Normative: Disregard lastIndex for non-global non-sticky regexps (tc3…

…9#627) With these changes , non-global non-sticky regexps with nonwritable lastIndex property should just work: * In RegExpBuiltinExec, remove any access to the lastIndex property for non-global, non-sticky regexp. * In RegExp.prototype.@@search, avoid to to set the lastIndex property when not necessary.
JaydenGui · Dec 21, 2016 · 395fede · 395fede
1 parent 2e6a254
commit 395fede
Showing 1 changed file with 8 additions and 4 deletions.
diff --git a/spec.html b/spec.html
@@ -29408,17 +29408,18 @@ <h1>Runtime Semantics: RegExpBuiltinExec ( _R_, _S_ )</h1>
             1. Assert: _R_ is an initialized RegExp instance.
             1. Assert: Type(_S_) is String.
             1. Let _length_ be the number of code units in _S_.
-            1. Let _lastIndex_ be ? ToLength(? Get(_R_, `"lastIndex"`)).
             1. Let _flags_ be _R_.[[OriginalFlags]].
             1. If _flags_ contains `"g"`, let _global_ be *true*, else let _global_ be *false*.
             1. If _flags_ contains `"y"`, let _sticky_ be *true*, else let _sticky_ be *false*.
             1. If _global_ is *false* and _sticky_ is *false*, let _lastIndex_ be 0.
+            1. Else, let _lastIndex_ be ? ToLength(? Get(_R_, `"lastIndex"`)).
             1. Let _matcher_ be _R_.[[RegExpMatcher]].
             1. If _flags_ contains `"u"`, let _fullUnicode_ be *true*, else let _fullUnicode_ be *false*.
             1. Let _matchSucceeded_ be *false*.
             1. Repeat, while _matchSucceeded_ is *false*
               1. If _lastIndex_ &gt; _length_, then
-                1. Perform ? Set(_R_, `"lastIndex"`, 0, *true*).
+                1. If _global_ is *true* or _sticky_ is *true*, then
+                  1. Perform ? Set(_R_, `"lastIndex"`, 0, *true*).
                 1. Return *null*.
               1. Let _r_ be _matcher_(_S_, _lastIndex_).
               1. If _r_ is ~failure~, then
@@ -29658,9 +29659,12 @@ <h1>RegExp.prototype [ @@search ] ( _string_ )</h1>
           1. If Type(_rx_) is not Object, throw a *TypeError* exception.
           1. Let _S_ be ? ToString(_string_).
           1. Let _previousLastIndex_ be ? Get(_rx_, `"lastIndex"`).
-          1. Perform ? Set(_rx_, `"lastIndex"`, 0, *true*).
+          1. If SameValue(_previousLastIndex_, 0) is *false*, then
+            1. Perform ? Set(_rx_, `"lastIndex"`, 0, *true*).
           1. Let _result_ be ? RegExpExec(_rx_, _S_).
-          1. Perform ? Set(_rx_, `"lastIndex"`, _previousLastIndex_, *true*).
+          1. Let _currentLastIndex_ be ? Get(_rx_, `"lastIndex"`).
+          1. If SameValue(_currentLastIndex_, _previousLastIndex_) is *false*, then
+            1. Perform ? Set(_rx_, `"lastIndex"`, _previousLastIndex_, *true*).
           1. If _result_ is *null*, return -1.
           1. Return ? Get(_result_, `"index"`).
         </emu-alg>