X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=man%2Fcustom-html.xsl;h=1ac247e6545be4861b599110a255e18c876de055;hb=e7f11b8ef6815c3a851cd1a74b75b4b78152dab0;hp=d5947d8fb5c895535e306da7e5449235c11a1b0c;hpb=c784f8fb150c50f55edb824737b536214f8e8e13;p=elogind.git

diff --git a/man/custom-html.xsl b/man/custom-html.xsl
index d5947d8fb..1ac247e65 100644
--- a/man/custom-html.xsl
+++ b/man/custom-html.xsl
@@ -113,80 +113,122 @@
   </a>
 </xsl:template>
 
-<xsl:template match="refsect1/title|refsect1/info/title">
-  <!-- the ID is output in the block.object call for refsect1 -->
-  <h2>
+<!--
+  - helper template to do conflict resolution between various headings with the same inferred ID attribute/tag from the headerlink template
+  - this conflict resolution is necessary to prevent malformed HTML ouput (multiple id attributes with the same value)
+  - and it fixes xsltproc warnings during compilation of HTML man pages
+  -
+  - A simple top-to-bottom numbering scheme is implemented for nodes with the same ID value to derive unique ID values for HTML output.
+  - It uses two parameters:
+      templateID  the proposed ID string to use which must be checked for conflicts
+      keyNode     the context node which 'produced' the given templateID.
+  -
+  - Conflicts are detected solely based on keyNode, templateID is not taken into account for that purpose.
+ -->
+<xsl:template name="generateID">
+  <!-- node which generatedID needs to assume as the 'source' of the ID -->
+  <xsl:param name="keyNode"/>
+  <!-- suggested value for generatedID output, a contextually meaningful ID string -->
+  <xsl:param name="templateID"/>
+  <xsl:variable name="conflictSource" select="preceding::refsect1/title|preceding::refsect1/info/title|
+					      preceding::refsect2/title|preceding::refsect2/info/title|
+					      preceding::varlistentry/term[1]"/>
+  <xsl:variable name="conflictCount" select="count($conflictSource[. = $keyNode])"/>
+  <xsl:choose>
+    <!-- special case conflictCount = 0 to preserve compatibility with URLs generated by previous versions of this XSL stylesheet where possible -->
+    <xsl:when test="$conflictCount = 0">
+      <xsl:value-of select="$templateID"/>
+    </xsl:when>
+    <xsl:otherwise>
+      <xsl:value-of select="concat($templateID, $conflictCount)"/>
+    </xsl:otherwise>
+  </xsl:choose>
+</xsl:template>
+
+<!--
+  - a helper template to abstract over the structure of generated subheading + permalink HTML output
+  - It helps reduce tedious repetition and groups all actual markup output (as opposed to URL/ID logic) in a single location.
+ -->
+<xsl:template name="permalink">
+  <xsl:param name="nodeType"/> <!-- local name of the element node to generate, e.g. 'h2' for <h2></h2> -->
+  <xsl:param name="nodeContent"/> <!-- nodeset to apply further templates to obtain the content of the subheading/term -->
+  <xsl:param name="linkTitle"/> <!-- value for title attribute of generated permalink, e.g. 'this is a permalink' -->
+
+  <!-- parameters passed to generateID template, otherwise unused. -->
+  <xsl:param name="keyNode"/>
+  <xsl:param name="templateID"/>
+
+  <!--
+    - If stable URLs with fragment markers (references to the ID) turn out not to be important:
+    - generatedID could simply take the value of generate-id(), and various other helper templates may be dropped entirely.
+    - Alternatively if xsltproc is patched to generate reproducible generate-id() output the same simplifications can be
+    - applied at the cost of breaking compatibility with URLs generated from output of previous versions of this stylesheet.
+   -->
+  <xsl:variable name="generatedID">
+    <xsl:call-template name="generateID">
+      <xsl:with-param name="keyNode" select="$keyNode"/>
+      <xsl:with-param name="templateID" select="$templateID"/>
+    </xsl:call-template>
+  </xsl:variable>
+
+  <xsl:element name="{$nodeType}">
     <xsl:attribute name="id">
-      <xsl:call-template name="inline.charseq"/>
+      <xsl:value-of select="$generatedID"/>
     </xsl:attribute>
-    <xsl:apply-templates/>
-    <a>
-      <xsl:attribute name="class">
-        <xsl:text>headerlink</xsl:text>
-      </xsl:attribute>
-      <xsl:attribute name="title">
-        <xsl:text>Permalink to this headline</xsl:text>
-      </xsl:attribute>
-      <xsl:attribute name="href">
-        <xsl:text>#</xsl:text>
-        <xsl:call-template name="inline.charseq"/>
-      </xsl:attribute>
-      <xsl:text>¶</xsl:text>
-    </a>
-  </h2>
+    <xsl:apply-templates select="$nodeContent"/>
+    <a class="headerlink" title="{$linkTitle}" href="#{$generatedID}">¶</a>
+  </xsl:element>
 </xsl:template>
 
