685 lines
18 KiB
JavaScript
685 lines
18 KiB
JavaScript
/**
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* @fileoverview A rule to control the use of single variable declarations.
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* @author Ian Christian Myers
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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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// Helpers
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//------------------------------------------------------------------------------
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/**
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* Determines whether the given node is in a statement list.
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* @param {ASTNode} node node to check
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* @returns {boolean} `true` if the given node is in a statement list
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*/
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function isInStatementList(node) {
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return astUtils.STATEMENT_LIST_PARENTS.has(node.parent.type);
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}
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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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"Enforce variables to be declared either together or separately in functions",
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recommended: false,
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frozen: true,
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url: "https://eslint.org/docs/latest/rules/one-var",
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},
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fixable: "code",
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schema: [
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{
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oneOf: [
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{
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enum: ["always", "never", "consecutive"],
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},
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{
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type: "object",
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properties: {
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separateRequires: {
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type: "boolean",
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},
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var: {
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enum: ["always", "never", "consecutive"],
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},
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let: {
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enum: ["always", "never", "consecutive"],
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},
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const: {
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enum: ["always", "never", "consecutive"],
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},
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},
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additionalProperties: false,
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},
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{
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type: "object",
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properties: {
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initialized: {
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enum: ["always", "never", "consecutive"],
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},
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uninitialized: {
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enum: ["always", "never", "consecutive"],
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},
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},
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additionalProperties: false,
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},
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],
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},
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],
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messages: {
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combineUninitialized:
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"Combine this with the previous '{{type}}' statement with uninitialized variables.",
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combineInitialized:
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"Combine this with the previous '{{type}}' statement with initialized variables.",
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splitUninitialized:
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"Split uninitialized '{{type}}' declarations into multiple statements.",
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splitInitialized:
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"Split initialized '{{type}}' declarations into multiple statements.",
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splitRequires:
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"Split requires to be separated into a single block.",
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combine: "Combine this with the previous '{{type}}' statement.",
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split: "Split '{{type}}' declarations into multiple statements.",
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},
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},
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create(context) {
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const MODE_ALWAYS = "always";
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const MODE_NEVER = "never";
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const MODE_CONSECUTIVE = "consecutive";
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const mode = context.options[0] || MODE_ALWAYS;
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const options = {};
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if (typeof mode === "string") {
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// simple options configuration with just a string
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options.var = { uninitialized: mode, initialized: mode };
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options.let = { uninitialized: mode, initialized: mode };
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options.const = { uninitialized: mode, initialized: mode };
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} else if (typeof mode === "object") {
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// options configuration is an object
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options.separateRequires = !!mode.separateRequires;
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options.var = { uninitialized: mode.var, initialized: mode.var };
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options.let = { uninitialized: mode.let, initialized: mode.let };
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options.const = {
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uninitialized: mode.const,
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initialized: mode.const,
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};
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if (Object.hasOwn(mode, "uninitialized")) {
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options.var.uninitialized = mode.uninitialized;
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options.let.uninitialized = mode.uninitialized;
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options.const.uninitialized = mode.uninitialized;
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}
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if (Object.hasOwn(mode, "initialized")) {
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options.var.initialized = mode.initialized;
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options.let.initialized = mode.initialized;
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options.const.initialized = mode.initialized;
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}
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}
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const sourceCode = context.sourceCode;
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//--------------------------------------------------------------------------
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// Helpers
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//--------------------------------------------------------------------------
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const functionStack = [];
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const blockStack = [];
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/**
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* Increments the blockStack counter.
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* @returns {void}
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* @private
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*/
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function startBlock() {
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blockStack.push({
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let: { initialized: false, uninitialized: false },
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const: { initialized: false, uninitialized: false },
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});
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}
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/**
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* Increments the functionStack counter.
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* @returns {void}
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* @private
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*/
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function startFunction() {
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functionStack.push({ initialized: false, uninitialized: false });
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startBlock();
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}
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/**
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* Decrements the blockStack counter.
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* @returns {void}
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* @private
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*/
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function endBlock() {
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blockStack.pop();
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}
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/**
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* Decrements the functionStack counter.
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* @returns {void}
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* @private
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*/
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function endFunction() {
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functionStack.pop();
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endBlock();
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}
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/**
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* Check if a variable declaration is a require.
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* @param {ASTNode} decl variable declaration Node
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* @returns {bool} if decl is a require, return true; else return false.
