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Re: [xsl] parsing parens in the park

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I missed something, Syd ...

At 2008-09-28 15:50 -0400, I wrote:

I think I may have solved it below ... please let me know if there are edge cases I didn't think of.

When I went to file this away I discovered a mistake. The code below appears to work better than my earlier post.

. . . . . . . . Ken


t:\ftemp>type syd.xml
<?xml version="1.0" encoding="US-ASCII"?>
<tests>
<test>name1(value1)name2(with(nested(parens((inside)of) value))name3(abc)</test>
<test>name1(value1)name2( with(nested(parens((inside)of) value)more)name3()</test>
<test>name1 (value1) name2 (value2) name3 (value3)</test>
<test>name1 (value1)name2 () name3(value3)</test>
</tests>

t:\ftemp>call xslt2 syd.xml syd.xsl syd.out

t:\ftemp>type syd.out
<?xml version="1.0" encoding="UTF-8"?>
<results>
<result name1="value1" name2="with(nested(parens((inside)of) value))" name3="abc"/>
<result name1="value1" name2=" with(nested(parens((inside)of) value)more)" name3=""/>
<result name1="value1" name2="value2" name3="value3"/>
<result name1="value1" name2="" name3="value3"/>
</results>
t:\ftemp>type syd.xsl
<?xml version="1.0" encoding="US-ASCII"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:c="uri:x-Crane"
exclude-result-prefixes="c"
version="2.0">

<xsl:output indent="yes"/>

<xsl:template match="tests">
  <results>
    <xsl:apply-templates select="test"/>
  </results>
</xsl:template>

<xsl:template match="test">
  <!--
  Debug: <xsl:value-of select="."/>
  <xsl:text>
</xsl:text>
  -->
  <result>
    <!--use a called template because of the need to generate structure-->
    <xsl:call-template name="c:values"/>
  </result>
</xsl:template>

<!--process a name/value specification-->
<xsl:template name="c:name-value-pair">
  <xsl:param name="name"/>
  <xsl:param name="value"/>

  <xsl:attribute name="{$name}" select="$value"/>
</xsl:template>

<!--find the first value specification in a string of value specifications-->
<xsl:template name="c:values">
  <xsl:param name="rest" select="."/>
  <xsl:if test="$rest">
    <!--walk through the string-->
    <xsl:analyze-string select="$rest" regex="\s*(\i\c*)\s*\((.*?)([()])(.*)">
      <xsl:matching-substring>
        <xsl:choose>
          <xsl:when test="regex-group(3)='('">
            <!--at the start of a nested parenthesized value, so find it-->
            <xsl:variable name="this-rest"
                          select="c:nested-value('',regex-group(4),1)"/>
            <!--process the name/value pair-->
            <xsl:call-template name="c:name-value-pair">
              <xsl:with-param name="name" select="regex-group(1)"/>
              <xsl:with-param name="value" select="concat(regex-group(2),'(',
                                                          $this-rest[1],')')"/>
            </xsl:call-template>
            <!--find the next value specification-->
            <xsl:call-template name="c:values">
              <xsl:with-param name="rest" select="$this-rest[2]"/>
            </xsl:call-template>
          </xsl:when>
          <xsl:otherwise>
            <!--process the name/value pair-->
            <xsl:call-template name="c:name-value-pair">
              <xsl:with-param name="name" select="regex-group(1)"/>
              <xsl:with-param name="value" select="regex-group(2)"/>
            </xsl:call-template>
            <!--find the next value specification-->
            <xsl:call-template name="c:values">
              <xsl:with-param name="rest" select="regex-group(4)"/>
            </xsl:call-template>
          </xsl:otherwise>
        </xsl:choose>
      </xsl:matching-substring>
      <xsl:non-matching-substring>
        <xsl:message>
          <xsl:text>Whoops!  What happened here? Not expected: </xsl:text>
          <xsl:value-of select="."/>
        </xsl:message>
      </xsl:non-matching-substring>
    </xsl:analyze-string>
  </xsl:if>
</xsl:template>

<!--recursively determine a parenthesized value assuming balanced parens-->
<xsl:function name="c:nested-value">
  <!--returning a sequence of two values: the value and the rest-->
  <xsl:param name="this"/>
  <xsl:param name="rest"/>
  <xsl:param name="depth"/>
  <xsl:if test="$rest">
    <!--there is still more to do-->
    <xsl:analyze-string select="$rest" regex="(.*?)([()])(.*)">
      <xsl:matching-substring>
        <xsl:choose>
          <xsl:when test="regex-group(2)='('">
            <!--yet another nested value-->
            <xsl:sequence select="c:nested-value( concat($this,regex-group(1),
                                                         '('),
                                                  regex-group(3),
                                                  $depth + 1)"/>
          </xsl:when>
          <xsl:when test="$depth=1">
            <!--found the last balanced parenthesis-->
            <xsl:sequence select="concat($this,regex-group(1)),
                                  regex-group(3)"/>
          </xsl:when>
          <xsl:otherwise>
            <!--found a nested balanced parenthesis-->
            <xsl:sequence select="c:nested-value(concat($this,regex-group(1),
                                                        ')'),
                                                 regex-group(3),
                                                 $depth - 1)"/>
          </xsl:otherwise>
        </xsl:choose>
      </xsl:matching-substring>
      <xsl:non-matching-substring>
        <xsl:message>
          <xsl:text>Nested whops!  Not expected:</xsl:text>
          <xsl:value-of select="."/>
        </xsl:message>
      </xsl:non-matching-substring>
    </xsl:analyze-string>
  </xsl:if>
</xsl:function>

</xsl:stylesheet>
t:\ftemp>rem Done!

--
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