enh(php) Left and right-side of double colon

Author: wkania

src/languages/php.js

@@ -340,6 +340,62 @@ export default function(hljs) {
     }
   };
 
+  // This will not detect camelCase classes
+  const PASCAL_CASE_CLASS_NAME = regex.concat("[A-Z]", IDENT_RE);
+
+  const CONSTANT_REFERENCE = regex.concat(IDENT_RE, "\\b(?!\\()");
+
+  const LEFT_AND_RIGHT_SIDE_OF_DOUBLE_COLON = {
+    variants: [
+      {
+        match: [
+          regex.concat(
+            /::/,
+            regex.lookahead(/(?!class\b)/)
+          ),
+          CONSTANT_REFERENCE,
+        ],
+        scope: {
+          2: "variable",
+        },
+      },
+      {
+        match: [
+          PASCAL_CASE_CLASS_NAME,
+          regex.concat(
+            "::",
+            regex.lookahead(/(?!class\b)/)
+          ),
+          CONSTANT_REFERENCE,
+        ],
+        scope: {
+          1: "title.class",
+          3: "variable",
+        },
+      },
+      {
+        match: [
+          /::/,
+          /class/,
+        ],
+        scope: {
+          2: "variable.language",
+        },
+      },
+      {
+        match: [
+          PASCAL_CASE_CLASS_NAME,
+          /::/,
+          /class/,
+        ],
+        scope: {
+          1: "title.class",
+          3: "variable.language",
+        },
+      }
+    ]
+  };
+
   return {
     case_insensitive: false,
     keywords: KEYWORDS,
@@ -380,6 +436,7 @@ export default function(hljs) {
       },
       VARIABLE,
       FUNCTION_INVOKE,
+      LEFT_AND_RIGHT_SIDE_OF_DOUBLE_COLON,
       {
         match: [
           /const/,
@@ -425,6 +482,7 @@ export default function(hljs) {
             contains: [
               'self',
               VARIABLE,
+              LEFT_AND_RIGHT_SIDE_OF_DOUBLE_COLON,
               hljs.C_BLOCK_COMMENT_MODE,
               STRING,
               NUMBER