127 lines
3.2 KiB
JavaScript
127 lines
3.2 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 =
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sourceCode.getFirstToken(parent);
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const closingElseCurly =
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sourceCode.getLastToken(parent);
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const elseKeyword =
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sourceCode.getTokenBefore(openingElseCurly);
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const tokenAfterElseBlock =
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sourceCode.getTokenAfter(closingElseCurly);
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const lastIfToken = sourceCode.getLastToken(
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node.consequent,
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);
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const sourceText = sourceCode.getText();
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if (
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sourceText
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.slice(
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openingElseCurly.range[1],
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node.range[0],
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)
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.trim() ||
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sourceText
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.slice(
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node.range[1],
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closingElseCurly.range[0],
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)
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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(
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tokenAfterElseBlock.value,
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) ||
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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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[
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openingElseCurly.range[0],
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closingElseCurly.range[1],
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],
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(elseKeyword.range[1] ===
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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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