAR@en[name]] be the property name.
= If [VAR@en[name]] is one of the [[supported property names]], return the value
that would be returned if the [CODE(DOMm)@en[[[setParameter]]]] method is invoked with
the parameter name whose [[Perl parameter name]] is [VAR@en[name]] and the assigned value.
For the purpose of this invocation only, the [COCDE(DOMm)@en[[[setParameter]]]] method [['''MUST NOT''']]
treat the [CODE(perl)@en[[[undef]]]] value as [[WebIDL]] [[null]].
]FIG]

[EG[
[110] The following code set "false" to the parameter:
[PRE(perl example code)[
$config = $document->dom_config;
$config->{manakai_strict_document_children} = undef;
ok not $config->{manakai_strict_document_children};
]PRE]

However, the following code unset the parameter:
[PRE(perl example code)[
$config->set_parameter ('manakai-strict-document-children', undef);
ok $config->{manakai_strict_document_children};
]PRE]

Since the default value of the parameter is "true", unsetting the parameter results
in the "true" value set to the parameter.
]EG]

[109] To [[delete an existing named property]] of a [CODE(DOMi)@en[[[DOMConfiguration]]]] object,
the following steps [['''MUST''']] be run:
[FIG[
= Let [VAR@en[name]] be the property name.
= If [VAR@en[name]] is one of the [[supported property names]], return the value
that would be returned if the [CODE(DOMm)@en[[[setParameter]]]] method is invoked with
the parameter name whose [[Perl parameter name]] is [VAR@en[name]] and [CODE(IDL)@en[[[null]]]].
]FIG]

[111] The [[IDL]] data type of the second argument to the [CODE(DOMm)@en[[[setParameter]]]] method 
is [CODE(DOMi)@en[[[DOMUserData]]]], which can be any [[Perl]] scalar value, while parameters have
their expected value type defined.  Therefore "casting" of the value is performed within the
[CODE(DOMm)@en[[[setParameter]]]] method.  It [['''MUST''']] be performed by applying the steps
to convert the Perl value into [[WebIDL]] value of appropriate data type.  If this fails,
as defined in the DOM3 Core specification, a "[CODE(DOMe)@en[[[TypeMismatchError]]]]" exception
is thrown.

** Constructor

[19] The [CODE(perl)@en[[[new]]]] method is reserved.


** Cloning method

[20] The [CODE(perl)@en[[[clone]]]] method is reserved.

@@ It is planned to make [CODE(DOMi)@en[[[Node]]]]'s
[CODE(perl)@en[[[clone]]]] method an alias of
[CODE(DOMm)@en[[[cloneNode]]]] method.


** Stringify method

[21] Method names [CODE(perl)@en[[[stringify]]]], [CODE(perl)@en[[[as_string]]]],
and [CODE(perl)@en[[[to_string]]]] are reserved.

@@ XXX What "reserved" means?

[60] If the WebIDL interface has the stringifier [SRC[WebIDL]] defined, the [CODE(perl)[""]]
operator of the class [['''MUST''']] be overloaded such that stringifying the object 
invoke the stringifier.

[61] Unless otherwise defined, the [CODE(perl)@en[bool]] operator of the class [['''MUST''']]
return a true value, whatever value is returned by the stringifier.

* Function-like interfaces

[22]
Several interfaces are defined as [DFN@en[function-like]].
Only Perl native [CODE(perl)@en[[[CODE]]]] references, i.e.
values whose [CODE(perl)@en[[[ref]]]] is [CODE(perl)@en[[[CODE]]]],
and objects for which the [CODE(perl)[[[&{}]]]] operation is defined
[['''MUST''']] be treated as if they implement the 
function-like interfaces and are referred to as objects
implementing the function-like interfaces.  Each function-like interface
has a method, typically named as [CODE(DOMm)@en[[[handleEvent]]]].
Invoking that method on the object implementing a function-like
interface from another language binding invokes the 
object itself, by [CODE(perl)[[[&{}]]]] operation.  In the Perl binding itself,
however, the method of the interface is not directly accessible on 
the object implementing the interface.

