node/tools/eslint/lib/rules/max-statements-per-line.js

/**
 * @fileoverview Specify the maximum number of statements allowed per line.
 * @author Kenneth Williams
 * @copyright 2016 Kenneth Williams. All rights reserved.
 * @copyright 2016 Michael Ficarra. All rights reserved.
 * See LICENSE file in root directory for full license.
 */
"use strict";

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

module.exports = function(context) {

    var options = context.options[0] || {},
        lastStatementLine = 0,
        numberOfStatementsOnThisLine = 0,
        maxStatementsPerLine = typeof options.max !== "undefined" ? options.max : 1;

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

    /**
     * Reports a node
     * @param {ASTNode} node The node to report
     * @returns {void}
     * @private
     */
    function report(node) {
        context.report(
            node,
            "This line has too many statements. Maximum allowed is {{max}}.",
            { max: maxStatementsPerLine });
    }

    /**
     * Enforce a maximum number of statements per line
     * @param {ASTNode} nodes Array of nodes to evaluate
     * @returns {void}
     * @private
     */
    function enforceMaxStatementsPerLine(nodes) {
        if (nodes.length < 1) {
            return;
        }

        for (var i = 0, l = nodes.length; i < l; ++i) {
            var currentStatement = nodes[i];

            if (currentStatement.loc.start.line === lastStatementLine) {
                ++numberOfStatementsOnThisLine;
            } else {
                numberOfStatementsOnThisLine = 1;
                lastStatementLine = currentStatement.loc.end.line;
            }
            if (numberOfStatementsOnThisLine === maxStatementsPerLine + 1) {
                report(currentStatement);
            }
        }
    }

    /**
     * Check each line in the body of a node
     * @param {ASTNode} node node to evaluate
     * @returns {void}
     * @private
     */
    function checkLinesInBody(node) {
        enforceMaxStatementsPerLine(node.body);
    }

    /**
     * Check each line in the consequent of a switch case
     * @param {ASTNode} node node to evaluate
     * @returns {void}
     * @private
     */
    function checkLinesInConsequent(node) {
        enforceMaxStatementsPerLine(node.consequent);
    }

    //--------------------------------------------------------------------------
    // Public API
    //--------------------------------------------------------------------------

    return {
        "Program": checkLinesInBody,
        "BlockStatement": checkLinesInBody,
        "SwitchCase": checkLinesInConsequent
    };

};

module.exports.schema = [
    {
        "type": "object",
        "properties": {
            "max": {
                "type": "integer"
            }
        },
        "additionalProperties": false
    }
];