--- /dev/null
+/**
+ * @fileoverview enforce a particular style for multiline comments
+ * @author Teddy Katz
+ */
+"use strict";
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+ meta: {
+ type: "suggestion",
+
+ docs: {
+ description: "enforce a particular style for multiline comments",
+ category: "Stylistic Issues",
+ recommended: false,
+ url: "https://eslint.org/docs/rules/multiline-comment-style"
+ },
+
+ fixable: "whitespace",
+ schema: [{ enum: ["starred-block", "separate-lines", "bare-block"] }],
+ messages: {
+ expectedBlock: "Expected a block comment instead of consecutive line comments.",
+ expectedBareBlock: "Expected a block comment without padding stars.",
+ startNewline: "Expected a linebreak after '/*'.",
+ endNewline: "Expected a linebreak before '*/'.",
+ missingStar: "Expected a '*' at the start of this line.",
+ alignment: "Expected this line to be aligned with the start of the comment.",
+ expectedLines: "Expected multiple line comments instead of a block comment."
+ }
+ },
+
+ create(context) {
+ const sourceCode = context.getSourceCode();
+ const option = context.options[0] || "starred-block";
+
+ //----------------------------------------------------------------------
+ // Helpers
+ //----------------------------------------------------------------------
+
+ /**
+ * Checks if a comment line is starred.
+ * @param {string} line A string representing a comment line.
+ * @returns {boolean} Whether or not the comment line is starred.
+ */
+ function isStarredCommentLine(line) {
+ return /^\s*\*/u.test(line);
+ }
+
+ /**
+ * Checks if a comment group is in starred-block form.
+ * @param {Token[]} commentGroup A group of comments, containing either multiple line comments or a single block comment.
+ * @returns {boolean} Whether or not the comment group is in starred block form.
+ */
+ function isStarredBlockComment([firstComment]) {
+ if (firstComment.type !== "Block") {
+ return false;
+ }
+
+ const lines = firstComment.value.split(astUtils.LINEBREAK_MATCHER);
+
+ // The first and last lines can only contain whitespace.
+ return lines.length > 0 && lines.every((line, i) => (i === 0 || i === lines.length - 1 ? /^\s*$/u : /^\s*\*/u).test(line));
+ }
+
+ /**
+ * Checks if a comment group is in JSDoc form.
+ * @param {Token[]} commentGroup A group of comments, containing either multiple line comments or a single block comment.
+ * @returns {boolean} Whether or not the comment group is in JSDoc form.
+ */
+ function isJSDocComment([firstComment]) {
+ if (firstComment.type !== "Block") {
+ return false;
+ }
+
+ const lines = firstComment.value.split(astUtils.LINEBREAK_MATCHER);
+
+ return /^\*\s*$/u.test(lines[0]) &&
+ lines.slice(1, -1).every(line => /^\s* /u.test(line)) &&
+ /^\s*$/u.test(lines[lines.length - 1]);
+ }
+
+ /**
+ * Processes a comment group that is currently in separate-line form, calculating the offset for each line.
+ * @param {Token[]} commentGroup A group of comments containing multiple line comments.
+ * @returns {string[]} An array of the processed lines.
+ */
+ function processSeparateLineComments(commentGroup) {
+ const allLinesHaveLeadingSpace = commentGroup
+ .map(({ value }) => value)
+ .filter(line => line.trim().length)
+ .every(line => line.startsWith(" "));
+
+ return commentGroup.map(({ value }) => (allLinesHaveLeadingSpace ? value.replace(/^ /u, "") : value));
+ }
+
+ /**
+ * Processes a comment group that is currently in starred-block form, calculating the offset for each line.
+ * @param {Token} comment A single block comment token in starred-block form.
+ * @returns {string[]} An array of the processed lines.
+ */
+ function processStarredBlockComment(comment) {
+ const lines = comment.value.split(astUtils.LINEBREAK_MATCHER)
+ .filter((line, i, linesArr) => !(i === 0 || i === linesArr.length - 1))
+ .map(line => line.replace(/^\s*$/u, ""));
+ const allLinesHaveLeadingSpace = lines
+ .map(line => line.replace(/\s*\*/u, ""))
+ .filter(line => line.trim().length)
+ .every(line => line.startsWith(" "));
+
+ return lines.map(line => line.replace(allLinesHaveLeadingSpace ? /\s*\* ?/u : /\s*\*/u, ""));
+ }
+
+ /**
+ * Processes a comment group that is currently in bare-block form, calculating the offset for each line.
