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- var assert = require("assert");
- var types = require("./types");
- var n = types.namedTypes;
- var Node = n.Node;
- var isArray = types.builtInTypes.array;
- var isNumber = types.builtInTypes.number;
-
- function FastPath(value) {
- assert.ok(this instanceof FastPath);
- this.stack = [value];
- }
-
- var FPp = FastPath.prototype;
- module.exports = FastPath;
-
- // Static convenience function for coercing a value to a FastPath.
- FastPath.from = function(obj) {
- if (obj instanceof FastPath) {
- // Return a defensive copy of any existing FastPath instances.
- return obj.copy();
- }
-
- if (obj instanceof types.NodePath) {
- // For backwards compatibility, unroll NodePath instances into
- // lightweight FastPath [..., name, value] stacks.
- var copy = Object.create(FastPath.prototype);
- var stack = [obj.value];
- for (var pp; (pp = obj.parentPath); obj = pp)
- stack.push(obj.name, pp.value);
- copy.stack = stack.reverse();
- return copy;
- }
-
- // Otherwise use obj as the value of the new FastPath instance.
- return new FastPath(obj);
- };
-
- FPp.copy = function copy() {
- var copy = Object.create(FastPath.prototype);
- copy.stack = this.stack.slice(0);
- return copy;
- };
-
- // The name of the current property is always the penultimate element of
- // this.stack, and always a String.
- FPp.getName = function getName() {
- var s = this.stack;
- var len = s.length;
- if (len > 1) {
- return s[len - 2];
- }
- // Since the name is always a string, null is a safe sentinel value to
- // return if we do not know the name of the (root) value.
- return null;
- };
-
- // The value of the current property is always the final element of
- // this.stack.
- FPp.getValue = function getValue() {
- var s = this.stack;
- return s[s.length - 1];
- };
-
- function getNodeHelper(path, count) {
- var s = path.stack;
-
- for (var i = s.length - 1; i >= 0; i -= 2) {
- var value = s[i];
- if (n.Node.check(value) && --count < 0) {
- return value;
- }
- }
-
- return null;
- }
-
- FPp.getNode = function getNode(count) {
- return getNodeHelper(this, ~~count);
- };
-
- FPp.getParentNode = function getParentNode(count) {
- return getNodeHelper(this, ~~count + 1);
- };
-
- // The length of the stack can be either even or odd, depending on whether
- // or not we have a name for the root value. The difference between the
- // index of the root value and the index of the final value is always
- // even, though, which allows us to return the root value in constant time
- // (i.e. without iterating backwards through the stack).
- FPp.getRootValue = function getRootValue() {
- var s = this.stack;
- if (s.length % 2 === 0) {
- return s[1];
- }
- return s[0];
- };
-
- // Temporarily push properties named by string arguments given after the
- // callback function onto this.stack, then call the callback with a
- // reference to this (modified) FastPath object. Note that the stack will
- // be restored to its original state after the callback is finished, so it
- // is probably a mistake to retain a reference to the path.
- FPp.call = function call(callback/*, name1, name2, ... */) {
- var s = this.stack;
- var origLen = s.length;
- var value = s[origLen - 1];
- var argc = arguments.length;
- for (var i = 1; i < argc; ++i) {
- var name = arguments[i];
- value = value[name];
- s.push(name, value);
- }
- var result = callback(this);
- s.length = origLen;
- return result;
- };
-
- // Similar to FastPath.prototype.call, except that the value obtained by
- // accessing this.getValue()[name1][name2]... should be array-like. The
- // callback will be called with a reference to this path object for each
- // element of the array.
- FPp.each = function each(callback/*, name1, name2, ... */) {
- var s = this.stack;
- var origLen = s.length;
- var value = s[origLen - 1];
- var argc = arguments.length;
-
- for (var i = 1; i < argc; ++i) {
- var name = arguments[i];
- value = value[name];
- s.push(name, value);
- }
-
- for (var i = 0; i < value.length; ++i) {
- if (i in value) {
- s.push(i, value[i]);
- // If the callback needs to know the value of i, call
- // path.getName(), assuming path is the parameter name.
