From 55ad6814e69648513378b92d8730879ba25a4271 Mon Sep 17 00:00:00 2001 From: Daniel Rosenwasser Date: Thu, 11 Jul 2019 22:23:37 -0700 Subject: [PATCH 1/7] Give nullish coalescing lower precedence than logical OR. --- spec.html | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/spec.html b/spec.html index 7222f19..c03c66e 100644 --- a/spec.html +++ b/spec.html @@ -22,10 +22,25 @@

Introduction

Syntax

+ ConditionalExpression[In, Yield, Await] : + LogicalORExpression[?In, ?Yield, ?Await] + LogicalORExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[?In, ?Yield, ?Await] + NullishExpression[?In, ?Yield, ?Await] + NullishExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[+In, ?Yield, ?Await] + + + NullishExpression[In, Yield, Await] : + LogicalORExpression[?In, ?Yield, ?Await] + LogicalORExpression[?In, ?Yield, ?Await] `??` NullishExpression[?In, ?Yield, ?Await] + + LogicalORExpression[In, Yield, Await] : LogicalANDExpression[?In, ?Yield, ?Await] LogicalORExpression[?In, ?Yield, ?Await] `||` LogicalANDExpression[?In, ?Yield, ?Await] - LogicalORExpression[?In, ?Yield, ?Await] `??` LogicalANDExpression[?In, ?Yield, ?Await] + + LogicalANDExpression[In, Yield, Await] : + BitwiseORExpression[?In, ?Yield, ?Await] + LogicalANDExpression[?In, ?Yield, ?Await] `&&` BitwiseORExpression[?In, ?Yield, ?Await] From 545e3437d9c19c16bc30df9325db1a07c7b81400 Mon Sep 17 00:00:00 2001 From: Daniel Rosenwasser Date: Fri, 12 Jul 2019 00:00:53 -0700 Subject: [PATCH 2/7] Fixed associativity of NullishExpression, omitted unnecessary productions. --- spec.html | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/spec.html b/spec.html index c03c66e..6d2cce0 100644 --- a/spec.html +++ b/spec.html @@ -31,16 +31,8 @@

Syntax

NullishExpression[In, Yield, Await] : LogicalORExpression[?In, ?Yield, ?Await] - LogicalORExpression[?In, ?Yield, ?Await] `??` NullishExpression[?In, ?Yield, ?Await] + NullishExpression[?In, ?Yield, ?Await] `??` LogicalORExpression[?In, ?Yield, ?Await] - - LogicalORExpression[In, Yield, Await] : - LogicalANDExpression[?In, ?Yield, ?Await] - LogicalORExpression[?In, ?Yield, ?Await] `||` LogicalANDExpression[?In, ?Yield, ?Await] - - LogicalANDExpression[In, Yield, Await] : - BitwiseORExpression[?In, ?Yield, ?Await] - LogicalANDExpression[?In, ?Yield, ?Await] `&&` BitwiseORExpression[?In, ?Yield, ?Await] From 46f9a4e62e69f467770efa13af9aee834be2cf4b Mon Sep 17 00:00:00 2001 From: Daniel Rosenwasser Date: Fri, 12 Jul 2019 12:03:37 -0700 Subject: [PATCH 3/7] Updated all sites of ConditionalExpression, LogicalORExpression, NullishExpression. --- spec.html | 157 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 157 insertions(+) diff --git a/spec.html b/spec.html index 6d2cce0..c9f32e2 100644 --- a/spec.html +++ b/spec.html @@ -49,3 +49,160 @@

Runtime Semantics: Evaluation

1. Otherwise, return _lval_. + + +

Binary Logical Operators

+

Syntax

+ + + NullishExpression[In, Yield, Await] : + LogicalORExpression[?In, ?Yield, ?Await] + NullishExpression[?In, ?Yield, ?Await] `??` LogicalORExpression[?In, ?Yield, ?Await] + + + + +

Static Semantics: IsFunctionDefinition

+ + + LogicalANDExpression : LogicalANDExpression `&&` BitwiseORExpression + + LogicalORExpression : LogicalORExpression `||` LogicalANDExpression + + NullishExpression : NullishExpression `??` LogicalORExpression + + + 1. Return *false*. + + + + +

Static Semantics: AssignmentTargetType

+ + + LogicalANDExpression : LogicalANDExpression `&&` BitwiseORExpression + + LogicalORExpression : LogicalORExpression `||` LogicalANDExpression + + NullishExpression : NullishExpression `??` LogicalORExpression + + + 1. Return ~invalid~. + + + + +

Runtime Semantics: Evaluation

+ + NullishExpression : NullishExpression `??` LogicalORExpression + + + 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_. + + + + + + +

Conditional Operator ( `? :` )

+

Syntax

+ + ConditionalExpression[In, Yield, Await] : + LogicalORExpression[?In, ?Yield, ?Await] + LogicalORExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[?In, ?Yield, ?Await] + NullishExpression[?In, ?Yield, ?Await] + NullishExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[+In, ?Yield, ?Await] + + + +

Static Semantics: IsFunctionDefinition

+ + + ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression + ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression + + + 1. Return *false*. + + + + +

Static Semantics: AssignmentTargetType

+ + + ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression + ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression + + + 1. Return ~invalid~. + + + + +

Runtime Semantics: Evaluation

+ + ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression + ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression + + + 1. Let _lref_ be the result of evaluating |LogicalORExpression|. + 1. Let _lref_ be the result of evaluating |NullishExpression|. + 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_). + + + + + +

Tail Position Calls

+ + +

Static Semantics: HasCallInTailPosition

+

With parameter _call_.