+ * @param {Token} comment A single block comment token in bare-block form.
+ * @returns {string[]} An array of the processed lines.
+ */
+ function processBareBlockComment(comment) {
+ const lines = comment.value.split(astUtils.LINEBREAK_MATCHER).map(line => line.replace(/^\s*$/u, ""));
+ const leadingWhitespace = `${sourceCode.text.slice(comment.range[0] - comment.loc.start.column, comment.range[0])} `;
+ let offset = "";
+
+ /*
+ * Calculate the offset of the least indented line and use that as the basis for offsetting all the lines.
+ * The first line should not be checked because it is inline with the opening block comment delimiter.
+ */
+ for (const [i, line] of lines.entries()) {
+ if (!line.trim().length || i === 0) {
+ continue;
+ }
+
+ const [, lineOffset] = line.match(/^(\s*\*?\s*)/u);
+
+ if (lineOffset.length < leadingWhitespace.length) {
+ const newOffset = leadingWhitespace.slice(lineOffset.length - leadingWhitespace.length);
+
+ if (newOffset.length > offset.length) {
+ offset = newOffset;
+ }
+ }
+ }
+
+ return lines.map(line => {
+ const match = line.match(/^(\s*\*?\s*)(.*)/u);
+ const [, lineOffset, lineContents] = match;
+
+ if (lineOffset.length > leadingWhitespace.length) {
+ return `${lineOffset.slice(leadingWhitespace.length - (offset.length + lineOffset.length))}${lineContents}`;
+ }
+
+ if (lineOffset.length < leadingWhitespace.length) {
+ return `${lineOffset.slice(leadingWhitespace.length)}${lineContents}`;
+ }
+
+ return lineContents;
+ });
+ }
+
+ /**
+ * Gets a list of comment lines in a group, formatting leading whitespace as necessary.
+ * @param {Token[]} commentGroup A group of comments containing either multiple line comments or a single block comment.
+ * @returns {string[]} A list of comment lines.
+ */
+ function getCommentLines(commentGroup) {
+ const [firstComment] = commentGroup;
+
+ if (firstComment.type === "Line") {
+ return processSeparateLineComments(commentGroup);
+ }
+
+ if (isStarredBlockComment(commentGroup)) {
+ return processStarredBlockComment(firstComment);
+ }
+
+ return processBareBlockComment(firstComment);
+ }
+
+ /**
+ * Gets the initial offset (whitespace) from the beginning of a line to a given comment token.
+ * @param {Token} comment The token to check.
+ * @returns {string} The offset from the beginning of a line to the token.
+ */
+ function getInitialOffset(comment) {
+ return sourceCode.text.slice(comment.range[0] - comment.loc.start.column, comment.range[0]);
+ }
+
+ /**
+ * Converts a comment into starred-block form
+ * @param {Token} firstComment The first comment of the group being converted
+ * @param {string[]} commentLinesList A list of lines to appear in the new starred-block comment
+ * @returns {string} A representation of the comment value in starred-block form, excluding start and end markers
+ */
+ function convertToStarredBlock(firstComment, commentLinesList) {
+ const initialOffset = getInitialOffset(firstComment);
+
+ return `/*\n${commentLinesList.map(line => `${initialOffset} * ${line}`).join("\n")}\n${initialOffset} */`;
+ }
+
+ /**
+ * Converts a comment into separate-line form
+ * @param {Token} firstComment The first comment of the group being converted
+ * @param {string[]} commentLinesList A list of lines to appear in the new starred-block comment
+ * @returns {string} A representation of the comment value in separate-line form
+ */
+ function convertToSeparateLines(firstComment, commentLinesList) {
+ return commentLinesList.map(line => `// ${line}`).join(`\n${getInitialOffset(firstComment)}`);
+ }
+
+ /**
+ * Converts a comment into bare-block form
+ * @param {Token} firstComment The first comment of the group being converted
+ * @param {string[]} commentLinesList A list of lines to appear in the new starred-block comment
+ * @returns {string} A representation of the comment value in bare-block form
+ */
+ function convertToBlock(firstComment, commentLinesList) {
+ return `/* ${commentLinesList.join(`\n${getInitialOffset(firstComment)} `)} */`;
+ }
+
+ /**
+ * Each method checks a group of comments to see if it's valid according to the given option.