- callback(this);
- s.length -= 2;
- }
- }
-
- s.length = origLen;
- };
-
- // Similar to FastPath.prototype.each, except that the results of the
- // callback function invocations are stored in an array and returned at
- // the end of the iteration.
- FPp.map = function map(callback/*, name1, name2, ... */) {
- var s = this.stack;
- var origLen = s.length;
- var value = s[origLen - 1];
- var argc = arguments.length;
-
- for (var i = 1; i < argc; ++i) {
- var name = arguments[i];
- value = value[name];
- s.push(name, value);
- }
-
- var result = new Array(value.length);
-
- for (var i = 0; i < value.length; ++i) {
- if (i in value) {
- s.push(i, value[i]);
- result[i] = callback(this, i);
- s.length -= 2;
- }
- }
-
- s.length = origLen;
-
- return result;
- };
-
- // Inspired by require("ast-types").NodePath.prototype.needsParens, but
- // more efficient because we're iterating backwards through a stack.
- FPp.needsParens = function(assumeExpressionContext) {
- var parent = this.getParentNode();
- if (!parent) {
- return false;
- }
-
- var name = this.getName();
- var node = this.getNode();
-
- // If the value of this path is some child of a Node and not a Node
- // itself, then it doesn't need parentheses. Only Node objects (in
- // fact, only Expression nodes) need parentheses.
- if (this.getValue() !== node) {
- return false;
- }
-
- // Only expressions need parentheses.
- if (!n.Expression.check(node)) {
- return false;
- }
-
- // Identifiers never need parentheses.
- if (node.type === "Identifier") {
- return false;
- }
-
- if (parent.type === "ParenthesizedExpression") {
- return false;
- }
-
- switch (node.type) {
- case "UnaryExpression":
- case "SpreadElement":
- case "SpreadProperty":
- return parent.type === "MemberExpression"
- && name === "object"
- && parent.object === node;
-
- case "BinaryExpression":
- case "LogicalExpression":
- switch (parent.type) {
- case "CallExpression":
- return name === "callee"
- && parent.callee === node;
-
- case "UnaryExpression":
- case "SpreadElement":
- case "SpreadProperty":
- return true;
-
- case "MemberExpression":
- return name === "object"
- && parent.object === node;
-
- case "BinaryExpression":
- case "LogicalExpression":
- var po = parent.operator;
- var pp = PRECEDENCE[po];
- var no = node.operator;
- var np = PRECEDENCE[no];
-
- if (pp > np) {
- return true;
- }
-
- if (pp === np && name === "right") {
- assert.strictEqual(parent.right, node);
- return true;
- }
-
- default:
- return false;
- }
-
- case "SequenceExpression":
- switch (parent.type) {
- case "ForStatement":
- // Although parentheses wouldn't hurt around sequence
- // expressions in the head of for loops, traditional style
- // dictates that e.g. i++, j++ should not be wrapped with
- // parentheses.
- return false;
-
- case "ExpressionStatement":
- return name !== "expression";
-
- default:
- // Otherwise err on the side of overparenthesization, adding
- // explicit exceptions above if this proves overzealous.
