Markdown: Added support for YAML front matter (#2634)

components.json

@@ -703,6 +703,7 @@
 		"markdown": {
 			"title": "Markdown",
 			"require": "markup",
+			"optional": "yaml",
 			"alias": "md",
 			"owner": "Golmote"
 		},

components/prism-markdown.js

@@ -26,6 +26,19 @@
 
 	Prism.languages.markdown = Prism.languages.extend('markup', {});
 	Prism.languages.insertBefore('markdown', 'prolog', {
+		'front-matter-block': {
+			pattern: /(^(?:\s*[\r\n])?)---(?!.)[\s\S]*?[\r\n]---(?!.)/,
+			lookbehind: true,
+			greedy: true,
+			inside: {
+				'punctuation': /^---|---$/,
+				'font-matter': {
+					pattern: /\S+(?:\s+\S+)*/,
+					alias: ['yaml', 'language-yaml'],
+					inside: Prism.languages.yaml
+				}
+			}
+		},
 		'blockquote': {
 			// > ...
 			pattern: /^>(?:[\t ]*>)*/m,

tests/languages/markdown/front-matter-block_empty_feature.test

@@ -0,0 +1,28 @@
+---
+---
+
+# Title
+
+---
+normal paragraph
+
+---
+
+----------------------------------------------------
+
+[
+	["front-matter-block", [
+		["punctuation", "---"],
+		["punctuation", "---"]
+	]],
+
+	["title", [
+		["punctuation", "#"],
+		" Title"
+	]],
+
+	["hr", "---"],
+	"\r\nnormal paragraph\r\n\r\n",
+
+	["hr", "---"]
+]

tests/languages/markdown/front-matter-block_feature.test

@@ -0,0 +1,31 @@
+---
+layout: post
+title: Blogging Like a Hacker
+---
+
+# Title
+
+---
+normal paragraph
+
+---
+
+----------------------------------------------------
+
+[
+	["front-matter-block", [
+		["punctuation", "---"],
+		["font-matter", "layout: post\r\ntitle: Blogging Like a Hacker"],
+		["punctuation", "---"]
+	]],
+
+	["title", [
+		["punctuation", "#"],
+		" Title"
+	]],
+
+	["hr", "---"],
+	"\r\nnormal paragraph\r\n\r\n",
+
+	["hr", "---"]
+]

tests/languages/yaml+markdown/front-matter_feature.test

@@ -0,0 +1,24 @@
+---
+layout: post
+title: Blogging Like a Hacker
+---
+
+# Title
+
+----------------------------------------------------
+
+[
+	["front-matter-block", [
+		["punctuation", "---"],
+		["font-matter", [
+			["key", "layout"], ["punctuation", ":"], " post\n",
+			["key", "title"], ["punctuation", ":"], " Blogging Like a Hacker"
+		]],
+		["punctuation", "---"]
+	]],
+
+	["title", [
+		["punctuation", "#"],
+		" Title"
+	]]
+]