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87 lines
2.7 KiB
87 lines
2.7 KiB
/**
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* @fileoverview Disallow reassignment of function parameters.
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* @author Nat Burns
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* @copyright 2014 Nat Burns. 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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// Helpers
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//--------------------------------------------------------------------------
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/**
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* Finds the declaration for a given variable by name, searching up the scope tree.
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* @param {Scope} scope The scope in which to search.
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* @param {String} name The name of the variable.
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* @returns {Variable} The declaration information for the given variable, or null if no declaration was found.
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*/
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function findDeclaration(scope, name) {
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var variables = scope.variables;
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for (var i = 0; i < variables.length; i++) {
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if (variables[i].name === name) {
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return variables[i];
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}
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}
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if (scope.upper) {
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return findDeclaration(scope.upper, name);
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} else {
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return null;
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}
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}
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/**
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* Determines if a given variable is declared as a function parameter.
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* @param {Variable} variable The variable declaration.
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* @returns {boolean} True if the variable is a function parameter, false otherwise.
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*/
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function isParameter(variable) {
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var defs = variable.defs;
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for (var i = 0; i < defs.length; i++) {
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if (defs[i].type === "Parameter") {
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return true;
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}
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}
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return false;
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}
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/**
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* Checks whether a given node is an assignment to a function parameter.
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* If so, a linting error will be reported.
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* @param {ASTNode} node The node to check.
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* @param {String} name The name of the variable being assigned to.
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* @returns {void}
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*/
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function checkParameter(node, name) {
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var declaration = findDeclaration(context.getScope(), name);
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if (declaration && isParameter(declaration)) {
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context.report(node, "Assignment to function parameter '{{name}}'.", { name: name });
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}
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}
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//--------------------------------------------------------------------------
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// Public
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//--------------------------------------------------------------------------
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return {
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"AssignmentExpression": function(node) {
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checkParameter(node, node.left.name);
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},
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"UpdateExpression": function(node) {
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checkParameter(node, node.argument.name);
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}
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};
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};
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module.exports.schema = [];
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