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Simplification of ES2015 RegExp semantics #89

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Simplification of ES2015 RegExp semantics #89

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bb7d2a3
Specialize RegExp methods to only work on real RegExp instances
littledan Oct 16, 2015
795cf17
Replace internal use of flag getters with [[OriginalFlags]]
littledan Oct 16, 2015
9acca20
Factor out a stateless InnerRegExpExec
littledan Oct 16, 2015
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151 changes: 58 additions & 93 deletions spec.html
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Expand Up @@ -29395,61 +29395,30 @@ <h1>RegExp.prototype.exec ( _string_ )</h1>
1. If _R_ does not have a [[RegExpMatcher]] internal slot, throw a *TypeError* exception.
1. Let _S_ be ToString(_string_).
1. ReturnIfAbrupt(_S_).
1. Return RegExpBuiltinExec(_R_, _S_).
1. Return RegExpExec(_R_, _S_).
</emu-alg>

<!-- es6num="21.2.5.2.1" -->
<emu-clause id="sec-regexpexec" aoid="RegExpExec">
<h1>Runtime Semantics: RegExpExec ( _R_, _S_ )</h1>
<p>The abstract operation RegExpExec with arguments _R_ and _S_ performs the following steps:</p>
<emu-alg>
1. Assert: Type(_R_) is Object.
1. Assert: Type(_S_) is String.
1. Let _exec_ be Get(_R_, `"exec"`).
1. ReturnIfAbrupt(_exec_).
1. If IsCallable(_exec_) is *true*, then
1. Let _result_ be Call(_exec_, _R_, &laquo;_S_&raquo;).
1. ReturnIfAbrupt(_result_).
1. If Type(_result_) is neither Object or Null, throw a *TypeError* exception.
1. Return _result_.
1. If _R_ does not have a [[RegExpMatcher]] internal slot, throw a *TypeError* exception.
1. Return RegExpBuiltinExec(_R_, _S_).
</emu-alg>
<emu-note>
<p>If a callable `exec` property is not found this algorithm falls back to attempting to use the built-in RegExp matching algorithm. This provides compatible behaviour for code written for prior editions where most built-in algorithms that use regular expressions did not perform a dynamic property lookup of `exec`.</p>
</emu-note>
</emu-clause>

<!-- es6num="21.2.5.2.2" -->
<emu-clause id="sec-regexpbuiltinexec" aoid="RegExpBuiltinExec">
<h1>Runtime Semantics: RegExpBuiltinExec ( _R_, _S_ )</h1>
<p>The abstract operation RegExpBuiltinExec with arguments _R_ and _S_ performs the following steps:</p>
<emu-clause id="sec-innerregexpexec" aoid="InnerRegExpExec">
<h1>Runtime Semantics: InnerRegExpExec ( _R_, _S_, _lastIndex_, _extraFlags_ )</h1>
<p>The abstract operation RegExpExec with arguments _R_, _S_, _lastIndex_ and _extraFlags_ performs the following steps:</p>
<emu-alg>
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. ReturnIfAbrupt(_lastIndex_).
1. Let _global_ be ToBoolean(Get(_R_, `"global"`)).
1. ReturnIfAbrupt(_global_).
1. Let _sticky_ be ToBoolean(Get(_R_, `"sticky"`)).
1. ReturnIfAbrupt(_sticky_).
1. Let _flags_ be the concatenation of _R_'s [[OriginalFlags]] internal slot and _extraFlags_.
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. Let _matcher_ be the value of _R_'s [[RegExpMatcher]] internal slot.
1. Let _flags_ be the value of _R_'s [[OriginalFlags]] internal slot.
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. Let _setStatus_ be Set(_R_, `"lastIndex"`, 0, *true*).
1. ReturnIfAbrupt(_setStatus_).
1. Return *null*.
1. Return { [[Matches]]: *null*, [[LastIndex]]: 0 }
1. Let _r_ be _matcher_(_S_, _lastIndex_).
1. If _r_ is ~failure~, then
1. If _sticky_ is *true*, then
1. Let _setStatus_ be Set(_R_, `"lastIndex"`, 0, *true*).
1. ReturnIfAbrupt(_setStatus_).
1. Return *null*.
1. Return { [[Matches]]: *null*, [[LastIndex]]: 0 }
1. Let _lastIndex_ be AdvanceStringIndex(_S_, _lastIndex_, _fullUnicode_).
1. Else,
1. Assert: _r_ is a State.
Expand All @@ -29458,9 +29427,6 @@ <h1>Runtime Semantics: RegExpBuiltinExec ( _R_, _S_ )</h1>
1. If _fullUnicode_ is *true*, then
1. _e_ is an index into the _Input_ character list, derived from _S_, matched by _matcher_. Let _eUTF_ be the smallest index into _S_ that corresponds to the character at element _e_ of _Input_. If _e_ is greater than or equal to the length of _Input_, then _eUTF_ is the number of code units in _S_.
