105 lines
3.2 KiB
JavaScript
105 lines
3.2 KiB
JavaScript
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/**
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* @fileoverview Rule to flag when the same variable is declared more then once.
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* @author Ilya Volodin
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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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type: "suggestion",
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docs: {
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description: "disallow variable redeclaration",
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category: "Best Practices",
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recommended: true,
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url: "https://eslint.org/docs/rules/no-redeclare"
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},
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schema: [
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{
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type: "object",
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properties: {
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builtinGlobals: { type: "boolean", default: false }
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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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create(context) {
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const options = {
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builtinGlobals: context.options[0] && context.options[0].builtinGlobals
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};
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/**
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* Find variables in a given scope and flag redeclared ones.
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* @param {Scope} scope - An eslint-scope scope object.
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* @returns {void}
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* @private
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*/
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function findVariablesInScope(scope) {
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scope.variables.forEach(variable => {
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const hasBuiltin = options.builtinGlobals && "writeable" in variable;
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const count = (hasBuiltin ? 1 : 0) + variable.identifiers.length;
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if (count >= 2) {
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variable.identifiers.sort((a, b) => a.range[1] - b.range[1]);
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for (let i = (hasBuiltin ? 0 : 1), l = variable.identifiers.length; i < l; i++) {
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context.report({ node: variable.identifiers[i], message: "'{{a}}' is already defined.", data: { a: variable.name } });
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}
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}
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});
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}
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/**
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* Find variables in the current scope.
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* @param {ASTNode} node - The Program node.
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* @returns {void}
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* @private
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*/
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function checkForGlobal(node) {
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const scope = context.getScope(),
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parserOptions = context.parserOptions,
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ecmaFeatures = parserOptions.ecmaFeatures || {};
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// Nodejs env or modules has a special scope.
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if (ecmaFeatures.globalReturn || node.sourceType === "module") {
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findVariablesInScope(scope.childScopes[0]);
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} else {
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findVariablesInScope(scope);
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}
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}
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/**
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* Find variables in the current scope.
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* @returns {void}
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* @private
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*/
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function checkForBlock() {
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findVariablesInScope(context.getScope());
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}
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if (context.parserOptions.ecmaVersion >= 6) {
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return {
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Program: checkForGlobal,
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BlockStatement: checkForBlock,
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SwitchStatement: checkForBlock
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};
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}
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return {
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Program: checkForGlobal,
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FunctionDeclaration: checkForBlock,
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FunctionExpression: checkForBlock,
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ArrowFunctionExpression: checkForBlock
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};
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}
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};
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