97 lines
4.2 KiB
JavaScript
97 lines
4.2 KiB
JavaScript
"use strict";
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/**
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* @license
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* Copyright 2017 Palantir Technologies, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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Object.defineProperty(exports, "__esModule", { value: true });
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var tslib_1 = require("tslib");
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var tsutils_1 = require("tsutils");
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var ts = require("typescript");
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var Lint = require("../index");
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var Rule = (function (_super) {
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tslib_1.__extends(Rule, _super);
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function Rule() {
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return _super !== null && _super.apply(this, arguments) || this;
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}
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/* tslint:enable:object-literal-sort-keys */
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Rule.FAILURE_STRING = function (assigned) {
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return "Use a conditional expression instead of assigning to '" + assigned + "' in multiple places.";
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};
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Rule.prototype.apply = function (sourceFile) {
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return this.applyWithFunction(sourceFile, walk);
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};
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return Rule;
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}(Lint.Rules.AbstractRule));
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/* tslint:disable:object-literal-sort-keys */
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Rule.metadata = {
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ruleName: "prefer-conditional-expression",
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description: (_a = ["\n Recommends to use a conditional expression instead of assigning to the same thing in each branch of an if statement."], _a.raw = ["\n Recommends to use a conditional expression instead of assigning to the same thing in each branch of an if statement."], Lint.Utils.dedent(_a)),
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rationale: (_b = ["\n This reduces duplication and can eliminate an unnecessary variable declaration."], _b.raw = ["\n This reduces duplication and can eliminate an unnecessary variable declaration."], Lint.Utils.dedent(_b)),
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optionsDescription: "Not configurable.",
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options: null,
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optionExamples: [true],
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type: "functionality",
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typescriptOnly: false,
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};
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exports.Rule = Rule;
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function walk(ctx) {
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var sourceFile = ctx.sourceFile;
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return ts.forEachChild(sourceFile, function cb(node) {
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if (tsutils_1.isIfStatement(node)) {
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var assigned = detect(node, sourceFile);
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if (assigned !== undefined) {
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ctx.addFailureAtNode(Lint.childOfKind(node, ts.SyntaxKind.IfKeyword), Rule.FAILURE_STRING(assigned.getText(sourceFile)));
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// Be careful not to fail again for the "else if"
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ts.forEachChild(node.expression, cb);
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ts.forEachChild(node.thenStatement, cb);
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if (node.elseStatement !== undefined) {
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ts.forEachChild(node.elseStatement, cb);
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}
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return;
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}
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}
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return ts.forEachChild(node, cb);
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});
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}
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function detect(_a, sourceFile) {
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var thenStatement = _a.thenStatement, elseStatement = _a.elseStatement;
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if (elseStatement === undefined) {
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return undefined;
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}
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var elze = tsutils_1.isIfStatement(elseStatement) ? detect(elseStatement, sourceFile) : getAssigned(elseStatement, sourceFile);
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if (elze === undefined) {
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return undefined;
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}
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var then = getAssigned(thenStatement, sourceFile);
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return then !== undefined && nodeEquals(elze, then, sourceFile) ? then : undefined;
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}
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/** Returns the left side of an assignment. */
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function getAssigned(node, sourceFile) {
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if (tsutils_1.isBlock(node)) {
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return node.statements.length === 1 ? getAssigned(node.statements[0], sourceFile) : undefined;
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}
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else if (tsutils_1.isExpressionStatement(node) && tsutils_1.isBinaryExpression(node.expression)) {
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var _a = node.expression, kind = _a.operatorToken.kind, left = _a.left, right = _a.right;
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return kind === ts.SyntaxKind.EqualsToken && tsutils_1.isSameLine(sourceFile, right.getStart(sourceFile), right.end) ? left : undefined;
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}
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else {
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return undefined;
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}
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}
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function nodeEquals(a, b, sourceFile) {
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return a.getText(sourceFile) === b.getText(sourceFile);
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}
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var _a, _b;
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