time-to-botec

Benchmark sampling in different programming languages
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object_inverse.js (3105B)

      1 /**
      2 * @license Apache-2.0
      3 *
      4 * Copyright (c) 2018 The Stdlib Authors.
      5 *
      6 * Licensed under the Apache License, Version 2.0 (the "License");
      7 * you may not use this file except in compliance with the License.
      8 * You may obtain a copy of the License at
      9 *
     10 *    http://www.apache.org/licenses/LICENSE-2.0
     11 *
     12 * Unless required by applicable law or agreed to in writing, software
     13 * distributed under the License is distributed on an "AS IS" BASIS,
     14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15 * See the License for the specific language governing permissions and
     16 * limitations under the License.
     17 */
     18 
     19 'use strict';
     20 
     21 // MODULES //
     22 
     23 var objectKeys = require( './../../keys' );
     24 var isArray = require( '@stdlib/assert/is-array' );
     25 var isObject = require( '@stdlib/assert/is-plain-object' );
     26 var isObjectLike = require( '@stdlib/assert/is-object-like' );
     27 var isBoolean = require( '@stdlib/assert/is-boolean' ).isPrimitive;
     28 var hasOwnProp = require( '@stdlib/assert/has-own-property' );
     29 
     30 
     31 // MAIN //
     32 
     33 /**
     34 * Inverts an object, such that keys become values and values become keys.
     35 *
     36 * @param {ObjectLike} obj - input object
     37 * @param {Options} [opts] - function options
     38 * @param {boolean} [opts.duplicates=true] - boolean indicating whether to store duplicate keys
     39 * @throws {TypeError} first argument must be object-like
     40 * @throws {TypeError} second argument must an an object
     41 * @throws {TypeError} must provide valid options
     42 * @returns {Object} inverted object
     43 *
     44 * @example
     45 * var out = invert({
     46 *     'a': 'beep',
     47 *     'b': 'boop'
     48 * });
     49 * // returns { 'beep': 'a', 'boop': 'b' }
     50 *
     51 * @example
     52 * var out = invert({
     53 *     'a': 'beep',
     54 *     'b': 'beep'
     55 * });
     56 * // returns { 'beep': [ 'a', 'b' ] }
     57 *
     58 * @example
     59 * var obj = {};
     60 * obj.a = 'beep';
     61 * obj.b = 'boop';
     62 * obj.c = 'beep'; // inserted after `a`
     63 *
     64 * var out = invert( obj, {
     65 *     'duplicates': false
     66 * });
     67 * // returns { 'beep': 'c', 'boop': 'b' }
     68 */
     69 function invert( obj, opts ) {
     70 	var allowDupes = true;
     71 	var keys;
     72 	var len;
     73 	var key;
     74 	var val;
     75 	var out;
     76 	var v;
     77 	var i;
     78 	if ( !isObjectLike( obj ) ) {
     79 		throw new TypeError( 'invalid argument. First argument must be object-like. Value: `' + obj + '`.' );
     80 	}
     81 	if ( arguments.length > 1 ) {
     82 		if ( !isObject( opts ) ) {
     83 			throw new TypeError( 'invalid argument. Options arguments must be an object. Value: `' + opts + '`.' );
     84 		}
     85 		if ( hasOwnProp( opts, 'duplicates' ) ) {
     86 			allowDupes = opts.duplicates;
     87 			if ( !isBoolean( allowDupes ) ) {
     88 				throw new TypeError( 'invalid argument. `duplicates` option must be a boolean primitive. Option: `' + allowDupes + '`.' );
     89 			}
     90 		}
     91 	}
     92 	keys = objectKeys( obj );
     93 	len = keys.length;
     94 	out = {};
     95 	if ( allowDupes ) {
     96 		for ( i = 0; i < len; i++ ) {
     97 			key = keys[ i ];
     98 			val = obj[ key ];
     99 			if ( !hasOwnProp( out, val ) ) {
    100 				out[ val ] = key;
    101 				continue;
    102 			}
    103 			v = out[ val ];
    104 			if ( isArray( v ) ) {
    105 				out[ val ].push( key );
    106 			} else {
    107 				out[ val ] = [ v, key ];
    108 			}
    109 		}
    110 	} else {
    111 		for ( i = 0; i < len; i++ ) {
    112 			key = keys[ i ];
    113 			out[ obj[ key ] ] = key;
    114 		}
    115 	}
    116 	return out;
    117 }
    118 
    119 
    120 // EXPORTS //
    121 
    122 module.exports = invert;