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Make the directionality account for missing parent element
The current algorithm has no defined exit for when an element has no parent element and its dir attribute is in the undefined state. And also rewrite it to make it easier to change as we want to account for shadow trees in a future version. This was inspired by work from Brian Kardell and fantasai in this area. Closes #9452.
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Original file line numberDiff line numberDiff line change
@@ -13443,161 +13443,167 @@ Transport Protocol">HTTP&lt;/abbr> today.&lt;/p></code></pre> <!-- DO NOT REWRAP
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specifies the element's text directionality. The attribute is an <span>enumerated attribute</span>
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with the following keywords and states:</p>
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<dl>
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<dt>The <dfn attr-value for="html-global/dir"><code data-x="attr-dir-ltr">ltr</code></dfn>
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keyword, which maps to the <dfn data-x="attr-dir-ltr-state">ltr</dfn> state</dt>
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<dd>
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<p>Indicates that the contents of the element are explicitly directionally isolated
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left-to-right text.</p>
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</dd>
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<dt>The <dfn attr-value for="html-global/dir"><code data-x="attr-dir-rtl">rtl</code></dfn>
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keyword, which maps to the <dfn data-x="attr-dir-rtl-state">rtl</dfn> state</dt>
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<dd>
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<p>Indicates that the contents of the element are explicitly directionally isolated
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right-to-left text.</p>
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</dd>
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<dt>The <dfn attr-value for="html-global/dir"><code data-x="attr-dir-auto">auto</code></dfn>
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keyword, which maps to the <dfn data-x="attr-dir-auto-state">auto</dfn> state</dt>
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<dd>
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<p>Indicates that the contents of the element are explicitly directionally isolated text, but
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that the direction is to be determined programmatically using the contents of the element (as
13469-
described below).</p>
13446+
<table>
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<thead>
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<tr>
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<th>Keyword</th>
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<th>State</th>
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<th>Brief description</th>
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</tr>
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</thead>
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<tbody>
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<tr>
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<td><dfn attr-value for="html-global/dir"><code data-x="attr-dir-ltr">ltr</code></dfn></td>
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<td><dfn data-x="attr-dir-ltr-state">ltr</dfn></td>
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<td>The contents of the element are explicitly directionally isolated left-to-right text.</td>
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</tr>
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<tr>
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<td><dfn attr-value for="html-global/dir"><code data-x="attr-dir-rtl">rtl</code></dfn></td>
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<td><dfn data-x="attr-dir-rtl-state">rtl</dfn></td>
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<td>The contents of the element are explicitly directionally isolated right-to-left text.</td>
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</tr>
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<tr>
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<td><dfn attr-value for="html-global/dir"><code data-x="attr-dir-auto">auto</code></dfn></td>
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<td><dfn data-x="attr-dir-auto-state">auto</dfn></td>
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<td>The contents of the element are explicitly directionally isolated text, but the direction
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is to be determined programmatically using the contents of the element (as described
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below).</td>
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</tr>
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</tbody>
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</table>
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<p class="note">The heuristic used by this state is very crude (it just looks at the first
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character with a strong directionality, in a manner analogous to the Paragraph Level
13473-
determination in the bidirectional algorithm). Authors are urged to only use this value as a
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last resort when the direction of the text is truly unknown and no better server-side heuristic
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can be applied. <ref>BIDI</ref></p>
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<div class="note">
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<p>The heuristic used by the <span data-x="attr-dir-auto-state">auto</span> state is very crude
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(it just looks at the first character with a strong directionality, in a manner analogous to the
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Paragraph Level determination in the bidirectional algorithm). Authors are urged to only use this
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value as a last resort when the direction of the text is truly unknown and no better server-side
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heuristic can be applied. <ref>BIDI</ref></p>
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<p class="note">For <code>textarea</code> and <code>pre</code> elements, the heuristic is
