/**
* @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
//----------------------------------------------------------------------
/**
* Gets a list of comment lines in a group
* @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) {
if (commentGroup[0].type === "Line") {
return commentGroup.map(comment => comment.value);
}
return commentGroup[0].value
.split(astUtils.LINEBREAK_MATCHER)
.map(line => line.replace(/^\s*\*?/u, ""));
}
/**
* 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 = sourceCode.text.slice(firstComment.range[0] - firstComment.loc.start.column, firstComment.range[0]);
const starredLines = commentLinesList.map(line => `${initialOffset} *${line}`);
return `\n${starredLines.join("\n")}\n${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) {
const initialOffset = sourceCode.text.slice(firstComment.range[0] - firstComment.loc.start.column, firstComment.range[0]);
const separateLines = commentLinesList.map(line => `// ${line.trim()}`);
return separateLines.join(`\n${initialOffset}`);
}
/**
* 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) {
const initialOffset = sourceCode.text.slice(firstComment.range[0] - firstComment.loc.start.column, firstComment.range[0]);
const blockLines = commentLinesList.map(line => line.trim());
return `/* ${blockLines.join(`\n${initialOffset} `)} */`;
}
/**
* Check a comment is JSDoc form
* @param {Token[]} commentGroup A group of comments, containing either multiple line comments or a single block comment
* @returns {boolean} if commentGroup is JSDoc form, return true
*/
function isJSDoc(commentGroup) {
const lines = commentGroup[0].value.split(astUtils.LINEBREAK_MATCHER);
return commentGroup[0].type === "Block" &&
/^\*\s*$/u.test(lines[0]) &&
lines.slice(1, -1).every(line => /^\s* /u.test(line)) &&
/^\s*$/u.test(lines[lines.length - 1]);
}
/**
* 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 commentLines = getCommentLines(commentGroup);
if (commentLines.some(value => value.includes("*/"))) {
return;
}
if (commentGroup.length > 1) {
context.report({
loc: {
start: commentGroup[0].loc.start,
end: commentGroup[commentGroup.length - 1].loc.end
},
messageId: "expectedBlock",
fix(fixer) {
const range = [commentGroup[0].range[0], commentGroup[commentGroup.length - 1].range[1]];
const starredBlock = `/*${convertToStarredBlock(commentGroup[0], commentLines)}*/`;
return commentLines.some(value => value.startsWith("/"))
? null
: fixer.replaceTextRange(range, starredBlock);
}
});
} else {
const block = commentGroup[0];
const lines = block.value.split(astUtils.LINEBREAK_MATCHER);
const expectedLinePrefix = `${sourceCode.text.slice(block.range[0] - block.loc.start.column, block.range[0])} *`;
if (!/^\*?\s*$/u.test(lines[0])) {
const start = block.value.startsWith("*") ? block.range[0] + 1 : block.range[0];
context.report({
loc: {
start: block.loc.start,
end: { line: block.loc.start.line, column: block.loc.start.column + 2 }
},
messageId: "startNewline",
fix: fixer => fixer.insertTextAfterRange([start, start + 2], `\n${expectedLinePrefix}`)
});
}
if (!/^\s*$/u.test(lines[lines.length - 1])) {
context.report({
loc: {
start: { line: block.loc.end.line, column: block.loc.end.column - 2 },
end: block.loc.end
},
messageId: "endNewline",
fix: fixer => fixer.replaceTextRange([block.range[1] - 2, block.range[1]], `\n${expectedLinePrefix}/`)
});
}
for (let lineNumber = block.loc.start.line + 1; lineNumber <= block.loc.end.line; lineNumber++) {
const lineText = sourceCode.lines[lineNumber - 1];
if (!lineText.startsWith(expectedLinePrefix)) {
context.report({
loc: {
start: { line: lineNumber, column: 0 },
end: { line: lineNumber, column: sourceCode.lines[lineNumber - 1].length }
},
messageId: /^\s*\*/u.test(lineText)
? "alignment"
: "missingStar",
fix(fixer) {
const lineStartIndex = sourceCode.getIndexFromLoc({ line: lineNumber, column: 0 });
const linePrefixLength = lineText.match(/^\s*\*? ?/u)[0].length;
const commentStartIndex = lineStartIndex + linePrefixLength;
const replacementText = lineNumber === block.loc.end.line || lineText.length === linePrefixLength
? expectedLinePrefix
: `${expectedLinePrefix} `;
return fixer.replaceTextRange([lineStartIndex, commentStartIndex], replacementText);
}
});
}
}
}
},
"separate-lines"(commentGroup) {
if (!isJSDoc(commentGroup) && commentGroup[0].type === "Block") {
const commentLines = getCommentLines(commentGroup);
const block = commentGroup[0];
const tokenAfter = sourceCode.getTokenAfter(block, { includeComments: true });
if (tokenAfter && block.loc.end.line === tokenAfter.loc.start.line) {
return;
}
context.report({
loc: {
start: block.loc.start,
end: { line: block.loc.start.line, column: block.loc.start.column + 2 }
},
messageId: "expectedLines",
fix(fixer) {
return fixer.replaceText(block, convertToSeparateLines(block, commentLines.filter(line => line)));
}
});
}
},
"bare-block"(commentGroup) {
if (!isJSDoc(commentGroup)) {
const commentLines = getCommentLines(commentGroup);
// disallows consecutive line comments in favor of using a block comment.
if (commentGroup[0].type === "Line" && commentLines.length > 1 &&
!commentLines.some(value => value.includes("*/"))) {
context.report({
loc: {
start: commentGroup[0].loc.start,
end: commentGroup[commentGroup.length - 1].loc.end
},
messageId: "expectedBlock",
fix(fixer) {
const range = [commentGroup[0].range[0], commentGroup[commentGroup.length - 1].range[1]];
const block = convertToBlock(commentGroup[0], commentLines.filter(line => line));
return fixer.replaceTextRange(range, block);
}
});
}
// prohibits block comments from having a * at the beginning of each line.
if (commentGroup[0].type === "Block") {
const block = commentGroup[0];
const lines = block.value.split(astUtils.LINEBREAK_MATCHER).filter(line => line.trim());
if (lines.length > 0 && lines.every(line => /^\s*\*/u.test(line))) {
context.report({
loc: {
start: block.loc.start,
end: { line: block.loc.start.line, column: block.loc.start.column + 2 }
},
messageId: "expectedBareBlock",
fix(fixer) {
return fixer.replaceText(block, convertToBlock(block, commentLines.filter(line => line)));
}
});
}
}
}
}
};
//----------------------------------------------------------------------
// 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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