+ * @param {Token[]} commentGroup A list of comments that appear together. This will either contain a single
+ * block comment or multiple line comments.
+ * @returns {void}
+ */
+ const commentGroupCheckers = {
+ "starred-block"(commentGroup) {
+ const [firstComment] = commentGroup;
+ const commentLines = getCommentLines(commentGroup);
+
+ if (commentLines.some(value => value.includes("*/"))) {
+ return;
+ }
+
+ if (commentGroup.length > 1) {
+ context.report({
+ loc: {
+ start: firstComment.loc.start,
+ end: commentGroup[commentGroup.length - 1].loc.end
+ },
+ messageId: "expectedBlock",
+ fix(fixer) {
+ const range = [firstComment.range[0], commentGroup[commentGroup.length - 1].range[1]];
+
+ return commentLines.some(value => value.startsWith("/"))
+ ? null
+ : fixer.replaceTextRange(range, convertToStarredBlock(firstComment, commentLines));
+ }
+ });
+ } else {
+ const lines = firstComment.value.split(astUtils.LINEBREAK_MATCHER);
+ const expectedLeadingWhitespace = getInitialOffset(firstComment);
+ const expectedLinePrefix = `${expectedLeadingWhitespace} *`;
+
+ if (!/^\*?\s*$/u.test(lines[0])) {
+ const start = firstComment.value.startsWith("*") ? firstComment.range[0] + 1 : firstComment.range[0];
+
+ context.report({
+ loc: {
+ start: firstComment.loc.start,
+ end: { line: firstComment.loc.start.line, column: firstComment.loc.start.column + 2 }
+ },
+ messageId: "startNewline",
+ fix: fixer => fixer.insertTextAfterRange([start, start + 2], `\n${expectedLinePrefix}`)
+ });
+ }
+
+ if (!/^\s*$/u.test(lines[lines.length - 1])) {
+ context.report({
+ loc: {
+ start: { line: firstComment.loc.end.line, column: firstComment.loc.end.column - 2 },
+ end: firstComment.loc.end
+ },
+ messageId: "endNewline",
+ fix: fixer => fixer.replaceTextRange([firstComment.range[1] - 2, firstComment.range[1]], `\n${expectedLinePrefix}/`)
+ });
+ }
+
+ for (let lineNumber = firstComment.loc.start.line + 1; lineNumber <= firstComment.loc.end.line; lineNumber++) {
+ const lineText = sourceCode.lines[lineNumber - 1];
+ const errorType = isStarredCommentLine(lineText)
+ ? "alignment"
+ : "missingStar";
+
+ if (!lineText.startsWith(expectedLinePrefix)) {
+ context.report({
+ loc: {
+ start: { line: lineNumber, column: 0 },
+ end: { line: lineNumber, column: lineText.length }
+ },
+ messageId: errorType,
+ fix(fixer) {
+ const lineStartIndex = sourceCode.getIndexFromLoc({ line: lineNumber, column: 0 });
+
+ if (errorType === "alignment") {
+ const [, commentTextPrefix = ""] = lineText.match(/^(\s*\*)/u) || [];
+ const commentTextStartIndex = lineStartIndex + commentTextPrefix.length;
+
+ return fixer.replaceTextRange([lineStartIndex, commentTextStartIndex], expectedLinePrefix);
+ }
+
+ const [, commentTextPrefix = ""] = lineText.match(/^(\s*)/u) || [];
+ const commentTextStartIndex = lineStartIndex + commentTextPrefix.length;
+ let offset;
+
+ for (const [idx, line] of lines.entries()) {
+ if (!/\S+/u.test(line)) {
+ continue;
+ }
+
+ const lineTextToAlignWith = sourceCode.lines[firstComment.loc.start.line - 1 + idx];
+ const [, prefix = "", initialOffset = ""] = lineTextToAlignWith.match(/^(\s*(?:\/?\*)?(\s*))/u) || [];
+
+ offset = `${commentTextPrefix.slice(prefix.length)}${initialOffset}`;
+ break;
+ }
+
