383 lines
16 KiB
JavaScript
383 lines
16 KiB
JavaScript
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/**
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* @fileoverview Rule to flag statements without curly braces
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* @author Nicholas C. Zakas
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require("../util/ast-utils");
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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module.exports = {
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meta: {
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type: "suggestion",
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docs: {
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description: "enforce consistent brace style for all control statements",
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category: "Best Practices",
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recommended: false,
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url: "https://eslint.org/docs/rules/curly"
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},
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schema: {
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anyOf: [
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{
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type: "array",
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items: [
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{
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enum: ["all"]
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}
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],
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minItems: 0,
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maxItems: 1
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},
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{
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type: "array",
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items: [
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{
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enum: ["multi", "multi-line", "multi-or-nest"]
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},
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{
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enum: ["consistent"]
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}
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],
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minItems: 0,
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maxItems: 2
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}
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]
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},
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fixable: "code",
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messages: {
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missingCurlyAfter: "Expected { after '{{name}}'.",
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missingCurlyAfterCondition: "Expected { after '{{name}}' condition.",
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unexpectedCurlyAfter: "Unnecessary { after '{{name}}'.",
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unexpectedCurlyAfterCondition: "Unnecessary { after '{{name}}' condition."
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}
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},
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create(context) {
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const multiOnly = (context.options[0] === "multi");
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const multiLine = (context.options[0] === "multi-line");
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const multiOrNest = (context.options[0] === "multi-or-nest");
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const consistent = (context.options[1] === "consistent");
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const sourceCode = context.getSourceCode();
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//--------------------------------------------------------------------------
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// Helpers
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//--------------------------------------------------------------------------
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/**
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* Determines if a given node is a one-liner that's on the same line as it's preceding code.
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* @param {ASTNode} node The node to check.
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* @returns {boolean} True if the node is a one-liner that's on the same line as it's preceding code.
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* @private
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*/
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function isCollapsedOneLiner(node) {
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const before = sourceCode.getTokenBefore(node);
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const last = sourceCode.getLastToken(node);
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const lastExcludingSemicolon = astUtils.isSemicolonToken(last) ? sourceCode.getTokenBefore(last) : last;
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return before.loc.start.line === lastExcludingSemicolon.loc.end.line;
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}
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/**
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* Determines if a given node is a one-liner.
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* @param {ASTNode} node The node to check.
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* @returns {boolean} True if the node is a one-liner.
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* @private
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*/
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function isOneLiner(node) {
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const first = sourceCode.getFirstToken(node),
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last = sourceCode.getLastToken(node);
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return first.loc.start.line === last.loc.end.line;
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}
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/**
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* Checks if the given token is an `else` token or not.
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*
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* @param {Token} token - The token to check.
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* @returns {boolean} `true` if the token is an `else` token.
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*/
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function isElseKeywordToken(token) {
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return token.value === "else" && token.type === "Keyword";
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}
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/**
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* Gets the `else` keyword token of a given `IfStatement` node.
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* @param {ASTNode} node - A `IfStatement` node to get.
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* @returns {Token} The `else` keyword token.
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*/
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function getElseKeyword(node) {
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return node.alternate && sourceCode.getFirstTokenBetween(node.consequent, node.alternate, isElseKeywordToken);
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}
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/**
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* Checks a given IfStatement node requires braces of the consequent chunk.
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* This returns `true` when below:
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*
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* 1. The given node has the `alternate` node.
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* 2. There is a `IfStatement` which doesn't have `alternate` node in the
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* trailing statement chain of the `consequent` node.
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*
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* @param {ASTNode} node - A IfStatement node to check.
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* @returns {boolean} `true` if the node requires braces of the consequent chunk.
