Add linking support for enumidentifier elements

When <enumidentifier> contains a fully qualified name with :: separator
(e.g., RoundingMode::HalfAwayFromZero), the enum name is extracted and
used to generate a link to the corresponding enum documentation page.

Links are not generated in enumsynopsis context (where enumidentifier
defines the case) or when the enum is not found in the index.

Refs #180

Author: lacatoire

phpdotnet/phd/Package/PHP/XHTML.php

@@ -125,6 +125,10 @@ abstract class Package_PHP_XHTML extends Package_Generic_XHTML {
                 'classsynopsis' => 'format_classsynopsis_oo_name_text',
             ]
         ],
+        'enumidentifier' => [
+            /* DEFAULT */ 'format_enumidentifier_text',
+            'enumsynopsis' => false,
+        ],
         'methodname'            => array(
             /* DEFAULT */          'format_function_text',
             'constructorsynopsis' => array(
@@ -898,6 +902,25 @@ public function format_classname_text($value, $tag) {
         return '<strong class="' .$tag. '">' .$value. '</strong>';
     }
 
+    public function format_enumidentifier_text($value, $tag) {
+        if (!str_contains($value, '::')) {
+            return $value;
+        }
+
+        list($enumName) = explode('::', $value);
+        $t = strtr($this->normalizeFQN($enumName), ["_" => "-", "\\" => "-"]);
+        $href = Format::getFilename("enum.$t");
+
+        if ($href === false) {
+            return $value;
+        }
+
+        if ($this->chunked) {
+            return '<a href="' . $href . $this->ext . '" class="' . $tag . '">' . $value . '</a>';
+        }
+        return '<a href="#' . $href . '" class="' . $tag . '">' . $value . '</a>';
+    }
+
 
     /*Chunk Functions*/
     private function isChunkedByAttributes(array $attributes): bool {

tests/package/php/data/enumidentifier_link_rendering.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?>
+<chapter xml:id="enumidentifier_link_rendering" xmlns="http://docbook.org/ns/docbook">
+
+ <section>
+  <para>1. Enum case inside enumsynopsis (no link - definition context)</para>
+  <enumsynopsis>
+   <enumname>TestEnum</enumname>
+   <enumitem>
+    <enumidentifier>CaseDefinition</enumidentifier>
+   </enumitem>
+  </enumsynopsis>
+ </section>
+
+ <section>
+  <para>2. Enum case reference with FQN (linked)</para>
+  <enumidentifier>Enum\Namespace\Existing_Enum::SomeCase</enumidentifier>
+ </section>
+
+ <section>
+  <para>3. Enum case reference with FQN and leading backslash (linked)</para>
+  <enumidentifier>\Enum\Namespace\Existing_Enum::AnotherCase</enumidentifier>
+ </section>
+
+ <section>
+  <para>4. Enum case without namespace separator (no link)</para>
+  <enumidentifier>JustCaseName</enumidentifier>
+ </section>
+
+ <section>
+  <para>5. Enum case for non-existent enum (no link)</para>
+  <enumidentifier>NonExistent\Enum::SomeCase</enumidentifier>
+ </section>
+
+</chapter>

tests/package/php/enumidentifier_link_rendering.phpt

@@ -0,0 +1,64 @@
+--TEST--
+Enum case (enumidentifier) link rendering
+--FILE--
+<?php
+namespace phpdotnet\phd;
+
+require_once __DIR__ . "/../../setup.php";
+
+$config->xmlFile = __DIR__ . "/data/enumidentifier_link_rendering.xml";
+
+$format = new TestPHPChunkedXHTML($config, $outputHandler);
+$format->SQLiteIndex(
+    null, // $context,
+    null, // $index,
+    "enum.enum-namespace-existing-enum", // $id,
+    "enum.enum-namespace-existing-enum", // $filename,
+    "", // $parent,
+    "", // $sdesc,
+    "", // $ldesc,
+    "phpdoc:classref", // $element,
+    "", // $previous,
+    "", // $next,
+    0, // $chunk
+);
+
+$render = new TestRender(new Reader($outputHandler), $config, $format);
+$render->run();
+?>
+--EXPECT--
+Filename: enumidentifier_link_rendering.html
+Content:
+<div id="enumidentifier_link_rendering" class="chapter">
+
+ <div class="section">
+  <p class="para">1. Enum case inside enumsynopsis (no link - definition context)</p>
+  <div class="classsynopsis"><div class="classsynopsisinfo">
+   <span class="modifier">enum</span> <strong class="classname"><strong class="enumname">TestEnum</strong></strong><br/>{</div>
+   <div class="fieldsynopsis">
+        <span class="modifier">case</span>  <span class="classname">CaseDefinition</span>
+   </div>
+  }</div>
+ </div>
+
+ <div class="section">
+  <p class="para">2. Enum case reference with FQN (linked)</p>
+      <span class="modifier">case</span>  <span class="classname"><a href="enum.enum-namespace-existing-enum.html" class="enumidentifier">Enum\Namespace\Existing_Enum::SomeCase</a></span>
+ </div>
+
+ <div class="section">
+  <p class="para">3. Enum case reference with FQN and leading backslash (linked)</p>
+      <span class="modifier">case</span>  <span class="classname"><a href="enum.enum-namespace-existing-enum.html" class="enumidentifier">\Enum\Namespace\Existing_Enum::AnotherCase</a></span>
+ </div>
+
+ <div class="section">
+  <p class="para">4. Enum case without namespace separator (no link)</p>
+      <span class="modifier">case</span>  <span class="classname">JustCaseName</span>
+ </div>
+
+ <div class="section">
+  <p class="para">5. Enum case for non-existent enum (no link)</p>
+      <span class="modifier">case</span>  <span class="classname">NonExistent\Enum::SomeCase</span>
+ </div>
+
+</div>