+ return fixer.replaceTextRange([lineStartIndex, commentTextStartIndex], `${expectedLinePrefix}${offset}`);
+ }
+ });
+ }
+ }
+ }
+ },
+ "separate-lines"(commentGroup) {
+ const [firstComment] = commentGroup;
+
+ if (firstComment.type !== "Block" || isJSDocComment(commentGroup)) {
+ return;
+ }
+
+ const commentLines = getCommentLines(commentGroup);
+ const tokenAfter = sourceCode.getTokenAfter(firstComment, { includeComments: true });
+
+ if (tokenAfter && firstComment.loc.end.line === tokenAfter.loc.start.line) {
+ return;
+ }
+
+ context.report({
+ loc: {
+ start: firstComment.loc.start,
+ end: { line: firstComment.loc.start.line, column: firstComment.loc.start.column + 2 }
+ },
+ messageId: "expectedLines",
+ fix(fixer) {
+ return fixer.replaceText(firstComment, convertToSeparateLines(firstComment, commentLines));
+ }
+ });
+ },
+ "bare-block"(commentGroup) {
+ if (isJSDocComment(commentGroup)) {
+ return;
+ }
+
+ const [firstComment] = commentGroup;
+ const commentLines = getCommentLines(commentGroup);
+
+ // Disallows consecutive line comments in favor of using a block comment.
+ if (firstComment.type === "Line" && commentLines.length > 1 &&
+ !commentLines.some(value => value.includes("*/"))) {
+ context.report({
+ loc: {
+ start: firstComment.loc.start,
+ end: commentGroup[commentGroup.length - 1].loc.end
+ },
+ messageId: "expectedBlock",
+ fix(fixer) {
+ return fixer.replaceTextRange(
+ [firstComment.range[0], commentGroup[commentGroup.length - 1].range[1]],
+ convertToBlock(firstComment, commentLines)
+ );
+ }
+ });
+ }
+
+ // Prohibits block comments from having a * at the beginning of each line.
+ if (isStarredBlockComment(commentGroup)) {
+ context.report({
+ loc: {
+ start: firstComment.loc.start,
+ end: { line: firstComment.loc.start.line, column: firstComment.loc.start.column + 2 }
+ },
+ messageId: "expectedBareBlock",
+ fix(fixer) {
+ return fixer.replaceText(firstComment, convertToBlock(firstComment, commentLines));
+ }
+ });
+ }
+ }
+ };
+
+ //----------------------------------------------------------------------
+ // Public
+ //----------------------------------------------------------------------
+
+ return {
+ Program() {
+ return sourceCode.getAllComments()
+ .filter(comment => comment.type !== "Shebang")
+ .filter(comment => !astUtils.COMMENTS_IGNORE_PATTERN.test(comment.value))
+ .filter(comment => {
+ const tokenBefore = sourceCode.getTokenBefore(comment, { includeComments: true });
+
+ return !tokenBefore || tokenBefore.loc.end.line < comment.loc.start.line;
+ })
+ .reduce((commentGroups, comment, index, commentList) => {
+ const tokenBefore = sourceCode.getTokenBefore(comment, { includeComments: true });
+
+ if (
+ comment.type === "Line" &&
+ index && commentList[index - 1].type === "Line" &&
+ tokenBefore && tokenBefore.loc.end.line === comment.loc.start.line - 1 &&
+ tokenBefore === commentList[index - 1]
+ ) {
+ commentGroups[commentGroups.length - 1].push(comment);
+ } else {
+ commentGroups.push([comment]);
+ }
+
+ return commentGroups;
+ }, [])
+ .filter(commentGroup => !(commentGroup.length === 1 && commentGroup[0].loc.start.line === commentGroup[0].loc.end.line))
+ .forEach(commentGroupCheckers[option]);
+ }
+ };
+ }
+};
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