Initial commit (from f5274cbdce4ae7c9e4b937dcdf95ac70ae436d5f)

node_modules/tslint/lib/rules/binaryExpressionOperandOrderRule.js

@@ -0,0 +1,97 @@
+"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 tsutils_1 = 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: "binary-expression-operand-order",
+        description: Lint.Utils.dedent(templateObject_1 || (templateObject_1 = tslib_1.__makeTemplateObject(["\n            In a binary expression, a literal should always be on the right-hand side if possible.\n            For example, prefer 'x + 1' over '1 + x'."], ["\n            In a binary expression, a literal should always be on the right-hand side if possible.\n            For example, prefer 'x + 1' over '1 + x'."]))),
+        optionsDescription: "Not configurable.",
+        options: null,
+        optionExamples: [true],
+        rationale: Lint.Utils.dedent(templateObject_2 || (templateObject_2 = tslib_1.__makeTemplateObject(["\n            Expressions like `1 + x` are sometimes referred to as \"Yoda\" expressions because they read\n            opposite to how we would normally speak the expression.\n\n            Sticking to a consistent grammar for conditions helps keep code readable and understandable.\n        "], ["\n            Expressions like \\`1 + x\\` are sometimes referred to as \"Yoda\" expressions because they read\n            opposite to how we would normally speak the expression.\n\n            Sticking to a consistent grammar for conditions helps keep code readable and understandable.\n        "]))),
+        type: "style",
+        typescriptOnly: false,
+    };
+    /* tslint:enable:object-literal-sort-keys */
+    Rule.FAILURE_STRING = "Literal expression should be on the right-hand side of a binary expression.";
+    return Rule;
+}(Lint.Rules.AbstractRule));
+exports.Rule = Rule;
+function walk(ctx) {
+    ts.forEachChild(ctx.sourceFile, function cb(node) {
+        if (tsutils_1.isBinaryExpression(node) &&
+            isLiteral(node.left) &&
+            !isLiteral(node.right) &&
+            !isAllowedOrderedOperator(node)) {
+            ctx.addFailureAtNode(node, Rule.FAILURE_STRING);
+        }
+        ts.forEachChild(node, cb);
+    });
+}
+/** Allows certain inherently ordered operators that can't easily be written with the literal on the right. */
+function isAllowedOrderedOperator(node) {
+    switch (node.operatorToken.kind) {
+        case ts.SyntaxKind.PlusToken:
+            // Allow `"foo" + x` but not `1 + x`.
+            return node.left.kind === ts.SyntaxKind.StringLiteral;
+        case ts.SyntaxKind.MinusToken:
+        case ts.SyntaxKind.SlashToken:
+        case ts.SyntaxKind.PercentToken:
+        case ts.SyntaxKind.LessThanLessThanToken:
+        case ts.SyntaxKind.GreaterThanGreaterThanToken:
+        case ts.SyntaxKind.GreaterThanGreaterThanGreaterThanToken:
+        case ts.SyntaxKind.AsteriskAsteriskToken:
+        case ts.SyntaxKind.InKeyword:
+        case ts.SyntaxKind.CommaToken:
+            return true;
+        default:
+            return false;
+    }
+}
+function isLiteral(node) {
+    switch (node.kind) {
+        case ts.SyntaxKind.StringLiteral:
+        case ts.SyntaxKind.NumericLiteral:
+        case ts.SyntaxKind.TrueKeyword:
+        case ts.SyntaxKind.FalseKeyword:
+        case ts.SyntaxKind.NullKeyword:
+            return true;
+        case ts.SyntaxKind.Identifier:
+            return node.originalKeywordKind === ts.SyntaxKind.UndefinedKeyword;
+        case ts.SyntaxKind.PrefixUnaryExpression:
+            return utils_1.isNegativeNumberLiteral(node);
+        case ts.SyntaxKind.ParenthesizedExpression:
+            return isLiteral(node.expression);
+        default:
+            return false;
+    }
+}
+var templateObject_1, templateObject_2;