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
 * @author Christophe Porteneuve
 * @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\u202f\u205f\u3000]+/mg,
        irregularLineTerminators = /[\u2028\u2029]/mg;

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

    // Comment nodes.  We accumulate these as we go, so we can be sure to trigger them after the whole `Program` entity is parsed, even for top-of-file comments.
    var commentNodes = [];

    // Lookup the `skipComments` option, which defaults to `false`.
    var options = context.options[0] || {};
    var skipComments = !!options.skipComments;

    /**
     * Removes errors that occur inside a string node
     * @param {ASTNode} node to check for matching errors.
     * @returns {void}
     * @private
     */
    function removeWhitespaceError(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 || errorLoc.line < locEnd.line)) {
                    return false;
                }
            }
            return true;
        });
    }

    /**
     * Checks identifier or literal nodes for errors that we are choosing to ignore and calls the relevant methods to remove the errors
     * @param {ASTNode} node to check for matching errors.
     * @returns {void}
     * @private
     */
    function removeInvalidNodeErrorsInIdentifierOrLiteral(node) {
        if (typeof node.value === "string") {

            // If we have irregular characters remove them from the errors list
            if (node.raw.match(irregularWhitespace) || node.raw.match(irregularLineTerminators)) {
                removeWhitespaceError(node);
            }
        }
    }

    /**
     * Checks comment nodes for errors that we are choosing to ignore and calls the relevant methods to remove the errors
     * @param {ASTNode} node to check for matching errors.
     * @returns {void}
     * @private
     */
    function removeInvalidNodeErrorsInComment(node) {
        if (node.value.match(irregularWhitespace) || node.value.match(irregularLineTerminators)) {
            removeWhitespaceError(node);
        }
    }

    /**
     * Checks the program source for irregular whitespace
     * @param {ASTNode} node The program node
     * @returns {void}
     * @private
     */
    function checkForIrregularWhitespace(node) {
        var sourceLines = context.getSourceLines();

        sourceLines.forEach(function(sourceLine, lineIndex) {
            var lineNumber = lineIndex + 1,
                location,
                match;

            while ((match = irregularWhitespace.exec(sourceLine)) !== null) {
                location = {
                    line: lineNumber,
                    column: match.index
                };

                errors.push([node, location, "Irregular whitespace not allowed"]);
            }
        });
    }

    /**
     * Checks the program source for irregular line terminators
     * @param {ASTNode} node The program node
     * @returns {void}
     * @private
     */
    function checkForIrregularLineTerminators(node) {
        var source = context.getSource(),
            sourceLines = context.getSourceLines(),
            linebreaks = source.match(/\r\n|\r|\n|\u2028|\u2029/g),
            lastLineIndex = -1,
            lineIndex,
            location,
            match;

        while ((match = irregularLineTerminators.exec(source)) !== null) {
            lineIndex = linebreaks.indexOf(match[0], lastLineIndex + 1) || 0;

            location = {
                line: lineIndex + 1,
                column: sourceLines[lineIndex].length
            };

            errors.push([node, location, "Irregular whitespace not allowed"]);
            lastLineIndex = lineIndex;
        }
    }

    /**
     * Stores a comment node (`LineComment` or `BlockComment`) for later stripping of errors within; a necessary deferring of processing to deal with top-of-file comments.
     * @param {ASTNode} node The comment node
     * @returns {void}
     * @private
     */
    function rememberCommentNode(node) {
        commentNodes.push(node);
    }

    /**
     * A no-op function to act as placeholder for comment accumulation when the `skipComments` option is `false`.
     * @returns {void}
     * @private
     */
    function noop() {}

    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.
             */

            checkForIrregularWhitespace(node);
            checkForIrregularLineTerminators(node);
        },

        "Identifier": removeInvalidNodeErrorsInIdentifierOrLiteral,
        "Literal": removeInvalidNodeErrorsInIdentifierOrLiteral,
        "LineComment": skipComments ? rememberCommentNode : noop,
        "BlockComment": skipComments ? rememberCommentNode : noop,
        "Program:exit": function() {

            if (skipComments) {

                // First strip errors occurring in comment nodes.  We have to do this post-`Program` to deal with top-of-file comments.
                commentNodes.forEach(removeInvalidNodeErrorsInComment);
            }

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

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