Ambiguous rule match in replacing style= attributes in XHTML via XSLT

风流意气都作罢 提交于 2019-12-31 02:21:26

问题


This is a followup to this question.

I have several <span> tags in a document with several semicolon separated style attributes. Right now I have 3 specific style attributes I'm looking for to translate into tags. All works well in the example above as long as the style attribute only contains one of the three style attributes. If a span has more, I get an ambiguous rule match.

The three style attributes I'm looking for are font-style:italic, font-weight:600, and text-decoration:underline which should be removed from the style attribute and transformed into <em>, <strong>, and <u>, respectively.

Here's my current XSLT:

<xsl:template match="node()|@*">
    <xsl:copy>
        <xsl:apply-templates select="node()|@*"/>
    </xsl:copy>
</xsl:template>

<xsl:template match="span[
    contains(translate(@style, ' ', ''), 'font-style:italic')
    ]">
    <xsl:copy>
       <xsl:attribute name="style">
            <xsl:value-of select="substring-before(@style, ' font-style')"/>
            <xsl:value-of select="substring-after(@style, 'italic;')"/>
        </xsl:attribute>
        <em>
            <xsl:apply-templates select="node()"/>
        </em>
    </xsl:copy>
</xsl:template>
<xsl:template match="span[
    contains(translate(@style, ' ', ''), 'font-weight:600')
    ]">
    <xsl:copy>
        <xsl:attribute name="style">
            <xsl:value-of select="substring-before(@style, ' font-weight')"/>
            <xsl:value-of select="substring-after(@style, '600;')"/>
        </xsl:attribute>
        <strong>
            <xsl:apply-templates select="node()"/>
        </strong>
    </xsl:copy>
</xsl:template>

<xsl:template match="span[ 
    contains(translate(@style, ' ', ''), 'text-decoration:underline')
    ]">
    <xsl:copy>
        <xsl:attribute name="style">
            <xsl:value-of select="substring-before(@style, ' text-decoration')"/>
            <xsl:value-of select="substring-after(@style, 'underline;')"/>
        </xsl:attribute>
        <u>
            <xsl:apply-templates select="node()"/>
        </u>
    </xsl:copy>
</xsl:template>

Which will generate the ambiguous rule warning doesn't work correctly on some elements that contain more than one of the listed attributes.

An example of the input:

<span style=" text-decoration: underline; font-weight:600; color:#555555">some text</span>

gets transformed to:

<span style=" font-weight:600; color:#555555"><u>some text</u></span>

when the desired result is:

<span style="color:#555555"><b><u>some text</u></b></span>

How can I fix the ambiguous rule match for this?

Thanks in advance


Update:

If i set priorty on each of the templates to descending values and run the XSLT again on the output of the first XSLT run, everything works as expected. There has to be an easier way than running it through the transformation twice. Any ideas?


As Alejandro and Tomalak suggested, replacing the style attributes with a class attribute for CSS classes is an option, too.


回答1:


EDIT: Just in case real problem gets hide, I have simplified the stylesheet:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:msxsl="urn:schemas-microsoft-com:xslt"
 xmlns:s="styles"
 exclude-result-prefixes="s msxsl">
    <s:s prop="font-style:italic" name="em"/>
    <s:s prop="font-weight:600" name="strong"/>
    <s:s prop="text-decoration:underline" name="u"/>
    <xsl:variable name="vStyles" select="document('')/*/s:s"/>
    <xsl:template match="node()|@*">
        <xsl:copy>
            <xsl:apply-templates select="node()|@*"/>
        </xsl:copy>
    </xsl:template>
    <xsl:template match="span[@style]">
        <xsl:variable name="vrtfProp">
            <xsl:call-template name="parser"/>
        </xsl:variable>
        <xsl:variable name="vProp"
                      select="msxsl:node-set($vrtfProp)/*"/>
        <xsl:copy>
            <xsl:apply-templates select="@*[name()!='style']"/>
            <xsl:attribute name="style">
                <xsl:for-each select="$vProp[not(.=$vStyles/@prop)]">
                    <xsl:value-of select="concat(.,';')"/>
                </xsl:for-each>
            </xsl:attribute>
            <xsl:call-template name="generate">
                <xsl:with-param
                     name="pElements"
                     select="$vStyles[@prop=$vProp]/@name"/>
            </xsl:call-template>
        </xsl:copy>
    </xsl:template>
    <xsl:template name="generate">
        <xsl:param name="pElements" select="/.."/>
        <xsl:choose>
            <xsl:when test="$pElements">
                <xsl:element name="{$pElements[1]}">
                    <xsl:call-template name="generate">
                        <xsl:with-param
                             name="pElements"
                             select="$pElements[position()>1]"/>
                    </xsl:call-template>
                </xsl:element>
            </xsl:when>
            <xsl:otherwise>
                <xsl:apply-templates/>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>
    <xsl:template name="parser">
        <xsl:param name="pString" select="concat(@style,';')"/>
        <xsl:if test="contains($pString,';')">
            <xsl:variable
                 name="vProp"
                 select="substring-before($pString,';')"/>
            <prop>
                <xsl:value-of
                     select="concat(
                                normalize-space(
                                   substring-before($vProp,':')
                                ),
                                ':',
                                normalize-space(
                                   substring-after($vProp,':')
                                )
                             )"/>
            </prop>
            <xsl:call-template name="parser">
                <xsl:with-param
                     name="pString"
                     select="substring-after($pString,';')"/>
            </xsl:call-template>
        </xsl:if>
    </xsl:template>
</xsl:stylesheet>

