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/**
* @fileoverview enforce a particular style for multiline comments
* @author Teddy Katz
*/
"use strict";
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "Enforce a particular style for multiline comments",
recommended: false,
url: "https://eslint.org/docs/latest/rules/multiline-comment-style"
},
fixable: "whitespace",
schema: {
anyOf: [
{
type: "array",
items: [
{
enum: ["starred-block", "bare-block"]
}
],
additionalItems: false
},
{
type: "array",
items: [
{
enum: ["separate-lines"]
},
{
type: "object",
properties: {
checkJSDoc: {
type: "boolean"
}
},
additionalProperties: false
}
],
additionalItems: false
}
]
},
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.sourceCode;
const option = context.options[0] || "starred-block";
const params = context.options[1] || {};
const checkJSDoc = !!params.checkJSDoc;
//----------------------------------------------------------------------
// 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)}${initialOffset}`;
if (/^\s*\//u.test(lineText) && offset.length === 0) {
offset += " ";
}
break;
}
return fixer.replaceTextRange([lineStartIndex, commentTextStartIndex], `${expectedLinePrefix}${offset}`);
}
});
}
}
}
},
"separate-lines"(commentGroup) {
const [firstComment] = commentGroup;
const isJSDoc = isJSDocComment(commentGroup);
if (firstComment.type !== "Block" || (!checkJSDoc && isJSDoc)) {
return;
}
let commentLines = getCommentLines(commentGroup);
if (isJSDoc) {
commentLines = commentLines.slice(1, commentLines.length - 1);
}
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]);
}
};
}
};