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*/
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function requiresBraceOfConsequent(node) {
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if (node.alternate && node.consequent.type === "BlockStatement") {
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if (node.consequent.body.length >= 2) {
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return true;
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}
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for (
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let currentNode = node.consequent.body[0];
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currentNode;
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currentNode = astUtils.getTrailingStatement(currentNode)
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) {
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if (currentNode.type === "IfStatement" && !currentNode.alternate) {
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return true;
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}
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}
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}
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return false;
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}
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/**
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* Determines if a semicolon needs to be inserted after removing a set of curly brackets, in order to avoid a SyntaxError.
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* @param {Token} closingBracket The } token
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* @returns {boolean} `true` if a semicolon needs to be inserted after the last statement in the block.
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*/
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function needsSemicolon(closingBracket) {
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const tokenBefore = sourceCode.getTokenBefore(closingBracket);
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const tokenAfter = sourceCode.getTokenAfter(closingBracket);
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const lastBlockNode = sourceCode.getNodeByRangeIndex(tokenBefore.range[0]);
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if (astUtils.isSemicolonToken(tokenBefore)) {
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// If the last statement already has a semicolon, don't add another one.
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return false;
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}
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if (!tokenAfter) {
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// If there are no statements after this block, there is no need to add a semicolon.
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return false;
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}
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if (lastBlockNode.type === "BlockStatement" && lastBlockNode.parent.type !== "FunctionExpression" && lastBlockNode.parent.type !== "ArrowFunctionExpression") {
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/*
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* If the last node surrounded by curly brackets is a BlockStatement (other than a FunctionExpression or an ArrowFunctionExpression),
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* don't insert a semicolon. Otherwise, the semicolon would be parsed as a separate statement, which would cause
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* a SyntaxError if it was followed by `else`.
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*/
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return false;
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}
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if (tokenBefore.loc.end.line === tokenAfter.loc.start.line) {
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// If the next token is on the same line, insert a semicolon.
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return true;
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}
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if (/^[([/`+-]/u.test(tokenAfter.value)) {
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// If the next token starts with a character that would disrupt ASI, insert a semicolon.
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return true;
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}
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if (tokenBefore.type === "Punctuator" && (tokenBefore.value === "++" || tokenBefore.value === "--")) {
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// If the last token is ++ or --, insert a semicolon to avoid disrupting ASI.
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return true;
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}
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// Otherwise, do not insert a semicolon.
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return false;
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}
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/**
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* Prepares to check the body of a node to see if it's a block statement.
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* @param {ASTNode} node The node to report if there's a problem.
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* @param {ASTNode} body The body node to check for blocks.
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* @param {string} name The name to report if there's a problem.
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* @param {{ condition: boolean }} opts Options to pass to the report functions
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* @returns {Object} a prepared check object, with "actual", "expected", "check" properties.
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* "actual" will be `true` or `false` whether the body is already a block statement.
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* "expected" will be `true` or `false` if the body should be a block statement or not, or
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* `null` if it doesn't matter, depending on the rule options. It can be modified to change
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* the final behavior of "check".
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* "check" will be a function reporting appropriate problems depending on the other
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* properties.
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*/
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function prepareCheck(node, body, name, opts) {
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const hasBlock = (body.type === "BlockStatement");
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let expected = null;
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if (node.type === "IfStatement" && node.consequent === body && requiresBraceOfConsequent(node)) {
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expected = true;
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} else if (multiOnly) {
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if (hasBlock && body.body.length === 1) {
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expected = false;
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}
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} else if (multiLine) {
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if (!isCollapsedOneLiner(body)) {
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expected = true;
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}
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} else if (multiOrNest) {
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if (hasBlock && body.body.length === 1 && isOneLiner(body.body[0])) {
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const leadingComments = sourceCode.getCommentsBefore(body.body[0]);
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expected = leadingComments.length > 0;
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} else if (!isOneLiner(body)) {
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expected = true;
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}
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} else {
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expected = true;
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}
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return {
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actual: hasBlock,
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expected,
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check() {
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if (this.expected !== null && this.expected !== this.actual) {
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if (this.expected) {
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context.report({
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node,
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loc: (name !== "else" ? node : getElseKeyword(node)).loc.start,
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messageId: opts && opts.condition ? "missingCurlyAfterCondition" : "missingCurlyAfter",
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data: {
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name
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},
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fix: fixer => fixer.replaceText(body, `{${sourceCode.getText(body)}}`)
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});
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} else {
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context.report({
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node,
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loc: (name !== "else" ? node : getElseKeyword(node)).loc.start,
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messageId: opts && opts.condition ? "unexpectedCurlyAfterCondition" : "unexpectedCurlyAfter",
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data: {
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name
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},
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fix(fixer) {
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/*
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* `do while` expressions sometimes need a space to be inserted after `do`.