- return true;
- }
-
- case "YieldExpression":
- switch (parent.type) {
- case "BinaryExpression":
- case "LogicalExpression":
- case "UnaryExpression":
- case "SpreadElement":
- case "SpreadProperty":
- case "CallExpression":
- case "MemberExpression":
- case "NewExpression":
- case "ConditionalExpression":
- case "YieldExpression":
- return true;
-
- default:
- return false;
- }
-
- case "Literal":
- return parent.type === "MemberExpression"
- && isNumber.check(node.value)
- && name === "object"
- && parent.object === node;
-
- case "AssignmentExpression":
- case "ConditionalExpression":
- switch (parent.type) {
- case "UnaryExpression":
- case "SpreadElement":
- case "SpreadProperty":
- case "BinaryExpression":
- case "LogicalExpression":
- return true;
-
- case "CallExpression":
- return name === "callee"
- && parent.callee === node;
-
- case "ConditionalExpression":
- return name === "test"
- && parent.test === node;
-
- case "MemberExpression":
- return name === "object"
- && parent.object === node;
-
- default:
- return false;
- }
-
- case "ArrowFunctionExpression":
- if(parent.type === 'CallExpression' &&
- name === 'callee') {
- return true;
- };
-
- return isBinary(parent);
-
- case "ObjectExpression":
- if (parent.type === "ArrowFunctionExpression" &&
- name === "body") {
- return true;
- }
-
- default:
- if (parent.type === "NewExpression" &&
- name === "callee" &&
- parent.callee === node) {
- return containsCallExpression(node);
- }
- }
-
- if (assumeExpressionContext !== true &&
- !this.canBeFirstInStatement() &&
- this.firstInStatement())
- return true;
-
- return false;
- };
-
- function isBinary(node) {
- return n.BinaryExpression.check(node)
- || n.LogicalExpression.check(node);
- }
-
- function isUnaryLike(node) {
- return n.UnaryExpression.check(node)
- // I considered making SpreadElement and SpreadProperty subtypes
- // of UnaryExpression, but they're not really Expression nodes.
- || (n.SpreadElement && n.SpreadElement.check(node))
- || (n.SpreadProperty && n.SpreadProperty.check(node));
- }
-
- var PRECEDENCE = {};
- [["||"],
- ["&&"],
- ["|"],
- ["^"],
- ["&"],
- ["==", "===", "!=", "!=="],
- ["<", ">", "<=", ">=", "in", "instanceof"],
- [">>", "<<", ">>>"],
- ["+", "-"],
- ["*", "/", "%"]
- ].forEach(function(tier, i) {
- tier.forEach(function(op) {
- PRECEDENCE[op] = i;
- });
- });
-
- function containsCallExpression(node) {
- if (n.CallExpression.check(node)) {
- return true;
- }
-
- if (isArray.check(node)) {
- return node.some(containsCallExpression);
- }
-
- if (n.Node.check(node)) {
- return types.someField(node, function(name, child) {
- return containsCallExpression(child);
- });
- }
-
- return false;
- }
-
- FPp.canBeFirstInStatement = function() {
- var node = this.getNode();
- return !n.FunctionExpression.check(node)
- && !n.ObjectExpression.check(node);
- };
-
- FPp.firstInStatement = function() {
- var s = this.stack;
- var parentName, parent;
- var childName, child;
-
- for (var i = s.length - 1; i >= 0; i -= 2) {
- if (n.Node.check(s[i])) {
- childName = parentName;
- child = parent;
- parentName = s[i - 1];
- parent = s[i];
- }
-
- if (!parent || !child) {
- continue;
- }
-
- if (n.BlockStatement.check(parent) &&
- parentName === "body" &&
- childName === 0) {
- assert.strictEqual(parent.body[0], child);
- return true;
- }
-
- if (n.ExpressionStatement.check(parent) &&
- childName === "expression") {
- assert.strictEqual(parent.expression, child);
- return true;
- }
-
- if (n.SequenceExpression.check(parent) &&
- parentName === "expressions" &&
- childName === 0) {
- assert.strictEqual(parent.expressions[0], child);
- continue;
- }
-
- if (n.CallExpression.check(parent) &&
- childName === "callee") {
- assert.strictEqual(parent.callee, child);
- continue;
- }
-
- if (n.MemberExpression.check(parent) &&
- childName === "object") {
- assert.strictEqual(parent.object, child);
- continue;
- }
-
- if (n.ConditionalExpression.check(parent) &&
- childName === "test") {
- assert.strictEqual(parent.test, child);
- continue;
- }
-
- if (isBinary(parent) &&
- childName === "left") {
- assert.strictEqual(parent.left, child);
- continue;
- }
-
- if (n.UnaryExpression.check(parent) &&
- !parent.prefix &&
- childName === "argument") {
- assert.strictEqual(parent.argument, child);
- continue;
- }
-
- return false;
- }
-
- return true;
- };
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