Method parseGroupExpression

src/parser.ts:1019–1142

()

    }

    parseGroupExpression(): ArrowParameterPlaceHolderNode | Node.Expression {
        let expr;

        this.expect('(');
        if (this.match(')')) {
            this.nextToken();
            if (!this.match('=>')) {
                this.expect('=>');
            }
            expr = {
                type: ArrowParameterPlaceHolder,
                params: [],
                async: false
            };
        } else {
            const startToken = this.lookahead;
            const params = [];
            if (this.match('...')) {
                expr = this.parseRestElement(params);
                this.expect(')');
                if (!this.match('=>')) {
                    this.expect('=>');
                }
                expr = {
                    type: ArrowParameterPlaceHolder,
                    params: [expr],
                    async: false
                };
            } else {
                let arrow = false;
                this.context.isBindingElement = true;
                expr = this.inheritCoverGrammar(this.parseAssignmentExpression);

                if (this.match(',')) {
                    const expressions: Node.Expression[] = [];

                    this.context.isAssignmentTarget = false;
                    expressions.push(expr);
                    while (this.lookahead.type !== Token.EOF) {
                        if (!this.match(',')) {
                            break;
                        }
                        this.nextToken();
                        if (this.match(')')) {
                            this.nextToken();
                            for (let i = 0; i < expressions.length; i++) {
                                this.reinterpretExpressionAsPattern(expressions[i]);
                            }
                            arrow = true;
                            expr = {
                                type: ArrowParameterPlaceHolder,
                                params: expressions,
                                async: false
                            };
                        } else if (this.match('...')) {
                            if (!this.context.isBindingElement) {
                                this.throwUnexpectedToken(this.lookahead);
                            }