Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

[Normative] Add RegExp lookbehind assertions #1029

Merged
merged 1 commit into from
Jan 26, 2018
Merged

[Normative] Add RegExp lookbehind assertions #1029

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
111 changes: 80 additions & 31 deletions spec.html
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -29113,6 +29113,8 @@ <h2>Syntax</h2>
`\` `B`
`(` `?` `=` Disjunction[?U] `)`
`(` `?` `!` Disjunction[?U] `)`
`(` `?` `&lt;=` Disjunction[?U] `)`
`(` `?` `&lt;!` Disjunction[?U] `)`

Quantifier ::
QuantifierPrefix
Expand Down Expand Up @@ -29682,7 +29684,7 @@ <h1>Notation</h1>
<h1>Pattern</h1>
<p>The production <emu-grammar>Pattern :: Disjunction</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Disjunction| to obtain a Matcher _m_.
1. Evaluate |Disjunction| with +1 as its _direction_ argument to obtain a Matcher _m_.
1. Return an internal closure that takes two arguments, a String _str_ and an integer _index_, and performs the following steps:
1. Assert: _index_ &le; the length of _str_.
1. If _Unicode_ is *true*, let _Input_ be a List consisting of the sequence of code points of _str_ interpreted as a UTF-16 encoded (<emu-xref href="#sec-ecmascript-language-types-string-type"></emu-xref>) Unicode string. Otherwise, let _Input_ be a List consisting of the sequence of code units that are the elements of _str_. _Input_ will be used throughout the algorithms in <emu-xref href="#sec-pattern-semantics"></emu-xref>. Each element of _Input_ is considered to be a character.
Expand All @@ -29701,15 +29703,16 @@ <h1>Pattern</h1>
<!-- es6num="21.2.2.3" -->
<emu-clause id="sec-disjunction">
<h1>Disjunction</h1>
<p>With argument _direction_.</p>
<p>The production <emu-grammar>Disjunction :: Alternative</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Alternative| to obtain a Matcher _m_.
1. Return _m_.
</emu-alg>
<p>The production <emu-grammar>Disjunction :: Alternative `|` Disjunction</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Alternative| to obtain a Matcher _m1_.
1. Evaluate |Disjunction| to obtain a Matcher _m2_.
1. Evaluate |Alternative| with argument _direction_ to obtain a Matcher _m1_.
1. Evaluate |Disjunction| with argument _direction_ to obtain a Matcher _m2_.
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps when evaluated:
1. Call _m1_(_x_, _c_) and let _r_ be its result.
1. If _r_ is not ~failure~, return _r_.
Expand All @@ -29724,32 +29727,41 @@ <h1>Disjunction</h1>
<pre><code class="javascript">["abc", "a", "a", undefined, "bc", undefined, "bc"]</code></pre>
<p>and not</p>
<pre><code class="javascript">["abc", "ab", undefined, "ab", "c", "c", undefined]</code></pre>
<p>The order in which the two alternatives are tried is independent of the value of _direction_.</p>
</emu-note>
</emu-clause>

<!-- es6num="21.2.2.4" -->
<emu-clause id="sec-alternative">
<h1>Alternative</h1>
<p>With argument _direction_.</p>
<p>The production <emu-grammar>Alternative :: [empty]</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Return a Matcher that takes two arguments, a State _x_ and a Continuation _c_, and returns the result of calling _c_(_x_).
</emu-alg>
<p>The production <emu-grammar>Alternative :: Alternative Term</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Alternative| to obtain a Matcher _m1_.
1. Evaluate |Term| to obtain a Matcher _m2_.
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps when evaluated:
1. Let _d_ be a Continuation that takes a State argument _y_ and returns the result of calling _m2_(_y_, _c_).
1. Call _m1_(_x_, _d_) and return its result.
1. Evaluate |Alternative| with argument _direction_ to obtain a Matcher _m1_.
1. Evaluate |Term| with argument _direction_ to obtain a Matcher _m2_.
1. If _direction_ is equal to +1, then
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps when evaluated:
1. Let _d_ be a Continuation that takes a State argument _y_ and returns the result of calling _m2_(_y_, _c_).
1. Call _m1_(_x_, _d_) and return its result.
1. Else,
1. Assert: _direction_ is equal to -1.
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps when evaluated:
1. Let _d_ be a Continuation that takes a State argument _y_ and returns the result of calling _m1_(_y_, _c_)
1. Call _m2_(_x_, _d_) and return its result.
</emu-alg>
<emu-note>
<p>Consecutive |Term|s try to simultaneously match consecutive portions of _Input_. If the left |Alternative|, the right |Term|, and the sequel of the regular expression all have choice points, all choices in the sequel are tried before moving on to the next choice in the right |Term|, and all choices in the right |Term| are tried before moving on to the next choice in the left |Alternative|.</p>
<p>Consecutive |Term|s try to simultaneously match consecutive portions of _Input_. When _direction_ is equal to +1, if the left |Alternative|, the right |Term|, and the sequel of the regular expression all have choice points, all choices in the sequel are tried before moving on to the next choice in the right |Term|, and all choices in the right |Term| are tried before moving on to the next choice in the left |Alternative|. When _direction_ is equal to -1, the evaluation order of |Alternative| and |Term| are reversed.</p>
</emu-note>
</emu-clause>

