Parse nullish coalescing (fix #2039)

ljqx · ariya · commit 3515f7e596a3 · 2020-12-02T07:18:48.000-08:00
diff --git a/src/nodes.ts b/src/nodes.ts
@@ -159,7 +159,7 @@ export class BinaryExpression {
     readonly left: Expression;
     readonly right: Expression;
     constructor(operator: string, left: Expression, right: Expression) {
-        const logical = (operator === '||' || operator === '&&');
+        const logical = (operator === '||' || operator === '&&' || operator === '??');
         this.type = logical ? Syntax.LogicalExpression : Syntax.BinaryExpression;
         this.operator = operator;
         this.left = left;
diff --git a/src/parser.ts b/src/parser.ts
@@ -103,27 +103,28 @@ export class Parser {
             ',': 0,
             '=': 0,
             ']': 0,
-            '||': 1,
-            '&&': 2,
-            '|': 3,
-            '^': 4,
-            '&': 5,
-            '==': 6,
-            '!=': 6,
-            '===': 6,
-            '!==': 6,
-            '<': 7,
-            '>': 7,
-            '<=': 7,
-            '>=': 7,
-            '<<': 8,
-            '>>': 8,
-            '>>>': 8,
-            '+': 9,
-            '-': 9,
-            '*': 11,
-            '/': 11,
-            '%': 11
+            '??': 5,
+            '||': 6,
+            '&&': 7,
+            '|': 8,
+            '^': 9,
+            '&': 10,
+            '==': 11,
+            '!=': 11,
+            '===': 11,
+            '!==': 11,
+            '<': 12,
+            '>': 12,
+            '<=': 12,
+            '>=': 12,
+            '<<': 13,
+            '>>': 13,
+            '>>>': 13,
+            '+': 14,
+            '-': 14,
+            '*': 15,
+            '/': 15,
+            '%': 15
         };
 
         this.lookahead = {
@@ -1478,7 +1479,7 @@ export class Parser {
         if (token.type === Token.Punctuator) {
             precedence = this.operatorPrecedence[op] || 0;
         } else if (token.type === Token.Keyword) {
-            precedence = (op === 'instanceof' || (this.context.allowIn && op === 'in')) ? 7 : 0;
+            precedence = (op === 'instanceof' || (this.context.allowIn && op === 'in')) ? 12 : 0;
         } else {
             precedence = 0;
         }
@@ -1490,9 +1491,21 @@ export class Parser {
 
         let expr = this.inheritCoverGrammar(this.parseExponentiationExpression);
 
+        let allowAndOr = true;
+        let allowNullishCoalescing = true;
+        const updateNullishCoalescingRestrictions = (token): void => {
+            if (token.value === '&&' || token.value === '||') {
+                allowNullishCoalescing = false;
+            }
+            if (token.value === '??') {
+                allowAndOr = false;
+            }
+        };
+
         const token = this.lookahead;
         let prec = this.binaryPrecedence(token);
         if (prec > 0) {
+            updateNullishCoalescingRestrictions(token);
             this.nextToken();
 
             this.context.isAssignmentTarget = false;
@@ -1509,6 +1522,11 @@ export class Parser {
                 if (prec <= 0) {
                     break;
                 }
+                if ((!allowAndOr && (this.lookahead.value === '&&' || this.lookahead.value === '||')) ||
+                    (!allowNullishCoalescing && this.lookahead.value === '??')) {
+                    this.throwUnexpectedToken(this.lookahead);
+                }
+                updateNullishCoalescingRestrictions(this.lookahead);
 
                 // Reduce: make a binary expression from the three topmost entries.
                 while ((stack.length > 2) && (prec <= precedences[precedences.length - 1])) {
diff --git a/src/scanner.ts b/src/scanner.ts
@@ -602,7 +602,6 @@ export class Scanner {
             case '[':
             case ']':
             case ':':
-            case '?':
             case '~':
                 ++this.index;
                 break;
@@ -623,17 +622,20 @@ export class Scanner {
 
                         // 2-character punctuators.
                         str = str.substr(0, 2);
-                        if (str === '&&' || str === '||' || str === '==' || str === '!=' ||
+                        if (str === '&&' || str === '||' || str === '??' ||
+                            str === '==' || str === '!=' ||
                             str === '+=' || str === '-=' || str === '*=' || str === '/=' ||
-                            str === '++' || str === '--' || str === '<<' || str === '>>' ||
+                            str === '++' || str === '--' ||
+                            str === '<<' || str === '>>' ||
                             str === '&=' || str === '|=' || str === '^=' || str === '%=' ||
-                            str === '<=' || str === '>=' || str === '=>' || str === '**') {
+                            str === '<=' || str === '>=' || str === '=>' ||
+                            str === '**') {
                             this.index += 2;
                         } else {
 