;; Unlike in ECMAScript language binding, arbitrary object
with [CODE(perl)@en[[[handle_event]]]] method (and no
[CODE(perl)[[[&{}]]]] operation defined) does not 
implement the function-like interfaces.

[43] Function-like interfaces are:
- [CODE(DOMi)@en[[[DOMErrorHandler]]]]
- [CODE(DOMi)@en[[[EventHandler]]]]
- [CODE(DOMi)@en[[[NodeFilter]]]]
- [CODE(DOMi)@en[[[UserDataHandler]]]]
- [CODE(DOMi)@en[[[VoidCallback]]]]

[44] 
When the method would be invoked, the [CODE(perl)[[[&{}]]]]
operation [['''MUST''']] be performed over the object with appropriate
arguments.  The return value of the [CODE(perl)[[[&{}]]]]
operation [['''MUST''']] be treated as if the return value
of the method.  If the [CODE(perl)[[[&{}]]]] operation
results in an exception is raised, it [['''MUST''']]
be treated as if it is an exception raised by the method.

;; For example, 
[PRE(perl example code)[
$node->add_event_listener ('click', sub {
  my $ev = shift;
  print $ev->details, "\n";
  return 0;
});
]PRE]

would make the subroutine invoked when the node is clicked.
The subroutine, implementing the [CODE(DOMi)@en[[[EventHandler]]]]
interface and treated as if it is the [CODE(DOMm)@en[[[handleEvent]]]]
method, would [CODE(perl)@en[[[print]]]]s the 
number of clicks and then cancel the default action
for the event.

[45] Though in some of function-like interfaces constants are defined,
they are not accessible via the object implemeting that interface
in the Perl binding.  Other interface might provide
such constants alternatively.  For example, 
objects implementing the [CODE(DOMi)@en[[[Node]]]]
interface provides contants in [CODE(DOMi)@en[[[UserDataHandler]]]]
interface (see >>42).


* Specifics


** The [CODE(DOMi)@en[Node]] interface

[27]
Multiple calles of the getter of 
[CODE(DOMa)@en[[[attributes]]]] or
[CODE(DOMa)@en[[[childNodes]]]] on a [CODE(DOMi)@en[[[Node]]]]
[['''MUST''']] return the same object respectively in terms
of Perl [CODE(perl)@en[[[eq]]]] operator.

;; For example, 
[PRE(perl example code)[
my $c1 = $node->child_nodes;
my $c2 = $node->child_nodes;
die unless $c1 eq $c2;
]PRE]

... must not die.

[34] The [CODE(DOMm)@en[[[manakaiAppendText]]]]
method of the [CODE(DOMi)@en[[[Node]]]] interface
accepts a scalar reference (>>33) as the first parameter.

[42]
A package that implements the [CODE(DOMi)@en[[[Node]]]]
interface [['''MUST''']] implement the [CODE(DOM)@en[[[OperationType]]]]
constant group of the [CODE(DOMi)@en[[[UserDataHandler]]]]
interface.

;; For example, [CODE(perl example)@en[[VAR[$node]]->NODE_CLONED]]
where [CODE(perl)@en[[VAR[$node]]]] is a [CODE(DOMi)@en[[[Node]]]]
object must return the value of [CODE(perl)[[[1]]]].


** The [CODE(DOMi)@en[Document]] interface


*** Qualified name methods

[119] Methods [CODE(DOMm)@en[[[createElementNS]]]], [CODE(DOMm)@en[[[createAttributeNS]]]],
[CODE(DOMm)@en[[[setAttributeNS]]]], [CODE(DOMm)@en[[[createDocument]]]]:

[13]
= If the second parameter, [CODE(DOMp)@en[[[qualifiedName]]]],
is an array reference, i.e. the [CODE(perl)@en[[[ref]]]]
operator with that parameter returns a string
of [CODE(perl)@en[[[ARRAY]]]], then the parameter 
[['''MUST''']] be interpreted as following:
-- The namespace prefix part of the qualified name
is the zeroth item in the array.  If it is 
[CODE(perl)@en[[[undef]]]], then there is
no namespace prefix (i.e. the qualified name has no
[CODE(char)@en[[[COLON]]]] character).
-- The local name part of the qualified name
is the first item in the array.  It [['''MUST NOT''']]
be [CODE(perl)@en[[[undef]]]]; if it is, then
it [['''MUST''']] be treated as if an empty string
is specified.

