Fix support for bracketed Unicode escapes in template literals (#350)

templates.js

@@ -1,8 +1,8 @@
 'use strict';
-const TEMPLATE_REGEX = /(?:\\(u[a-f\d]{4}|x[a-f\d]{2}|.))|(?:\{(~)?(\w+(?:\([^)]*\))?(?:\.\w+(?:\([^)]*\))?)*)(?:[ \t]|(?=\r?\n)))|(\})|((?:.|[\r\n\f])+?)/gi;
+const TEMPLATE_REGEX = /(?:\\(u(?:[a-f\d]{4}|\{[a-f\d]{1,6}\})|x[a-f\d]{2}|.))|(?:\{(~)?(\w+(?:\([^)]*\))?(?:\.\w+(?:\([^)]*\))?)*)(?:[ \t]|(?=\r?\n)))|(\})|((?:.|[\r\n\f])+?)/gi;
 const STYLE_REGEX = /(?:^|\.)(\w+)(?:\(([^)]*)\))?/g;
 const STRING_REGEX = /^(['"])((?:\\.|(?!\1)[^\\])*)\1$/;
-const ESCAPE_REGEX = /\\(u[a-f\d]{4}|x[a-f\d]{2}|.)|([^\\])/gi;
+const ESCAPE_REGEX = /\\(u(?:[a-f\d]{4}|\{[a-f\d]{1,6}\})|x[a-f\d]{2}|.)|([^\\])/gi;
 
 const ESCAPES = new Map([
 	['n', '\n'],
@@ -18,10 +18,17 @@ const ESCAPES = new Map([
 ]);
 
 function unescape(c) {
-	if ((c[0] === 'u' && c.length === 5) || (c[0] === 'x' && c.length === 3)) {
+	const u = c[0] === 'u';
+	const bracket = c[1] === '{';
+
+	if ((u && !bracket && c.length === 5) || (c[0] === 'x' && c.length === 3)) {
 		return String.fromCharCode(parseInt(c.slice(1), 16));
 	}
 
+	if (u && bracket) {
+		return String.fromCodePoint(parseInt(c.slice(2, -1), 16));
+	}
+
 	return ESCAPES.get(c) || c;
 }
 

test/template-literal.js

@@ -168,3 +168,10 @@ test('should properly handle undefined template interpolated values', t => {
 	t.is(instance`hello ${undefined}`, 'hello undefined');
 	t.is(instance`hello ${null}`, 'hello null');
 });
+
+test('should allow bracketed Unicode escapes', t => {
+	const instance = new chalk.Instance({level: 3});
+	t.is(instance`\u{AB}`, '\u{AB}');
+	t.is(instance`This is a {bold \u{AB681}} test`, 'This is a \u001B[1m\u{AB681}\u001B[22m test');
+	t.is(instance`This is a {bold \u{10FFFF}} test`, 'This is a \u001B[1m\u{10FFFF}\u001B[22m test');
+});