Add PlainTextRange interface

dom.bs

@@ -9892,6 +9892,144 @@ and {{Range/getBoundingClientRect()}} methods are defined in other specification
 [[CSSOM-VIEW]]
 
 
+<h3 id=interface-plaintext-range>Interface {{PlainTextRange}}</h3>
+
+<pre class=idl>
+[Exposed=Window]
+interface PlainTextRange : AbstractRange {
+  DOMRectList getClientRects();
+  DOMRect getBoundingClientRect();
+  stringifier;
+};
+</pre>
+
+<p>Objects implementing the {{PlainTextRange}} interface are known as {{PlainTextRange}} objects.</p>
+
+<dl class=domintro>
+ <dt><code><var ignore>rects</var> = <var ignore>range</var> . {{PlainTextRange/getClientRects()}}</code>
+ <dd>Returns a {{DOMRectList}} of client rectangles that enclose the selected portion of the host's
+ <a href="#plaintext-range-string">plain text range string</a>. If the range has no
+ <a for=PlainTextRange>host</a>, is {{AbstractRange/collapsed}} with no visible caret, or the host
+ has computed <code>display</code> of <code>none</code> or is not <a>connected</a>, returns an
+ empty list.
+
+ <dt><code><var ignore>rect</var> = <var ignore>range</var> . {{PlainTextRange/getBoundingClientRect()}}</code>
+ <dd>Returns a {{DOMRect}} that is the union of the rectangles from
+ {{PlainTextRange/getClientRects()}}. For a {{AbstractRange/collapsed}} range in a visible host,
+ returns a rectangle of zero width whose height equals the line height at the caret position. If the
+ host has computed <code>display</code> of <code>none</code> or is not <a>connected</a>, returns a
+ rectangle with zero width and height.
+</dl>
+
+<p>A {{PlainTextRange}} is a range whose <a>boundary points</a> are defined as offsets in a
+host-defined <a href="#plaintext-range-string">plain text range string</a> rather than in the
+<a>node tree</a>. It has no associated container node; its {{AbstractRange/startContainer}} and
+{{AbstractRange/endContainer}} getters return null, and its {{AbstractRange/startOffset}} and
+{{AbstractRange/endOffset}} getters return indices into that string.</p>
+
+<p>A {{PlainTextRange}} has associated state:</p>
+
+<ul>
+ <li><p><dfn export for=PlainTextRange id=plaintext-range-host>host</dfn> (null or an
+ {{Element}}).</p></li>
+ <li><p><dfn export for=PlainTextRange id=plaintext-range-start>start offset</dfn> (a non-negative
+ integer).</p></li>
+ <li><p><dfn export for=PlainTextRange id=plaintext-range-end>end offset</dfn> (a non-negative
+ integer).</p></li>
+</ul>
+
+<p>The {{AbstractRange/startContainer}} getter steps for {{PlainTextRange}} objects are to return
+null.</p>
+
+<p>The {{AbstractRange/endContainer}} getter steps for {{PlainTextRange}} objects are to return
+null.</p>
+
+<p>The {{AbstractRange/startOffset}} getter steps for {{PlainTextRange}} objects are to return
+<a>this</a>'s <a for=PlainTextRange>start offset</a>.</p>
+
+<p>The {{AbstractRange/endOffset}} getter steps for {{PlainTextRange}} objects are to return
+<a>this</a>'s <a for=PlainTextRange>end offset</a>.</p>
+
+<p>The {{AbstractRange/collapsed}} getter steps for {{PlainTextRange}} objects are to return true
+if <a>this</a>'s <a for=PlainTextRange>start offset</a> equals <a for=PlainTextRange>end
+offset</a>; otherwise false.</p>
+
+<p>An {{Element}} <var>el</var> <dfn export id=supports-plaintext-range>supports plain text
+ranges</dfn> if its specification defines that it does.</p>
+
+<p class=note>The HTML Standard defines that certain {{HTMLInputElement}} types and
+{{HTMLTextAreaElement}} support plain text ranges over their <code>value</code>. Other
+specifications may define additional elements, including custom elements, that support plain text
+ranges.</p>
+
+<p>For an element <var>el</var> that <a lt="supports plain text ranges">supports plain text
+ranges</a>, its <dfn export id=plaintext-range-string>plain text range string</dfn> is a
+specification-defined string that represents the linear editable text for that element. In HTML,
+this is typically the string exposed by the element's IDL <code>value</code> attribute. Offsets for