<!-- es6num="21.2.2.5" -->
<emu-clause id="sec-term">
<h1>Term</h1>
<p>With argument _direction_.</p>
<p>The production <emu-grammar>Term :: Assertion</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps when evaluated:
Expand All @@ -29758,13 +29770,16 @@ <h1>Term</h1>
1. If _r_ is *false*, return ~failure~.
1. Call _c_(_x_) and return its result.
</emu-alg>
<emu-note>
<p>The AssertionTester is independent of _direction_.</p>
</emu-note>
<p>The production <emu-grammar>Term :: Atom</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Return the Matcher that is the result of evaluating |Atom|.
1. Return the Matcher that is the result of evaluating |Atom| with argument _direction_.
</emu-alg>
<p>The production <emu-grammar>Term :: Atom Quantifier</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Atom| to obtain a Matcher _m_.
1. Evaluate |Atom| with argument _direction_ to obtain a Matcher _m_.
1. Evaluate |Quantifier| to obtain the three results: an integer _min_, an integer (or &infin;) _max_, and Boolean _greedy_.
1. Assert: If _max_ is finite, then _max_ is not less than _min_.
1. Let _parenIndex_ be the number of left-capturing parentheses in the entire regular expression that occur to the left of this |Term|. This is the total number of <emu-grammar>Atom :: `(` Disjunction `)`</emu-grammar> Parse Nodes prior to or enclosing this |Term|.
Expand Down Expand Up @@ -29886,7 +29901,7 @@ <h1>Assertion</h1>
</emu-alg>
<p>The production <emu-grammar>Assertion :: `(` `?` `=` Disjunction `)`</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Disjunction| to obtain a Matcher _m_.
1. Evaluate |Disjunction| with +1 as its _direction_ argument to obtain a Matcher _m_.
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps:
1. Let _d_ be a Continuation that always returns its State argument as a successful MatchResult.
1. Call _m_(_x_, _d_) and let _r_ be its result.
Expand All @@ -29899,7 +29914,29 @@ <h1>Assertion</h1>
</emu-alg>
<p>The production <emu-grammar>Assertion :: `(` `?` `!` Disjunction `)`</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Disjunction| to obtain a Matcher _m_.
1. Evaluate |Disjunction| with +1 as its _direction_ argument to obtain a Matcher _m_.
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps:
1. Let _d_ be a Continuation that always returns its State argument as a successful MatchResult.
1. Call _m_(_x_, _d_) and let _r_ be its result.
1. If _r_ is not ~failure~, return ~failure~.
1. Call _c_(_x_) and return its result.
</emu-alg>
<p>The production <emu-grammar>Assertion :: `(` `?` `&lt;=` Disjunction `)`</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Disjunction| with -1 as its _direction_ argument to obtain a Matcher _m_.
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps:
1. Let _d_ be a Continuation that always returns its State argument as a successful MatchResult.
1. Call _m_(_x_, _d_) and let _r_ be its result.
1. If _r_ is ~failure~, return ~failure~.
1. Let _y_ be _r_'s State.
1. Let _cap_ be _y_'s _captures_ List.
1. Let _xe_ be _x_'s _endIndex_.
1. Let _z_ be the State (_xe_, _cap_).
1. Call _c_(_z_) and return its result.
</emu-alg>
<p>The production <emu-grammar>Assertion :: `(` `?` `&lt;!` Disjunction `)`</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Disjunction| with -1 as its _direction_ argument to obtain a Matcher _m_.
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps:
1. Let _d_ be a Continuation that always returns its State argument as a successful MatchResult.