1. Let _e_ be _eUTF_.
1. If _global_ is *true* or _sticky_ is *true*,
1. Let _setStatus_ be Set(_R_, `"lastIndex"`, _e_, *true*).
1. ReturnIfAbrupt(_setStatus_).
1. Let _n_ be the length of _r_'s _captures_ List. (This is the same value as <emu-xref href="#sec-notation"></emu-xref>'s _NcapturingParens_.)
1. Let _A_ be ArrayCreate(_n_ + 1).
1. Assert: The value of _A_'s `"length"` property is _n_ + 1.
Expand All @@ -29480,7 +29446,24 @@ <h1>Runtime Semantics: RegExpBuiltinExec ( _R_, _S_ )</h1>
1. Assert: _captureI_ is a List of code units.
1. Let _capturedValue_ be a string consisting of the code units of _captureI_.
1. Perform CreateDataProperty(_A_, ToString(_i_) , _capturedValue_).
1. Return _A_.
1. If _global_ is *true* or _sticky_ is *true*,
1. Return { [[Matches]]: _A_, [[LastIndex]]: _e_ }.
1. Otherwise, return { [[Matches]]: _A_ }.
</emu-alg>
</emu-clause>

<emu-clause id="sec-regexpexec" aoid="RegExpExec">
<h1>Runtime Semantics: RegExpExec ( _R_, _S_ )</h1>
<p>The abstract operation RegExpExec with arguments _R_ and _S_ performs the following steps:</p>
<emu-alg>
1. Let _lastIndex_ be ToLength(Get(_R_,`"lastIndex"`)).
1. ReturnIfAbrupt(_lastIndex_).
1. Let _result_ be InnerRegExpExec(_R_, _S_, _lastIndex_, `""`).
1. ReturnIfAbrupt(_result_).
1. If _result_ has a [[LastIndex]] entry,
1. Let _setStatus_ be Set(_R_, `"lastIndex"`, _result_.[[LastIndex]], *true*).
1. ReturnIfAbrupt(_setStatus_).
1. Return _result_.[[Matches]].
</emu-alg>
</emu-clause>

Expand Down Expand Up @@ -29511,22 +29494,14 @@ <h1>get RegExp.prototype.flags</h1>
<emu-alg>
1. Let _R_ be the *this* value.
1. If Type(_R_) is not Object, throw a *TypeError* exception.
1. If _rx_ does not have a [[OriginalFlags]] internal slot, throw a *TypeError* exception.
1. Let _result_ be the empty String.
1. Let _global_ be ToBoolean(Get(_R_, `"global"`)).
1. ReturnIfAbrupt(_global_).
1. If _global_ is *true*, append `"g"` as the last code unit of _result_.
1. Let _ignoreCase_ be ToBoolean(Get(_R_, `"ignoreCase"`)).
1. ReturnIfAbrupt(_ignoreCase_).
1. If _ignoreCase_ is *true*, append `"i"` as the last code unit of _result_.
1. Let _multiline_ be ToBoolean(Get(_R_, `"multiline"`)).
1. ReturnIfAbrupt(_multiline_).
1. If _multiline_ is *true*, append `"m"` as the last code unit of _result_.
1. Let _unicode_ be ToBoolean(Get(_R_, `"unicode"`)).
1. ReturnIfAbrupt(_unicode_).
1. If _unicode_ is *true*, append `"u"` as the last code unit of _result_.
1. Let _sticky_ be ToBoolean(Get(_R_, `"sticky"`)).
1. ReturnIfAbrupt(_sticky_).
1. If _sticky_ is *true*, append `"y"` as the last code unit of _result_.
1. Let _flags_ be the value of _R_'s [[OriginalFlags]] internal slot.
1. If _flags_ contains `"g"`, append `"g"` as the last code unit of _result_.
1. If _flags_ contains `"i"`, append `"i"` as the last code unit of _result_.
1. If _flags_ contains `"m"`, append `"m"` as the last code unit of _result_.
1. If _flags_ contains `"u"`, append `"u"` as the last code unit of _result_.
1. If _flags_ contains `"y"`, append `"y"` as the last code unit of _result_.
1. Return _result_.
</emu-alg>
</emu-clause>
Expand Down Expand Up @@ -29566,15 +29541,15 @@ <h1>RegExp.prototype [ @@match ] ( _string_ )</h1>
