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Give nullish coalescing lower precedence than logical OR. #40

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Give nullish coalescing lower precedence than logical OR. #40

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55ad681
Give nullish coalescing lower precedence than logical OR.
DanielRosenwasser Jul 12, 2019
545e343
Fixed associativity of NullishExpression, omitted unnecessary product…
DanielRosenwasser Jul 12, 2019
46f9a4e
Updated all sites of ConditionalExpression, LogicalORExpression, Null…
DanielRosenwasser Jul 12, 2019
fa43019
Remove duplicated spec text.
DanielRosenwasser Jul 12, 2019
57ac967
Update intro.
DanielRosenwasser Jul 12, 2019
1ecbcf0
Fixed ordered list, fixed runtime semantics.
DanielRosenwasser Jul 13, 2019
8d78990
Merge branch 'master' into coalescing-with-lower-precedence
DanielRosenwasser Jul 13, 2019
e374942
Merge branch 'master' into coalescing-with-lower-precedence
DanielRosenwasser Jul 13, 2019
c93a215
Merge branch 'master' into coalescing-with-lower-precedence
DanielRosenwasser Jul 18, 2019
b66c7f1
Newline.
DanielRosenwasser Jul 20, 2019
42099a8
Merge branch 'master' into coalescing-with-lower-precedence
DanielRosenwasser Jul 22, 2019
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172 changes: 168 additions & 4 deletions spec.html
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Expand Up @@ -22,10 +22,17 @@ <h1>Introduction</h1>
<h1>Syntax</h1>

<emu-grammar>
LogicalORExpression[In, Yield, Await] :
LogicalANDExpression[?In, ?Yield, ?Await]
LogicalORExpression[?In, ?Yield, ?Await] `||` LogicalANDExpression[?In, ?Yield, ?Await]
<ins>LogicalORExpression[?In, ?Yield, ?Await] `??` LogicalANDExpression[?In, ?Yield, ?Await]</ins>
ConditionalExpression[In, Yield, Await] :
<del>LogicalORExpression[?In, ?Yield, ?Await]</del>
<del>LogicalORExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[?In, ?Yield, ?Await]</del>
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<ins>NullishExpression[?In, ?Yield, ?Await]</ins>
<ins>NullishExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[+In, ?Yield, ?Await]</ins>

<ins>
NullishExpression[In, Yield, Await] :
LogicalORExpression[?In, ?Yield, ?Await]
NullishExpression[?In, ?Yield, ?Await] `??` LogicalORExpression[?In, ?Yield, ?Await]
</ins>
</emu-grammar>
</emu-clause>
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Seems like these two tentative <emu-clause>s can be deleted if they're now incorporated into the context below.

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Should be fixed now both here and in #39.


Expand All @@ -42,3 +49,160 @@ <h1>Runtime Semantics: Evaluation</h1>
1. Otherwise, return _lval_.
</emu-alg>
</emu-clause>

<emu-clause id="sec-binary-logical-operators">
<h1>Binary Logical Operators</h1>
<h2>Syntax</h2>
<emu-grammar type="definition">
<ins>
NullishExpression[In, Yield, Await] :
LogicalORExpression[?In, ?Yield, ?Await]
NullishExpression[?In, ?Yield, ?Await] `??` LogicalORExpression[?In, ?Yield, ?Await]
</ins>
</emu-grammar>

<emu-clause id="sec-binary-logical-operators-static-semantics-isfunctiondefinition">
<h1>Static Semantics: IsFunctionDefinition</h1>
<emu-see-also-para op="IsFunctionDefinition"></emu-see-also-para>
<emu-grammar>
LogicalANDExpression : LogicalANDExpression `&amp;&amp;` BitwiseORExpression

LogicalORExpression : LogicalORExpression `||` LogicalANDExpression

<ins>NullishExpression : NullishExpression `??` LogicalORExpression</ins>
</emu-grammar>
<emu-alg>
1. Return *false*.
</emu-alg>
</emu-clause>

<emu-clause oldids="sec-binary-logical-operators-static-semantics-isvalidsimpleassignmenttarget" id="sec-binary-logical-operators-static-semantics-assignmenttargettype">
<h1>Static Semantics: AssignmentTargetType</h1>
<emu-see-also-para op="AssignmentTargetType"></emu-see-also-para>
<emu-grammar>
LogicalANDExpression : LogicalANDExpression `&amp;&amp;` BitwiseORExpression

LogicalORExpression : LogicalORExpression `||` LogicalANDExpression

<ins>NullishExpression : NullishExpression `??` LogicalORExpression</ins>
</emu-grammar>
<emu-alg>
1. Return ~invalid~.
</emu-alg>
</emu-clause>

