/
comma-spacing.js
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/
comma-spacing.js
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/**
* @fileoverview Comma spacing - validates spacing before and after comma
* @author Vignesh Anand aka vegetableman.
* @copyright 2014 Vignesh Anand. All rights reserved.
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = function(context) {
var options = {
before: context.options[0] ? !!context.options[0].before : false,
after: context.options[0] ? !!context.options[0].after : true
};
//--------------------------------------------------------------------------
// Helpers
//--------------------------------------------------------------------------
/**
* Determines whether two adjacent tokens have whitespace between them.
* @param {Object} left - The left token object.
* @param {Object} right - The right token object.
* @returns {boolean} Whether or not there is space between the tokens.
*/
function isSpaced(left, right) {
var punctuationLength = context.getTokensBetween(left, right).length; // the length of any parenthesis
return (left.range[1] + punctuationLength) < right.range[0];
}
/**
* Checks whether two tokens are on the same line.
* @param {ASTNode} left The leftmost token.
* @param {ASTNode} right The rightmost token.
* @returns {boolean} True if the tokens are on the same line, false if not.
* @private
*/
function isSameLine(left, right) {
return left.loc.end.line === right.loc.start.line;
}
/**
* Determines if a given token is a comma operator.
* @param {ASTNode} token The token to check.
* @returns {boolean} True if the token is a comma, false if not.
* @private
*/
function isComma(token) {
return !!token && (token.type === "Punctuator") && (token.value === ",");
}
/**
* Run report.
* @param {ASTNode} node The binary expression node to check.
* @param {string} msg The error msg to show.
* @private
* @returns {void}
*/
function report(node, msg) {
context.report(node, msg);
}
/**
* Show space required message.
* @param {string} dir The location of spacing.
* @private
* @returns {string} The spacing error msg.
*/
function getSpaceReqMsg(dir) {
return "A space is required " + dir + " ','.";
}
/**
* Show no space message.
* @param {string} dir The location of spacing
* @private
* @returns {string} The spacing error msg.
*/
function getNoSpaceMsg(dir) {
return "There should be no space " + dir + " ','.";
}
/**
* Validates the spacing around single items in lists.
* @param {Token} previousItemToken The last token from the previous item.
* @param {Token} commaToken The token representing the comma.
* @param {Token} currentItemToken The first token of the current item.
* @param {Token} reportItem The item to use when reporting an error.
* @returns {void}
* @private
*/
function validateCommaItemSpacing(previousItemToken, commaToken, currentItemToken, reportItem) {
if (isSameLine(previousItemToken, commaToken) &&
isSameLine(commaToken, currentItemToken)) {
if (options.before && options.after) {
if (!isSpaced(previousItemToken, commaToken)) {
report(reportItem, getSpaceReqMsg("before"));
}
if (!isSpaced(commaToken, currentItemToken)) {
report(reportItem, getSpaceReqMsg("after"));
}
} else if (options.before) {
if (!isSpaced(previousItemToken, commaToken)) {
report(reportItem, getSpaceReqMsg("before"));
}
if (isSpaced(commaToken, currentItemToken)) {
report(reportItem, getNoSpaceMsg("after"));
}
} else if (options.after) {
if (!isSpaced(commaToken, currentItemToken)) {
report(reportItem, getSpaceReqMsg("after"));
}
if (isSpaced(previousItemToken, commaToken)) {
report(reportItem, getNoSpaceMsg("before"));
}
} else {
if (isSpaced(previousItemToken, commaToken)) {
report(reportItem, getNoSpaceMsg("before"));
}
if (isSpaced(commaToken, currentItemToken)) {
report(reportItem, getNoSpaceMsg("after"));
}
}
}
}
/**
* Validates the spacing before and after commas.
* @param {ASTNode} node The binary expression node to check.
* @param {string} property The property of the node.
* @returns {void}
* @private
*/
function validateCommaSpacing(node, property) {
var items = node[property],
previousItemToken,
arrayLiteral = (node.type === "ArrayExpression");
if (items && (items.length > 1 || arrayLiteral)) {
// seed as opening [
previousItemToken = context.getFirstToken(node);
items.forEach(function(item) {
var commaToken = item ? context.getTokenBefore(item) : previousItemToken,
currentItemToken = item ? context.getFirstToken(item) : context.getTokenAfter(commaToken),
reportItem = item || currentItemToken;
/*
* This works by comparing three token locations:
* - previousItemToken is the last token of the previous item
* - commaToken is the location of the comma before the current item
* - currentItemToken is the first token of the current item
*
* These values get switched around if item is undefined.
* previousItemToken will refer to the last token not belonging
* to the current item, which could be a comma or an opening
* square bracket. currentItemToken could be a comma.
*
* All comparisons are done based on these tokens directly, so
* they are always valid regardless of an undefined item.
*/
if (isComma(commaToken)) {
validateCommaItemSpacing(previousItemToken, commaToken,
currentItemToken, reportItem);
}
previousItemToken = item ? context.getLastToken(item) : previousItemToken;
});
/*
* Special case for array literals that have empty last items, such
* as [ 1, 2, ]. These arrays only have two items show up in the
* AST, so we need to look at the token to verify that there's no
* dangling comma.
*/
if (arrayLiteral) {
var lastToken = context.getLastToken(node),
nextToLastToken = context.getTokenBefore(lastToken);
if (isComma(nextToLastToken)) {
validateCommaItemSpacing(
context.getTokenBefore(nextToLastToken),
nextToLastToken,
lastToken,
lastToken
);
}
}
}
}
//--------------------------------------------------------------------------
// Public
//--------------------------------------------------------------------------
return {
"VariableDeclaration": function(node) {
validateCommaSpacing(node, "declarations");
},
"ObjectExpression": function(node) {
validateCommaSpacing(node, "properties");
},
"ArrayExpression": function(node) {
validateCommaSpacing(node, "elements");
},
"SequenceExpression": function(node) {
validateCommaSpacing(node, "expressions");
},
"FunctionExpression": function(node) {
validateCommaSpacing(node, "params");
},
"FunctionDeclaration": function(node) {
validateCommaSpacing(node, "params");
},
"CallExpression": function(node) {
validateCommaSpacing(node, "arguments");
},
"NewExpression": function(node) {
validateCommaSpacing(node, "arguments");
}
};
};