From 53bf94ce78aa314af58ec89137c35f430201ef77 Mon Sep 17 00:00:00 2001
From: John-David Dalton <john.david.dalton@gmail.com>
Date: Fri, 18 Sep 2015 08:43:24 -0700
Subject: [PATCH] Expand existing support for zero-width-joiners.

---
 lodash.js | 29 ++++++++++++-----------------
 1 file changed, 12 insertions(+), 17 deletions(-)

diff --git a/lodash.js b/lodash.js
index 5b8b43c70..978b93601 100644
--- a/lodash.js
+++ b/lodash.js
@@ -142,36 +142,31 @@
   /** Used to match unescaped characters in compiled string literals. */
   var reUnescapedString = /['\n\r\u2028\u2029\\]/g;
 
-  /** Used to compose `reStrSymbol` and `reWord`. */
+  /** Used to compose `reAdvSymbol`, `reStrSymbol`, and `reWord`. */
   var rsAstralRange = '\\ud800-\\udfff',
       rsAstral = '[' + rsAstralRange + ']',
       rsDigits = '\\d+',
       rsLowers = '[a-z\\xdf-\\xf6\\xf8-\\xff]+',
       rsNonAstral = '[^' + rsAstralRange + ']',
       rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}',
+      rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]',
       rsUpper = '[A-Z\\xc0-\\xd6\\xd8-\\xde]',
       rsZWJ = '\\u200d',
-      rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]',
-      rsSurrPairs = rsSurrPair + '(?:' + rsZWJ + rsSurrPair + ')*';
+      rsJoiner = '(?:' + rsZWJ + '(?:' + [rsNonAstral, rsRegional, rsSurrPair].join('|') + '))*',
+      rsSymbol = '(?:' + [rsNonAstral, rsRegional, rsSurrPair, rsAstral].join('|') + ')';
 
-  /** Used to match code points from the astral planes. */
-  var reAstral = RegExp(rsAstral);
+  /** Used to match [zero-width joiners and code points from the astral planes](http://eev.ee/blog/2015/09/12/dark-corners-of-unicode/). */
+  var reAdvSymbol = RegExp('[' + rsZWJ + rsAstralRange + ']');
 
   /** Used to match [string symbols](https://mathiasbynens.be/notes/javascript-unicode). */
-  var reStrSymbol = RegExp([
-    rsNonAstral,
-    rsRegional,
-    rsSurrPairs,
-    rsAstral
-  ].join('|'), 'g');
+  var reStrSymbol = RegExp(rsSymbol + rsJoiner, 'g');
 
   /** Used to match words to create compound words. */
   var reWord = RegExp([
     rsUpper + '+(?=' + rsUpper + rsLowers + ')',
     rsUpper + '?' + rsLowers,
     rsUpper + '+',
-    rsRegional,
-    rsSurrPairs,
+    '(?:' + rsRegional + '|' + rsSurrPair + ')' + rsJoiner,
     rsDigits
   ].join('|'), 'g');
 
@@ -1202,7 +1197,7 @@
    * @returns {number} Returns the string size.
    */
   function stringSize(string) {
-    if (!(string && reAstral.test(string))) {
+    if (!(string && reAdvSymbol.test(string))) {
       return string.length;
     }
     var result = reStrSymbol.lastIndex = 0;
@@ -3647,7 +3642,7 @@
       chars = chars === undefined ? ' ' : (chars + '');
 
       var result = repeat(chars, nativeCeil(padLength / stringSize(chars)));
-      return reAstral.test(chars)
+      return reAdvSymbol.test(chars)
         ? stringToArray(result).slice(0, padLength).join('')
         : result.slice(0, padLength);
     }
@@ -10388,7 +10383,7 @@
       if (!string) {
         return string;
       }
-      if (reAstral.test(string)) {
+      if (reAdvSymbol.test(string)) {
         var strSymbols = stringToArray(string);
         return strSymbols[0].toUpperCase() + strSymbols.slice(1).join('');
       }
@@ -11128,7 +11123,7 @@
       string = baseToString(string);
 
       var strLength = string.length;
-      if (reAstral.test(string)) {
+      if (reAdvSymbol.test(string)) {
         var strSymbols = stringToArray(string);
         strLength = strSymbols.length;
       }