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1862 Coercing to a record type changes map order #1874

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1862 Coercing to a record type changes map order #1874

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44 changes: 38 additions & 6 deletions specifications/xquery-40/src/expressions.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -7021,6 +7021,12 @@ declare record Particle (
The coercion rules now allow conversion in either direction between <code>xs:hexBinary</code>
and <code>xs:base64Binary</code>.
</change>
<change issue="1318" PR="1501">
The coercion rules now apply recursively to the members of an array and the entries in a map.
</change>
<change issue="1862">
The coercion rules now reorder the entries in a map when the required type is a record type.
</change>
</changes>

<p diff="chg" at="2022-11-17">
Expand Down Expand Up @@ -7146,15 +7152,31 @@ declare record Particle (

<olist>
<item><p>If <var>J</var> matches (is an instance of) one of the alternatives
in <var>R</var>, then:</p>
in <var>R</var>, then <var>J</var> is coerced to the first alternative in
<var>R</var> that <var>J</var> matches.</p>

<note>
<p>There are two situations where coercing an item to a type that
it already matches does not simply return the item unchanged:</p>

<ulist>
<item><p>When the required type is a typed function type
(see <specref ref="id-function-test"/>),
then function coercion is applied to coerce <var>J</var> to that
function type, as described in <specref ref="id-function-coercion"/>.</p></item>
<item><p>When the required type is a record type and the supplied
value is a map, then coercion may change the <xtermref spec="DM40" ref="dt-entry-order"/>
of the entries in the map.</p></item>
</ulist>
</note>

<olist>
<!--<olist>
<item><p>If the first alternative in <var>R</var> that <var>J</var>
matches is a typed function type (see <specref ref="id-function-test"/>),
then function coercion is applied to coerce <var>J</var> to that
function type, as described in <specref ref="id-function-coercion"/>.</p></item>
<item><p>Otherwise, <var>J</var> is used as is.</p></item>
</olist>
</olist>-->

</item>

Expand Down Expand Up @@ -7357,6 +7379,7 @@ declare record Particle (
<errorref class="TY" code="0004"/>.</p></item>
<item><p>The corresponding value is converted to the required
map value type by applying the coercion rules recursively.</p></item>
<item><p>The order of entries in the map remains unchanged.</p></item>
</olist>

<note><p>For example, if the required type is
Expand All @@ -7376,16 +7399,23 @@ declare record Particle (
to a new map as follows:</p>
<olist>
<item><p>The keys in the supplied map are unchanged.</p></item>
<item><p>In any map entry whose key is an <code>xs:string</code> equal to the
name of one of the field declarations in <var>R</var>, the corresponding
<item><p>In any map entry whose key is equal to the
name of one of the field declarations in <var>R</var> (under the rules
of the <function>atomic-equal</function> function), the corresponding
value is converted to the required type defined by that field declaration,
by applying the coercion rules recursively
(but with XPath 1.0 compatibility mode treated as false).</p></item>
<item><p>The order of entries in the map is changed: entries whose keys correspond
to the names of field declarations in <var>R</var> appear first, in the order
of the corresponding field declarations, and (if the record type is extensible)
other entries then follow retaining their relative order in <var>J</var>.</p></item>
</olist>

<note><p>For example, if the required type is
<code>record(longitude as xs:double, latitude as xs:double)</code> and the supplied value is <code>{ "longitude": 0, "latitude": 53.2 }</code>,
<code>record(longitude as xs:double, latitude as xs:double)</code> and the supplied value is
<code>{ "latitude": 53.2, "longitude": 0 }</code>,
then the map is converted to <code>{ "longitude": 0.0e0, "latitude": 53.2e0 }</code>.</p></note>

</item>

<item>
Expand Down Expand Up @@ -8123,6 +8153,8 @@ return $f(12.3)]]></eg>
<p>Suppose the required type is <code>(record(x as xs:decimal, y as xs:decimal, *) | record(size as enum("S", "M", "L", "XL"), *))</code>.</p>

<table role="medium">
<col width="40%"/>
<col width="60%"/>
<thead>
<tr>
<th align="left">Supplied Value</th>
Expand Down