Output:

<span style="color:#555555;"><strong><u>some text</u></strong></span>

Note: Simpler parsing with space normalization to match properties in an existencial comparison. Generating content without optimization (selecting no match, selecting match). "Stateful" or "stackful" named template for output nested elements. Either way there are two rules (identity and span with @style overwriting it) and two names templates (parser/tokenizer and generator of nested content)

Original stylesheet:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:msxsl="urn:schemas-microsoft-com:xslt"
 xmlns:s="styles"
 xmlns:t="tokenizer"
 exclude-result-prefixes="s t msxsl">
    <s:s r="font-style" v="italic" e="em"/>
    <s:s r="font-weight" v="600" e="strong"/>
    <s:s r="text-decoration" v="underline" e="u"/>
    <t:t s=";" n="p"/>
    <t:t s=":" n="t"/>
    <xsl:variable name="vStyles" select="document('')/*/s:s"/>
    <xsl:template match="node()|@*">
        <xsl:copy>
            <xsl:apply-templates select="node()|@*"/>
        </xsl:copy>
    </xsl:template>
    <xsl:template match="span[@style]">
        <xsl:variable name="vrtfStyles">
            <xsl:call-template name="tokenizer"/>
        </xsl:variable>
        <xsl:copy>
            <xsl:apply-templates select="@*[name()!='style']"/>
            <xsl:call-template name="generate">
                <xsl:with-param name="pStyles"
                                select="msxsl:node-set($vrtfStyles)/*"/>
            </xsl:call-template>
        </xsl:copy>
    </xsl:template>
    <xsl:template name="generate">
        <xsl:param name="pStyles" select="/.."/>
        <xsl:param name="pAttributes" select="/.."/>
        <xsl:param name="pElements" select="/.."/>
        <xsl:choose>
            <xsl:when test="$pStyles">
                <xsl:variable name="vMatch"
                              select="$vStyles[@r=$pStyles[1]/t[1]]
                                              [@v=$pStyles[1]/t[2]]"/>
                <xsl:call-template name="generate">
                    <xsl:with-param name="pStyles"
                                    select="$pStyles[position()>1]"/>
                    <xsl:with-param name="pAttributes"
                                    select="$pAttributes|
                                            $pStyles[1][not($vMatch)]"/>
                    <xsl:with-param name="pElements"
                                    select="$pElements|$vMatch"/>
                </xsl:call-template>
            </xsl:when>
            <xsl:when test="$pAttributes">
                <xsl:attribute name="style">
                    <xsl:for-each select="$pAttributes">
                        <xsl:value-of select="concat(t[1],':',t[2],';')"/>
                    </xsl:for-each>
                </xsl:attribute>
                <xsl:call-template name="generate">
                    <xsl:with-param name="pElements" select="$pElements"/>
                </xsl:call-template>
            </xsl:when>
            <xsl:when test="$pElements">
                <xsl:element name="{$pElements[1]/@e}">
                    <xsl:call-template name="generate">
                        <xsl:with-param name="pElements"
                                        select="$pElements[position()>1]"/>
                    </xsl:call-template>
                </xsl:element>
            </xsl:when>
            <xsl:otherwise>
                <xsl:apply-templates/>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>
    <xsl:template name="tokenizer">
        <xsl:param name="pTokenizer" select="document('')/*/t:t"/>
        <xsl:param name="pString" select="@style"/>
        <xsl:choose>
            <xsl:when test="not($pTokenizer)">
                <xsl:value-of select="normalize-space($pString)"/>
            </xsl:when>
            <xsl:when test="contains($pString,$pTokenizer[1]/@s)">
                <xsl:call-template name="tokenizer">
                    <xsl:with-param name="pTokenizer" select="$pTokenizer"/>
                    <xsl:with-param name="pString"
                                    select="substring-before(
                                               $pString,
                                               $pTokenizer[1]/@s
                                            )"/>
                </xsl:call-template>
                <xsl:call-template name="tokenizer">
                    <xsl:with-param name="pTokenizer" select="$pTokenizer"/>
                    <xsl:with-param name="pString"
                                    select="substring-after(
                                               $pString,
                                               $pTokenizer[1]/@s
                                            )"/>
                </xsl:call-template>
            </xsl:when>
            <xsl:otherwise>
                <xsl:element name="{$pTokenizer[1]/@n}">
                    <xsl:call-template name="tokenizer">
                        <xsl:with-param name="pTokenizer"
                                        select="$pTokenizer[position()>1]"/>
                        <xsl:with-param name="pString" select="$pString"/>
                    </xsl:call-template>
                </xsl:element>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>
</xsl:stylesheet>