1. Call _m_(_x_, _d_) and let _r_ be its result.
Expand Down Expand Up @@ -30210,64 +30247,74 @@ <h1>Quantifier</h1>
<!-- es6num="21.2.2.8" -->
<emu-clause id="sec-atom">
<h1>Atom</h1>
<p>With argument _direction_.</p>
<p>The production <emu-grammar>Atom :: PatternCharacter</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Let _ch_ be the character matched by |PatternCharacter|.
1. Let _A_ be a one-element CharSet containing the character _ch_.
1. Call CharacterSetMatcher(_A_, *false*) and return its Matcher result.
1. Call CharacterSetMatcher(_A_, *false*, _direction_) and return its Matcher result.
</emu-alg>
<p>The production <emu-grammar>Atom :: `.`</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. If _DotAll_ is *true*, then
1. Let _A_ be the set of all characters.
1. Otherwise, let _A_ be the set of all characters except |LineTerminator|.
1. Call CharacterSetMatcher(_A_, *false*) and return its Matcher result.
1. Call CharacterSetMatcher(_A_, *false*, _direction_) and return its Matcher result.
</emu-alg>
<p>The production <emu-grammar>Atom :: `\` AtomEscape</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Return the Matcher that is the result of evaluating |AtomEscape|.
1. Return the Matcher that is the result of evaluating |AtomEscape| with argument _direction_.
</emu-alg>
<p>The production <emu-grammar>Atom :: CharacterClass</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |CharacterClass| to obtain a CharSet _A_ and a Boolean _invert_.
1. Call CharacterSetMatcher(_A_, _invert_) and return its Matcher result.
1. Call CharacterSetMatcher(_A_, _invert_, _direction_) and return its Matcher result.
</emu-alg>
<p>The production <emu-grammar>Atom :: `(` Disjunction `)`</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |Disjunction| to obtain a Matcher _m_.
1. Evaluate |Disjunction| with argument _direction_ to obtain a Matcher _m_.
1. Let _parenIndex_ be the number of left-capturing parentheses in the entire regular expression that occur to the left of this |Atom|. This is the total number of <emu-grammar>Atom :: `(` Disjunction `)`</emu-grammar> Parse Nodes prior to or enclosing this |Atom|.
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps:
1. Let _d_ be an internal Continuation closure that takes one State argument _y_ and performs the following steps:
1. Let _cap_ be a copy of _y_'s _captures_ List.
1. Let _xe_ be _x_'s _endIndex_.
1. Let _ye_ be _y_'s _endIndex_.
1. Let _s_ be a new List whose characters are the characters of _Input_ at indices _xe_ (inclusive) through _ye_ (exclusive).
1. If _direction_ is equal to +1, then
1. Assert: _xe_ &lte; _ye_.
1. Let _s_ be a fresh List whose characters are the characters of _Input_ at indices _xe_ (inclusive) through _ye_ (exclusive).
1. Else,
1. Assert: _direction_ is equal to -1.
1. Assert: _ye_ &lte; _xe_.
1. Let _s_ be a fresh List whose characters are the characters of _Input_ at indices _ye_ (inclusive) through _xe_ (exclusive).
1. Set _cap_[_parenIndex_+1] to _s_.
1. Let _z_ be the State (_ye_, _cap_).
1. Call _c_(_z_) and return its result.
1. Call _m_(_x_, _d_) and return its result.
</emu-alg>
<p>The production <emu-grammar>Atom :: `(` `?` `:` Disjunction `)`</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Return the Matcher that is the result of evaluating |Disjunction|.
1. Return the Matcher that is the result of evaluating |Disjunction| with argument _direction_.
</emu-alg>

