Add support for the 'y' flag to the RegExp constructor

packages/core-js-compat/src/data.js

@@ -787,6 +787,12 @@ module.exports = {
     firefox: '37',
     safari: '9.0',
   },
+  'es.regexp.sticky': {
+    chrome: '49',
+    edge: '13',
+    firefox: '3',
+    safari: '10.0',
+  },
   'es.regexp.to-string': {
     chrome: '50',
     firefox: '46',

packages/core-js/es/index.js

@@ -102,6 +102,7 @@ require('../modules/es.string.sup');
 require('../modules/es.regexp.constructor');
 require('../modules/es.regexp.exec');
 require('../modules/es.regexp.flags');
+require('../modules/es.regexp.sticky');
 require('../modules/es.regexp.to-string');
 require('../modules/es.parse-int');
 require('../modules/es.parse-float');

packages/core-js/es/regexp/index.js

@@ -2,6 +2,7 @@ require('../../modules/es.regexp.constructor');
 require('../../modules/es.regexp.to-string');
 require('../../modules/es.regexp.exec');
 require('../../modules/es.regexp.flags');
+require('../../modules/es.regexp.sticky');
 require('../../modules/es.string.match');
 require('../../modules/es.string.replace');
 require('../../modules/es.string.search');

packages/core-js/es/regexp/sticky.js

@@ -0,0 +1,5 @@
+require('../../modules/es.regexp.sticky');
+
+module.exports = function (it) {
+  return it.sticky;
+};

packages/core-js/internals/fix-regexp-well-known-symbol-logic.js

@@ -1,5 +1,4 @@
 'use strict';
-var hide = require('../internals/hide');
 var redefine = require('../internals/redefine');
 var fails = require('../internals/fails');
 var wellKnownSymbol = require('../internals/well-known-symbol');
@@ -20,6 +19,12 @@ var REPLACE_SUPPORTS_NAMED_GROUPS = !fails(function () {
   return ''.replace(re, '$<a>') !== '7';
 });
 
+// IE <= 11 replaces $0 with the whole match, as if it was $&
+// https://stackoverflow.com/questions/6024666/getting-ie-to-replace-a-regex-with-the-literal-string-0
+var REPLACE_KEEPS_$0 = (function () {
+  return 'a'.replace(/./, '$0') === '$0';
+})();
+
 // Chrome 51 has a buggy "split" implementation when RegExp#exec !== nativeExec
 // Weex JS has frozen built-in prototypes, so use try / catch wrapper
 var SPLIT_WORKS_WITH_OVERWRITTEN_EXEC = !fails(function () {
@@ -30,7 +35,7 @@ var SPLIT_WORKS_WITH_OVERWRITTEN_EXEC = !fails(function () {
   return result.length !== 2 || result[0] !== 'a' || result[1] !== 'b';
 });
 
-module.exports = function (KEY, length, exec, sham) {
+module.exports = function (KEY, length, exec) {
   var SYMBOL = wellKnownSymbol(KEY);
 
   var DELEGATES_TO_SYMBOL = !fails(function () {
@@ -60,7 +65,7 @@ module.exports = function (KEY, length, exec, sham) {
   if (
     !DELEGATES_TO_SYMBOL ||
     !DELEGATES_TO_EXEC ||
-    (KEY === 'replace' && !REPLACE_SUPPORTS_NAMED_GROUPS) ||
+    (KEY === 'replace' && !(REPLACE_SUPPORTS_NAMED_GROUPS && REPLACE_KEEPS_$0)) ||
     (KEY === 'split' && !SPLIT_WORKS_WITH_OVERWRITTEN_EXEC)
   ) {
     var nativeRegExpMethod = /./[SYMBOL];
@@ -75,7 +80,7 @@ module.exports = function (KEY, length, exec, sham) {
         return { done: true, value: nativeMethod.call(str, regexp, arg2) };
       }
       return { done: false };
-    });
+    }, { REPLACE_KEEPS_$0: REPLACE_KEEPS_$0 });
     var stringMethod = methods[0];
     var regexMethod = methods[1];
 
