--- /dev/null
+/**
+ * @fileoverview Rule to flag block statements that do not use the one true brace style
+ * @author Ian Christian Myers
+ */
+
+"use strict";
+
+const astUtils = require("./utils/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",
+ default: false
+ }
+ },
+ 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));
+ }
+ }
+ };
+ }
+};
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