110 lines
3.5 KiB
JavaScript
110 lines
3.5 KiB
JavaScript
/**
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* @fileoverview Rule to disallow if as the only statement in an else block
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* @author Brandon Mills
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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('./utils/ast-utils');
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../types').Rule.RuleModule} */
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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:
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'Disallow `if` statements as the only statement in `else` blocks',
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recommended: false,
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frozen: true,
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url: 'https://eslint.org/docs/latest/rules/no-lonely-if',
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},
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schema: [],
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fixable: 'code',
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messages: {
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unexpectedLonelyIf:
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'Unexpected if as the only statement in an else block.',
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},
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},
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create(context) {
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const sourceCode = context.sourceCode;
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return {
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IfStatement(node) {
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const parent = node.parent,
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grandparent = parent.parent;
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if (
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parent &&
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parent.type === 'BlockStatement' &&
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parent.body.length === 1 &&
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!astUtils.areBracesNecessary(parent, sourceCode) &&
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grandparent &&
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grandparent.type === 'IfStatement' &&
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parent === grandparent.alternate
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) {
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context.report({
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node,
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messageId: 'unexpectedLonelyIf',
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fix(fixer) {
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const openingElseCurly = sourceCode.getFirstToken(parent);
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const closingElseCurly = sourceCode.getLastToken(parent);
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const elseKeyword = sourceCode.getTokenBefore(openingElseCurly);
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const tokenAfterElseBlock =
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sourceCode.getTokenAfter(closingElseCurly);
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const lastIfToken = sourceCode.getLastToken(node.consequent);
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const sourceText = sourceCode.getText();
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if (
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sourceText
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.slice(openingElseCurly.range[1], node.range[0])
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.trim() ||
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sourceText
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.slice(node.range[1], closingElseCurly.range[0])
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.trim()
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) {
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// Don't fix if there are any non-whitespace characters interfering (e.g. comments)
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return null;
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}
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if (
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node.consequent.type !== 'BlockStatement' &&
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lastIfToken.value !== ';' &&
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tokenAfterElseBlock &&
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(node.consequent.loc.end.line ===
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tokenAfterElseBlock.loc.start.line ||
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/^[([/+`-]/u.test(tokenAfterElseBlock.value) ||
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lastIfToken.value === '++' ||
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lastIfToken.value === '--')
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) {
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/*
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* If the `if` statement has no block, and is not followed by a semicolon, make sure that fixing
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* the issue would not change semantics due to ASI. If this would happen, don't do a fix.
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*/
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return null;
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}
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return fixer.replaceTextRange(
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[openingElseCurly.range[0], closingElseCurly.range[1]],
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(elseKeyword.range[1] === openingElseCurly.range[0] ?
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' '
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: '') + sourceCode.getText(node)
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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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