;; Second (third) or more items, if any, are ignored.

[122] In addition to qualified name's syntax tests performed by these methods, following steps
[['''MUST''']] be run:
[FIG[
= If the namespace prefix is not [[null]] and is not an XML [[NCName]], throw a "[CODE(DOM)@en[[[NamespaceError]]]]"
exception.
= If the local name is not an XML [[NCName]], throw a "[CODE(DOM)@en[[[NamespaceError]]]]" exception.
]FIG]

;; The [CODE(DOMa)@en[[[strictErrorChecking]]]] attribute also affects these checks.

;; Unlike these methods, the [CODE(DOMp)@en[[[qualifiedName]]]]
parameter of the [CODE(DOMm)@en[[[createDocumentType]]]]
method of the [CODE(DOMi)@en[[[DOMImplementation]]]]
interface has ''no'' special interpretation for
an array reference, since the method does not
parse the parameter as a pair of 
namespace prefix and local name.

*** The [CODE(DOMm)@en[createDocumentType]] method

[125] If the second or third argument to the [CODE(DOMm)@en[[[createDocumentType]]]] method of the 
[CODE(DOMi)@en[[[DOMImplementation]]]] interface is [CODE(perl)@en[[[undef]]]], it [['''MUST''']]
be converted to the empty string.

*** Methods [CODE(DOMm)@en[createTextNode]], [CODE(DOMm)@en[createComment]], [CODE(DOMm)@en[createCDATASection]]

[32] Methods [CODE(DOMm)@en[[[createTextNode]]]],
[CODE(DOMm)@en[[[createComment]]]], and
[CODE(DOMm)@en[[[createCDATASection]]]] of the 
[CODE(DOMi)@en[[[Document]]]] interface
accept a scalar reference (>>33) as the first parameter.


** The [CODE(DOMi)@en[DOMStringList]] interface

@@ ==

@@ Should we allow any Perl array reference
as [CODE(DOMp)@en[[[arg]]]]?


** The [CODE(DOMi)@en[NodeList]] interface

[DEL[
[30]
For any [CODE(DOMi)@en[[[NodeList]]]] object,
the [CODE(perl)[[[==]]]] operator [['''MUST''']]
be so overloaded that it returns whether 
two arguments are equal in the equality defined
for the [CODE(DOMa)@en[[[isEqualNode]]]] method
of the [CODE(DOMi)@en[[[Node]]]] interface.

''However'', if the other operand is not a
[CODE(DOMi)@en[[[NodeList]]]] object, then
it [['''MUST''']] return a false value.
]DEL]

** The [CODE(DOMi)@en[NamedNodeMap]] interface

[DEL[
[31]
For any [CODE(DOMi)@en[[[NamedNodeMap]]]] object,
the [CODE(perl)[[[==]]]] operator [['''MUST''']]
be so overloaded that it returns whether 
two arguments are equal in the equality defined
for the [CODE(DOMa)@en[[[isEqualNode]]]] method
of the [CODE(DOMi)@en[[[Node]]]] interface.
]DEL]

[130] The [CODE(DOMi)@en[[[NamedNodeMap]]]] object [['''MUST''']] be treated as a hash-like object,
where keys are those accessible via the [CODE(DOMm)@en[[[getNamedItem]]]] method.

;; [131] If there are multiple items with same name in the [CODE(DOMi)@en[[[NamedNodeMap]]]],
the [CODE(DOMm)@en[[[getNamedItem]]]] method returns the first one.

@@ [132] This definition is not so strict...