<emu-clause id="sec-binary-logical-operators-runtime-semantics-evaluation">
<h1>Runtime Semantics: Evaluation</h1>

<emu-grammar><ins>NullishExpression : NullishExpression `??` LogicalORExpression</ins></emu-grammar>
<emu-alg>
<ins>
1. Let _lref_ be the result of evaluating |LogicalORExpression|.
1. Let _lval_ be ? GetValue(_lref_).
1. If _lval_ is *undefined* or *null*,
1. Let _rref_ be the result of evaluating |LogicalANDExpression|.
1. Return ? GetValue(_rref_).
1. Otherwise, return _lval_.
</ins>
</emu-alg>
</emu-clause>
</emu-clause>

<emu-clause id="sec-conditional-operator">
<h1>Conditional Operator ( `? :` )</h1>
<h2>Syntax</h2>
<emu-grammar type="definition">
ConditionalExpression[In, Yield, Await] :
<del>LogicalORExpression[?In, ?Yield, ?Await]</del>
<del>LogicalORExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[?In, ?Yield, ?Await]</del>
<ins>NullishExpression[?In, ?Yield, ?Await]</ins>
<ins>NullishExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[+In, ?Yield, ?Await]</ins>
</emu-grammar>

<emu-clause id="sec-conditional-operator-static-semantics-isfunctiondefinition">
<h1>Static Semantics: IsFunctionDefinition</h1>
<emu-see-also-para op="IsFunctionDefinition"></emu-see-also-para>
<emu-grammar>
<del>ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression</del>
<ins>ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression</ins>
</emu-grammar>
<emu-alg>
1. Return *false*.
</emu-alg>
</emu-clause>

<emu-clause oldids="sec-conditional-operator-static-semantics-isvalidsimpleassignmenttarget" id="sec-conditional-operator-static-semantics-assignmenttargettype">
<h1>Static Semantics: AssignmentTargetType</h1>
<emu-see-also-para op="AssignmentTargetType"></emu-see-also-para>
<emu-grammar>
<del>ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression</del>
<ins>ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression</ins>
</emu-grammar>
<emu-alg>
1. Return ~invalid~.
</emu-alg>
</emu-clause>

<emu-clause id="sec-conditional-operator-runtime-semantics-evaluation">
<h1>Runtime Semantics: Evaluation</h1>
<emu-grammar>
<del>ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression</del>
<ins>ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression</ins>
</emu-grammar>
<emu-alg>
1. <del>Let _lref_ be the result of evaluating |LogicalORExpression|.</del>
1. <ins>Let _lref_ be the result of evaluating |NullishExpression|.</ins>
1. Let _lval_ be ToBoolean(? GetValue(_lref_)).
1. If _lval_ is *true*, then
1. Let _trueRef_ be the result of evaluating the first |AssignmentExpression|.
1. Return ? GetValue(_trueRef_).
1. Else,
1. Let _falseRef_ be the result of evaluating the second |AssignmentExpression|.
1. Return ? GetValue(_falseRef_).
</emu-alg>
</emu-clause>
</emu-clause>

<emu-clause id="sec-tail-position-calls">
<h1>Tail Position Calls</h1>

<emu-clause id="sec-static-semantics-hascallintailposition">
<h1>Static Semantics: HasCallInTailPosition</h1>
<p>With parameter _call_.</p>

<emu-clause id="sec-expression-rules">
<h1>Expression Rules</h1>
<emu-grammar>
<del>ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression</del>
<ins>ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression</ins>
</emu-grammar>
<emu-alg>
1. Let _has_ be HasCallInTailPosition of the first |AssignmentExpression| with argument _call_.
1. If _has_ is *true*, return *true*.
1. Return HasCallInTailPosition of the second |AssignmentExpression| with argument _call_.
</emu-alg>
<emu-grammar>
<del>ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression</del>
<ins>ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression</ins>
</emu-grammar>
<emu-grammar>LogicalANDExpression : LogicalANDExpression `&amp;&amp;` BitwiseORExpression</emu-grammar>
<emu-alg>
1. Return HasCallInTailPosition of |BitwiseORExpression| with argument _call_.
</emu-alg>
<emu-grammar>LogicalORExpression : LogicalORExpression `||` LogicalANDExpression</emu-grammar>
<emu-alg>
1. Return HasCallInTailPosition of |LogicalANDExpression| with argument _call_.
</emu-alg>
<emu-grammar>
<ins>
NullishExpression : NullishExpression `??` LogicalORExpression
</ins>
</emu-grammar>
<emu-alg>
<ins>
1. Return HasCallInTailPosition of |LogicalORExpression| with argument _call_.
</ins>
</emu-alg>
</emu-clause>
</emu-clause>
</emu-clause>
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