@@ -88,6 +93,5 @@ module.exports = function (KEY, length, exec, sham) {
       // 21.2.5.9 RegExp.prototype[@@search](string)
       : function (string) { return regexMethod.call(string, this); }
     );
-    if (sham) hide(RegExp.prototype[SYMBOL], 'sham', true);
   }
 };

packages/core-js/internals/regexp-exec.js

@@ -1,6 +1,7 @@
 'use strict';
 
 var regexpFlags = require('./regexp-flags');
+var stickyHelpers = require('./regexp-sticky-helpers');
 
 var nativeExec = RegExp.prototype.exec;
 // This always refers to the native implementation, because the
@@ -18,24 +19,41 @@ var UPDATES_LAST_INDEX_WRONG = (function () {
   return re1.lastIndex !== 0 || re2.lastIndex !== 0;
 })();
 
+var UNSUPPORTED_Y = stickyHelpers.UNSUPPORTED_Y || stickyHelpers.BROKEN_CARET;
+
 // nonparticipating capturing group, copied from es5-shim's String#split patch.
 var NPCG_INCLUDED = /()??/.exec('')[1] !== undefined;
 
-var PATCH = UPDATES_LAST_INDEX_WRONG || NPCG_INCLUDED;
+var PATCH = UPDATES_LAST_INDEX_WRONG || NPCG_INCLUDED || UNSUPPORTED_Y;
 
 if (PATCH) {
   patchedExec = function exec(str) {
     var re = this;
     var lastIndex, reCopy, match, i;
+    var sticky = UNSUPPORTED_Y && re.sticky;
+
+    if (sticky) {
+      var flags = (re.ignoreCase ? 'i' : '') +
+                  (re.multiline ? 'm' : '') +
+                  (re.unicode ? 'u' : '') +
+                  'g';
 
+      // ^(? + rx + ) is needed, in combination with some str slicing, to
+      // simulate the 'y' flag.
+      reCopy = new RegExp('^(?:' + re.source + ')', flags);
+      str = String(str).slice(re.lastIndex);
+    }
     if (NPCG_INCLUDED) {
       reCopy = new RegExp('^' + re.source + '$(?!\\s)', regexpFlags.call(re));
     }
     if (UPDATES_LAST_INDEX_WRONG) lastIndex = re.lastIndex;
 
-    match = nativeExec.call(re, str);
+    match = nativeExec.call(sticky ? reCopy : re, str);
 
-    if (UPDATES_LAST_INDEX_WRONG && match) {
+    if (sticky) {
+      if (match) re.lastIndex += match[0].length;
+      else re.lastIndex = 0;
+    } else if (UPDATES_LAST_INDEX_WRONG && match) {
       re.lastIndex = re.global ? match.index + match[0].length : lastIndex;
     }
     if (NPCG_INCLUDED && match && match.length > 1) {

packages/core-js/internals/regexp-sticky-helpers.js

@@ -0,0 +1,23 @@
+'use strict';
+
+var fails = require('./fails');
+
+// babel-minify transpiles RegExp('a', 'y') -> /a/y and it causes SyntaxError,
+// so we use an intermediate function.
+function RE(s, f) {
+  return RegExp(s, f);
+}
+
+exports.UNSUPPORTED_Y = fails(function () {
+  // babel-minify transpiles RegExp('a', 'y') -> /a/y and it causes SyntaxError
+  var re = RE('a', 'y');
+  re.lastIndex = 2;
+  return re.exec('abcd') != null;
+});
+
+exports.BROKEN_CARET = fails(function () {
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=773687
+  var re = RE('^r', 'gy');
+  re.lastIndex = 2;
+  return re.exec('str') != null;
+});

packages/core-js/modules/es.regexp.constructor.js

@@ -1,14 +1,17 @@
 var DESCRIPTORS = require('../internals/descriptors');
 var MATCH = require('../internals/well-known-symbol')('match');
+var hide = require('../internals/hide');
 var global = require('../internals/global');
 var isForced = require('../internals/is-forced');
 var inheritIfRequired = require('../internals/inherit-if-required');
 var defineProperty = require('../internals/object-define-property').f;
 var getOwnPropertyNames = require('../internals/object-get-own-property-names').f;
 var isRegExp = require('../internals/is-regexp');
 var getFlags = require('../internals/regexp-flags');
+var stickyHelpers = require('../internals/regexp-sticky-helpers');
 var redefine = require('../internals/redefine');
 var fails = require('../internals/fails');
+var setInternalState = require('../internals/internal-state').set;
 var NativeRegExp = global.RegExp;
 var RegExpPrototype = NativeRegExp.prototype;
 var re1 = /a/g;
@@ -17,7 +20,9 @@ var re2 = /a/g;
 // "new" should create a new object, old webkit bug
 var CORRECT_NEW = new NativeRegExp(re1) !== re1;
 
