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92 lines
2.9 KiB
92 lines
2.9 KiB
10 years ago
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/**
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* @fileoverview A rule to suggest using of const declaration for variables that are never modified after declared.
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* @author Toru Nagashima
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* @copyright 2015 Toru Nagashima. All rights reserved.
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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 = function(context) {
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/**
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* Checks whether a reference is the initializer.
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* @param {Reference} reference - A reference to check.
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* @returns {boolean} Whether or not the reference is the initializer.
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*/
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function isInitializer(reference) {
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return reference.init === true;
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}
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/**
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* Checks whether a reference is read-only or the initializer.
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* @param {Reference} reference - A reference to check.
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* @returns {boolean} Whether or not the reference is read-only or the initializer.
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*/
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function isReadOnlyOrInitializer(reference) {
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return reference.isReadOnly() || reference.init === true;
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}
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/**
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* Searches and reports variables that are never modified after declared.
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* @param {Scope} scope - A scope of the search domain.
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* @returns {void}
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*/
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function checkForVariables(scope) {
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// Skip the TDZ type.
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if (scope.type === "TDZ") {
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return;
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}
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var variables = scope.variables;
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for (var i = 0, end = variables.length; i < end; ++i) {
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var variable = variables[i];
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var def = variable.defs[0];
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var declaration = def && def.parent;
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var statement = declaration && declaration.parent;
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var references = variable.references;
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var identifier = variable.identifiers[0];
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if (statement != null &&
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identifier != null &&
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declaration.type === "VariableDeclaration" &&
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declaration.kind === "let" &&
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(statement.type !== "ForStatement" || statement.init !== declaration) &&
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references.some(isInitializer) &&
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references.every(isReadOnlyOrInitializer)
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) {
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context.report(
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identifier,
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"`{{name}}` is never modified, use `const` instead.",
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{name: identifier.name});
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}
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}
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}
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/**
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* Adds multiple items to the tail of an array.
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* @param {any[]} array - A destination to add.
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* @param {any[]} values - Items to be added.
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* @returns {void}
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*/
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var pushAll = Function.apply.bind(Array.prototype.push);
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return {
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"Program:exit": function () {
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var stack = [context.getScope()];
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while (stack.length) {
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var scope = stack.pop();
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pushAll(stack, scope.childScopes);
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checkForVariables(scope);
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}
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}
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};
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};
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module.exports.schema = [];
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