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Optimal m0v0s* single-distinct-@on scalar match 

See comments for more information.

This will require a polyfill for Array.prototype.includes for IE11, if we
stick with it.
master
Mike Gerwitz 2021-01-20 14:50:50 -05:00
parent 1f72f756ca
commit a880605511
1 changed files with 35 additions and 9 deletions
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44
src/current/compiler/js.xsl
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@ -726,15 +726,41 @@
<variable name="cop" as="xs:string"
select="if ( @any = 'true' ) then '||' else '&amp;&amp;'" />
<sequence select="concat( $var, '=!!(', $yield-to, '=+(',
string-join(
for $s in $scalars
return concat(
compiler:match-name-on( $symtable-map, $s ),
'===',
compiler:match-value( $symtable-map, $s ) ),
$cop ),
'));' )" />
<choose>
<!-- if all the matches are on the same @on, we can optimize even
further (unless it's a single match, in which case the fallback
is the optimal way to proceed) -->
<when test="$ns > 1 and count( distinct-values( $scalars/@on ) ) = 1">
<!-- if this is not @any, then it's nonsense -->
<if test="not( @any = 'true' )">
<message terminate="yes"
select="concat( 'error: ', @as, ' match ', $scalars[0]/@on,
'will never succeed' )" />
</if>
<sequence select="concat( $var, '=!!(', $yield-to, '=+[',
string-join(
for $s in $scalars
return compiler:match-value( $symtable-map, $s ),
',' ),
'].includes(',
compiler:match-name-on( $symtable-map, $scalars[1] ),
'));' )" />
</when>
<!-- either a single match or matches on >1 distinct @on -->
<otherwise>
<sequence select="concat( $var, '=!!(', $yield-to, '=+(',
string-join(
for $s in $scalars
return concat(
compiler:match-name-on( $symtable-map, $s ),
'===',
compiler:match-value( $symtable-map, $s ) ),
$cop ),
'));' )" />
</otherwise>
</choose>
</when>
<!-- the terribly ineffeient way -->