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Merged
merged 2 commits into from
Mar 18, 2025
Merged

1869 duplicate values #1873

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c5e628e
expand spec of distinct-values and duplicate-values
michaelhkay Mar 14, 2025
0bdabac
Improve diagnostics on build error
michaelhkay Mar 14, 2025
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61 changes: 34 additions & 27 deletions specifications/xpath-functions-40/src/function-catalog.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -14417,12 +14417,21 @@ return exists($break)
<item><p>The items that are returned appear in the order of their first
appearance within <code>$values</code>.</p></item>
</ulist>





</fos:rules>
<fos:equivalent style="xpath-expression">
filter($values,
fn($item, $pos) {
empty(
filter(
subsequence($values, 1, $pos - 1),
deep-equal(?, $item, $collation)
)
)
}
)
</fos:equivalent>
<fos:notes>
<p>If <code>$values</code> is the empty sequence, the function returns the empty sequence.</p>

Expand Down Expand Up @@ -14494,39 +14503,39 @@ return exists($break)
selected according to the rules in <specref ref="choosing-a-collation"/>.</p>
<p>From each resulting set of values that are considered equal, one value will be
returned if the set contains more than one value.</p>
<p>The ordering of the result is as follows:</p>

<p>Specifically, the function returns those items in <code>$values</code> that are
equal (under this definition) to exactly one item appearing earlier in the sequence</p>

<p>This means that the ordering of the result is as follows:</p>

<ulist>
<item><p>For any set of values that compare equal, the one that is
returned is the one that appears first in <code>$values</code>.</p></item>
<item><p>The items that are returned appear in the order of their first
returned is the one that appears second in <code>$values</code>.</p></item>
<item><p>The items that are returned appear in the order of their second
appearance within <code>$values</code>.</p></item>
</ulist>


</fos:rules>
<fos:equivalent style="xpath-expression">
filter($values,
fn($item, $pos) {
count(
filter(
subsequence($values, 1, $pos - 1),
deep-equal(?, $item, $collation)
)
) eq 1
}
)
</fos:equivalent>

<fos:notes>
<p>The effect of the function is equivalent to the following XSLT expression:</p>
<eg><![CDATA[
<xsl:for-each-group select="$values" group-by="." collation="{ $collation }">
<xsl:sequence select="current-group()[2]"/>
</xsl:for-each>
]]></eg>
<p>The following XQuery expression is equivalent if no collation is specified
(<code>group by</code> requires collation URIs to be static):</p>
<eg>
for $group in $values
group by $value := $group
where count($group) > 1
return $value
</eg>
</fos:notes>
<fos:examples>
<fos:example>
<fos:test>
<fos:expression>duplicate-values((1, 2, 3, 1.0, 1e0))</fos:expression>
<fos:result>1</fos:result>
<fos:result>1.0</fos:result>
</fos:test>
</fos:example>
<fos:example>
Expand All @@ -14538,7 +14547,7 @@ return $value
<fos:example>
<fos:test spec="XQuery">
<fos:expression><![CDATA[duplicate-values(('1', <x>1</x>, '2', 2))]]></fos:expression>
<fos:result>"1"</fos:result>
<fos:result>xs:untypedAtomic("1")</fos:result>
<fos:postamble>The string <code>"1"</code> and the untyped value of the
element node are considered equal, whereas the string <code>"2"</code>
and the integer are considered unequal.</fos:postamble>
Expand All @@ -14552,9 +14561,7 @@ return error((), 'Duplicate IDs found: ' || string-join($ids, ', '))</eg>
</fos:example>
</fos:examples>
<fos:changes>
<fos:change issue="123" PR="614"><p>New in 4.0</p></fos:change>
<fos:change issue="628" PR="987"><p>The order of results is now prescribed;
it was previously implementation-dependent.</p></fos:change>
<fos:change issue="123 628 1869" PR="614 987"><p>New in 4.0</p></fos:change>
</fos:changes>
</fos:function>

Expand Down
2 changes: 1 addition & 1 deletion specifications/xpath-functions-40/style/merge-function-specs.xsl
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Original file line number Diff line number Diff line change
Expand Up @@ -408,7 +408,7 @@
</xsl:template>

<xsl:template match="fos:equivalent">
<xsl:message terminate="yes">Non-matching fos:equivalent for {../@name}</xsl:message>
<xsl:message terminate="yes">On fos:equivalent for {../@name}, @style is missing or invalid</xsl:message>
</xsl:template>

<xsl:template match="fos:example">
Expand Down