Liquid: Added empty keyword (#2997)

Author: JaKXz

components/prism-liquid.js

@@ -32,7 +32,11 @@ Prism.languages.liquid = {
 	// https://github.com/Shopify/liquid/blob/698f5e0d967423e013f6169d9111bd969bd78337/lib/liquid/lexer.rb#L21
 	'number': /\b\d+(?:\.\d+)?\b/,
 	'operator': /[!=]=|<>|[<>]=?|[|?:=-]|\b(?:and|or|contains(?=\s))\b/,
-	'punctuation': /[.,\[\]()]/
+	'punctuation': /[.,\[\]()]/,
+	'empty': {
+		pattern: /\bempty\b/,
+		alias: 'keyword'
+	},
 };
 
 Prism.hooks.add('before-tokenize', function (env) {

components/prism-liquid.min.js

@@ -0,0 +1,78 @@
+{% unless pages == empty %}
+  <!-- This will only print if the page with handle "about" is not empty -->
+  <h1>{{ pages.frontpage.not_empty_title }}</h1>
+  <div>{{ pages.frontpage.content }}</div>
+{% endunless %}
+
+----------------------------------------------------
+
+[
+	["liquid", [
+		["delimiter", "{%"],
+		["keyword", "unless"],
+		" pages ",
+		["operator", "=="],
+		["empty", "empty"],
+		["delimiter", "%}"]
+	]],
+
+	["comment", "<!-- This will only print if the page with handle \"about\" is not empty -->"],
+
+	["tag", [
+		["tag", [
+			["punctuation", "<"],
+			"h1"
+		]],
+		["punctuation", ">"]
+	]],
+	["liquid", [
+		["delimiter", "{{"],
+		" pages",
+		["punctuation", "."],
+		"frontpage",
+		["punctuation", "."],
+		"not_empty_title ",
+		["delimiter", "}}"]
+	]],
+	["tag", [
+		["tag", [
+			["punctuation", "</"],
+			"h1"
+		]],
+		["punctuation", ">"]
+	]],
+
+	["tag", [
+		["tag", [
+			["punctuation", "<"],
+			"div"
+		]],
+		["punctuation", ">"]
+	]],
+	["liquid", [
+		["delimiter", "{{"],
+		" pages",
+		["punctuation", "."],
+		"frontpage",
+		["punctuation", "."],
+		"content ",
+		["delimiter", "}}"]
+	]],
+	["tag", [
+		["tag", [
+			["punctuation", "</"],
+			"div"
+		]],
+		["punctuation", ">"]
+	]],
+
+	["liquid", [
+		["delimiter", "{%"],
+		["keyword", "endunless"],
+		["delimiter", "%}"]
+	]]
+]
+
+----------------------------------------------------
+
+Test for the 'empty' keyword / special thing.