<emu-alg>
1. Let _rx_ be the *this* value.
1. If Type(_rx_) is not Object, throw a *TypeError* exception.
1. If _rx_ does not have a [[RegExpMatcher]] internal slot, throw a *TypeError* exception.
1. Let _S_ be ToString(_string_)
1. ReturnIfAbrupt(_S_).
1. Let _global_ be ToBoolean(Get(_rx_, `"global"`)).
1. ReturnIfAbrupt(_global_).
1. Let _flags_ be the value of _R_'s [[OriginalFlags]] internal slot.
1. If _flags_ contains `"g"`, let _global_ be *true*, else let _global_ be *false*.
1. If _global_ is *false*, then
1. Return RegExpExec(_rx_, _S_).
1. Else _global_ is *true*,
1. Let _fullUnicode_ be ToBoolean(Get(_rx_, `"unicode"`)).
1. ReturnIfAbrupt(_fullUnicode_).
1. If _flags_ contains `"u"`, let _fullUnicode_ be *true*, else let _fullUnicode_ be *false*.
1. Let _setStatus_ be Set(_rx_, `"lastIndex"`, 0, *true*).
1. ReturnIfAbrupt(_setStatus_).
1. Let _A_ be ArrayCreate(0).
Expand Down Expand Up @@ -29625,18 +29600,18 @@ <h1>RegExp.prototype [ @@replace ] ( _string_, _replaceValue_ )</h1>
<emu-alg>
1. Let _rx_ be the *this* value.
1. If Type(_rx_) is not Object, throw a *TypeError* exception.
1. If _rx_ does not have a [[RegExpMatcher]] internal slot, throw a *TypeError* exception.
1. Let _S_ be ToString(_string_).
1. ReturnIfAbrupt(_S_).
1. Let _lengthS_ be the number of code unit elements in _S_.
1. Let _functionalReplace_ be IsCallable(_replaceValue_).
1. If _functionalReplace_ is *false*, then
1. Let _replaceValue_ be ToString(_replaceValue_).
1. ReturnIfAbrupt(_replaceValue_).
1. Let _global_ be ToBoolean(Get(_rx_, `"global"`)).
1. ReturnIfAbrupt(_global_).
1. Let _flags_ be the value of _R_'s [[OriginalFlags]] internal slot.
1. If _flags_ contains `"g"`, let _global_ be *true*, else let _global_ be *false*.
1. If _global_ is *true*, then
1. Let _fullUnicode_ be ToBoolean(Get(_rx_, `"unicode"`)).
1. ReturnIfAbrupt(_fullUnicode_).
1. If _flags_ contains `"u"`, let _fullUnicode_ be *true*, else let _fullUnicode_ be *false*.
1. Let _setStatus_ be Set(_rx_, `"lastIndex"`, 0, *true*).
1. ReturnIfAbrupt(_setStatus_).
1. Let _results_ be a new empty List.
Expand Down Expand Up @@ -29705,18 +29680,14 @@ <h1>RegExp.prototype [ @@search ] ( _string_ )</h1>
<emu-alg>
1. Let _rx_ be the *this* value.
1. If Type(_rx_) is not Object, throw a *TypeError* exception.
1. If _rx_ does not have a [[RegExpMatcher]] internal slot, throw a *TypeError* exception.
1. Let _S_ be ToString(_string_).
1. ReturnIfAbrupt(_S_).
1. Let _previousLastIndex_ be Get(_rx_, `"lastIndex"`).
1. ReturnIfAbrupt(_previousLastIndex_).
1. Let _status_ be Set(_rx_, `"lastIndex"`, 0, *true*).
1. ReturnIfAbrupt(_status_).
1. Let _result_ be RegExpExec(_rx_, _S_).
1. Let _result_ be InnerRegExpExec(_rx_, _S_, 0, `""`).
1. ReturnIfAbrupt(_result_).
1. Let _status_ be Set(_rx_, `"lastIndex"`, _previousLastIndex_, *true*).
1. ReturnIfAbrupt(_status_).
1. If _result_ is *null*, return -1.
1. Return Get(_result_, `"index"`).
1. Let _matches_ = _result_.[[Matches]].
1. If _matches_ is *null*, return -1.
1. Return Get(_matches_, `"index"`).
</emu-alg>
<p>The value of the `name` property of this function is `"[Symbol.search]"`.</p>
<emu-note>
Expand Down Expand Up @@ -29760,18 +29731,14 @@ <h1>RegExp.prototype [ @@split ] ( _string_, _limit_ )</h1>
