time-to-botec

Benchmark sampling in different programming languages
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funseq_async.js (3133B)

      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 isFunction = require( '@stdlib/assert/is-function' );
     24 
     25 
     26 // MAIN //
     27 
     28 /**
     29 * Function sequence.
     30 *
     31 * @param {...Function} f - functions to evaluate in sequential order
     32 * @throws {Error} must provide more than one argument
     33 * @throws {TypeError} must provide functions
     34 * @returns {Function} pipeline function
     35 *
     36 * @example
     37 * function a( x, next ) {
     38 *     setTimeout( onTimeout, 0 );
     39 *     function onTimeout() {
     40 *         next( null, 2*x );
     41 *     }
     42 * }
     43 *
     44 * function b( x, next ) {
     45 *     setTimeout( onTimeout, 0 );
     46 *     function onTimeout() {
     47 *         next( null, x+3 );
     48 *     }
     49 * }
     50 *
     51 * function c( x, next ) {
     52 *     setTimeout( onTimeout, 0 );
     53 *     function onTimeout() {
     54 *         next( null, x/5 );
     55 *     }
     56 * }
     57 *
     58 * var f = funseqAsync( a, b, c );
     59 *
     60 * function done( error, result ) {
     61 *     if ( error ) {
     62 *         throw error;
     63 *     }
     64 *     console.log( result );
     65 *     // => 3
     66 * }
     67 *
     68 * f( 6, done );
     69 */
     70 function funseqAsync() {
     71 	var nFuncs;
     72 	var f;
     73 	var i;
     74 	nFuncs = arguments.length;
     75 	if ( nFuncs < 2 ) {
     76 		throw new Error( 'insufficient input arguments. Must provide multiple functions to execute sequentially.' );
     77 	}
     78 	f = new Array( nFuncs );
     79 	for ( i = 0; i < nFuncs; i++ ) {
     80 		f[ i ] = arguments[ i ];
     81 		if ( !isFunction( f[ i ] ) ) {
     82 			throw new TypeError( 'invalid argument. All arguments must be functions. Value: `'+f[ i ]+'`.' );
     83 		}
     84 	}
     85 	return pipeline;
     86 
     87 	/**
     88 	* Pipeline function.
     89 	*
     90 	* @private
     91 	* @param {...*} args - arguments
     92 	* @param {Callback} done - callback to invoke after invoking all functions
     93 	*/
     94 	function pipeline() {
     95 		var done;
     96 		var args;
     97 		var i;
     98 
     99 		// Cache the callback function:
    100 		done = arguments[ arguments.length-1 ];
    101 
    102 		// Copy arguments which should be provided to the first invoked function...
    103 		args = new Array( arguments.length-1 );
    104 		for ( i = 0; i < args.length; i++ ) {
    105 			args[ i ] = arguments[ i ];
    106 		}
    107 		// Append the callback an invoked function should call upon completion:
    108 		args.push( next );
    109 
    110 		// Start invoking provided functions:
    111 		i = 0;
    112 		f[ i ].apply( null, args );
    113 
    114 		/**
    115 		* Callback invoked upon completion of a provided function.
    116 		*
    117 		* @private
    118 		* @param {(Error|null)} error - error object
    119 		* @param {*} result - result to pass to next function
    120 		* @returns {void}
    121 		*/
    122 		function next( error, result ) {
    123 			if ( error ) {
    124 				return done( error );
    125 			}
    126 			i += 1;
    127 			if ( i === nFuncs ) {
    128 				return done( null, result );
    129 			}
    130 			f[ i ]( result, next );
    131 		}
    132 	}
    133 }
    134 
    135 
    136 // EXPORTS //
    137 
    138 module.exports = funseqAsync;