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"use strict";
/**
* @license
* Copyright 2017 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 OPTION_MIN_CASES = "min-cases";
var Rule = (function (_super) {
tslib_1.__extends(Rule, _super);
function Rule() {
return _super !== null && _super.apply(this, arguments) || this;
}
Rule.prototype.apply = function (sourceFile) {
var minCases = 3;
if (this.ruleArguments.length !== 0) {
var obj = this.ruleArguments[0];
minCases = obj[OPTION_MIN_CASES];
}
return this.applyWithFunction(sourceFile, walk, minCases);
};
return Rule;
}(Lint.Rules.AbstractRule));
/* tslint:disable:object-literal-sort-keys */
Rule.metadata = {
ruleName: "prefer-switch",
description: "Prefer a `switch` statement to an `if` statement with simple `===` comparisons.",
optionsDescription: (_a = ["\n An optional object with the property '", "'.\n This is the number cases needed before a switch statement is recommended.\n Defaults to 3."], _a.raw = ["\n An optional object with the property '", "'.\n This is the number cases needed before a switch statement is recommended.\n Defaults to 3."], Lint.Utils.dedent(_a, OPTION_MIN_CASES)),
options: {
type: "object",
properties: (_b = {},
_b[OPTION_MIN_CASES] = { type: "number" },
_b),
},
optionExamples: [true, [true, (_c = {}, _c[OPTION_MIN_CASES] = 2, _c)]],
type: "style",
typescriptOnly: false,
};
/* tslint:enable:object-literal-sort-keys */
Rule.FAILURE_STRING = "Use a switch statement instead of using multiple '===' checks.";
exports.Rule = Rule;
function walk(ctx) {
var minCases = ctx.options, sourceFile = ctx.sourceFile;
return ts.forEachChild(sourceFile, function cb(node) {
if (utils.isIfStatement(node) && check(node, sourceFile, minCases)) {
var expression = node.expression, thenStatement = node.thenStatement, elseStatement = node.elseStatement;
ctx.addFailureAtNode(expression, Rule.FAILURE_STRING);
// Be careful not to fail again for the "else if"
ts.forEachChild(expression, cb);
ts.forEachChild(thenStatement, cb);
if (elseStatement !== undefined) {
ts.forEachChild(elseStatement, cb);
}
}
else {
return ts.forEachChild(node, cb);
}
});
}
function check(node, sourceFile, minCases) {
var switchVariable;
var casesSeen = 0;
var couldBeSwitch = everyCase(node, function (expr) {
casesSeen++;
if (switchVariable !== undefined) {
return nodeEquals(expr, switchVariable, sourceFile);
}
else {
switchVariable = expr;
return true;
}
});
return couldBeSwitch && casesSeen >= minCases;
}
function everyCase(_a, test) {
var expression = _a.expression, elseStatement = _a.elseStatement;
if (!everyCondition(expression, test)) {
return false;
}
return elseStatement === undefined || !utils.isIfStatement(elseStatement) || everyCase(elseStatement, test);
}
function everyCondition(node, test) {
if (!utils.isBinaryExpression(node)) {
return false;
}
var operatorToken = node.operatorToken, left = node.left, right = node.right;
switch (operatorToken.kind) {
case ts.SyntaxKind.BarBarToken:
return everyCondition(left, test) && everyCondition(right, test);
case ts.SyntaxKind.EqualsEqualsEqualsToken:
return isSimple(left) && isSimple(right) && test(left);
default:
return false;
}
}
function nodeEquals(a, b, sourceFile) {
return a.getText(sourceFile) === b.getText(sourceFile);
}
function isSimple(node) {
switch (node.kind) {
case ts.SyntaxKind.PropertyAccessExpression:
return isSimple(node.expression);
case ts.SyntaxKind.PrefixUnaryExpression:
switch (node.operator) {
case ts.SyntaxKind.PlusPlusToken:
case ts.SyntaxKind.MinusMinusToken:
return false;
default:
return isSimple(node.operand);
}
case ts.SyntaxKind.Identifier:
case ts.SyntaxKind.NumericLiteral:
case ts.SyntaxKind.StringLiteral:
case ts.SyntaxKind.ThisKeyword:
case ts.SyntaxKind.NoSubstitutionTemplateLiteral:
case ts.SyntaxKind.TrueKeyword:
case ts.SyntaxKind.FalseKeyword:
case ts.SyntaxKind.NullKeyword:
return true;
default:
return false;
}
}
var _a, _b, _c;
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