                             // 1-character punctuators.
                             str = this.source[this.index];
-                            if ('<>=!+-*%&|^/'.indexOf(str) >= 0) {
+                            if ('<>=!+-*%&|?^/'.indexOf(str) >= 0) {
                                 ++this.index;
                             }
                         }
diff --git a/src/tokenizer.ts b/src/tokenizer.ts
@@ -34,7 +34,7 @@ class Reader {
             '&=', '|=', '^=', ',',
             // binary/unary operators
             '+', '-', '*', '**', '/', '%', '++', '--', '<<', '>>', '>>>', '&',
-            '|', '^', '!', '~', '&&', '||', '?', ':', '===', '==', '>=',
+            '|', '^', '!', '~', '&&', '||', '??', '?', ':', '===', '==', '>=',
             '<=', '<', '>', '!=', '!=='].indexOf(t) >= 0;
     }
 
diff --git a/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-and-head.failure.json b/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-and-head.failure.json
@@ -0,0 +1 @@
+{"index":7,"lineNumber":1,"column":8,"message":"Error: Line 1: Unexpected token ??","description":"Unexpected token ??"}
diff --git a/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-and-head.js b/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-and-head.js
@@ -0,0 +1 @@
+1 && 2 ?? 3
diff --git a/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-and-tail.failure.json b/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-and-tail.failure.json
@@ -0,0 +1 @@
+{"index":7,"lineNumber":1,"column":8,"message":"Error: Line 1: Unexpected token &&","description":"Unexpected token &&"}
diff --git a/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-and-tail.js b/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-and-tail.js
@@ -0,0 +1 @@
+1 ?? 2 && 3
diff --git a/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-or-tail.failure.json b/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-or-tail.failure.json
@@ -0,0 +1 @@
+{"index":7,"lineNumber":1,"column":8,"message":"Error: Line 1: Unexpected token ||","description":"Unexpected token ||"}
diff --git a/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-or-tail.js b/test/fixtures/es2020/nullish-coalescing/invalid-nullish-coalescing-chain-or-tail.js
@@ -0,0 +1 @@
+1 ?? 2 || 3
diff --git a/test/test-262-whitelist.txt b/test/test-262-whitelist.txt
@@ -15338,8 +15338,6 @@ test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-await-expression.js(default)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-await-expression.js(strict mode)
-test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-expression-coalesce.js(default)
-test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-expression-coalesce.js(strict mode)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-integer-separators.js(default)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-integer-separators.js(strict mode)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-assignment-expression-coalesce.js(default)
@@ -15350,8 +15348,6 @@ test/language/expressions/class/cpn-class-expr-computed-property-name-from-assig
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-await-expression.js(default)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-await-expression.js(strict mode)
-test/language/expressions/class/cpn-class-expr-computed-property-name-from-expression-coalesce.js(default)
-test/language/expressions/class/cpn-class-expr-computed-property-name-from-expression-coalesce.js(strict mode)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-integer-separators.js(default)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-integer-separators.js(strict mode)
 test/language/expressions/class/cpn-class-expr-fields-computed-property-name-from-additive-expression-add.js(default)
@@ -15558,46 +15554,6 @@ test/language/expressions/class/private-static-method-brand-check-multiple-evalu
 test/language/expressions/class/private-static-method-brand-check-multiple-evaluations-of-class-factory.js(strict mode)
 test/language/expressions/class/private-static-setter-multiple-evaluations-of-class-factory.js(default)
 test/language/expressions/class/private-static-setter-multiple-evaluations-of-class-factory.js(strict mode)
-test/language/expressions/coalesce/abrupt-is-a-short-circuit.js(default)
-test/language/expressions/coalesce/abrupt-is-a-short-circuit.js(strict mode)
-test/language/expressions/coalesce/chainable-if-parenthesis-covered-logical-and.js(default)
-test/language/expressions/coalesce/chainable-if-parenthesis-covered-logical-and.js(strict mode)
-test/language/expressions/coalesce/chainable-if-parenthesis-covered-logical-or.js(default)
-test/language/expressions/coalesce/chainable-if-parenthesis-covered-logical-or.js(strict mode)
-test/language/expressions/coalesce/chainable-with-bitwise-and.js(default)
-test/language/expressions/coalesce/chainable-with-bitwise-and.js(strict mode)
-test/language/expressions/coalesce/chainable-with-bitwise-or.js(default)
-test/language/expressions/coalesce/chainable-with-bitwise-or.js(strict mode)
-test/language/expressions/coalesce/chainable-with-bitwise-xor.js(default)
-test/language/expressions/coalesce/chainable-with-bitwise-xor.js(strict mode)
-test/language/expressions/coalesce/chainable.js(default)
-test/language/expressions/coalesce/chainable.js(strict mode)
-test/language/expressions/coalesce/follows-null.js(default)
-test/language/expressions/coalesce/follows-null.js(strict mode)
-test/language/expressions/coalesce/follows-undefined.js(default)
-test/language/expressions/coalesce/follows-undefined.js(strict mode)
-test/language/expressions/coalesce/short-circuit-number-0.js(default)
