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