time-to-botec

Benchmark sampling in different programming languages
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factory.js (2950B)

      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 isFunctionArray = require( '@stdlib/assert/is-function-array' );
     24 var isFunction = require( '@stdlib/assert/is-function' );
     25 
     26 
     27 // MAIN //
     28 
     29 /**
     30 * Returns a reusable waterfall function.
     31 *
     32 * @param {FunctionArray} fcns - array of functions
     33 * @param {Callback} clbk - callback to invoke upon completion
     34 * @param {*} [thisArg] - function context
     35 * @throws {TypeError} first argument must be an array of functions
     36 * @throws {TypeError} second argument must be a function
     37 * @returns {Function} waterfall function
     38 *
     39 * @example
     40 * function foo( next ) {
     41 *     next( null, 'beep' );
     42 * }
     43 *
     44 * function bar( str, next ) {
     45 *     console.log( str );
     46 *     // => 'beep'
     47 *
     48 *     next();
     49 * }
     50 *
     51 * function done( error ) {
     52 *     if ( error ) {
     53 *         throw error;
     54 *     }
     55 * }
     56 *
     57 * var fcns = [ foo, bar ];
     58 *
     59 * var waterfall = factory( fcns, done );
     60 *
     61 * waterfall();
     62 * waterfall();
     63 * waterfall();
     64 */
     65 function factory( fcns, clbk, thisArg ) {
     66 	if ( !isFunctionArray( fcns ) ) {
     67 		throw new TypeError( 'invalid argument. First argument must be a function array. Value: `' + fcns + '`.' );
     68 	}
     69 	if ( !isFunction( clbk ) ) {
     70 		throw new TypeError( 'invalid argument. Second argument must be a function. Value: `' + clbk + '`.' );
     71 	}
     72 	return waterfall;
     73 
     74 	/**
     75 	* Executes functions in series, passing the results of one function as arguments to the next function.
     76 	*
     77 	* @private
     78 	*/
     79 	function waterfall() {
     80 		var idx = -1;
     81 		next(); // eslint-disable-line callback-return
     82 
     83 		/**
     84 		* Executes the next function in the series.
     85 		*
     86 		* @private
     87 		* @param {(Error|null)} error - error object
     88 		* @param {...*} args - results to pass to next callback
     89 		* @returns {void}
     90 		*/
     91 		function next() {
     92 			var args;
     93 			var len;
     94 			var i;
     95 
     96 			// Check for an error...
     97 			if ( arguments[ 0 ] ) {
     98 				return clbk( arguments[ 0 ] );
     99 			}
    100 			// Update the counter and check if we have run all functions...
    101 			idx += 1;
    102 			if ( idx >= fcns.length ) {
    103 				return clbk();
    104 			}
    105 			// Copy the remaining arguments...
    106 			len = arguments.length;
    107 			args = new Array( len );
    108 			for ( i = 0; i < len-1; i++ ) {
    109 				args[ i ] = arguments[ i+1 ];
    110 			}
    111 			// Add the callback:
    112 			args[ i ] = next;
    113 
    114 			// Apply the arguments to the next function in the waterfall:
    115 			fcns[ idx ].apply( thisArg, args );
    116 		}
    117 	}
    118 }
    119 
    120 
    121 // EXPORTS //
    122 
    123 module.exports = factory;