<!-- es6num="21.2.2.8.1" -->
<emu-clause id="sec-runtime-semantics-charactersetmatcher-abstract-operation" aoid="CharacterSetMatcher">
<h1>Runtime Semantics: CharacterSetMatcher ( _A_, _invert_ )</h1>
<p>The abstract operation CharacterSetMatcher takes two arguments, a CharSet _A_ and a Boolean flag _invert_, and performs the following steps:</p>
<h1>Runtime Semantics: CharacterSetMatcher ( _A_, _invert_, _direction_ )</h1>
<p>The abstract operation CharacterSetMatcher takes three arguments, a CharSet _A_, a Boolean flag _invert_, and an integer _direction_, and performs the following steps:</p>
<emu-alg>
1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps when evaluated:
1. Let _e_ be _x_'s _endIndex_.
1. If _e_ is _InputLength_, return ~failure~.
1. Let _ch_ be the character _Input_[_e_].
1. Let _f_ be _e_ + _direction_.
1. If _f_ &lt; 0 or _f_ > _InputLength_, return ~failure~.
1. Let _index_ be min(_e_, _f_).
1. Let _ch_ be the character _Input_[_index_].
1. Let _cc_ be Canonicalize(_ch_).
1. If _invert_ is *false*, then
1. If there does not exist a member _a_ of set _A_ such that Canonicalize(_a_) is _cc_, return ~failure~.
1. Else _invert_ is *true*,
1. Else,
1. Assert: _invert_ is *true*.
1. If there exists a member _a_ of set _A_ such that Canonicalize(_a_) is _cc_, return ~failure~.
1. Let _cap_ be _x_'s _captures_ List.
1. Let _y_ be the State (_e_+1, _cap_).
1. Let _y_ be the State (_f_, _cap_).
1. Call _c_(_y_) and return its result.
</emu-alg>
</emu-clause>
Expand Down Expand Up @@ -30365,6 +30412,7 @@ <h1>Runtime Semantics: UnicodeMatchPropertyValue ( _p_, _v_ )</h1>
<!-- es6num="21.2.2.9" -->
<emu-clause id="sec-atomescape">
<h1>AtomEscape</h1>
<p>With argument _direction_.</p>
<p>The production <emu-grammar>AtomEscape :: DecimalEscape</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |DecimalEscape| to obtain an integer _n_.
Expand All @@ -30375,12 +30423,12 @@ <h1>AtomEscape</h1>
<emu-alg>
1. Evaluate |CharacterEscape| to obtain a character _ch_.
1. Let _A_ be a one-element CharSet containing the character _ch_.
1. Call CharacterSetMatcher(_A_, *false*) and return its Matcher result.
1. Call CharacterSetMatcher(_A_, *false*, _direction_) and return its Matcher result.
</emu-alg>
<p>The production <emu-grammar>AtomEscape :: CharacterClassEscape</emu-grammar> evaluates as follows:</p>
<emu-alg>
1. Evaluate |CharacterClassEscape| to obtain a CharSet _A_.
1. Call CharacterSetMatcher(_A_, *false*) and return its Matcher result.
1. Call CharacterSetMatcher(_A_, *false*, _direction_) and return its Matcher result.
</emu-alg>
<emu-note>
<p>An escape sequence of the form `\\` followed by a nonzero decimal number _n_ matches the result of the _n_th set of capturing parentheses (<emu-xref href="#sec-notation"></emu-xref>). It is an error if the regular expression has fewer than _n_ capturing parentheses. If the regular expression has _n_ or more capturing parentheses but the _n_th one is *undefined* because it has not captured anything, then the backreference always succeeds.</p>
Expand Down Expand Up @@ -31291,9 +31339,10 @@ <h1>Runtime Semantics: BackreferenceMatcher Abstract Operation</h1>
1. If _s_ is *undefined*, return _c_(_x_).
1. Let _e_ be _x_'s _endIndex_.
1. Let _len_ be the number of elements in _s_.
1. Let _f_ be _e_ + _len_.
1. If _f_ &gt; _InputLength_, return ~failure~.
1. If there exists an integer _i_ between 0 (inclusive) and _len_ (exclusive) such that Canonicalize(_s_[_i_]) is not the same character value as Canonicalize(_Input_[_e_ + _i_]), return ~failure~.
1. Let _f_ be _e_ + _direction_ &times; _len_.
1. If _f_ &lt; 0 or _f_ &gt; _InputLength_, return ~failure~.
1. Let _g_ be min(_e_, _f_).
1. If there exists an integer _i_ between 0 (inclusive) and _len_ (exclusive) such that Canonicalize(_s_[_i_]) is not the same character value as Canonicalize(_Input_[_g_ + _i_]), return ~failure~.
1. Let _y_ be the State (_f_, _cap_).
1. Call _c_(_y_) and return its result.
</emu-alg>
Expand Down