-<xsl:template match="refsect2/title|refsect2/info/title">
-  <h3>
-    <xsl:attribute name="id">
+<!-- simple wrapper around permalink to avoid repeating common info for each level of subheading covered by the permalink logic (h2, h3) -->
+<xsl:template name="headerlink">
+  <xsl:param name="nodeType"/>
+  <xsl:call-template name="permalink">
+    <xsl:with-param name="nodeType" select="$nodeType"/>
+    <xsl:with-param name="linkTitle" select="'Permalink to this headline'"/>
+    <xsl:with-param name="nodeContent" select="node()"/>
+    <xsl:with-param name="keyNode" select="."/>
+    <!--
+      - To retain compatibility with IDs generated by previous versions of the template, inline.charseq must be called.
+      - The purpose of that template is to generate markup (according to docbook documentation its purpose is to mark/format something as plain text).
+      - The only reason to call this template is to get the auto-generated text such as brackets ([]) before flattening it.
+     -->
+    <xsl:with-param name="templateID">
       <xsl:call-template name="inline.charseq"/>
-    </xsl:attribute>
-    <xsl:apply-templates/>
-    <a>
-      <xsl:attribute name="class">
-        <xsl:text>headerlink</xsl:text>
-      </xsl:attribute>
-      <xsl:attribute name="title">
-        <xsl:text>Permalink to this headline</xsl:text>
-      </xsl:attribute>
-      <xsl:attribute name="href">
-        <xsl:text>#</xsl:text>
-        <xsl:call-template name="inline.charseq"/>
-      </xsl:attribute>
-      <xsl:text>¶</xsl:text>
-    </a>
-  </h3>
+    </xsl:with-param>
+  </xsl:call-template>
+</xsl:template>
+
+<xsl:template match="refsect1/title|refsect1/info/title">
+  <!-- the ID is output in the block.object call for refsect1 -->
+  <xsl:call-template name="headerlink">
+    <xsl:with-param name="nodeType" select="'h2'"/>
+  </xsl:call-template>
+</xsl:template>
+
+<xsl:template match="refsect2/title|refsect2/info/title">
+  <xsl:call-template name="headerlink">
+    <xsl:with-param name="nodeType" select="'h3'"/>
+  </xsl:call-template>
 </xsl:template>
 
 <xsl:template match="varlistentry">
-  <dt>
-    <xsl:attribute name="id">
+  <xsl:call-template name="permalink">
+    <xsl:with-param name="nodeType" select="'dt'"/>
+    <xsl:with-param name="linkTitle" select="'Permalink to this term'"/>
+    <xsl:with-param name="nodeContent" select="term"/>
+    <xsl:with-param name="keyNode" select="term[1]"/>
+    <!--
+      - To retain compatibility with IDs generated by previous versions of the template, inline.charseq must be called.
+      - The purpose of that template is to generate markup (according to docbook documentation its purpose is to mark/format something as plain text).
+      - The only reason to call this template is to get the auto-generated text such as brackets ([]) before flattening it.
+     -->
+    <xsl:with-param name="templateID">
       <xsl:call-template name="inline.charseq">
-        <xsl:with-param name="content">
-          <xsl:copy-of select="term[position()=1]" />
-        </xsl:with-param>
+	<xsl:with-param name="content" select="term[1]"/>
       </xsl:call-template>
-    </xsl:attribute>
-    <xsl:apply-templates select="term"/>
-    <a>
-      <xsl:attribute name="class">
-        <xsl:text>headerlink</xsl:text>
-      </xsl:attribute>
-      <xsl:attribute name="title">
-        <xsl:text>Permalink to this term</xsl:text>
-      </xsl:attribute>
-      <xsl:attribute name="href">
-        <!--        <xsl:call-template name="href.target.uri" /> -->
-        <xsl:text>#</xsl:text>
-        <xsl:call-template name="inline.charseq">
-          <xsl:with-param name="content">
-            <xsl:copy-of select="term[position()=1]" />
-          </xsl:with-param>
-        </xsl:call-template>
-      </xsl:attribute>
-      <xsl:text>¶</xsl:text>
-    </a>
-  </dt>
+    </xsl:with-param>
+  </xsl:call-template>
   <dd>
     <xsl:apply-templates select="listitem"/>
   </dd>