-var FORCED = isForced('RegExp', DESCRIPTORS && (!CORRECT_NEW || fails(function () {
+var UNSUPPORTED_Y = stickyHelpers.UNSUPPORTED_Y;
+
+var FORCED = isForced('RegExp', DESCRIPTORS && (!CORRECT_NEW || UNSUPPORTED_Y || fails(function () {
   re2[MATCH] = false;
   // RegExp constructor can alter flags and IsRegExp works correct with @@match
   return NativeRegExp(re1) != re1 || NativeRegExp(re2) == re2 || NativeRegExp(re1, 'i') != '/a/i';
@@ -30,13 +35,32 @@ if (FORCED) {
     var thisIsRegExp = this instanceof RegExpWrapper;
     var patternIsRegExp = isRegExp(pattern);
     var flagsAreUndefined = flags === undefined;
-    return !thisIsRegExp && patternIsRegExp && pattern.constructor === RegExpWrapper && flagsAreUndefined ? pattern
-      : inheritIfRequired(CORRECT_NEW
-        ? new NativeRegExp(patternIsRegExp && !flagsAreUndefined ? pattern.source : pattern, flags)
-        : NativeRegExp((patternIsRegExp = pattern instanceof RegExpWrapper)
-          ? pattern.source
-          : pattern, patternIsRegExp && flagsAreUndefined ? getFlags.call(pattern) : flags)
-      , thisIsRegExp ? this : RegExpPrototype, RegExpWrapper);
+
+    if (!thisIsRegExp && patternIsRegExp && pattern.constructor === RegExpWrapper && flagsAreUndefined) {
+      return pattern;
+    }
+
+    if (CORRECT_NEW) {
+      if (patternIsRegExp && !flagsAreUndefined) pattern = pattern.source;
+    } else if (pattern instanceof RegExpWrapper) {
+      if (flagsAreUndefined) flags = getFlags.call(pattern);
+      pattern = pattern.source;
+    }
+
+    if (UNSUPPORTED_Y) {
+      var sticky = !!flags && flags.indexOf('y') > -1;
+      if (sticky) flags = flags.replace(/y/g, '');
+    }
+
+    var result = inheritIfRequired(
+      CORRECT_NEW ? new NativeRegExp(pattern, flags) : NativeRegExp(pattern, flags),
+      thisIsRegExp ? this : RegExpPrototype,
+      RegExpWrapper
+    );
+
+    if (UNSUPPORTED_Y) setInternalState(result, { sticky: sticky });
+
+    return result;
   };
   var proxy = function (key) {
     key in RegExpWrapper || defineProperty(RegExpWrapper, key, {
@@ -51,6 +75,8 @@ if (FORCED) {
   RegExpPrototype.constructor = RegExpWrapper;
   RegExpWrapper.prototype = RegExpPrototype;
   redefine(global, 'RegExp', RegExpWrapper);
+
+  if (UNSUPPORTED_Y) hide(RegExpWrapper, 'sham', true);
 }
 
 // https://tc39.github.io/ecma262/#sec-get-regexp-@@species

packages/core-js/modules/es.regexp.flags.js

@@ -1,6 +1,11 @@
 // `RegExp.prototype.flags` getter
 // https://tc39.github.io/ecma262/#sec-get-regexp.prototype.flags
-if (require('../internals/descriptors') && /./g.flags != 'g') {
+if (
+  require('../internals/descriptors') && (
+    /./g.flags != 'g' ||
+    require('../internals/regexp-sticky-helpers').UNSUPPORTED_Y
+  )
+) {
   require('../internals/object-define-property').f(RegExp.prototype, 'flags', {
     configurable: true,
     get: require('../internals/regexp-flags')

packages/core-js/modules/es.regexp.sticky.js

@@ -0,0 +1,21 @@
+var DESCRIPTORS = require('../internals/descriptors');
+var UNSUPPORTED_Y = require('../internals/regexp-sticky-helpers').UNSUPPORTED_Y;
+var defineProperty = require('../internals/object-define-property').f;
+var getInternalState = require('../internals/internal-state').get;
+var RegExpPrototype = RegExp.prototype;
+
+// `RegExp.prototype.sticky` getter
+if (DESCRIPTORS && UNSUPPORTED_Y) {
+  defineProperty(RegExp.prototype, 'sticky', {
+    configurable: true,
+    get: function () {
+      if (this === RegExpPrototype) return undefined;
+      // We can't use InternalStateModule.getterFor because
+      // we don't add metadata for regexps created by a literal.
+      if (this instanceof RegExp) {
+        return !!getInternalState(this).sticky;
+      }
+      throw TypeError('Incompatible receiver, RegExp required');
+    }
+  });
+}