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applied on a per-paragraph level.</p>
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</dd>
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</dl>
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<p>For <code>textarea</code> and <code>pre</code> elements, the heuristic is applied on a
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per-paragraph level.</p>
13484+
</div>
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13482-
<p>The attribute has no <i data-x="invalid value default">invalid value default</i> and no <i data-x="missing value default">missing value default</i>.</p>
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<p>The <code data-x="attr-dir">dir</code> attribute's <i data-x="invalid value default">invalid
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value default</i> and <i data-x="missing value default">missing value default</i> are both the
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<dfn data-x="attr-dir-undefined-state">undefined</dfn> state.</p>
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1348413490
<hr>
1348513491

13486-
<p><dfn>The directionality</dfn> of an element (any element, not just an <span data-x="HTML
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elements">HTML element</span>) is either '<dfn data-x="concept-ltr">ltr</dfn>' or '<dfn
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data-x="concept-rtl">rtl</dfn>', and is determined as per the first appropriate set of steps from
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the following list:</p>
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<p>The <dfn data-x="the directionality">directionality</dfn> of an element (any element, not just
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an <span data-x="HTML elements">HTML element</span>) is either '<dfn
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data-x="concept-ltr">ltr</dfn>' or '<dfn data-x="concept-rtl">rtl</dfn>'. To compute the <span
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data-x="the directionality">directionality</span> given an element <var>element</var>, switch on
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<var>element</var>'s <code data-x="attr-dir">dir</code> attribute state:</p>
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1349113498
<dl class="switch">
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<dt><span data-x="attr-dir-ltr-state">ltr</span></dt>
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<dd><p>Return '<span data-x="concept-ltr">ltr</span>'.</p></dd>
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13502+
<dt><span data-x="attr-dir-rtl-state">rtl</span></dt>
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<dd><p>Return '<span data-x="concept-rtl">rtl</span>'.</p></dd>
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<dt>If the element's <code data-x="attr-dir">dir</code> attribute is in the <span
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data-x="attr-dir-ltr-state">ltr</span> state</dt>
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<dt>If the element is a <span>document element</span> and the <code data-x="attr-dir">dir</code>
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attribute is not in a defined state (i.e. it is not present or has an invalid value)</dt>
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13500-
<dt>If the element is an <code>input</code> element whose <code
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data-x="attr-input-type">type</code> attribute is in the <span
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data-x="attr-input-type-tel">Telephone</span> state, and the <code data-x="attr-dir">dir</code>
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attribute is not in a defined state (i.e. it is not present or has an invalid value)</dt>
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<dd><p><span>The directionality</span> of the element is '<span
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data-x="concept-ltr">ltr</span>'.</p></dd>
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<dt>If the element's <code data-x="attr-dir">dir</code> attribute is in the <span
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data-x="attr-dir-rtl-state">rtl</span> state</dt>
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<dd><p><span>The directionality</span> of the element is '<span
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data-x="concept-rtl">rtl</span>'.</p></dd>
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13515-
<dt>If the element is an <code>input</code> element whose <code
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data-x="attr-input-type">type</code> attribute is in the <span
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data-x="attr-input-type-text">Text</span>, <span data-x="attr-input-type-search">Search</span>,
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<span data-x="attr-input-type-tel">Telephone</span>, <span
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data-x="attr-input-type-url">URL</span>, or <span data-x="attr-input-type-email">Email</span>
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state, and the <code data-x="attr-dir">dir</code> attribute is in the <span
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data-x="attr-dir-auto-state">auto</span> state</dt>
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13523-
<dt>If the element is a <code>textarea</code> element and the <code data-x="attr-dir">dir</code>
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attribute is in the <span data-x="attr-dir-auto-state">auto</span> state</dt>
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<dt><span data-x="attr-dir-auto-state">auto</span></dt>
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<dd><p>Return the <span>auto directionality</span> of <var>element</var>.</p></dd>
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<dt><span data-x="attr-dir-undefined-state">undefined</span></dt>
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<dd>
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<p>If the element's <span data-x="concept-fe-value">value</span> contains a character of
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bidirectional character type AL or R, and there is no character of bidirectional character type
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L anywhere before it in the element's <span data-x="concept-fe-value">value</span>, then
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<span>the directionality</span> of the element is '<span data-x="concept-rtl">rtl</span>'.
