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/**
* @fileoverview Comma style - enforces comma styles of two types: last and first
* @author Vignesh Anand aka vegetableman
*/
"use strict";
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "layout",
docs: {
description: "enforce consistent comma style",
recommended: false,
url: "https://eslint.org/docs/rules/comma-style"
},
fixable: "code",
schema: [
{
enum: ["first", "last"]
},
{
type: "object",
properties: {
exceptions: {
type: "object",
additionalProperties: {
type: "boolean"
}
}
},
additionalProperties: false
}
],
messages: {
unexpectedLineBeforeAndAfterComma: "Bad line breaking before and after ','.",
expectedCommaFirst: "',' should be placed first.",
expectedCommaLast: "',' should be placed last."
}
},
create(context) {
const style = context.options[0] || "last",
sourceCode = context.getSourceCode();
const exceptions = {
ArrayPattern: true,
ArrowFunctionExpression: true,
CallExpression: true,
FunctionDeclaration: true,
FunctionExpression: true,
ImportDeclaration: true,
ObjectPattern: true,
NewExpression: true
};
if (context.options.length === 2 && Object.prototype.hasOwnProperty.call(context.options[1], "exceptions")) {
const keys = Object.keys(context.options[1].exceptions);
for (let i = 0; i < keys.length; i++) {
exceptions[keys[i]] = context.options[1].exceptions[keys[i]];
}
}
//--------------------------------------------------------------------------
// Helpers
//--------------------------------------------------------------------------
/**
* Modified text based on the style
* @param {string} styleType Style type
* @param {string} text Source code text
* @returns {string} modified text
* @private
*/
function getReplacedText(styleType, text) {
switch (styleType) {
case "between":
return `,${text.replace(astUtils.LINEBREAK_MATCHER, "")}`;
case "first":
return `${text},`;
case "last":
return `,${text}`;
default:
return "";
}
}
/**
* Determines the fixer function for a given style.
* @param {string} styleType comma style
* @param {ASTNode} previousItemToken The token to check.
* @param {ASTNode} commaToken The token to check.
* @param {ASTNode} currentItemToken The token to check.
* @returns {Function} Fixer function
* @private
*/
function getFixerFunction(styleType, previousItemToken, commaToken, currentItemToken) {
const text =
sourceCode.text.slice(previousItemToken.range[1], commaToken.range[0]) +
sourceCode.text.slice(commaToken.range[1], currentItemToken.range[0]);
const range = [previousItemToken.range[1], currentItemToken.range[0]];
return function(fixer) {
return fixer.replaceTextRange(range, getReplacedText(styleType, text));
};
}
/**
* 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 single line
if (astUtils.isTokenOnSameLine(commaToken, currentItemToken) &&
astUtils.isTokenOnSameLine(previousItemToken, commaToken)) {
// do nothing.
} else if (!astUtils.isTokenOnSameLine(commaToken, currentItemToken) &&
!astUtils.isTokenOnSameLine(previousItemToken, commaToken)) {
const comment = sourceCode.getCommentsAfter(commaToken)[0];
const styleType = comment && comment.type === "Block" && astUtils.isTokenOnSameLine(commaToken, comment)
? style
: "between";
// lone comma
context.report({
node: reportItem,
loc: commaToken.loc,
messageId: "unexpectedLineBeforeAndAfterComma",
fix: getFixerFunction(styleType, previousItemToken, commaToken, currentItemToken)
});
} else if (style === "first" && !astUtils.isTokenOnSameLine(commaToken, currentItemToken)) {
context.report({
node: reportItem,
loc: commaToken.loc,
messageId: "expectedCommaFirst",
fix: getFixerFunction(style, previousItemToken, commaToken, currentItemToken)
});
} else if (style === "last" && astUtils.isTokenOnSameLine(commaToken, currentItemToken)) {
context.report({
node: reportItem,
loc: commaToken.loc,
messageId: "expectedCommaLast",
fix: getFixerFunction(style, previousItemToken, commaToken, currentItemToken)
});
}
}
/**
* Checks the comma placement with regards to a declaration/property/element
* @param {ASTNode} node The binary expression node to check
* @param {string} property The property of the node containing child nodes.
* @private
* @returns {void}
*/
function validateComma(node, property) {
const items = node[property],
arrayLiteral = (node.type === "ArrayExpression" || node.type === "ArrayPattern");
if (items.length > 1 || arrayLiteral) {
// seed as opening [
let previousItemToken = sourceCode.getFirstToken(node);
items.forEach(item => {
const commaToken = item ? sourceCode.getTokenBefore(item) : previousItemToken,
currentItemToken = item ? sourceCode.getFirstToken(item) : sourceCode.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 (astUtils.isCommaToken(commaToken)) {
validateCommaItemSpacing(previousItemToken, commaToken, currentItemToken, reportItem);
}
if (item) {
const tokenAfterItem = sourceCode.getTokenAfter(item, astUtils.isNotClosingParenToken);
previousItemToken = tokenAfterItem
? sourceCode.getTokenBefore(tokenAfterItem)
: sourceCode.ast.tokens[sourceCode.ast.tokens.length - 1];
} else {
previousItemToken = currentItemToken;
}
});
/*
* 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) {
const lastToken = sourceCode.getLastToken(node),
nextToLastToken = sourceCode.getTokenBefore(lastToken);
if (astUtils.isCommaToken(nextToLastToken)) {
validateCommaItemSpacing(
sourceCode.getTokenBefore(nextToLastToken),
nextToLastToken,
lastToken,
lastToken
);
}
}
}
}
//--------------------------------------------------------------------------
// Public
//--------------------------------------------------------------------------
const nodes = {};
if (!exceptions.VariableDeclaration) {
nodes.VariableDeclaration = function(node) {
validateComma(node, "declarations");
};
}
if (!exceptions.ObjectExpression) {
nodes.ObjectExpression = function(node) {
validateComma(node, "properties");
};
}
if (!exceptions.ObjectPattern) {
nodes.ObjectPattern = function(node) {
validateComma(node, "properties");
};
}
if (!exceptions.ArrayExpression) {
nodes.ArrayExpression = function(node) {
validateComma(node, "elements");
};
}
if (!exceptions.ArrayPattern) {
nodes.ArrayPattern = function(node) {
validateComma(node, "elements");
};
}
if (!exceptions.FunctionDeclaration) {
nodes.FunctionDeclaration = function(node) {
validateComma(node, "params");
};
}
if (!exceptions.FunctionExpression) {
nodes.FunctionExpression = function(node) {
validateComma(node, "params");
};
}
if (!exceptions.ArrowFunctionExpression) {
nodes.ArrowFunctionExpression = function(node) {
validateComma(node, "params");
};
}
if (!exceptions.CallExpression) {
nodes.CallExpression = function(node) {
validateComma(node, "arguments");
};
}
if (!exceptions.ImportDeclaration) {
nodes.ImportDeclaration = function(node) {
validateComma(node, "specifiers");
};
}
if (!exceptions.NewExpression) {
nodes.NewExpression = function(node) {
validateComma(node, "arguments");
};
}
return nodes;
}
};
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