makefile: improve support

Improve support for makefile syntax:
- simple variables (eg `$(var)`) and special variables (eg `$@`)
- variable inside strings (eg `"blabla $(var) blabla"`)
- functions (eg `$(patsubst arg,arg,$(var))`)
- variable assignement (eg `var=toto`, `var+=toto`, `var:=toto`)
- targets (eg `all: dependency $(var)`)
- language keywords (`define`, `endef`, `ifeq`, etc.)

Signed-off-by: Joel Porquet <joel@porquet.org>

Author: joel-porquet

src/languages/makefile.js

@@ -1,50 +1,87 @@
 /*
 Language: Makefile
 Author: Ivan Sagalaev <maniac@softwaremaniacs.org>
+Contributors: Joël Porquet <joel@porquet.org>
 Category: common
 */
 
 function(hljs) {
+  /* Variables: simple (eg $(var)) and special (eg $@) */
   var VARIABLE = {
     className: 'variable',
-    begin: /\$\(/, end: /\)/,
-    contains: [hljs.BACKSLASH_ESCAPE]
-  };
-  return {
-    aliases: ['mk', 'mak'],
-    contains: [
-      hljs.HASH_COMMENT_MODE,
-      {
-        begin: /^\w+\s*\W*=/, returnBegin: true,
-        relevance: 0,
-        starts: {
-          end: /\s*\W*=/, excludeEnd: true,
-          starts: {
-            end: /$/,
-            relevance: 0,
-            contains: [
-              VARIABLE
-            ]
-          }
-        }
-      },
+    variants: [
       {
-        className: 'section',
-        begin: /^[\w]+:\s*$/
+        begin: '\\$\\(' + hljs.UNDERSCORE_IDENT_RE + '\\)',
+        contains: [hljs.BACKSLASH_ESCAPE],
       },
       {
-        className: 'meta',
-        begin: /^\.PHONY:/, end: /$/,
-        keywords: {'meta-keyword': '.PHONY'}, lexemes: /[\.\w]+/
+        begin: /\$[@%<?\^\+\*]/
       },
+    ]
+  };
+  /* Quoted string with variables inside */
+  var QUOTE_STRING = {
+    className: 'string',
+    begin: /"/, end: /"/,
+    contains: [
+      hljs.BACKSLASH_ESCAPE,
+      VARIABLE,
+    ]
+  };
+  /* Function: $(func arg,...) */
+  var FUNC = {
+    className: 'variable',
+    begin: /\$\([\w-]+\s/, end: /\)/,
+    keywords: {
+      built_in:
+        'subst patsubst strip findstring filter filter-out sort ' +
+        'word wordlist firstword lastword dir notdir suffix basename ' +
+        'addsuffix addprefix join wildcard realpath abspath error warning ' +
+        'shell origin flavor foreach if or and call eval file value',
+    },
+    contains: [
+      VARIABLE,
+    ]
+  };
+  /* Variable assignment */
+  var VAR_ASSIG = {
+    begin: '^' + hljs.UNDERSCORE_IDENT_RE + '\\s*[:+?]?=',
+    illegal: '\\n',
+    returnBegin: true,
+    contains: [
       {
-        begin: /^\t+/, end: /$/,
-        relevance: 0,
-        contains: [
-          hljs.QUOTE_STRING_MODE,
-          VARIABLE
-        ]
+        begin: '^' + hljs.UNDERSCORE_IDENT_RE, end: '[:+?]?=',
+        excludeEnd: true,
       }
     ]
   };
+  /* Meta targets (.PHONY) */
+  var META = {
+    className: 'meta',
+    begin: /^\.PHONY:/, end: /$/,
+    keywords: {'meta-keyword': '.PHONY'},
+    lexemes: /[\.\w]+/
+  };
+  /* Targets */
+  var TARGET = {
+    className: 'section',
+    begin: /^[^\s]+:/, end: /$/,
+    contains: [VARIABLE,]
+  };
+  return {
+    aliases: ['mk', 'mak'],
+    keywords:
+      'define endef undefine ifdef ifndef ifeq ifneq else endif ' +
+      'include -include sinclude override export unexport private vpath',
+    lexemes: /[\w-]+/,
+    contains: [
+      hljs.HASH_COMMENT_MODE,
+      VARIABLE,
+      QUOTE_STRING,
+      FUNC,
+      VAR_ASSIG,
+      META,
+      TARGET,
+    ]
+  };
 }