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<ref>BIDI</ref></p>
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<ol>
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<li><p>If <var>element</var> is a <code>bdi</code> element, then return the <span>auto
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directionality</span> of <var>element</var>.</p></li>
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<p>Otherwise, if the element's <span data-x="concept-fe-value">value</span> is not the empty
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string, or if the element is a <span>document element</span>, <span>the directionality</span> of
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the element is '<span data-x="concept-ltr">ltr</span>'.</p>
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<li><p>If <var>element</var> is an <code>input</code> element whose <code
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data-x="attr-input-type">type</code> attribute is in the <span
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data-x="attr-input-type-tel">Telephone</span> state, then return '<span
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data-x="concept-ltr">ltr</span>'.</p></li>
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13537-
<p>Otherwise, <span>the directionality</span> of the element is the same as the element's parent
13538-
element's <span data-x="the directionality">directionality</span>.</p>
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<li><p>Return the <span>parent directionality</span> of <var>element</var>.</p></li>
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</ol>
1353913521
</dd>
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</dl>
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<p class="note">Since the <code data-x="attr-dir">dir</code> attribute is only defined for
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<span>HTML elements</span>, it cannot be present on elements from other namespaces. Thus, elements
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from other namespaces always end up using the <span>parent directionality</span>.</p>
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13528+
<p>To compute the <dfn>auto directionality</dfn> given an element <var>element</var>:</p>
1354213529

13543-
<dt>If the element's <code data-x="attr-dir">dir</code> attribute is in the <span
13544-
data-x="attr-dir-auto-state">auto</span> state</dt>
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<ol>
13531+
<li>
13532+
<p>If <var>element</var> is an <code>input</code> element whose <code
13533+
data-x="attr-input-type">type</code> attribute is in the <span
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data-x="attr-input-type-text">Text</span>, <span data-x="attr-input-type-search">Search</span>,
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<span data-x="attr-input-type-tel">Telephone</span>, <span
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data-x="attr-input-type-url">URL</span>, or <span data-x="attr-input-type-email">Email</span>
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state, or <var>element</var> is a <code>textarea</code> element, then:</p>
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13546-
<dt>If the element is a <code>bdi</code> element and the <code data-x="attr-dir">dir</code>
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attribute is not in a defined state (i.e. it is not present or has an invalid value)</dt>
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<ol>
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<li><p>If <var>element</var>'s <span data-x="concept-fe-value">value</span> contains a
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character of bidirectional character type AL or R, and there is no character of bidirectional
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character type L anywhere before it in the element's <span
13543+
data-x="concept-fe-value">value</span>, then return '<span data-x="concept-rtl">rtl</span>'.
13544+
<ref>BIDI</ref></p></li>
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13549-
<dd>
13550-
<p>Find the first character in <span>tree order</span> that matches the following criteria:</p>
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<li><p>If <var>element</var>'s <span data-x="concept-fe-value">value</span> is not the empty
13547+
string, then return '<span data-x="concept-ltr">ltr</span>'.</p></li>
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13552-
<ul>
13549+
<li><p>Return the <span>parent directionality</span> of <var>element</var>.</p></li>
13550+
</ol>
13551+
</li>
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13554-
<li><p>The character is from a <code>Text</code> node that is a descendant of the element whose
13555-
<span data-x="the directionality">directionality</span> is being determined.</p></li>
13553+
<li><p>Let <var>codePoint</var> be null.</p></li>
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13557-
<li><p>The character is of bidirectional character type L, AL, or R. <ref>BIDI</ref></li>
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<li>
13556+
<p>For each <code>Text</code> node <var>text</var> that is a descendant of <var>element</var>,
13557+
in <span>tree order</span>:</p>
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13559+
<ol>
1355913560
<li>
13560-
<p>The character is not in a <code>Text</code> node that has an ancestor element that is a
13561-
descendant of the element whose <span data-x="the directionality">directionality</span> is
13562-
being determined and that is either:</p>
13561+
<p>If <var>text</var> has an ancestor element that is a descendant of <var>element</var> and
13562+
is also one of</p>
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1356413564
<ul class="brief">
13565-
<li>A <code>bdi</code> element.