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* e.g. `do{foo()} while (bar)` should be corrected to `do foo() while (bar)`
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*/
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const needsPrecedingSpace = node.type === "DoWhileStatement" &&
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sourceCode.getTokenBefore(body).range[1] === body.range[0] &&
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!astUtils.canTokensBeAdjacent("do", sourceCode.getFirstToken(body, { skip: 1 }));
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const openingBracket = sourceCode.getFirstToken(body);
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const closingBracket = sourceCode.getLastToken(body);
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const lastTokenInBlock = sourceCode.getTokenBefore(closingBracket);
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if (needsSemicolon(closingBracket)) {
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/*
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* If removing braces would cause a SyntaxError due to multiple statements on the same line (or
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* change the semantics of the code due to ASI), don't perform a fix.
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*/
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return null;
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}
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const resultingBodyText = sourceCode.getText().slice(openingBracket.range[1], lastTokenInBlock.range[0]) +
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sourceCode.getText(lastTokenInBlock) +
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sourceCode.getText().slice(lastTokenInBlock.range[1], closingBracket.range[0]);
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return fixer.replaceText(body, (needsPrecedingSpace ? " " : "") + resultingBodyText);
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}
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});
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}
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}
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}
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};
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}
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/**
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* Prepares to check the bodies of a "if", "else if" and "else" chain.
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* @param {ASTNode} node The first IfStatement node of the chain.
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* @returns {Object[]} prepared checks for each body of the chain. See `prepareCheck` for more
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* information.
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*/
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function prepareIfChecks(node) {
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const preparedChecks = [];
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for (let currentNode = node; currentNode; currentNode = currentNode.alternate) {
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preparedChecks.push(prepareCheck(currentNode, currentNode.consequent, "if", { condition: true }));
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if (currentNode.alternate && currentNode.alternate.type !== "IfStatement") {
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preparedChecks.push(prepareCheck(currentNode, currentNode.alternate, "else"));
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break;
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}
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}
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if (consistent) {
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/*
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* If any node should have or already have braces, make sure they
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* all have braces.
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* If all nodes shouldn't have braces, make sure they don't.
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*/
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const expected = preparedChecks.some(preparedCheck => {
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if (preparedCheck.expected !== null) {
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return preparedCheck.expected;
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}
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return preparedCheck.actual;
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});
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preparedChecks.forEach(preparedCheck => {
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preparedCheck.expected = expected;
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});
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}
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return preparedChecks;
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}
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//--------------------------------------------------------------------------
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// Public
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//--------------------------------------------------------------------------
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return {
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IfStatement(node) {
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if (node.parent.type !== "IfStatement") {
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prepareIfChecks(node).forEach(preparedCheck => {
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preparedCheck.check();
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});
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}
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},
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WhileStatement(node) {
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prepareCheck(node, node.body, "while", { condition: true }).check();
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},
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DoWhileStatement(node) {
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prepareCheck(node, node.body, "do").check();
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},
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ForStatement(node) {
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prepareCheck(node, node.body, "for", { condition: true }).check();
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},
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ForInStatement(node) {
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prepareCheck(node, node.body, "for-in").check();
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},
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ForOfStatement(node) {
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prepareCheck(node, node.body, "for-of").check();
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}
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};
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}
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};
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