Added support for ANTLR4 (#2063)

This adds support for ANTLR4.

Languages embedded via actions are not highlighted.

components.json

@@ -92,6 +92,11 @@
 			"title": "Ada",
 			"owner": "Lucretia"
 		},
+		"antlr4": {
+			"title": "ANTLR4",
+			"alias": "g4",
+			"owner": "RunDevelopment"
+		},
 		"apacheconf": {
 			"title": "Apache Configuration",
 			"owner": "GuiTeK"

components/prism-antlr4.js

@@ -0,0 +1,65 @@
+Prism.languages.antlr4 = {
+	'comment': /\/\/.*|\/\*[\s\S]*?(?:\*\/|$)/,
+	'string': {
+		pattern: /'(?:\\.|[^\\'\r\n])*'/,
+		greedy: true
+	},
+	'character-class': {
+		pattern: /\[(?:\\.|[^\\\]\r\n])*\]/,
+		greedy: true,
+		alias: 'regex',
+		inside: {
+			'range': {
+				pattern: /([^[]|(?:^|[^\\])(?:\\\\)*\\\[)-(?!\])/,
+				lookbehind: true,
+				alias: 'punctuation'
+			},
+			'escape': /\\(?:u(?:[a-fA-F\d]{4}|\{[a-fA-F\d]+\})|[pP]\{[=\w-]+\}|[^\r\nupP])/,
+			'punctuation': /[\[\]]/
+		}
+	},
+	'action': {
+		pattern: /\{(?:[^{}]|\{(?:[^{}]|\{(?:[^{}]|\{[^{}]*\})*\})*\})*\}/,
+		greedy: true,
+		inside: {
+			'content': {
+				// this might be C, C++, Python, Java, C#, or any other language ANTLR4 compiles to
+				pattern: /(\{)[\s\S]+(?=\})/,
+				lookbehind: true
+			},
+			'punctuation': /[{}]/
+		}
+	},
+	'command': {
+		pattern: /(->\s*)(?:\s*(?:,\s*)?[a-z]\w*(?:\s*\([^()\r\n]*\))?)+(?=\s*;)/i,
+		lookbehind: true,
+		inside: {
+			'function': /\b\w+(?=\s*(?:[,(]|$))/,
+			'punctuation': /[,()]/
+		}
+	},
+	'annotation': {
+		pattern: /@\w+(?:::\w+)*/,
+		alias: 'keyword'
+	},
+	'label': {
+		pattern: /#[ \t]*\w+/,
+		alias: 'punctuation'
+	},
+	'keyword': /\b(?:catch|channels|finally|fragment|grammar|import|lexer|locals|mode|options|parser|returns|throws|tokens)\b/,
+	'definition': [
+		{
+			pattern: /\b[a-z]\w*(?=\s*:)/,
+			alias: ['rule', 'class-name']
+		},
+		{
+			pattern: /\b[A-Z]\w*(?=\s*:)/,
+			alias: ['token', 'constant']
+		},
+	],
+	'constant': /\b[A-Z][A-Z_]*\b/,
+	'operator': /\.\.|->|[|~]|[*+?]\??/,
+	'punctuation': /[;:()=]/
+};
+
+Prism.languages.g4 = Prism.languages.antlr4;

plugins/autoloader/prism-autoloader.js

@@ -133,6 +133,7 @@
 		"svg": "markup",
 		"mathml": "markup",
 		"js": "javascript",
+		"g4": "antlr4",
 		"adoc": "asciidoc",
 		"shell": "bash",
 		"rbnf": "bnf",

plugins/show-language/prism-show-language.js

@@ -21,6 +21,8 @@
 		"js": "JavaScript",
 		"abap": "ABAP",
 		"abnf": "Augmented Backus–Naur form",
+		"antlr4": "ANTLR4",
+		"g4": "ANTLR4",
 		"apacheconf": "Apache Configuration",
 		"apl": "APL",
 		"aql": "AQL",

tests/languages/antlr4/action_feature.test

@@ -0,0 +1,49 @@
+options { superClass = LexerAdaptor; }
+
+@lexer::header {
+  import { Token } from 'antlr4ts/Token';
+  import { CommonToken } from 'antlr4ts/CommonToken';
+  import { Python3Parser } from './Python3Parser';
+}
+
+END : 'end' {System.out.println("found an end");} ;
+
+@header {
+from LexerAdaptor import LexerAdaptor
+}
+
+----------------------------------------------------
+
+[
+	["keyword", "options"],
+	["action", [
+		["punctuation", "{"],
+		["content", " superClass = LexerAdaptor; "],
+		["punctuation", "}"]
+	]],
+	["annotation", "@lexer::header"],
+	["action", [
+		["punctuation", "{"],
+		["content", "\n  import { Token } from 'antlr4ts/Token';\n  import { CommonToken } from 'antlr4ts/CommonToken';\n  import { Python3Parser } from './Python3Parser';\n"],
+		["punctuation", "}"]
+	]],
+	["definition", "END"],
+	["punctuation", ":"],
+	["string", "'end'"],
+	["action", [
+		["punctuation", "{"],
+		["content", "System.out.println(\"found an end\");"],
+		["punctuation", "}"]
+	]],
+	["punctuation", ";"],
+	["annotation", "@header"],
+	["action", [
+		["punctuation", "{"],
+		["content", "\nfrom LexerAdaptor import LexerAdaptor\n"],
+		["punctuation", "}"]
+	]]
+]
+
+----------------------------------------------------
+
+Checks for actions.

tests/languages/antlr4/annotation_feature.test

@@ -0,0 +1,21 @@
+@header {}
+@lexer::header {}
+
+----------------------------------------------------
+
+[
+	["annotation", "@header"],
+	["action", [
+		["punctuation", "{"],
+		["punctuation", "}"]
+	]],
+	["annotation", "@lexer::header"],
+	["action", [
+		["punctuation", "{"],
+		["punctuation", "}"]
+	]]
+]
+
+----------------------------------------------------
+
+Checks for annotations.