** The [CODE(DOMi)@en[NSResolver]] Interface

[46]
A Perl [CODE(perl)@en[[[CODE]]]] reference (or any object
that can be dereferenced as if it were a [CODE(perl)@en[[[CODE]]]]
reference) can be specified as if it were
an [CODE(DOMi)@en[[[NSResolver]]]] interface.

When the [CODE(DOMm)@en[[[lookupNamespaceURI]]]] method
of an [CODE(DOMi)@en[[[NSResolver]]]] object [VAR@en[$obj]]
is invoked, it [['''MUST''']] be done by the algorithm
(or its equivalents) represented by the following subroutine
where [VAR@en[$_[0] ]] is the parameter to the method:
[PRE(perl code)[
sub {
  my $prefix = $_[0];
  if (UNIVERSAL::can ($obj, 'lookup_namespace_uri')) {
    return $obj->lookup_namespace_uri ($prefix);
  } else {
    return $obj->($prefix);
  }
}
]PRE]

;; Since the statement above assumes that [VAR@en[$obj]]
''is'' invoked, [VAR@en[$obj]] is not [CODE(perl)@en[[[undef]]]].

[47]
Invoking the [CODE(DOMm)@en[[[lookupNamespaceURI]]]]
method on the object implementing the [CODE(DOMi)@en[[[NSResolver]]]]
interface from another language binding [['''MUST''']]
behave as if the algorithm above is executed.
Note that in the Perl binding itself, however,
the method of the interface is not directly accessible
on the object implementing the interface when 
the object is a [CODE(perl)@en[[[CODE]]]] reference in fact.

** The [CODE(DOMi)@en[DOMImplementation]] interface

[37] If the class for the [CODE(DOMi)@en[[[DOMImplementation]]]] interface has the
constructor method, i.e. the [CODE(perl)@en[[[new]]]] method, it [['''MUST''']]
follow these steps:
[FIG[
= Let [VAR@en[document]] be the document returned by invoking the [CODE(DOMi)@en[[[Document]]]] constructor [SRC[DOM]].
= Return the [CODE(DOMi)@en[[[DOMImplementation]]]] object that is associated with
[VAR@en[document]].
]FIG]

* Garbage collection

[101] Since [[Perl]]'s garbage collection is [[reference count]], simply implementing various [[DOM]]
attributes as references could cause objects that could not be freed at all.  To work around this
situation, implementations can adopt different strategies, including:
- [102] Force the application to explicitly invoke some method to destroy a tree
- [103] Force the application to keep a reference to the root node
- [104] Implement implementation's own garbage collection mechanism

For the purpose of DOM conformance, limitations caused by those strategies are considered
"platform-specific limitations" <http://dom.spec.whatwg.org/#conformance>.

* References


** Normative References

:[DOMBinding]:
@@ DOM Bindings

Specifications listed below are only normative for implementations
that support features defined by those specification.

:[DOMCore]:
@@
:[DOMEvents]:
@@
:[DOMLS]:
@@
:[DOMTraversal]:
@@
:[HTML5]:
@@
:[SelectorsAPI]:
[CITE@en[Selectors API]], W3C Editor's Draft, 29 August 2007, 
<http://dev.w3.org/cvsweb/~checkout~/2006/webapi/selectors-api/Overview.html?rev=1.28&content-type=text/html;%20charset=utf-8>. 
The latest published version of Selectors API is available at 
<http://www.w3.org/TR/selectors-api/>. 
(Latest version of the specifcation whose maturity level is higher 
than Candidate Recommendation, if any, or latest Editor's Draft 
is referenced.)


** Informative References

:[SVGPB]:
@@ SVG's Perl binding


* memo

[35]

@@ Maybe we should define "==" for DOMImplementationList
(and any other array like objects)
([[名無しさん]])

[36]

@@ DOMImplementationList.push (non-dom-impl)

[38]

@@ %Message::DOM::DOMImplementationRegistry::SourceClass
([[名無しさん]])

[39]
>>38 $SourceClass

[41]

@@ Node.isEqualNode == Node.==

[49]

>In binding languages that support setting to a readonly attribute setting media to a string must set the value of mediaText on the MediaList object.

[CSSOM]