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* @private
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*/
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function isRequire(decl) {
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return (
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decl.init &&
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decl.init.type === "CallExpression" &&
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decl.init.callee.name === "require"
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);
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}
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/**
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* Records whether initialized/uninitialized/required variables are defined in current scope.
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* @param {string} statementType node.kind, one of: "var", "let", or "const"
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* @param {ASTNode[]} declarations List of declarations
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* @param {Object} currentScope The scope being investigated
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* @returns {void}
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* @private
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*/
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function recordTypes(statementType, declarations, currentScope) {
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for (let i = 0; i < declarations.length; i++) {
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if (declarations[i].init === null) {
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if (
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options[statementType] &&
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options[statementType].uninitialized === MODE_ALWAYS
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) {
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currentScope.uninitialized = true;
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}
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} else {
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if (
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options[statementType] &&
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options[statementType].initialized === MODE_ALWAYS
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) {
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if (
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options.separateRequires &&
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isRequire(declarations[i])
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) {
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currentScope.required = true;
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} else {
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currentScope.initialized = true;
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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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* Determines the current scope (function or block)
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* @param {string} statementType node.kind, one of: "var", "let", or "const"
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* @returns {Object} The scope associated with statementType
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*/
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function getCurrentScope(statementType) {
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let currentScope;
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if (statementType === "var") {
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currentScope = functionStack.at(-1);
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} else if (statementType === "let") {
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currentScope = blockStack.at(-1).let;
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} else if (statementType === "const") {
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currentScope = blockStack.at(-1).const;
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}
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return currentScope;
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}
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/**
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* Counts the number of initialized and uninitialized declarations in a list of declarations
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* @param {ASTNode[]} declarations List of declarations
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* @returns {Object} Counts of 'uninitialized' and 'initialized' declarations
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* @private
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*/
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function countDeclarations(declarations) {
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const counts = { uninitialized: 0, initialized: 0 };
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for (let i = 0; i < declarations.length; i++) {
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if (declarations[i].init === null) {
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counts.uninitialized++;
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} else {
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counts.initialized++;
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}
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}
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return counts;
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}
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/**
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* Determines if there is more than one var statement in the current scope.
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* @param {string} statementType node.kind, one of: "var", "let", or "const"
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* @param {ASTNode[]} declarations List of declarations
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* @returns {boolean} Returns true if it is the first var declaration, false if not.
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* @private
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*/
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function hasOnlyOneStatement(statementType, declarations) {
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const declarationCounts = countDeclarations(declarations);
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const currentOptions = options[statementType] || {};
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const currentScope = getCurrentScope(statementType);
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const hasRequires = declarations.some(isRequire);
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if (
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currentOptions.uninitialized === MODE_ALWAYS &&
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currentOptions.initialized === MODE_ALWAYS
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) {
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if (currentScope.uninitialized || currentScope.initialized) {
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if (!hasRequires) {
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return false;
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}
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}
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}
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if (declarationCounts.uninitialized > 0) {
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if (
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currentOptions.uninitialized === MODE_ALWAYS &&
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currentScope.uninitialized
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) {
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return false;
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}
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}
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if (declarationCounts.initialized > 0) {
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if (
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currentOptions.initialized === MODE_ALWAYS &&
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currentScope.initialized
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) {
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if (!hasRequires) {
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return false;
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}
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}
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}
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if (currentScope.required && hasRequires) {
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return false;
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}
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recordTypes(statementType, declarations, currentScope);
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return true;
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}
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/**
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* Fixer to join VariableDeclaration's into a single declaration
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* @param {VariableDeclarator[]} declarations The `VariableDeclaration` to join
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* @returns {Function} The fixer function
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*/
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function joinDeclarations(declarations) {
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const declaration = declarations[0];
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const body = Array.isArray(declaration.parent.parent.body)
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? declaration.parent.parent.body