+{{PlainTextRange}} are indices into this <a href="#plaintext-range-string">plain text range
+string</a> in the inclusive range [0, <code>string.length</code>].</p>
+
+<p>When a {{PlainTextRange}} is created, its <a for=PlainTextRange>host</a> must be set to null and
+its <a for=PlainTextRange>start offset</a> and <a for=PlainTextRange>end offset</a> must be set to
+0.</p>
+
+<p>To <dfn export id=concept-plaintext-range-set>set a plain text range</dfn> for a
+{{PlainTextRange}} <var>range</var> over an {{Element}} <var>host</var> from
+<var>startOffset</var> to <var>endOffset</var>, run these steps:</p>
+
+<ol>
+ <li><p>If <var>host</var> does not <a>support plain text ranges</a>, then <a>throw</a> a
+ "{{NotSupportedError!!exception}}" {{DOMException}}.</p></li>
+ <li><p>Let <var>string</var> be <var>host</var>'s <a href="#plaintext-range-string">plain text
+ range string</a>. Let <var>len</var> be <var>string</var>'s <a for=string>length</a>.</p></li>
+ <li><p>If <var>startOffset</var> &gt; <var>len</var> or <var>endOffset</var> &gt; <var>len</var>,
+ then <a>throw</a> an "{{IndexSizeError!!exception}}" {{DOMException}}.</p></li>
+ <li><p>If <var>startOffset</var> &gt; <var>endOffset</var>, then set <var>endOffset</var> to
+ <var>startOffset</var>.</p></li>
+ <li><p>Set <var>range</var>'s <a for=PlainTextRange>host</a> to <var>host</var>, its
+ <a for=PlainTextRange>start offset</a> to <var>startOffset</var>, and its
+ <a for=PlainTextRange>end offset</a> to <var>endOffset</var>.</p></li>
+</ol>
+
+<p>A {{PlainTextRange}} is live: when its host's <a href="#plaintext-range-string">plain text range
+string</a> changes, the range's <a for=PlainTextRange>start offset</a> and <a
+for=PlainTextRange>end offset</a> are updated automatically to preserve the same logical content.
+These behaviors mirror {{Range}} boundary adjustments in the DOM but are applied to the UTF-16 code
+units of the host's string.</p>
+
+<ul>
+ <li><p>Edits before the range: Offsets shift by the net length change.</p></li>
+ <li><p>Edits after the range: Offsets remain unchanged.</p></li>
+ <li><p>Edits overlapping the range: If a boundary falls inside text that was removed, move it to
+ the start of the change. If the edit also inserted new text, remap the boundary into the inserted
+ span at the closest corresponding offset, not exceeding its end.</p></li>
+ <li><p>Insertion at the start boundary: A non-{{AbstractRange/collapsed}} range expands to include
+ the new text. A collapsed range moves after the insertion.</p></li>
+ <li><p>Insertion at the end boundary: A non-collapsed range does not expand to include the new
+ text. A collapsed range moves after the insertion.</p></li>
+ <li><p>Clamping and collapse: Offsets are clamped to the current string length. If the
+ {{AbstractRange/startOffset}} would exceed the {{AbstractRange/endOffset}}, set the end to the
+ start.</p></li>
+</ul>
+
+<p class=note>Specifications that define elements which <a>support plain text ranges</a> (such as
+the HTML Standard for text controls) must normatively define when a {{PlainTextRange}} is created,
+how it is associated with a host, when its host becomes null, and when its boundary points are
+updated using the rules above.</p>
+
+<p>The <dfn export for=PlainTextRange id=dom-plaintext-range-stringifier>stringification
+behavior</dfn> must run these steps:</p>
+
+<ol>
+ <li><p>If <a>this</a>'s <a for=PlainTextRange>host</a> is null, then return the empty
+ string.</p></li>
+ <li><p>Let <var>string</var> be <a>this</a>'s <a for=PlainTextRange>host</a>'s
+ <a href="#plaintext-range-string">plain text range string</a>.</p></li>
+ <li><p>Let <var>start</var> be <a>this</a>'s <a for=PlainTextRange>start offset</a>, and let
+ <var>end</var> be <a for=PlainTextRange>end offset</a>.</p></li>
+ <li><p>Return the substring of <var>string</var> from <var>start</var> to <var>end</var>.</p></li>
+</ol>
+
 
 <h2 id="traversal">Traversal</h2>