90 lines
3.7 KiB
JavaScript
90 lines
3.7 KiB
JavaScript
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/**
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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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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../shared/types').Rule} */
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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: "disallow `if` statements as the only statement in `else` blocks",
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recommended: false,
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url: "https://eslint.org/docs/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: "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.getSourceCode();
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return {
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IfStatement(node) {
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const ancestors = context.getAncestors(),
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parent = ancestors.pop(),
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grandparent = ancestors.pop();
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if (parent && parent.type === "BlockStatement" &&
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parent.body.length === 1 && grandparent &&
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grandparent.type === "IfStatement" &&
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parent === grandparent.alternate) {
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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 = 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 (sourceText.slice(openingElseCurly.range[1],
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node.range[0]).trim() || sourceText.slice(node.range[1], closingElseCurly.range[0]).trim()) {
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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" && lastIfToken.value !== ";" && tokenAfterElseBlock &&
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(
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node.consequent.loc.end.line === 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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/*
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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] ? " " : "") + 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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