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/**
* @fileoverview Rule to flag block statements that do not use the one true brace style
* @author Ian Christian Myers
*/
"use strict";
const astUtils = require("../util/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "layout",
docs: {
description: "enforce consistent brace style for blocks",
category: "Stylistic Issues",
recommended: false,
url: "https://eslint.org/docs/rules/brace-style"
},
schema: [
{
enum: ["1tbs", "stroustrup", "allman"]
},
{
type: "object",
properties: {
allowSingleLine: {
type: "boolean"
}
},
additionalProperties: false
}
],
fixable: "whitespace",
messages: {
nextLineOpen: "Opening curly brace does not appear on the same line as controlling statement.",
sameLineOpen: "Opening curly brace appears on the same line as controlling statement.",
blockSameLine: "Statement inside of curly braces should be on next line.",
nextLineClose: "Closing curly brace does not appear on the same line as the subsequent block.",
singleLineClose: "Closing curly brace should be on the same line as opening curly brace or on the line after the previous block.",
sameLineClose: "Closing curly brace appears on the same line as the subsequent block."
}
},
create(context) {
const style = context.options[0] || "1tbs",
params = context.options[1] || {},
sourceCode = context.getSourceCode();
//--------------------------------------------------------------------------
// Helpers
//--------------------------------------------------------------------------
/**
* Fixes a place where a newline unexpectedly appears
* @param {Token} firstToken The token before the unexpected newline
* @param {Token} secondToken The token after the unexpected newline
* @returns {Function} A fixer function to remove the newlines between the tokens
*/
function removeNewlineBetween(firstToken, secondToken) {
const textRange = [firstToken.range[1], secondToken.range[0]];
const textBetween = sourceCode.text.slice(textRange[0], textRange[1]);
// Don't do a fix if there is a comment between the tokens
if (textBetween.trim()) {
return null;
}
return fixer => fixer.replaceTextRange(textRange, " ");
}
/**
* Validates a pair of curly brackets based on the user's config
* @param {Token} openingCurly The opening curly bracket
* @param {Token} closingCurly The closing curly bracket
* @returns {void}
*/
function validateCurlyPair(openingCurly, closingCurly) {
const tokenBeforeOpeningCurly = sourceCode.getTokenBefore(openingCurly);
const tokenAfterOpeningCurly = sourceCode.getTokenAfter(openingCurly);
const tokenBeforeClosingCurly = sourceCode.getTokenBefore(closingCurly);
const singleLineException = params.allowSingleLine && astUtils.isTokenOnSameLine(openingCurly, closingCurly);
if (style !== "allman" && !astUtils.isTokenOnSameLine(tokenBeforeOpeningCurly, openingCurly)) {
context.report({
node: openingCurly,
messageId: "nextLineOpen",
fix: removeNewlineBetween(tokenBeforeOpeningCurly, openingCurly)
});
}
if (style === "allman" && astUtils.isTokenOnSameLine(tokenBeforeOpeningCurly, openingCurly) && !singleLineException) {
context.report({
node: openingCurly,
messageId: "sameLineOpen",
fix: fixer => fixer.insertTextBefore(openingCurly, "\n")
});
}
if (astUtils.isTokenOnSameLine(openingCurly, tokenAfterOpeningCurly) && tokenAfterOpeningCurly !== closingCurly && !singleLineException) {
context.report({
node: openingCurly,
messageId: "blockSameLine",
fix: fixer => fixer.insertTextAfter(openingCurly, "\n")
});
}
if (tokenBeforeClosingCurly !== openingCurly && !singleLineException && astUtils.isTokenOnSameLine(tokenBeforeClosingCurly, closingCurly)) {
context.report({
node: closingCurly,
messageId: "singleLineClose",
fix: fixer => fixer.insertTextBefore(closingCurly, "\n")
});
}
}
/**
* Validates the location of a token that appears before a keyword (e.g. a newline before `else`)
* @param {Token} curlyToken The closing curly token. This is assumed to precede a keyword token (such as `else` or `finally`).
* @returns {void}
*/
function validateCurlyBeforeKeyword(curlyToken) {
const keywordToken = sourceCode.getTokenAfter(curlyToken);
if (style === "1tbs" && !astUtils.isTokenOnSameLine(curlyToken, keywordToken)) {
context.report({
node: curlyToken,
messageId: "nextLineClose",
fix: removeNewlineBetween(curlyToken, keywordToken)
});
}
if (style !== "1tbs" && astUtils.isTokenOnSameLine(curlyToken, keywordToken)) {
context.report({
node: curlyToken,
messageId: "sameLineClose",
fix: fixer => fixer.insertTextAfter(curlyToken, "\n")
});
}
}
//--------------------------------------------------------------------------
// Public API
//--------------------------------------------------------------------------
return {
BlockStatement(node) {
if (!astUtils.STATEMENT_LIST_PARENTS.has(node.parent.type)) {
validateCurlyPair(sourceCode.getFirstToken(node), sourceCode.getLastToken(node));
}
},
ClassBody(node) {
validateCurlyPair(sourceCode.getFirstToken(node), sourceCode.getLastToken(node));
},
SwitchStatement(node) {
const closingCurly = sourceCode.getLastToken(node);
const openingCurly = sourceCode.getTokenBefore(node.cases.length ? node.cases[0] : closingCurly);
validateCurlyPair(openingCurly, closingCurly);
},
IfStatement(node) {
if (node.consequent.type === "BlockStatement" && node.alternate) {
// Handle the keyword after the `if` block (before `else`)
validateCurlyBeforeKeyword(sourceCode.getLastToken(node.consequent));
}
},
TryStatement(node) {
// Handle the keyword after the `try` block (before `catch` or `finally`)
validateCurlyBeforeKeyword(sourceCode.getLastToken(node.block));
if (node.handler && node.finalizer) {
// Handle the keyword after the `catch` block (before `finally`)
validateCurlyBeforeKeyword(sourceCode.getLastToken(node.handler.body));
}
}
};
}
};