+ + +

Expression Rules

+ + ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression + ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression + + + 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_. + + + ConditionalExpression : LogicalORExpression `?` AssignmentExpression `:` AssignmentExpression + ConditionalExpression : NullishExpression `?` AssignmentExpression `:` AssignmentExpression + + LogicalANDExpression : LogicalANDExpression `&&` BitwiseORExpression + + 1. Return HasCallInTailPosition of |BitwiseORExpression| with argument _call_. + + LogicalORExpression : LogicalORExpression `||` LogicalANDExpression + + 1. Return HasCallInTailPosition of |LogicalANDExpression| with argument _call_. + + + + NullishExpression : NullishExpression `??` LogicalORExpression + + + + + 1. Return HasCallInTailPosition of |LogicalORExpression| with argument _call_. + + + + + \ No newline at end of file From fa4301985abcf956546c08ab88c70ba418ac97df Mon Sep 17 00:00:00 2001 From: Daniel Rosenwasser Date: Fri, 12 Jul 2019 16:36:42 -0700 Subject: [PATCH 4/7] Remove duplicated spec text. --- spec.html | 32 -------------------------------- 1 file changed, 32 deletions(-) diff --git a/spec.html b/spec.html index c9f32e2..dd00f16 100644 --- a/spec.html +++ b/spec.html @@ -18,38 +18,6 @@

Introduction

- -

Syntax

- - - ConditionalExpression[In, Yield, Await] : - LogicalORExpression[?In, ?Yield, ?Await] - LogicalORExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[?In, ?Yield, ?Await] - NullishExpression[?In, ?Yield, ?Await] - NullishExpression[?In, ?Yield, ?Await] `?` AssignmentExpression[+In, ?Yield, ?Await] `:` AssignmentExpression[+In, ?Yield, ?Await] - - - NullishExpression[In, Yield, Await] : - LogicalORExpression[?In, ?Yield, ?Await] - NullishExpression[?In, ?Yield, ?Await] `??` LogicalORExpression[?In, ?Yield, ?Await] - - - - - -

Runtime Semantics: Evaluation

- - LogicalORExpression : LogicalORExpression `??` LogicalANDExpression - - 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_. - - -

Binary Logical Operators

Syntax

From 57ac9675672622a3e567c86e864e0074c27a46b5 Mon Sep 17 00:00:00 2001 From: Daniel Rosenwasser Date: Fri, 12 Jul 2019 16:39:55 -0700 Subject: [PATCH 5/7] Update intro. --- spec.html | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/spec.html b/spec.html index dd00f16..375f9c7 100644 --- a/spec.html +++ b/spec.html @@ -1,9 +1,9 @@ 
-title: Nullish coalescing operator
+title: Nullish Coalescing Operator
 stage: 2
-contributors: Daniel Ehrenberg
+contributors: Daniel Ehrenberg, Daniel Rosenwasser
@@ -12,7 +12,7 @@

Introduction

The main design decisions made in this specification are:

  1. The right argument of `??` is evaluated only if needed ("short circuiting").
    2. -
  2. `??` has the same precedence as `||`.
    3. +
  3. `??` has lower precedence than `||`.
  4. The right argument is selected if the left argument is `null` or `undefined`.

From 1ecbcf0daa6a97911203a12fc88397d5c0eb279b Mon Sep 17 00:00:00 2001 From: Daniel Rosenwasser Date: Fri, 12 Jul 2019 23:02:36 -0700 Subject: [PATCH 6/7] Fixed ordered list, fixed runtime semantics. --- spec.html | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/spec.html b/spec.html index 375f9c7..2d05344 100644 --- a/spec.html +++ b/spec.html @@ -64,14 +64,12 @@

Runtime Semantics: Evaluation

NullishExpression : NullishExpression `??` LogicalORExpression - - 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_. - + 1. Let _lref_ be the result of evaluating |NullishExpression|. + 1. Let _lval_ be ? GetValue(_lref_). + 1. If _lval_ is *undefined* or *null*, + 1. Let _rref_ be the result of evaluating |LogicalORExpression|. + 1. Return ? GetValue(_rref_). + 1. Otherwise, return _lval_. From b66c7f11d759c2cde999892f3bb441f6e65ad3c9 Mon Sep 17 00:00:00 2001 From: Daniel Rosenwasser Date: Sat, 20 Jul 2019 00:40:59 -0700 Subject: [PATCH 7/7] Newline. --- spec.html | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/spec.html b/spec.html index 99c0017..752d59f 100644 --- a/spec.html +++ b/spec.html @@ -171,4 +171,4 @@

Expression Rules

- \ No newline at end of file +