368 lines
14 KiB
JavaScript
368 lines
14 KiB
JavaScript
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/**
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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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// Rule Definition
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//------------------------------------------------------------------------------
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module.exports = {
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meta: {
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docs: {
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description: "enforce variables to be declared either together or separately in functions",
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category: "Stylistic Issues",
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recommended: false
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},
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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"]
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},
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{
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type: "object",
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properties: {
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var: {
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enum: ["always", "never"]
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},
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let: {
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enum: ["always", "never"]
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},
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const: {
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enum: ["always", "never"]
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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"]
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},
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uninitialized: {
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enum: ["always", "never"]
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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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},
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create(context) {
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const MODE_ALWAYS = "always",
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MODE_NEVER = "never";
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const mode = context.options[0] || MODE_ALWAYS;
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const options = {
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};
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if (typeof mode === "string") { // 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") { // options configuration is an object
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if (mode.hasOwnProperty("var") && typeof mode.var === "string") {
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options.var = { uninitialized: mode.var, initialized: mode.var };
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}
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if (mode.hasOwnProperty("let") && typeof mode.let === "string") {
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options.let = { uninitialized: mode.let, initialized: mode.let };
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}
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if (mode.hasOwnProperty("const") && typeof mode.const === "string") {
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options.const = { uninitialized: mode.const, initialized: mode.const };
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}
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if (mode.hasOwnProperty("uninitialized")) {
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if (!options.var) {
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options.var = {};
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}
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if (!options.let) {
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options.let = {};
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}
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if (!options.const) {
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options.const = {};
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}
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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 (mode.hasOwnProperty("initialized")) {
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if (!options.var) {
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options.var = {};
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}
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if (!options.let) {
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options.let = {};
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}
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if (!options.const) {
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options.const = {};
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}
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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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//--------------------------------------------------------------------------
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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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* Records whether initialized or uninitialized 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 (options[statementType] && options[statementType].uninitialized === MODE_ALWAYS) {
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currentScope.uninitialized = true;
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}
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} else {
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if (options[statementType] && options[statementType].initialized === MODE_ALWAYS) {
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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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* 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[functionStack.length - 1];
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} else if (statementType === "let") {
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currentScope = blockStack[blockStack.length - 1].let;
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} else if (statementType === "const") {
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currentScope = blockStack[blockStack.length - 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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if (currentOptions.uninitialized === MODE_ALWAYS && currentOptions.initialized === MODE_ALWAYS) {
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if (currentScope.uninitialized || currentScope.initialized) {
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return false;
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}
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}
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if (declarationCounts.uninitialized > 0) {
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if (currentOptions.uninitialized === MODE_ALWAYS && currentScope.uninitialized) {
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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 (currentOptions.initialized === MODE_ALWAYS && currentScope.initialized) {
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return false;
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}
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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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// Public API
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//--------------------------------------------------------------------------
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return {
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Program: startFunction,
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FunctionDeclaration: startFunction,
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FunctionExpression: startFunction,
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ArrowFunctionExpression: startFunction,
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BlockStatement: startBlock,
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ForStatement: startBlock,
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ForInStatement: startBlock,
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ForOfStatement: startBlock,
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SwitchStatement: startBlock,
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VariableDeclaration(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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// always
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if (!hasOnlyOneStatement(type, declarations)) {
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if (options[type].initialized === MODE_ALWAYS && options[type].uninitialized === MODE_ALWAYS) {
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context.report({
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node,
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message: "Combine this with the previous '{{type}}' statement.",
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data: {
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type
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}
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});
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} else {
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if (options[type].initialized === MODE_ALWAYS) {
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context.report({
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node,
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message: "Combine this with the previous '{{type}}' statement with initialized variables.",
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data: {
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type
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}
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});
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}
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if (options[type].uninitialized === MODE_ALWAYS) {
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if (node.parent.left === node && (node.parent.type === "ForInStatement" || node.parent.type === "ForOfStatement")) {
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return;
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}
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context.report({
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node,
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message: "Combine this with the previous '{{type}}' statement with uninitialized variables.",
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data: {
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type
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}
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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) {
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const totalDeclarations = declarationCounts.uninitialized + declarationCounts.initialized;
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if (totalDeclarations > 1) {
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if (options[type].initialized === MODE_NEVER && options[type].uninitialized === MODE_NEVER) {
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// both initialized and uninitialized
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context.report({
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node,
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message: "Split '{{type}}' declarations into multiple statements.",
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data: {
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type
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}
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});
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} else if (options[type].initialized === MODE_NEVER && declarationCounts.initialized > 0) {
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// initialized
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context.report({
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node,
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message: "Split initialized '{{type}}' declarations into multiple statements.",
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data: {
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type
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}
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});
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} else if (options[type].uninitialized === MODE_NEVER && declarationCounts.uninitialized > 0) {
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// uninitialized
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context.report({
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node,
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message: "Split uninitialized '{{type}}' declarations into multiple statements.",
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data: {
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type
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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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"ForStatement:exit": endBlock,
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"ForOfStatement:exit": endBlock,
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"ForInStatement:exit": endBlock,
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"SwitchStatement:exit": endBlock,
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"BlockStatement:exit": endBlock,
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"Program:exit": endFunction,
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"FunctionDeclaration:exit": endFunction,
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"FunctionExpression:exit": endFunction,
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"ArrowFunctionExpression:exit": endFunction
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};
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}
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};
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