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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 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;
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