148 lines
5.6 KiB
JavaScript
148 lines
5.6 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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var _a, _b;
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.Rule = void 0;
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var tslib_1 = require("tslib");
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var utils = require("tsutils");
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var ts = require("typescript");
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var Lint = require("../index");
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var OPTION_MIN_CASES = "min-cases";
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var Rule = /** @class */ (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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Rule.prototype.apply = function (sourceFile) {
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var minCases = 3;
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if (this.ruleArguments.length !== 0) {
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var obj = this.ruleArguments[0];
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minCases = obj[OPTION_MIN_CASES];
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}
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return this.applyWithFunction(sourceFile, walk, minCases);
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};
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/* tslint:disable:object-literal-sort-keys */
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Rule.metadata = {
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ruleName: "prefer-switch",
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description: "Prefer a `switch` statement to an `if` statement with simple `===` comparisons.",
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optionsDescription: Lint.Utils.dedent(templateObject_1 || (templateObject_1 = tslib_1.__makeTemplateObject(["\n An optional object with the property '", "'.\n This is the number cases needed before a switch statement is recommended.\n Defaults to 3."], ["\n An optional object with the property '", "'.\n This is the number cases needed before a switch statement is recommended.\n Defaults to 3."])), OPTION_MIN_CASES),
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options: {
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type: "object",
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properties: (_a = {},
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_a[OPTION_MIN_CASES] = { type: "number" },
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_a),
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},
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optionExamples: [true, [true, (_b = {}, _b[OPTION_MIN_CASES] = 2, _b)]],
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type: "style",
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typescriptOnly: false,
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};
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/* tslint:enable:object-literal-sort-keys */
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Rule.FAILURE_STRING = "Use a switch statement instead of using multiple '===' checks.";
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return Rule;
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}(Lint.Rules.AbstractRule));
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exports.Rule = Rule;
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function walk(ctx) {
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var minCases = ctx.options, sourceFile = ctx.sourceFile;
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return ts.forEachChild(sourceFile, function cb(node) {
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if (utils.isIfStatement(node) && check(node, sourceFile, minCases)) {
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var expression = node.expression, thenStatement = node.thenStatement, elseStatement = node.elseStatement;
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ctx.addFailureAtNode(expression, Rule.FAILURE_STRING);
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// Be careful not to fail again for the "else if"
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ts.forEachChild(expression, cb);
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ts.forEachChild(thenStatement, cb);
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if (elseStatement !== undefined) {
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ts.forEachChild(elseStatement, cb);
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}
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}
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else {
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return ts.forEachChild(node, cb);
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}
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});
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}
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function check(node, sourceFile, minCases) {
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var switchVariable;
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var casesSeen = 0;
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var elseStatement = node.elseStatement;
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if (elseStatement === undefined) {
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return false;
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}
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var couldBeSwitch = everyCase(node, function (expr) {
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casesSeen++;
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if (switchVariable !== undefined) {
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return nodeEquals(expr, switchVariable, sourceFile);
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}
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else {
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switchVariable = expr;
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return true;
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}
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});
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return couldBeSwitch && casesSeen >= minCases;
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}
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function everyCase(_a, test) {
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var expression = _a.expression, elseStatement = _a.elseStatement;
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if (!everyCondition(expression, test)) {
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return false;
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}
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return (elseStatement === undefined ||
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!utils.isIfStatement(elseStatement) ||
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everyCase(elseStatement, test));
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}
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function everyCondition(node, test) {
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if (!utils.isBinaryExpression(node)) {
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return false;
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}
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var operatorToken = node.operatorToken, left = node.left, right = node.right;
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switch (operatorToken.kind) {
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case ts.SyntaxKind.BarBarToken:
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return everyCondition(left, test) && everyCondition(right, test);
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case ts.SyntaxKind.EqualsEqualsEqualsToken:
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return isSimple(left) && isSimple(right) && test(left);
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default:
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return false;
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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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function isSimple(node) {
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switch (node.kind) {
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case ts.SyntaxKind.PropertyAccessExpression:
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return isSimple(node.expression);
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case ts.SyntaxKind.PrefixUnaryExpression:
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switch (node.operator) {
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case ts.SyntaxKind.PlusPlusToken:
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case ts.SyntaxKind.MinusMinusToken:
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return false;
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default:
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return isSimple(node.operand);
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}
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case ts.SyntaxKind.Identifier:
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case ts.SyntaxKind.NumericLiteral:
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case ts.SyntaxKind.StringLiteral:
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case ts.SyntaxKind.ThisKeyword:
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case ts.SyntaxKind.NoSubstitutionTemplateLiteral:
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case ts.SyntaxKind.TrueKeyword:
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case ts.SyntaxKind.FalseKeyword:
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case ts.SyntaxKind.NullKeyword:
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return true;
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default:
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return false;
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}
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}
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var templateObject_1;
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