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: [];
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const currentIndex = body.findIndex(
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node => node.range[0] === declaration.parent.range[0],
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);
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const previousNode = body[currentIndex - 1];
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return fixer => {
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const type = sourceCode.getTokenBefore(declaration);
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const prevSemi = sourceCode.getTokenBefore(type);
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const res = [];
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if (
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previousNode &&
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previousNode.kind === sourceCode.getText(type)
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) {
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if (prevSemi.value === ";") {
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res.push(fixer.replaceText(prevSemi, ","));
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} else {
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res.push(fixer.insertTextAfter(prevSemi, ","));
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}
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res.push(fixer.replaceText(type, ""));
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}
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return res;
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};
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}
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/**
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* Fixer to split a VariableDeclaration into individual declarations
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* @param {VariableDeclaration} declaration The `VariableDeclaration` to split
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* @returns {Function|null} The fixer function
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*/
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function splitDeclarations(declaration) {
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const { parent } = declaration;
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// don't autofix code such as: if (foo) var x, y;
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if (
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!isInStatementList(
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parent.type === "ExportNamedDeclaration"
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? parent
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: declaration,
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)
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) {
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return null;
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}
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return fixer =>
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declaration.declarations
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.map(declarator => {
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const tokenAfterDeclarator =
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sourceCode.getTokenAfter(declarator);
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if (tokenAfterDeclarator === null) {
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return null;
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}
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const afterComma = sourceCode.getTokenAfter(
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tokenAfterDeclarator,
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{ includeComments: true },
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);
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if (tokenAfterDeclarator.value !== ",") {
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return null;
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}
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const exportPlacement =
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declaration.parent.type === "ExportNamedDeclaration"
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? "export "
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: "";
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/*
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* `var x,y`
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* tokenAfterDeclarator ^^ afterComma
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*/
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if (
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afterComma.range[0] ===
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tokenAfterDeclarator.range[1]
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) {
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return fixer.replaceText(
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tokenAfterDeclarator,
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`; ${exportPlacement}${declaration.kind} `,
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);
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}
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/*
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* `var x,
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* tokenAfterDeclarator ^
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* y`
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* ^ afterComma
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*/
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if (
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afterComma.loc.start.line >
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tokenAfterDeclarator.loc.end.line ||
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afterComma.type === "Line" ||
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afterComma.type === "Block"
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) {
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let lastComment = afterComma;
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while (
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lastComment.type === "Line" ||
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lastComment.type === "Block"
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) {
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lastComment = sourceCode.getTokenAfter(
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lastComment,
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{ includeComments: true },
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);
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}
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return fixer.replaceTextRange(
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[
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tokenAfterDeclarator.range[0],
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lastComment.range[0],
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],
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`;${sourceCode.text.slice(tokenAfterDeclarator.range[1], lastComment.range[0])}${exportPlacement}${declaration.kind} `,
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);
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}
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return fixer.replaceText(
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tokenAfterDeclarator,
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`; ${exportPlacement}${declaration.kind}`,
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);
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})
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.filter(x => x);
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}
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/**
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* Checks a given VariableDeclaration node for errors.
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* @param {ASTNode} node The VariableDeclaration node to check
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* @returns {void}
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* @private
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*/
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function checkVariableDeclaration(node) {
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const parent = node.parent;
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const type = node.kind;
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if (!options[type]) {
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return;
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}
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const declarations = node.declarations;
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const declarationCounts = countDeclarations(declarations);
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const mixedRequires =
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declarations.some(isRequire) && !declarations.every(isRequire);
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if (options[type].initialized === MODE_ALWAYS) {
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if (options.separateRequires && mixedRequires) {
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context.report({
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node,
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messageId: "splitRequires",
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});
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}
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}
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// consecutive
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const nodeIndex =
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(parent.body &&
