--- /dev/null
+/**
+ * @fileoverview Rule to enforce linebreaks after open and before close array brackets
+ * @author Jan Peer Stöcklmair <https://github.com/JPeer264>
+ */
+
+"use strict";
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+ meta: {
+ type: "layout",
+
+ docs: {
+ description: "enforce linebreaks after opening and before closing array brackets",
+ category: "Stylistic Issues",
+ recommended: false,
+ url: "https://eslint.org/docs/rules/array-bracket-newline"
+ },
+
+ fixable: "whitespace",
+
+ schema: [
+ {
+ oneOf: [
+ {
+ enum: ["always", "never", "consistent"]
+ },
+ {
+ type: "object",
+ properties: {
+ multiline: {
+ type: "boolean"
+ },
+ minItems: {
+ type: ["integer", "null"],
+ minimum: 0
+ }
+ },
+ additionalProperties: false
+ }
+ ]
+ }
+ ],
+
+ messages: {
+ unexpectedOpeningLinebreak: "There should be no linebreak after '['.",
+ unexpectedClosingLinebreak: "There should be no linebreak before ']'.",
+ missingOpeningLinebreak: "A linebreak is required after '['.",
+ missingClosingLinebreak: "A linebreak is required before ']'."
+ }
+ },
+
+ 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 consistent = false;
+ let multiline = false;
+ let minItems = 0;
+
+ if (option) {
+ if (option === "consistent") {
+ consistent = true;
+ minItems = Number.POSITIVE_INFINITY;
+ } else 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;
+ }
+ } else {
+ consistent = false;
+ multiline = true;
+ minItems = Number.POSITIVE_INFINITY;
+ }
+
+ return { consistent, 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 linebreak after the first token
+ * @param {ASTNode} node The node to report in the event of an error.
+ * @param {Token} token The token to use for the report.
+ * @returns {void}
+ */
+ function reportNoBeginningLinebreak(node, token) {
+ context.report({
+ node,
+ loc: token.loc,
+ messageId: "unexpectedOpeningLinebreak",
+ fix(fixer) {
+ const nextToken = sourceCode.getTokenAfter(token, { includeComments: true });
+
+ if (astUtils.isCommentToken(nextToken)) {
+ return null;
+ }
+
+ return fixer.removeRange([token.range[1], nextToken.range[0]]);
+ }
+ });
+ }
+
+ /**
+ * Reports that there shouldn't be a linebreak before the last token
+ * @param {ASTNode} node The node to report in the event of an error.
+ * @param {Token} token The token to use for the report.
+ * @returns {void}
+ */
+ function reportNoEndingLinebreak(node, token) {
+ context.report({
+ node,
+ loc: token.loc,
+ messageId: "unexpectedClosingLinebreak",
+ fix(fixer) {
+ const previousToken = sourceCode.getTokenBefore(token, { includeComments: true });
+
+ if (astUtils.isCommentToken(previousToken)) {
+ return null;
+ }
+
+ return fixer.removeRange([previousToken.range[1], token.range[0]]);
+ }
+ });
+ }
+
+ /**
+ * Reports that there should be a linebreak after the first token
+ * @param {ASTNode} node The node to report in the event of an error.
+ * @param {Token} token The token to use for the report.
+ * @returns {void}
+ */
+ function reportRequiredBeginningLinebreak(node, token) {
+ context.report({
+ node,
+ loc: token.loc,
+ messageId: "missingOpeningLinebreak",
+ fix(fixer) {
+ return fixer.insertTextAfter(token, "\n");
+ }
+ });
+ }
+
+ /**
+ * Reports that there should be a linebreak before the last token
+ * @param {ASTNode} node The node to report in the event of an error.
+ * @param {Token} token The token to use for the report.
+ * @returns {void}
+ */
+ function reportRequiredEndingLinebreak(node, token) {
+ context.report({
+ node,
+ loc: token.loc,
+ messageId: "missingClosingLinebreak",
+ fix(fixer) {
+ return fixer.insertTextBefore(token, "\n");
+ }
+ });
+ }
+
+ /**
+ * Reports a given node if it violated this rule.
+ * @param {ASTNode} node A node to check. This is an ArrayExpression node or an ArrayPattern node.
+ * @returns {void}
+ */
+ function check(node) {
+ const elements = node.elements;
+ const normalizedOptions = normalizeOptions(context.options[0]);
+ const options = normalizedOptions[node.type];
+ const openBracket = sourceCode.getFirstToken(node);
+ const closeBracket = sourceCode.getLastToken(node);
+ const firstIncComment = sourceCode.getTokenAfter(openBracket, { includeComments: true });
+ const lastIncComment = sourceCode.getTokenBefore(closeBracket, { includeComments: true });
+ const first = sourceCode.getTokenAfter(openBracket);
+ const last = sourceCode.getTokenBefore(closeBracket);
+
+ const needsLinebreaks = (
+ elements.length >= options.minItems ||
+ (
+ options.multiline &&
+ elements.length > 0 &&
+ firstIncComment.loc.start.line !== lastIncComment.loc.end.line
+ ) ||
+ (
+ elements.length === 0 &&
+ firstIncComment.type === "Block" &&
+ firstIncComment.loc.start.line !== lastIncComment.loc.end.line &&
+ firstIncComment === lastIncComment
+ ) ||
+ (
+ options.consistent &&
+ openBracket.loc.end.line !== first.loc.start.line
+ )
+ );
+
+ /*
+ * Use tokens or comments to check multiline or not.
+ * But use only tokens to check whether linebreaks are needed.
+ * This allows:
+ * var arr = [ // eslint-disable-line foo
+ * 'a'
+ * ]
+ */
+
+ if (needsLinebreaks) {
+ if (astUtils.isTokenOnSameLine(openBracket, first)) {
+ reportRequiredBeginningLinebreak(node, openBracket);
+ }
+ if (astUtils.isTokenOnSameLine(last, closeBracket)) {
+ reportRequiredEndingLinebreak(node, closeBracket);
+ }
+ } else {
+ if (!astUtils.isTokenOnSameLine(openBracket, first)) {
+ reportNoBeginningLinebreak(node, openBracket);
+ }
+ if (!astUtils.isTokenOnSameLine(last, closeBracket)) {
+ reportNoEndingLinebreak(node, closeBracket);
+ }
+ }
+ }
+
+ //----------------------------------------------------------------------
+ // Public
+ //----------------------------------------------------------------------
+
+ return {
+ ArrayPattern: check,
+ ArrayExpression: check
+ };
+ }
+};