packages/core-js/modules/es.string.replace.js

@@ -21,7 +21,7 @@ var maybeToString = function (it) {
 require('../internals/fix-regexp-well-known-symbol-logic')(
   'replace',
   2,
-  function (REPLACE, nativeReplace, maybeCallNative) {
+  function (REPLACE, nativeReplace, maybeCallNative, reason) {
     return [
       // `String.prototype.replace` method
       // https://tc39.github.io/ecma262/#sec-string.prototype.replace
@@ -35,8 +35,14 @@ require('../internals/fix-regexp-well-known-symbol-logic')(
       // `RegExp.prototype[@@replace]` method
       // https://tc39.github.io/ecma262/#sec-regexp.prototype-@@replace
       function (regexp, replaceValue) {
-        var res = maybeCallNative(nativeReplace, regexp, this, replaceValue);
-        if (res.done) return res.value;
+        if (
+          reason.REPLACE_KEEPS_$0 || (
+            typeof replaceValue === 'string' && replaceValue.indexOf('$0') === -1
+          )
+        ) {
+          var res = maybeCallNative(nativeReplace, regexp, this, replaceValue);
+          if (res.done) return res.value;
+        }
 
         var rx = anObject(regexp);
         var S = String(this);

packages/core-js/modules/es.string.split.js

@@ -8,14 +8,10 @@ var advanceStringIndex = require('../internals/advance-string-index');
 var toLength = require('../internals/to-length');
 var callRegExpExec = require('../internals/regexp-exec-abstract');
 var regexpExec = require('../internals/regexp-exec');
-var fails = require('../internals/fails');
 var arrayPush = [].push;
 var min = Math.min;
 var MAX_UINT32 = 0xffffffff;
 
-// babel-minify transpiles RegExp('x', 'y') -> /x/y and it causes SyntaxError
-var SUPPORTS_Y = !fails(function () { return !RegExp(MAX_UINT32, 'y'); });
-
 // @@split logic
 require('../internals/fix-regexp-well-known-symbol-logic')(
   'split',
@@ -99,24 +95,22 @@ require('../internals/fix-regexp-well-known-symbol-logic')(
         var flags = (rx.ignoreCase ? 'i' : '') +
                     (rx.multiline ? 'm' : '') +
                     (rx.unicode ? 'u' : '') +
-                    (SUPPORTS_Y ? 'y' : 'g');
+                    'y';
 
-        // ^(? + rx + ) is needed, in combination with some S slicing, to
-        // simulate the 'y' flag.
-        var splitter = new C(SUPPORTS_Y ? rx : '^(?:' + rx.source + ')', flags);
+        var splitter = new C(rx, flags);
         var lim = limit === undefined ? MAX_UINT32 : limit >>> 0;
         if (lim === 0) return [];
         if (S.length === 0) return callRegExpExec(splitter, S) === null ? [S] : [];
         var p = 0;
         var q = 0;
         var A = [];
         while (q < S.length) {
-          splitter.lastIndex = SUPPORTS_Y ? q : 0;
-          var z = callRegExpExec(splitter, SUPPORTS_Y ? S : S.slice(q));
+          splitter.lastIndex = q;
+          var z = callRegExpExec(splitter, S);
           var e;
           if (
             z === null ||
-            (e = min(toLength(splitter.lastIndex + (SUPPORTS_Y ? 0 : q)), S.length)) === p
+            (e = min(toLength(splitter.lastIndex), S.length)) === p
           ) {
             q = advanceStringIndex(S, q, unicodeMatching);
           } else {
@@ -133,6 +127,5 @@ require('../internals/fix-regexp-well-known-symbol-logic')(
         return A;
       }
     ];
-  },
-  !SUPPORTS_Y
+  }
 );

tests/compat/tests.js

@@ -710,6 +710,13 @@ GLOBAL.tests = {
   'es.regexp.flags': function () {
     return /./g.flags === 'g';
   },
+  'es.regexp.sticky': function () {
+    try {
+      return new RegExp('a', 'y').sticky === true;
+    } catch (e) {
+      return false;
+    }
+  },
   'es.regexp.to-string': function () {
     return RegExp.prototype.toString.call({ source: 'a', flags: 'b' }) === '/a/b'
       && RegExp.prototype.toString.name === 'toString';