node/tools/eslint/lib/rules/spaced-line-comment.js

/**
 * @fileoverview Enforces or disallows a space beginning a single-line comment.
 * @author Greg Cochard
 * @copyright 2014 Greg Cochard. All rights reserved.
 */
"use strict";

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

module.exports = function(context) {

    // Unless the first option is never, require a space
    var requireSpace = context.options[0] !== "never";

    // Default to match anything, so all will fail if there are no exceptions
    var exceptionMatcher = new RegExp(" ");

    // Grab the exceptions array and build a RegExp matcher for it
    var hasExceptions = context.options.length === 2;
    var unescapedExceptions = hasExceptions ? context.options[1].exceptions : [];
    var exceptions;

    if (unescapedExceptions.length) {
        exceptions = unescapedExceptions.map(function(s) {
            return s.replace(/([.*+?${}()|\^\[\]\/\\])/g, "\\$1");
        });
        exceptionMatcher = new RegExp("(^(" + exceptions.join(")+$)|(^(") + ")+$)");
    }


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

    return {

        "LineComment": function checkCommentForSpace(node) {

            if (requireSpace) {

                // If length is zero, ignore it
                if (node.value.length === 0) {
                    return;
                }

                // Space expected and not found
                if (node.value.indexOf(" ") !== 0 && node.value.indexOf("\t") !== 0) {

                    /*
                     * Do two tests; one for space starting the line,
                     * and one for a comment comprised only of exceptions
                     */
                    if (hasExceptions && !exceptionMatcher.test(node.value)) {
                        context.report(node, "Expected exception block, space or tab after // in comment.");
                    } else if (!hasExceptions) {
                        context.report(node, "Expected space or tab after // in comment.");
                    }
                }

            } else {

                if (node.value.indexOf(" ") === 0 || node.value.indexOf("\t") === 0) {
                    context.report(node, "Unexpected space or tab after // in comment.");
                }
            }
        }

    };
};

module.exports.schema = [
    {
        "enum": ["always", "never"]
    },
    {
        "type": "object",
        "properties": {
            "exceptions": {
                "type": "array",
                "items": {
                    "type": "string"
                }
            }
        },
        "additionalProperties": false
    }
];