add(php-template) Explicit language to detect PHP templates (#2417)

- Adds a separate language to detect PHP templates to avoid overloading
  `xml`

XML never should have built-in PHP support in the first place as there
are any number of templating languages out there, and they all can't be
built into XML.

This rectifies that situation.

Author: joshgoebel

CHANGES.md

@@ -2,6 +2,7 @@
 
 New languages:
 
+- (php-template) Explicit language to detect PHP templates (vs xml) [Josh Goebel][]
 - enh(python) Added `python-repl` for Python REPL sessions
 
 New themes:

VERSION_10_BREAKING.md

@@ -1,13 +1,16 @@
 ## Version 10 Breaking Changes
 
 Incompatibilities:
+
 - chore(parser): compressed version 9.x language definitions no longer supported (rebuild them minified) [Josh Goebel][]
 - `nohightlight` and `no-highlight` are the only "ignore me" css classes now (`plain` and `text` no longer count)
   (to get the old behavior you can customize `noHighlightRe`)
 - a grammar with a top-level `self` reference will now always throw an error
   (previously in safe mode this would be silently ignored)
+- PHP templates are now detected as `php-template`, not `xml`
 
 Renamed Language Files:
+
 - chore(parser): rename `nimrod.js` to `nim.js` [Josh Goebel][]
 - chore(parser): rename `cs.js` to `csharp.js` [Josh Goebel][]
 - chore(parser): rename `tex.js` to `latex.js` [Josh Goebel][]
@@ -19,11 +22,13 @@ Renamed Language Files:
   (https://github.com/highlightjs/highlight.js/issues/2146)
 
 Legacy Browser Issues:
+
 - **We're now using ES2015 features in the codebase.  Internet Explorer 11 is no longer supported.**
 - In general legacy browsers are no longer supported.
 - chore(parser): remove `load` listener in favor of only the newer `DOMContentLoaded` [Josh Goebel][]
 
 Removed styles:
+
 - chore(styles): darkula.css (use darcula.css instead) [Josh Goebel][]
 
 [Josh Goebel]: https://github.com/yyyc514

src/languages/php-template.js

@@ -0,0 +1,30 @@
+/*
+Language: PHP Template
+Requires: xml.js, php.js
+Author: Josh Goebel <[email protected]>
+Website: https://www.php.net
+Category: common
+*/
+
+export default function(hljs) {
+  return {
+    name: "PHP template",
+    subLanguage: 'xml',
+    contains: [
+      {
+        begin: /<\?(php|=)?/,
+        end: /\?>/,
+        subLanguage: 'php',
+        contains: [
+          // We don't want the php closing tag ?> to close the PHP block when
+          // inside any of the following blocks:
+          {begin: '/\\*', end: '\\*/', skip: true},
+          {begin: 'b"', end: '"', skip: true},
+          {begin: 'b\'', end: '\'', skip: true},
+          hljs.inherit(hljs.APOS_STRING_MODE, {illegal: null, className: null, contains: null, skip: true}),
+          hljs.inherit(hljs.QUOTE_STRING_MODE, {illegal: null, className: null, contains: null, skip: true})
+        ]
+      }
+    ]
+  };
+}

src/languages/php.js

@@ -11,7 +11,12 @@ export default function(hljs) {
     begin: '\\$+[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*'
   };
   var PREPROCESSOR = {
-    className: 'meta', begin: /<\?(php|=)?|\?>/
+    className: 'meta',
+    variants: [
+      { begin: /<\?php/, relevance: 10 }, // boost for obvious PHP
+      { begin: /<\?[=]?/ },
+      { begin: /\?>/ } // end php tag
+    ]
   };
   var STRING = {
     className: 'string',

src/languages/xml.js

@@ -97,19 +97,6 @@ export default function(hljs) {
         className: 'meta',
         begin: /<\?xml/, end: /\?>/, relevance: 10
       },
-      {
-        begin: /<\?(php)?/, end: /\?>/,
-        subLanguage: 'php',
-        contains: [
-          // We don't want the php closing tag ?> to close the PHP block when
-          // inside any of the following blocks:
-          {begin: '/\\*', end: '\\*/', skip: true},
-          {begin: 'b"', end: '"', skip: true},
-          {begin: 'b\'', end: '\'', skip: true},
-          hljs.inherit(hljs.APOS_STRING_MODE, {illegal: null, className: null, contains: null, skip: true}),
-          hljs.inherit(hljs.QUOTE_STRING_MODE, {illegal: null, className: null, contains: null, skip: true})
-        ]
-      },
       {
         className: 'tag',
         /*

test/detect/php-template/default.txt

@@ -0,0 +1,8 @@
+<html>
+</html>
+<body>
+<?php
+# Here echo command is used to print
+echo "Hello, world!";
+?>
+</body>

test/fixtures/expect/sublanguages.txt

@@ -1,4 +1,5 @@
-<span class="php"><span class="hljs-meta">&lt;?</span> <span class="hljs-keyword">echo</span> <span class="hljs-string">'php'</span>; <span class="hljs-comment">/* ?&gt; */</span> <span class="hljs-meta">?&gt;</span></span>
+<span class="php"><span class="hljs-meta">&lt;?</span> <span class="hljs-keyword">echo</span> <span class="hljs-string">'php'</span>; <span class="hljs-comment">/* ?&gt; */</span> <span class="hljs-meta">?&gt;</span></span><span class="xml">
 <span class="hljs-tag">&lt;<span class="hljs-name">body</span>&gt;</span>
 <span class="hljs-tag">&lt;<span class="hljs-name">script</span>&gt;</span><span class="javascript"><span class="hljs-built_in">document</span>.write(<span class="hljs-string">'Legacy code'</span>);</span><span class="hljs-tag">&lt;/<span class="hljs-name">script</span>&gt;</span>
 <span class="hljs-tag">&lt;/<span class="hljs-name">body</span>&gt;</span>
+</span>