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parent.body.length > 0 &&
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parent.body.indexOf(node)) ||
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0;
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if (nodeIndex > 0) {
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const previousNode = parent.body[nodeIndex - 1];
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const isPreviousNodeDeclaration =
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previousNode.type === "VariableDeclaration";
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const declarationsWithPrevious = declarations.concat(
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previousNode.declarations || [],
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);
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if (
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isPreviousNodeDeclaration &&
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previousNode.kind === type &&
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!(
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declarationsWithPrevious.some(isRequire) &&
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!declarationsWithPrevious.every(isRequire)
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)
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) {
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const previousDeclCounts = countDeclarations(
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previousNode.declarations,
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);
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if (
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options[type].initialized === MODE_CONSECUTIVE &&
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options[type].uninitialized === MODE_CONSECUTIVE
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) {
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context.report({
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node,
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messageId: "combine",
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data: {
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type,
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},
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fix: joinDeclarations(declarations),
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});
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} else if (
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options[type].initialized === MODE_CONSECUTIVE &&
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declarationCounts.initialized > 0 &&
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previousDeclCounts.initialized > 0
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) {
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context.report({
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node,
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messageId: "combineInitialized",
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data: {
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type,
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},
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fix: joinDeclarations(declarations),
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});
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} else if (
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options[type].uninitialized === MODE_CONSECUTIVE &&
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declarationCounts.uninitialized > 0 &&
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previousDeclCounts.uninitialized > 0
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) {
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context.report({
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node,
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messageId: "combineUninitialized",
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data: {
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type,
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},
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fix: joinDeclarations(declarations),
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});
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}
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}
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}
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// always
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if (!hasOnlyOneStatement(type, declarations)) {
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if (
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options[type].initialized === MODE_ALWAYS &&
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options[type].uninitialized === MODE_ALWAYS
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) {
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context.report({
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node,
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messageId: "combine",
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data: {
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type,
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},
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fix: joinDeclarations(declarations),
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});
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} else {
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if (
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options[type].initialized === MODE_ALWAYS &&
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declarationCounts.initialized > 0
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) {
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context.report({
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node,
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messageId: "combineInitialized",
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data: {
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type,
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},
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fix: joinDeclarations(declarations),
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});
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}
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if (
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options[type].uninitialized === MODE_ALWAYS &&
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declarationCounts.uninitialized > 0
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) {
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if (
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node.parent.left === node &&
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(node.parent.type === "ForInStatement" ||
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node.parent.type === "ForOfStatement")
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) {
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return;
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}
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context.report({
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node,
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messageId: "combineUninitialized",
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data: {
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type,
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},
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fix: joinDeclarations(declarations),
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});
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}
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}
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}
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// never
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|
if (parent.type !== "ForStatement" || parent.init !== node) {
|
|
const totalDeclarations =
|
|
declarationCounts.uninitialized +
|
|
declarationCounts.initialized;
|
|
|
|
if (totalDeclarations > 1) {
|
|
if (
|
|
options[type].initialized === MODE_NEVER &&
|
|
options[type].uninitialized === MODE_NEVER
|
|
) {
|
|
// both initialized and uninitialized
|
|
context.report({
|
|
node,
|
|
messageId: "split",
|
|
data: {
|
|
type,
|
|
},
|
|
fix: splitDeclarations(node),
|
|
});
|
|
} else if (
|
|
options[type].initialized === MODE_NEVER &&
|
|
declarationCounts.initialized > 0
|
|
) {
|
|
// initialized
|
|
context.report({
|
|
node,
|
|
messageId: "splitInitialized",
|
|
data: {
|
|
type,
|
|
},
|
|
fix: splitDeclarations(node),
|
|
});
|
|
} else if (
|
|
options[type].uninitialized === MODE_NEVER &&
|
|
declarationCounts.uninitialized > 0
|
|
) {
|
|
// uninitialized
|
|
context.report({
|
|
node,
|
|
messageId: "splitUninitialized",
|
|
data: {
|
|
type,
|
|
},
|
|
fix: splitDeclarations(node),
|
|
});
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//--------------------------------------------------------------------------
|
|
// Public API
|
|
//--------------------------------------------------------------------------
|
|
|
|
return {
|
|
Program: startFunction,
|
|
FunctionDeclaration: startFunction,
|
|
FunctionExpression: startFunction,
|
|
ArrowFunctionExpression: startFunction,
|
|
StaticBlock: startFunction, // StaticBlock creates a new scope for `var` variables
|
|
|
|
BlockStatement: startBlock,
|
|
ForStatement: startBlock,
|
|
ForInStatement: startBlock,
|
|
ForOfStatement: startBlock,
|
|
SwitchStatement: startBlock,
|
|
VariableDeclaration: checkVariableDeclaration,
|
|
"ForStatement:exit": endBlock,
|
|
"ForOfStatement:exit": endBlock,
|
|
"ForInStatement:exit": endBlock,
|
|
"SwitchStatement:exit": endBlock,
|
|
"BlockStatement:exit": endBlock,
|
|
|
|
"Program:exit": endFunction,
|
|
"FunctionDeclaration:exit": endFunction,
|
|
"FunctionExpression:exit": endFunction,
|
|
"ArrowFunctionExpression:exit": endFunction,
|
|
"StaticBlock:exit": endFunction,
|
|
};
|
|
},
|
|
};
|