eslint-plugin-sonarjs/lib/rules/prefer-single-boolean-return.js

SonarJS rules for ESLint

"use strict";
/*
 * eslint-plugin-sonarjs
 * Copyright (C) 2018 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
// https://jira.sonarsource.com/browse/RSPEC-1126
const nodes_1 = require("../utils/nodes");
const rule = {
    meta: {
        type: "suggestion",
    },
    create(context) {
        return {
            IfStatement(node) {
                const ifStmt = node;
                if (
                // ignore `else if`
                !nodes_1.isIfStatement(nodes_1.getParent(context)) &&
                    // `ifStmt.alternate` can be `null`, replace it with `undefined` in this case
                    returnsBoolean(ifStmt.alternate || undefined) &&
                    returnsBoolean(ifStmt.consequent)) {
                    context.report({
                        message: "Replace this if-then-else statement by a single return statement.",
                        node: ifStmt,
                    });
                }
            },
        };
        function returnsBoolean(statement) {
            return (statement !== undefined &&
                (isBlockReturningBooleanLiteral(statement) || isSimpleReturnBooleanLiteral(statement)));
        }
        function isBlockReturningBooleanLiteral(statement) {
            return (nodes_1.isBlockStatement(statement) && statement.body.length === 1 && isSimpleReturnBooleanLiteral(statement.body[0]));
        }
        function isSimpleReturnBooleanLiteral(statement) {
            // `statement.argument` can be `null`, replace it with `undefined` in this case
            return nodes_1.isReturnStatement(statement) && nodes_1.isBooleanLiteral(statement.argument || undefined);
        }
    },
};
module.exports = rule;
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