Note: Recursion paradise. Nested tokenizer for parsing style properties. "Stateful" template for nested content (and performance matching properties, by the way)




回答2:


Here is an XSLT 1.0 solution using the str-split-to-words template/function of FXSL:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:ext="http://exslt.org/common"
 exclude-result-prefixes="ext"
>
  <xsl:import href="strSplit-to-Words.xsl"/>
  <xsl:output indent="yes" omit-xml-declaration="yes"/>

  <xsl:param name="pStyleReps">
    <r s="font-style:italic"><em/></r>
    <r s="font-weight:600"><strong/></r>
    <r s="text-decoration:underline"><u/></r>
  </xsl:param>

  <xsl:variable name="vReps" select=
  "document('')/*/xsl:param[@name='pStyleReps']/*"/>

   <xsl:template match="span">
       <xsl:variable name="vrtfStyles">
         <xsl:call-template name="str-split-to-words">
          <xsl:with-param name="pStr" select="@style"/>
          <xsl:with-param name="pDelimiters" select="';'"/>
         </xsl:call-template>
       </xsl:variable>

       <xsl:variable name="vStyles" select=
       "ext:node-set($vrtfStyles)/*"/>

       <xsl:choose>
        <xsl:when test=
         "not($vReps/@s[contains(current()/@style, .)])">
          <xsl:copy-of select="."/>
        </xsl:when>
        <xsl:otherwise>
          <span>
           <xsl:copy-of select="@*"/>
           <xsl:attribute name="style">
             <xsl:for-each select=
              "$vStyles[not(translate(.,' ','')=$vReps/@s)]">
              <xsl:value-of select="."/>
              <xsl:if test="not(position()=last())">;</xsl:if>
             </xsl:for-each>
           </xsl:attribute>

           <xsl:call-template name="styles2markup">
             <xsl:with-param name="pStyles" select=
             "$vReps/@s
                 [contains
                   (translate(current()/@style, ' ', ''),
                    .
                    )
                 ]"/>
           </xsl:call-template>
          </span>
        </xsl:otherwise>
       </xsl:choose>
    </xsl:template>

    <xsl:template name="styles2markup">
     <xsl:param name="pResult" select="text()"/>
     <xsl:param name="pStyles"/>

     <xsl:choose>
     <xsl:when test="not($pStyles)">
      <xsl:copy-of select="$pResult"/>
     </xsl:when>
     <xsl:otherwise>
      <xsl:variable name="vrtfnewResult">
        <xsl:element name="{name($pStyles[1]/../*)}">
         <xsl:copy-of select="$pResult"/>
        </xsl:element>
      </xsl:variable>

      <xsl:call-template name="styles2markup">
       <xsl:with-param name="pStyles" select=
       "$pStyles[position()>1]"/>
       <xsl:with-param name="pResult" select=
       "ext:node-set($vrtfnewResult)/*"/>
      </xsl:call-template>
     </xsl:otherwise>
     </xsl:choose>
    </xsl:template>
</xsl:stylesheet>

when this transformation is applied on the provided XML document:

<span style=" text-decoration: underline; font-weight:600; color:#555555">some text</span>

the wanted, correct result is produced:

<span style=" color:#555555">
   <u>
      <strong>some text</strong>
   </u>
</span>


来源:https://stackoverflow.com/questions/4903860/ambiguous-rule-match-in-replacing-style-attributes-in-xhtml-via-xslt

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