13566-
<li>A <code>script</code> element.
13567-
<li>A <code>style</code> element.
13568-
<li>A <code>textarea</code> element.
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<li>An element with a <code data-x="attr-dir">dir</code> attribute in a defined state.
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<li>a <code>bdi</code> element</li>
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<li>a <code>script</code> element</li>
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<li>a <code>style</code> element</li>
13568+
<li>a <code>textarea</code> element</li>
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<li>an element whose <code data-x="attr-dir">dir</code> attribute is not in the <span
13570+
data-x="attr-dir-undefined-state">undefined</span> state</li>
1357013571
</ul>
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13573+
<p>then <span>continue</span>.</p>
1357113574
</li>
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13573-
</ul>
13576+
<li><p>If <var>text</var>'s <span data-x="concept-cd-data">data</span> does not contain a code
13577+
point whose bidirectional character type is L, AL, or R, then <span>continue</span>.
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<ref>BIDI</ref></p></li>
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13575-
<p>If such a character is found and it is of bidirectional character type AL or R, <span>the
13576-
directionality</span> of the element is '<span data-x="concept-rtl">rtl</span>'.</p>
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<li><p>Set <var>codePoint</var> to the first code point in <var>text</var>'s <span
13581+
data-x="concept-cd-data">data</span> whose bidirectional character type is L, AL, or
13582+
R.</p></li>
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13578-
<p>If such a character is found and it is of bidirectional character type L, <span>the
13579-
directionality</span> of the element is '<span data-x="concept-ltr">ltr</span>'.</p>
13584+
<li><p><span>Break</span>.</p></li>
13585+
</ol>
13586+
</li>
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13581-
<p>Otherwise, if the element is a <span>document element</span>, <span>the directionality</span>
13582-
of the element is '<span data-x="concept-ltr">ltr</span>'.</p>
13588+
<li><p>If <var>codePoint</var> is null, then return the <span>parent directionality</span> of
13589+
<var>element</var>.</p></li>
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13584-
<p>Otherwise, <span>the directionality</span> of the element is the same as the element's parent
13585-
element's <span data-x="the directionality">directionality</span>.</p>
13586-
</dd>
13591+
<li><p>If <var>codePoint</var> is of bidirectional character type AL or R, then return '<span
13592+
data-x="concept-rtl">rtl</span>'.</p></li>
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13594+
<li><p>If <var>codePoint</var> is of bidirectional character type L, then return '<span
13595+
data-x="concept-ltr">ltr</span>'.</p></li>
13596+
</ol>
1358813597

13589-
<dt>If the element has a parent element and the <code data-x="attr-dir">dir</code> attribute is
13590-
not in a defined state (i.e. it is not present or has an invalid value)</dt>
13598+
<p>To compute the <dfn>parent directionality</dfn> given an element <var>element</var>:</p>
1359113599

13592-
<dd><p><span>The directionality</span> of the element is the same as the element's parent
13593-
element's <span data-x="the directionality">directionality</span>.</p></dd>
13594-
</dl>
13600+
<ol>
13601+
<li><p>If <var>element</var> has no <span>parent element</span>, then return '<span
13602+
data-x="concept-ltr">ltr</span>'.</p></li>
1359513603

13596-
<p class="note">Since the <code data-x="attr-dir">dir</code> attribute is only defined for
13597-
<span>HTML elements</span>, it cannot be present on elements from other namespaces. Thus, elements
13598-
from other namespaces always just inherit their <span data-x="the
13599-
directionality">directionality</span> from their parent element, or, if they don't have one,
13600-
default to '<span data-x="concept-ltr">ltr</span>'.</p>
13604+
<li><p>Return <span data-x="the directionality">directionality</span> of <var>element</var>'s
13605+
<span data-x="parent element">parent</span>.</p></li>
13606+
</ol>
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<div w-nodev>
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