-test/language/expressions/coalesce/short-circuit-number-0.js(strict mode)
-test/language/expressions/coalesce/short-circuit-number-42.js(default)
-test/language/expressions/coalesce/short-circuit-number-42.js(strict mode)
-test/language/expressions/coalesce/short-circuit-number-empty-string.js(default)
-test/language/expressions/coalesce/short-circuit-number-empty-string.js(strict mode)
-test/language/expressions/coalesce/short-circuit-number-false.js(default)
-test/language/expressions/coalesce/short-circuit-number-false.js(strict mode)
-test/language/expressions/coalesce/short-circuit-number-object.js(default)
-test/language/expressions/coalesce/short-circuit-number-object.js(strict mode)
-test/language/expressions/coalesce/short-circuit-number-string.js(default)
-test/language/expressions/coalesce/short-circuit-number-string.js(strict mode)
-test/language/expressions/coalesce/short-circuit-number-symbol.js(default)
-test/language/expressions/coalesce/short-circuit-number-symbol.js(strict mode)
-test/language/expressions/coalesce/short-circuit-number-true.js(default)
-test/language/expressions/coalesce/short-circuit-number-true.js(strict mode)
-test/language/expressions/coalesce/short-circuit-prevents-evaluation.js(default)
-test/language/expressions/coalesce/short-circuit-prevents-evaluation.js(strict mode)
-test/language/expressions/coalesce/tco-pos-null.js(strict mode)
-test/language/expressions/coalesce/tco-pos-undefined.js(strict mode)
-test/language/expressions/conditional/coalesce-expr-ternary.js(default)
-test/language/expressions/conditional/coalesce-expr-ternary.js(strict mode)
 test/language/expressions/logical-assignment/lgcl-and-assignment-operator-bigint.js(default)
 test/language/expressions/logical-assignment/lgcl-and-assignment-operator-bigint.js(strict mode)
 test/language/expressions/logical-assignment/lgcl-and-assignment-operator-lhs-before-rhs.js(default)
@@ -15752,8 +15708,6 @@ test/language/expressions/object/cpn-obj-lit-computed-property-name-from-assignm
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-await-expression.js(default)
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-await-expression.js(strict mode)
-test/language/expressions/object/cpn-obj-lit-computed-property-name-from-expression-coalesce.js(default)
-test/language/expressions/object/cpn-obj-lit-computed-property-name-from-expression-coalesce.js(strict mode)
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-integer-separators.js(default)
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-integer-separators.js(strict mode)
 test/language/expressions/object/ident-name-method-def-break-escaped.js(default)
@@ -16007,8 +15961,6 @@ test/language/statements/class/cpn-class-decl-accessors-computed-property-name-f
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-await-expression.js(default)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-await-expression.js(strict mode)
-test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-expression-coalesce.js(default)
-test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-expression-coalesce.js(strict mode)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-integer-separators.js(default)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-integer-separators.js(strict mode)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-assignment-expression-coalesce.js(default)
@@ -16019,8 +15971,6 @@ test/language/statements/class/cpn-class-decl-computed-property-name-from-assign
 test/language/statements/class/cpn-class-decl-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-await-expression.js(default)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-await-expression.js(strict mode)
-test/language/statements/class/cpn-class-decl-computed-property-name-from-expression-coalesce.js(default)
-test/language/statements/class/cpn-class-decl-computed-property-name-from-expression-coalesce.js(strict mode)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-integer-separators.js(default)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-integer-separators.js(strict mode)
 test/language/statements/class/cpn-class-decl-fields-computed-property-name-from-additive-expression-add.js(default)
@@ -16221,8 +16171,6 @@ test/language/statements/class/ident-name-method-def-with-escaped.js(default)
 test/language/statements/class/ident-name-method-def-with-escaped.js(strict mode)
 test/language/statements/switch/scope-lex-async-generator.js(default)
 test/language/statements/switch/scope-lex-async-generator.js(strict mode)
-test/annexB/language/expressions/coalesce/emulates-undefined.js(default)
-test/annexB/language/expressions/coalesce/emulates-undefined.js(strict mode)
 test/annexB/language/expressions/logical-assignment/emulates-undefined-and.js(default)
 test/annexB/language/expressions/logical-assignment/emulates-undefined-and.js(strict mode)
 test/annexB/language/expressions/logical-assignment/emulates-undefined-coalesce.js(default)

Original file line number	Diff line number	Diff line change
`@@ -34,7 +34,7 @@ class Reader {`
`34`	`34`	`'&=', '\|=', '^=', ',',`
`35`	`35`	`// binary/unary operators`
`36`	`36`	`'+', '-', '', '*', '/', '%', '++', '--', '<<', '>>', '>>>', '&',`
`37`		`- '\|', '^', '!', '~', '&&', '\|\|', '?', ':', '===', '==', '>=',`
	`37`	`+ '\|', '^', '!', '~', '&&', '\|\|', '??', '?', ':', '===', '==', '>=',`
`38`	`38`	`'<=', '<', '>', '!=', '!=='].indexOf(t) >= 0;`
`39`	`39`	`}`
`40`	`40`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+{"index":7,"lineNumber":1,"column":8,"message":"Error: Line 1: Unexpected token ??","description":"Unexpected token ??"}`