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Editorial: make String{,Last}IndexOf return not-found #3300

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Mar 27, 2024
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Editorial: make String{,Last}IndexOf return not-found #3300

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96ceb67
Editorial: make String{,Last}IndexOf return not-found (#3300)
bakkot Mar 27, 2024
5d8f62d
Editorial: swap order of steps in String.p.includes (#3300)
bakkot Mar 27, 2024
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30 changes: 17 additions & 13 deletions spec.html
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Original file line number Diff line number Diff line change
Expand Up @@ -1152,7 +1152,7 @@ <h1>
_string_: a String,
_searchValue_: a String,
_fromIndex_: a non-negative integer,
): a non-negative integer or -1
): a non-negative integer or ~not-found~
</h1>
<dl class="header">
</dl>
Expand All @@ -1163,13 +1163,13 @@ <h1>
1. For each integer _i_ such that _fromIndex_ ≤ _i_ ≤ _len_ - _searchLen_, in ascending order, do
1. Let _candidate_ be the substring of _string_ from _i_ to _i_ + _searchLen_.
1. If _candidate_ is _searchValue_, return _i_.
1. Return -1.
1. Return ~not-found~.
</emu-alg>
<emu-note>
<p>If _searchValue_ is the empty String and _fromIndex_ ≤ the length of _string_, this algorithm returns _fromIndex_. The empty String is effectively found at every position within a string, including after the last code unit.</p>
</emu-note>
<emu-note>
<p>This algorithm always returns -1 if _fromIndex_ + the length of _searchValue_ > the length of _string_.</p>
<p>This algorithm always returns ~not-found~ if _fromIndex_ + the length of _searchValue_ > the length of _string_.</p>
</emu-note>
</emu-clause>

Expand All @@ -1179,7 +1179,7 @@ <h1>
_string_: a String,
_searchValue_: a String,
_fromIndex_: a non-negative integer,
): a non-negative integer or -1
): a non-negative integer or ~not-found~
</h1>
<dl class="header">
</dl>
Expand All @@ -1190,7 +1190,7 @@ <h1>
1. For each integer _i_ such that 0 ≤ _i_ ≤ _fromIndex_, in descending order, do
1. Let _candidate_ be the substring of _string_ from _i_ to _i_ + _searchLen_.
1. If _candidate_ is _searchValue_, return _i_.
1. Return -1.
1. Return ~not-found~.
</emu-alg>
<emu-note>
<p>If _searchValue_ is the empty String, this algorithm returns _fromIndex_. The empty String is effectively found at every position within a string, including after the last code unit.</p>
Expand Down Expand Up @@ -34605,8 +34605,8 @@ <h1>String.prototype.includes ( _searchString_ [ , _position_ ] )</h1>
1. Let _len_ be the length of _S_.
1. Let _start_ be the result of clamping _pos_ between 0 and _len_.
1. Let _index_ be StringIndexOf(_S_, _searchStr_, _start_).
1. If _index_ ≠ -1, return *true*.
1. Return *false*.
1. If _index_ is ~not-found~, return *false*.
1. Return *true*.
</emu-alg>
<emu-note>
<p>If _searchString_ appears as a <emu-not-ref>substring</emu-not-ref> of the result of converting this object to a String, at one or more indices that are greater than or equal to _position_, this function returns *true*; otherwise, it returns *false*. If _position_ is *undefined*, 0 is assumed, so as to search all of the String.</p>
Expand All @@ -34633,7 +34633,9 @@ <h1>String.prototype.indexOf ( _searchString_ [ , _position_ ] )</h1>
1. Assert: If _position_ is *undefined*, then _pos_ is 0.
1. Let _len_ be the length of _S_.
1. Let _start_ be the result of clamping _pos_ between 0 and _len_.
1. Return 𝔽(StringIndexOf(_S_, _searchStr_, _start_)).
1. Let _result_ be StringIndexOf(_S_, _searchStr_, _start_).
1. If _result_ is ~not-found~, return *-1*<sub>𝔽</sub>.
1. Return 𝔽(_result_).
</emu-alg>
<emu-note>
<p>This method is intentionally generic; it does not require that its *this* value be a String object. Therefore, it can be transferred to other kinds of objects for use as a method.</p>
Expand Down Expand Up @@ -34666,7 +34668,9 @@ <h1>String.prototype.lastIndexOf ( _searchString_ [ , _position_ ] )</h1>
1. Let _len_ be the length of _S_.
1. Let _searchLen_ be the length of _searchStr_.
1. Let _start_ be the result of clamping _pos_ between 0 and _len_ - _searchLen_.
1. Return 𝔽(StringLastIndexOf(_S_, _searchStr_, _start_)).
1. Let _result_ be StringLastIndexOf(_S_, _searchStr_, _start_).
1. If _result_ is ~not-found~, return *-1*<sub>𝔽</sub>.
1. Return 𝔽(_result_).
</emu-alg>
<emu-note>
<p>This method is intentionally generic; it does not require that its *this* value be a String object. Therefore, it can be transferred to other kinds of objects for use as a method.</p>
Expand Down Expand Up @@ -34896,7 +34900,7 @@ <h1>String.prototype.replace ( _searchValue_, _replaceValue_ )</h1>
1. Set _replaceValue_ to ? ToString(_replaceValue_).
1. Let _searchLength_ be the length of _searchString_.
1. Let _position_ be StringIndexOf(_string_, _searchString_, 0).
1. If _position_ = -1, return _string_.
1. If _position_ is ~not-found~, return _string_.
1. Let _preceding_ be the substring of _string_ from 0 to _position_.
1. Let _following_ be the substring of _string_ from _position_ + _searchLength_.
1. If _functionalReplace_ is *true*, then
Expand Down Expand Up @@ -34970,7 +34974,7 @@ <h1>
1. Let _refReplacement_ be _ref_.
1. Else if _templateRemainder_ starts with *"$&lt;"*, then
1. Let _gtPos_ be StringIndexOf(_templateRemainder_, *">"*, 0).
1. If _gtPos_ = -1 or _namedCaptures_ is *undefined*, then
1. If _gtPos_ is ~not-found~ or _namedCaptures_ is *undefined*, then
1. Let _ref_ be *"$&lt;"*.
1. Let _refReplacement_ be _ref_.
1. Else,
Expand Down Expand Up @@ -35016,7 +35020,7 @@ <h1>String.prototype.replaceAll ( _searchValue_, _replaceValue_ )</h1>
1. Let _advanceBy_ be max(1, _searchLength_).
1. Let _matchPositions_ be a new empty List.
1. Let _position_ be StringIndexOf(_string_, _searchString_, 0).
1. Repeat, while _position_ ≠ -1,
1. Repeat, while _position_ is not ~not-found~,
1. Append _position_ to _matchPositions_.
1. Set _position_ to StringIndexOf(_string_, _searchString_, _position_ + _advanceBy_).
1. Let _endOfLastMatch_ be 0.
Expand Down Expand Up @@ -35105,7 +35109,7 @@ <h1>String.prototype.split ( _separator_, _limit_ )</h1>
1. Let _substrings_ be a new empty List.
1. Let _i_ be 0.
1. Let _j_ be StringIndexOf(_S_, _R_, 0).
1. Repeat, while _j_ ≠ -1,
1. Repeat, while _j_ is not ~not-found~,
1. Let _T_ be the substring of _S_ from _i_ to _j_.
1. Append _T_ to _substrings_.
1. If the number of elements in _substrings_ is _lim_, return CreateArrayFromList(_substrings_).
Expand Down
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