/**
* @fileoverview Rule to enforce line breaks after each array element
* @author Jan Peer Stöcklmair <https://github.com/JPeer264>
*/
"use strict";
const astUtils = require("../ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
docs: {
description: "enforce line breaks after each array element",
category: "Stylistic Issues",
recommended: false,
url: "https://eslint.org/docs/rules/array-element-newline"
},
fixable: "whitespace",
schema: [
{
oneOf: [
{
enum: ["always", "never"]
},
{
type: "object",
properties: {
multiline: {
type: "boolean"
},
minItems: {
type: ["integer", "null"],
minimum: 0
}
},
additionalProperties: false
}
]
}
]
},
create(context) {
const sourceCode = context.getSourceCode();
//----------------------------------------------------------------------
// Helpers
//----------------------------------------------------------------------
/**
* Normalizes a given option value.
*
* @param {string|Object|undefined} option - An option value to parse.
* @returns {{multiline: boolean, minItems: number}} Normalized option object.
*/
function normalizeOptionValue(option) {
let multiline = false;
let minItems;
option = option || "always";
if (option === "always" || option.minItems === 0) {
minItems = 0;
} else if (option === "never") {
minItems = Number.POSITIVE_INFINITY;
} else {
multiline = Boolean(option.multiline);
minItems = option.minItems || Number.POSITIVE_INFINITY;
}
return { multiline, minItems };
}
/**
* Normalizes a given option value.
*
* @param {string|Object|undefined} options - An option value to parse.
* @returns {{ArrayExpression: {multiline: boolean, minItems: number}, ArrayPattern: {multiline: boolean, minItems: number}}} Normalized option object.
*/
function normalizeOptions(options) {
const value = normalizeOptionValue(options);
return { ArrayExpression: value, ArrayPattern: value };
}
/**
* Reports that there shouldn't be a line break after the first token
* @param {Token} token - The token to use for the report.
* @returns {void}
*/
function reportNoLineBreak(token) {
const tokenBefore = sourceCode.getTokenBefore(token, { includeComments: true });
context.report({
loc: {
start: tokenBefore.loc.end,
end: token.loc.start
},
message: "There should be no linebreak here.",
fix(fixer) {
if (astUtils.isCommentToken(tokenBefore)) {
return null;
}
if (!astUtils.isTokenOnSameLine(tokenBefore, token)) {
return fixer.replaceTextRange([tokenBefore.range[1], token.range[0]], " ");
}
/*
* This will check if the comma is on the same line as the next element
* Following array:
* [
* 1
* , 2
* , 3
* ]
*
* will be fixed to:
* [
* 1, 2, 3
* ]
*/
const twoTokensBefore = sourceCode.getTokenBefore(tokenBefore, { includeComments: true });
if (astUtils.isCommentToken(twoTokensBefore)) {
return null;
}
return fixer.replaceTextRange([twoTokensBefore.range[1], tokenBefore.range[0]], "");
}
});
}
/**
* Reports that there should be a line break after the first token
* @param {Token} token - The token to use for the report.
* @returns {void}
*/
function reportRequiredLineBreak(token) {
const tokenBefore = sourceCode.getTokenBefore(token, { includeComments: true });
context.report({
loc: {
start: tokenBefore.loc.end,
end: token.loc.start
},
message: "There should be a linebreak after this element.",
fix(fixer) {
return fixer.replaceTextRange([tokenBefore.range[1], token.range[0]], "\n");
}
});
}
/**
* Reports a given node if it violated this rule.
*
* @param {ASTNode} node - A node to check. This is an ObjectExpression node or an ObjectPattern node.
* @param {{multiline: boolean, minItems: number}} options - An option object.
* @returns {void}
*/
function check(node) {
const elements = node.elements;
const normalizedOptions = normalizeOptions(context.options[0]);
const options = normalizedOptions[node.type];
let elementBreak = false;
/*
* MULTILINE: true
* loop through every element and check
* if at least one element has linebreaks inside
* this ensures that following is not valid (due to elements are on the same line):
*
* [
* 1,
* 2,
* 3
* ]
*/
if (options.multiline) {
elementBreak = elements
.filter(element => element !== null)
.some(element => element.loc.start.line !== element.loc.end.line);
}
const needsLinebreaks = (
elements.length >= options.minItems ||
(
options.multiline &&
elementBreak
)
);
elements.forEach((element, i) => {
const previousElement = elements[i - 1];
if (i === 0 || element === null || previousElement === null) {
return;
}
const commaToken = sourceCode.getFirstTokenBetween(previousElement, element, astUtils.isCommaToken);
const lastTokenOfPreviousElement = sourceCode.getTokenBefore(commaToken);
const firstTokenOfCurrentElement = sourceCode.getTokenAfter(commaToken);
if (needsLinebreaks) {
if (astUtils.isTokenOnSameLine(lastTokenOfPreviousElement, firstTokenOfCurrentElement)) {
reportRequiredLineBreak(firstTokenOfCurrentElement);
}
} else {
if (!astUtils.isTokenOnSameLine(lastTokenOfPreviousElement, firstTokenOfCurrentElement)) {
reportNoLineBreak(firstTokenOfCurrentElement);
}
}
});
}
//----------------------------------------------------------------------
// Public
//----------------------------------------------------------------------
return {
ArrayPattern: check,
ArrayExpression: check
};
}
};