eslint/lib/rules/curly.js

/**
 * @fileoverview Rule to flag statements without curly braces
 * @author Nicholas C. Zakas
 */
"use strict";

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

module.exports = function(context) {

    var multiOnly = (context.options[0] === "multi");

    //--------------------------------------------------------------------------
    // Helpers
    //--------------------------------------------------------------------------

    /**
     * Checks the body of a node to see if it's a block statement. Depending on
     * the rule options, reports the appropriate problems.
     * @param {ASTNode} node The node to report if there's a problem.
     * @param {ASTNode} body The body node to check for blocks.
     * @param {string} name The name to report if there's a problem.
     * @param {string} suffix Additional string to add to the end of a report.
     * @returns {void}
     */
    function checkBody(node, body, name, suffix) {
        var hasBlock = (body.type === "BlockStatement");

        if (multiOnly) {
            if (hasBlock && body.body.length === 1) {
                context.report(node, "Unnecessary { after '{{name}}'{{suffix}}.",
                    {
                        name: name,
                        suffix: (suffix ? " " + suffix : "")
                    }
                );
            }
        } else {
            if (!hasBlock) {
                context.report(node, "Expected { after '{{name}}'{{suffix}}.",
                    {
                        name: name,
                        suffix: (suffix ? " " + suffix : "")
                    }
                );
            }
        }
    }

    //--------------------------------------------------------------------------
    // Public
    //--------------------------------------------------------------------------

    return {

        "IfStatement": function(node) {

            checkBody(node, node.consequent, "if", "condition");

            if (node.alternate && node.alternate.type !== "IfStatement") {
                checkBody(node, node.alternate, "else");
            }

        },

        "WhileStatement": function(node) {
            checkBody(node, node.body, "while", "condition");
        },

        "DoWhileStatement": function (node) {
            checkBody(node, node.body, "do");
        },

        "ForStatement": function(node) {
            checkBody(node, node.body, "for", "condition");
        }
    };

};