<emu-alg>
1. Let _rx_ be the *this* value.
1. If Type(_rx_) is not Object, throw a *TypeError* exception.
1. If _rx_ does not have a [[RegExpMatcher]] internal slot, throw a *TypeError* exception.
1. Let _S_ be ToString(_string_).
1. ReturnIfAbrupt(_S_).
1. Let _C_ be SpeciesConstructor(_rx_, %RegExp%).
1. ReturnIfAbrupt(_C_).
1. Let _flags_ be ToString(Get(_rx_, `"flags"`)).
1. ReturnIfAbrupt(_flags_).
1. Let _flags_ be the value of _R_'s [[OriginalFlags]] internal slot.
1. If _flags_ contains `"u"`, let _unicodeMatching_ be *true*.
1. Else, let _unicodeMatching_ be *false*.
1. If _flags_ contains `"y"`, let _newFlags_ be _flags_.
1. Else, let _newFlags_ be the string that is the concatenation of _flags_ and `"y"`.
1. Let _splitter_ be Construct(_C_, &laquo;_rx_, _newFlags_&raquo;).
1. ReturnIfAbrupt(_splitter_).
1. Let _A_ be ArrayCreate(0).
1. Let _lengthA_ be 0.
1. If _limit_ is *undefined*, let _lim_ be 2<sup>53</sup>-1; else let _lim_ be ToLength(_limit_).
Expand All @@ -29780,22 +29747,19 @@ <h1>RegExp.prototype [ @@split ] ( _string_, _limit_ )</h1>
1. Let _p_ be 0.
1. If _lim_ = 0, return _A_.
1. If _size_ = 0, then
1. Let _z_ be RegExpExec(_splitter_, _S_).
1. Let _z_ be InnerRegExpExec(_splitter_, _S_, 0, `"y"`).
1. ReturnIfAbrupt(_z_).
1. If _z_ is not *null*, return _A_.
1. If _z_.[[Matches]] is not *null*, return _A_.
1. Assert: The following call will never result in an abrupt completion.
1. Perform CreateDataProperty(_A_, `"0"`, _S_).
1. Return _A_.
1. Let _q_ be _p_.
1. Repeat, while _q_ &lt; _size_
1. Let _setStatus_ be Set(_splitter_, `"lastIndex"`, _q_, *true*).
1. ReturnIfAbrupt(_setStatus_).
1. Let _z_ be RegExpExec(_splitter_, _S_).
1. Let _z_ be InnerRegExpExec(_splitter_, _S_, _q_, `"y"`).
1. ReturnIfAbrupt(_z_).
1. If _z_ is *null*, let _q_ be AdvanceStringIndex(_S_, _q_, _unicodeMatching_).
1. Else _z_ is not *null*,
1. Let _e_ be ToLength(Get(_splitter_, `"lastIndex"`)).
1. ReturnIfAbrupt(_e_).
1. If _z_.[[Matches]] is *null*, let _q_ be AdvanceStringIndex(_S_, _q_, _unicodeMatching_).
1. Else _z_.[[Matches]] is not *null*,
1. Let _e_ be _z_.[[LastIndex]].
1. If _e_ = _p_, let _q_ be AdvanceStringIndex(_S_, _q_, _unicodeMatching_).
1. Else _e_ &ne; _p_,
1. Let _T_ be a String value equal to the substring of _S_ consisting of the elements at indices _p_ (inclusive) through _q_ (exclusive).
Expand All @@ -29804,12 +29768,12 @@ <h1>RegExp.prototype [ @@split ] ( _string_, _limit_ )</h1>
1. Let _lengthA_ be _lengthA_ +1.
1. If _lengthA_ = _lim_, return _A_.
1. Let _p_ be _e_.
1. Let _numberOfCaptures_ be ToLength(Get(_z_, `"length"`)).
1. Let _numberOfCaptures_ be ToLength(Get(_z_.[[Matches]], `"length"`)).
1. ReturnIfAbrupt(_numberOfCaptures_).
1. Let _numberOfCaptures_ be max(_numberOfCaptures_-1, 0).
1. Let _i_ be 1.
1. Repeat, while _i_ &le; _numberOfCaptures_.
1. Let _nextCapture_ be Get(_z_, ToString(_i_)).
1. Let _nextCapture_ be Get(_z_.[[Matches]], ToString(_i_)).
1. ReturnIfAbrupt(_nextCapture_).
1. Perform CreateDataProperty(_A_, ToString(_lengthA_), _nextCapture_).
1. Let _i_ be _i_ +1.
Expand Down Expand Up @@ -29849,6 +29813,7 @@ <h1>RegExp.prototype.test( _S_ )</h1>
<emu-alg>
1. Let _R_ be the *this* value.
1. If Type(_R_) is not Object, throw a *TypeError* exception.
1. If _R_ does not have a [[RegExpMatcher]] internal slot, throw a *TypeError* exception.
1. Let _string_ be ToString(_S_).
1. ReturnIfAbrupt(_string_).
1. Let _match_ be RegExpExec(_R_, _string_).
Expand Down