Initial commit (from f5274cbdce4ae7c9e4b937dcdf95ac70ae436d5f)

node_modules/tslint/lib/rules/preferSwitchRule.js

@@ -0,0 +1,146 @@
+"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.
+ */
+var _a, _b;
+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 = /** @class */ (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);
+    };
+    /* tslint:disable:object-literal-sort-keys */
+    Rule.metadata = {
+        ruleName: "prefer-switch",
+        description: "Prefer a `switch` statement to an `if` statement with simple `===` comparisons.",
+        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),
+        options: {
+            type: "object",
+            properties: (_a = {},
+                _a[OPTION_MIN_CASES] = { type: "number" },
+                _a),
+        },
+        optionExamples: [true, [true, (_b = {}, _b[OPTION_MIN_CASES] = 2, _b)]],
+        type: "style",
+        typescriptOnly: false,
+    };
+    /* tslint:enable:object-literal-sort-keys */
+    Rule.FAILURE_STRING = "Use a switch statement instead of using multiple '===' checks.";
+    return Rule;
+}(Lint.Rules.AbstractRule));
+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 elseStatement = node.elseStatement;
+    if (elseStatement === undefined) {
+        return false;
+    }
+    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 templateObject_1;