node/tools/eslint/lib/rules/space-in-parens.js

/**
 * @fileoverview Disallows or enforces spaces inside of parentheses.
 * @author Jonathan Rajavuori
 * @copyright 2014 David Clark. All rights reserved.
 * @copyright 2014 Jonathan Rajavuori. All rights reserved.
 */
"use strict";

var astUtils = require("../ast-utils");

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

module.exports = function(context) {

    var MISSING_SPACE_MESSAGE = "There must be a space inside this paren.",
        REJECTED_SPACE_MESSAGE = "There should be no spaces inside this paren.",
        ALWAYS = context.options[0] === "always",

        exceptionsArrayOptions = (context.options.length === 2) ? context.options[1].exceptions : [],
        options = {},
        exceptions;

    if (exceptionsArrayOptions.length) {
        options.braceException = exceptionsArrayOptions.indexOf("{}") !== -1;
        options.bracketException = exceptionsArrayOptions.indexOf("[]") !== -1;
        options.parenException = exceptionsArrayOptions.indexOf("()") !== -1;
        options.empty = exceptionsArrayOptions.indexOf("empty") !== -1;
    }

    /**
     * Produces an object with the opener and closer exception values
     * @param {Object} opts The exception options
     * @returns {Object} `openers` and `closers` exception values
     * @private
     */
    function getExceptions() {
        var openers = [],
            closers = [];
        if (options.braceException) {
            openers.push("{");
            closers.push("}");
        }

        if (options.bracketException) {
            openers.push("[");
            closers.push("]");
        }

        if (options.parenException) {
            openers.push("(");
            closers.push(")");
        }

        if (options.empty) {
            openers.push(")");
            closers.push("(");
        }

        return {
            openers: openers,
            closers: closers
        };
    }

    //--------------------------------------------------------------------------
    // Helpers
    //--------------------------------------------------------------------------
    var sourceCode = context.getSourceCode();

    /**
     * Determines if a token is one of the exceptions for the opener paren
     * @param {Object} token The token to check
     * @returns {boolean} True if the token is one of the exceptions for the opener paren
     */
    function isOpenerException(token) {
        return token.type === "Punctuator" && exceptions.openers.indexOf(token.value) >= 0;
    }

    /**
     * Determines if a token is one of the exceptions for the closer paren
     * @param {Object} token The token to check
     * @returns {boolean} True if the token is one of the exceptions for the closer paren
     */
    function isCloserException(token) {
        return token.type === "Punctuator" && exceptions.closers.indexOf(token.value) >= 0;
    }

    /**
     * Determines if an opener paren should have a missing space after it
     * @param {Object} left The paren token
     * @param {Object} right The token after it
     * @returns {boolean} True if the paren should have a space
     */
    function shouldOpenerHaveSpace(left, right) {
        if (sourceCode.isSpaceBetweenTokens(left, right)) {
            return false;
        }

        if (ALWAYS) {
            if (right.type === "Punctuator" && right.value === ")") {
                return false;
            }
            return !isOpenerException(right);
        } else {
            return isOpenerException(right);
        }
    }

    /**
     * Determines if an closer paren should have a missing space after it
     * @param {Object} left The token before the paren
     * @param {Object} right The paren token
     * @returns {boolean} True if the paren should have a space
     */
    function shouldCloserHaveSpace(left, right) {
        if (left.type === "Punctuator" && left.value === "(") {
            return false;
        }

        if (sourceCode.isSpaceBetweenTokens(left, right)) {
            return false;
        }

        if (ALWAYS) {
            return !isCloserException(left);
        } else {
            return isCloserException(left);
        }
    }

    /**
     * Determines if an opener paren should not have an existing space after it
     * @param {Object} left The paren token
     * @param {Object} right The token after it
     * @returns {boolean} True if the paren should reject the space
     */
    function shouldOpenerRejectSpace(left, right) {
        if (right.type === "Line") {
            return false;
        }

        if (!astUtils.isTokenOnSameLine(left, right)) {
            return false;
        }

        if (!sourceCode.isSpaceBetweenTokens(left, right)) {
            return false;
        }

        if (ALWAYS) {
            return isOpenerException(right);
        } else {
            return !isOpenerException(right);
        }
    }

    /**
     * Determines if an closer paren should not have an existing space after it
     * @param {Object} left The token before the paren
     * @param {Object} right The paren token
     * @returns {boolean} True if the paren should reject the space
     */
    function shouldCloserRejectSpace(left, right) {
        if (left.type === "Punctuator" && left.value === "(") {
            return false;
        }

        if (!astUtils.isTokenOnSameLine(left, right)) {
            return false;
        }

        if (!sourceCode.isSpaceBetweenTokens(left, right)) {
            return false;
        }

        if (ALWAYS) {
            return isCloserException(left);
        } else {
            return !isCloserException(left);
        }
    }

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

    return {
        "Program": function checkParenSpaces(node) {
            var tokens, prevToken, nextToken;
            exceptions = getExceptions();
            tokens = sourceCode.tokensAndComments;

            tokens.forEach(function(token, i) {
                prevToken = tokens[i - 1];
                nextToken = tokens[i + 1];

                if (token.type !== "Punctuator") {
                    return;
                }

                if (token.value !== "(" && token.value !== ")") {
                    return;
                }

                if (token.value === "(" && shouldOpenerHaveSpace(token, nextToken)) {
                    context.report({
                        node: node,
                        loc: token.loc.start,
                        message: MISSING_SPACE_MESSAGE,
                        fix: function(fixer) {
                            return fixer.insertTextAfter(token, " ");
                        }
                    });
                } else if (token.value === "(" && shouldOpenerRejectSpace(token, nextToken)) {
                    context.report({
                        node: node,
                        loc: token.loc.start,
                        message: REJECTED_SPACE_MESSAGE,
                        fix: function(fixer) {
                            return fixer.removeRange([token.range[1], nextToken.range[0]]);
                        }
                    });
                } else if (token.value === ")" && shouldCloserHaveSpace(prevToken, token)) {
                    // context.report(node, token.loc.start, MISSING_SPACE_MESSAGE);
                    context.report({
                        node: node,
                        loc: token.loc.start,
                        message: MISSING_SPACE_MESSAGE,
                        fix: function(fixer) {
                            return fixer.insertTextBefore(token, " ");
                        }
                    });
                } else if (token.value === ")" && shouldCloserRejectSpace(prevToken, token)) {
                    context.report({
                        node: node,
                        loc: token.loc.start,
                        message: REJECTED_SPACE_MESSAGE,
                        fix: function(fixer) {
                            return fixer.removeRange([prevToken.range[1], token.range[0]]);
                        }
                    });
                }
            });
        }
    };

};

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