135 lines
2.8 KiB
JavaScript
135 lines
2.8 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var objectKeys = require( '@stdlib/utils/keys' );
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// FUNCTIONS //
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/**
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* Tests if a value is an object.
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*
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* ## Notes
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*
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* - The function excludes `null`.
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*
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* @private
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* @param {*} value - value to test
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* @returns {boolean} boolean indicating if a value is an object
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*/
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function isObject( value ) {
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var type = typeof value;
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return ( value !== null && ( type === 'object' || type === 'function' ) );
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}
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/**
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* Tests if the seen array contains a search value.
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*
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* @private
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* @param {Array} seen - array of seen objects
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* @param {*} searchValue - search value
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* @returns {boolean} boolean indicating whether array contains search value
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*/
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function contains( seen, searchValue ) {
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var i;
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for ( i = 0; i < seen.length; i++ ) {
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if ( seen[ i ] === searchValue ) {
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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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* Tests if an object contains a circular reference by recursively traversing object keys.
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*
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* @private
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* @param {Object} obj - object to test
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* @param {Array} seen - array of seen objects
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* @returns {boolean} boolean indicating whether object contains a circular reference
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*/
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function isCircObj( obj, seen ) {
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var keys;
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var val;
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var i;
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seen.push( obj );
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keys = objectKeys( obj );
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if ( keys.length === 0 ) {
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return false;
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}
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for ( i = 0; i < keys.length; i++ ) {
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val = obj[ keys[ i ] ];
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if ( isObject( val ) && ( contains( seen, val ) || isCircObj( val, seen ) ) ) { // eslint-disable-line max-len
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return true;
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}
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}
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seen.pop( obj );
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return false;
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}
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// MAIN //
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/**
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* Tests if an object-like value contains a circular reference.
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*
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* @param {*} value - value to test
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* @returns {boolean} boolean indicating whether value is object-like and contains a circular reference
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*
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* @example
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* var obj = {
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* 'a': 'beep',
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* 'b': {
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* 'c': 'boop'
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* }
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* };
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* obj.b.self = obj;
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* var bool = isCircular( obj );
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* // returns true
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*
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* @example
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* var arr = [ 1, 2, 3 ];
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* arr.push( arr );
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* var bool = isCircular( arr );
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* // returns true
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*
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* @example
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* var bool = isCircular( {} );
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* // returns false
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*
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* @example
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* var bool = isCircular( null );
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* // returns false
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*/
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function isCircular( value ) {
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if ( !isObject( value ) ) {
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return false;
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}
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return isCircObj( value, [] );
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}
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// EXPORTS //
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module.exports = isCircular;
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