+++ /dev/null
-"use strict";
-/**
- * @license
- * Copyright 2018 Palantir Technologies, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-Object.defineProperty(exports, "__esModule", { value: true });
-var tslib_1 = require("tslib");
-var utils = require("tsutils");
-var ts = require("typescript");
-var Lint = require("../index");
-var utils_1 = require("../language/utils");
-var Rule = /** @class */ (function (_super) {
- tslib_1.__extends(Rule, _super);
- function Rule() {
- return _super !== null && _super.apply(this, arguments) || this;
- }
- Rule.prototype.apply = function (sourceFile) {
- return this.applyWithFunction(sourceFile, walk);
- };
- /* tslint:disable:object-literal-sort-keys */
- Rule.metadata = {
- ruleName: "prefer-for-of",
- description: "Recommends a 'for-of' loop over a standard 'for' loop if the index is only used to access the array being iterated.",
- rationale: "A for(... of ...) loop is easier to implement and read when the index is not needed.",
- optionsDescription: "Not configurable.",
- options: null,
- optionExamples: [true],
- type: "typescript",
- typescriptOnly: false,
- };
- /* tslint:enable:object-literal-sort-keys */
- Rule.FAILURE_STRING = "Expected a 'for-of' loop instead of a 'for' loop with this simple iteration";
- return Rule;
-}(Lint.Rules.AbstractRule));
-exports.Rule = Rule;
-function walk(ctx) {
- var sourceFile = ctx.sourceFile;
- var variables;
- return ts.forEachChild(sourceFile, function cb(node) {
- if (utils.isForStatement(node)) {
- visitForStatement(node);
- }
- return ts.forEachChild(node, cb);
- });
- function visitForStatement(node) {
- var arrayNodeInfo = getForLoopHeaderInfo(node);
- if (arrayNodeInfo === undefined) {
- return;
- }
- var indexVariable = arrayNodeInfo.indexVariable, arrayExpr = arrayNodeInfo.arrayExpr;
- if (variables === undefined) {
- variables = utils.collectVariableUsage(sourceFile);
- }
- for (var _i = 0, _a = variables.get(indexVariable).uses; _i < _a.length; _i++) {
- var location = _a[_i].location;
- if (location.pos < node.initializer.end ||
- location.pos >= node.end || // bail out on use outside of for loop
- (location.pos >= node.statement.pos && // only check uses in loop body
- isNonSimpleIncrementorUse(location, arrayExpr, sourceFile))) {
- return;
- }
- }
- ctx.addFailure(node.getStart(sourceFile), node.statement.pos, Rule.FAILURE_STRING);
- }
-}
-function isNonSimpleIncrementorUse(node, arrayExpr, sourceFile) {
- // check if iterator is used for something other than reading data from array
- var parent = node.parent;
- return (!utils.isElementAccessExpression(parent) ||
- // `a[i] = ...` or similar
- utils.isReassignmentTarget(parent) ||
- // `b[i]`
- !nodeEquals(arrayExpr, utils_1.unwrapParentheses(parent.expression), sourceFile));
-}
-function nodeEquals(a, b, sourceFile) {
- return a.getText(sourceFile) === b.getText(sourceFile);
-}
-// returns the iterator and array of a `for` loop if the `for` loop is basic.
-function getForLoopHeaderInfo(forLoop) {
- var initializer = forLoop.initializer, condition = forLoop.condition, incrementor = forLoop.incrementor;
- if (initializer === undefined || condition === undefined || incrementor === undefined) {
- return undefined;
- }
- // Must start with `var i = 0;` or `let i = 0;`
- if (!utils.isVariableDeclarationList(initializer) || initializer.declarations.length !== 1) {
- return undefined;
- }
- var _a = initializer.declarations[0], indexVariable = _a.name, indexInit = _a.initializer;
- if (indexVariable.kind !== ts.SyntaxKind.Identifier ||
- indexInit === undefined ||
- !isNumber(indexInit, "0")) {
- return undefined;
- }
- // Must end with `i++`
- if (!isIncremented(incrementor, indexVariable.text)) {
- return undefined;
- }
- // Condition must be `i < arr.length;`
- if (!utils.isBinaryExpression(condition)) {
- return undefined;
- }
- var left = condition.left, operatorToken = condition.operatorToken, right = condition.right;
- if (!isIdentifierNamed(left, indexVariable.text) ||
- operatorToken.kind !== ts.SyntaxKind.LessThanToken ||
- !utils.isPropertyAccessExpression(right)) {
- return undefined;
- }
- var arrayExpr = right.expression, name = right.name;
- if (name.text !== "length") {
- return undefined;
- }
- return { indexVariable: indexVariable, arrayExpr: arrayExpr };
-}
-function isIncremented(node, indexVariableName) {
- switch (node.kind) {
- case ts.SyntaxKind.PrefixUnaryExpression:
- case ts.SyntaxKind.PostfixUnaryExpression: {
- var _a = node, operator = _a.operator, operand = _a.operand;
- // `++x` or `x++`
- return operator === ts.SyntaxKind.PlusPlusToken && isVar(operand);
- }
- case ts.SyntaxKind.BinaryExpression:
- var _b = node, operatorToken = _b.operatorToken, updatedVar = _b.left, rhs = _b.right;
- if (!isVar(updatedVar)) {
- return false;
- }
- switch (operatorToken.kind) {
- case ts.SyntaxKind.PlusEqualsToken:
- // x += 1
- return isOne(rhs);
- case ts.SyntaxKind.EqualsToken: {
- if (!utils.isBinaryExpression(rhs)) {
- return false;
- }
- var rhsOp = rhs.operatorToken, left = rhs.left, right = rhs.right;
- // `x = 1 + x` or `x = x + 1`
- return (rhsOp.kind === ts.SyntaxKind.PlusToken &&
- ((isVar(left) && isOne(right)) || (isOne(left) && isVar(right))));
- }
- default:
- return false;
- }
- default:
- return false;
- }
- function isVar(id) {
- return isIdentifierNamed(id, indexVariableName);
- }
-}
-function isIdentifierNamed(node, text) {
- return utils.isIdentifier(node) && node.text === text;
-}
-function isOne(node) {
- return isNumber(node, "1");
-}
-function isNumber(node, value) {
- return utils.isNumericLiteral(node) && node.text === value;
-}
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