/*
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Copyright (C) 2015 Yusuke Suzuki <utatane.tea@gmail.com>
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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"use strict";
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/* eslint-disable no-undefined */
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const Syntax = require("estraverse").Syntax;
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const esrecurse = require("esrecurse");
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/**
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* Get last array element
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* @param {array} xs - array
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* @returns {any} Last elment
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*/
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function getLast(xs) {
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return xs[xs.length - 1] || null;
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}
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class PatternVisitor extends esrecurse.Visitor {
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static isPattern(node) {
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const nodeType = node.type;
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return (
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nodeType === Syntax.Identifier ||
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nodeType === Syntax.ObjectPattern ||
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nodeType === Syntax.ArrayPattern ||
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nodeType === Syntax.SpreadElement ||
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nodeType === Syntax.RestElement ||
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nodeType === Syntax.AssignmentPattern
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);
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}
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constructor(options, rootPattern, callback) {
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super(null, options);
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this.rootPattern = rootPattern;
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this.callback = callback;
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this.assignments = [];
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this.rightHandNodes = [];
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this.restElements = [];
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}
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Identifier(pattern) {
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const lastRestElement = getLast(this.restElements);
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this.callback(pattern, {
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topLevel: pattern === this.rootPattern,
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rest: lastRestElement !== null && lastRestElement !== undefined && lastRestElement.argument === pattern,
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assignments: this.assignments
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});
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}
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Property(property) {
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// Computed property's key is a right hand node.
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if (property.computed) {
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this.rightHandNodes.push(property.key);
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}
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// If it's shorthand, its key is same as its value.
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// If it's shorthand and has its default value, its key is same as its value.left (the value is AssignmentPattern).
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// If it's not shorthand, the name of new variable is its value's.
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this.visit(property.value);
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}
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ArrayPattern(pattern) {
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for (let i = 0, iz = pattern.elements.length; i < iz; ++i) {
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const element = pattern.elements[i];
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this.visit(element);
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}
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}
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AssignmentPattern(pattern) {
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this.assignments.push(pattern);
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this.visit(pattern.left);
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this.rightHandNodes.push(pattern.right);
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this.assignments.pop();
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}
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RestElement(pattern) {
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this.restElements.push(pattern);
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this.visit(pattern.argument);
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this.restElements.pop();
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}
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MemberExpression(node) {
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// Computed property's key is a right hand node.
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if (node.computed) {
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this.rightHandNodes.push(node.property);
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}
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// the object is only read, write to its property.
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this.rightHandNodes.push(node.object);
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}
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//
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// ForInStatement.left and AssignmentExpression.left are LeftHandSideExpression.
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// By spec, LeftHandSideExpression is Pattern or MemberExpression.
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// (see also: https://github.com/estree/estree/pull/20#issuecomment-74584758)
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// But espree 2.0 parses to ArrayExpression, ObjectExpression, etc...
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//
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SpreadElement(node) {
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this.visit(node.argument);
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}
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ArrayExpression(node) {
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node.elements.forEach(this.visit, this);
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}
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AssignmentExpression(node) {
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this.assignments.push(node);
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this.visit(node.left);
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this.rightHandNodes.push(node.right);
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this.assignments.pop();
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}
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CallExpression(node) {
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// arguments are right hand nodes.
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node.arguments.forEach(a => {
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this.rightHandNodes.push(a);
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});
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this.visit(node.callee);
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}
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}
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module.exports = PatternVisitor;
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/* vim: set sw=4 ts=4 et tw=80 : */
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