node/tools/eslint/lib/rules/no-irregular-whitespace.js

/**
 * @fileoverview Rule to disalow whitespace that is not a tab or space, whitespace inside strings and comments are allowed
 * @author Jonathan Kingston
 * @copyright 2014 Jonathan Kingston. All rights reserved.
 */

"use strict";

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

module.exports = function(context) {

    var irregularWhitespace = /[\u0085\u00A0\ufeff\f\v\u00a0\u1680\u180e\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u200b\u2028\u2029\u202f\u205f\u3000]+/mg;

    // Module store of errors that we have found
    var errors = [];

    /**
     * Removes errors that occur inside a string node
     * @param {ASTNode} node to check for matching errors.
     * @returns {void}
     * @private
     */
    function removeStringError(node) {
        var locStart = node.loc.start;
        var locEnd = node.loc.end;

        errors = errors.filter(function (error) {
            var errorLoc = error[1];
            if (errorLoc.line >= locStart.line && errorLoc.line <= locEnd.line) {
                if (errorLoc.column >= locStart.column && errorLoc.column <= locEnd.column) {
                    return false;
                }
            }
            return true;
        });
    }

    /**
     * Checks nodes for errors that we are choosing to ignore and calls the relevent methods to remove the errors
     * @param {ASTNode} node to check for matching errors.
     * @returns {void}
     * @private
     */
    function removeInvalidNodeErrors(node) {
        if (typeof node.value === "string") {
            // If we have irregular characters remove them from the errors list
            if (node.value.match(irregularWhitespace)) {
                removeStringError(node);
            }
        }
    }

    return {
        "Program": function (node) {
            /**
             * As we can easily fire warnings for all white space issues with all the source its simpler to fire them here
             * This means we can check all the application code without having to worry about issues caused in the parser tokens
             * When writing this code also evaluating per node was missing out connecting tokens in some cases
             * We can later filter the errors when they are found to be not an issue in nodes we don't care about
             */
            var sourceLines = context.getSourceLines();

            sourceLines.forEach(function (sourceLine, lineIndex) {
                var location,
                    match = irregularWhitespace.exec(sourceLine);

                if (match !== null) {
                    location = {
                        line: lineIndex + 1,
                        column: match.index
                    };

                    errors.push([node, location, "Irregular whitespace not allowed"]);
                }
            });
        },
        "Identifier": removeInvalidNodeErrors,
        "Literal": removeInvalidNodeErrors,
        "Statement": removeInvalidNodeErrors,
        "Expression": removeInvalidNodeErrors,
        "Program:exit": function () {

            // If we have any errors remaining report on them
            errors.forEach(function (error) {
                context.report.apply(this, error);
            });
        }
    };
};