time-to-botec

main.js (6230B)

---

 /**
 * @license Apache-2.0
 *
 * Copyright (c) 2020 The Stdlib Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
 'use strict';
 
 // MODULES //
 
 var setReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
 var isFunction = require( '@stdlib/assert/is-function' );
 var isIteratorLike = require( '@stdlib/assert/is-iterator-like' );
 var isNumber = require( '@stdlib/assert/is-number' ).isPrimitive;
 var hasOwnProp = require( '@stdlib/assert/has-own-property' );
 var iteratorSymbol = require( '@stdlib/symbol/iterator' );
 var validate = require( './validate.js' );
 
 
 // MAIN //
 
 /**
 * Returns an iterator which invokes a binary function accepting numeric arguments for each iterated value.
 *
 * ## Notes
 *
 * -   When invoked, the input function is provided two arguments:
 *
 *     -   `x`: iterated value from first input iterator
 *     -   `y`: iterated value from second input iterator
 *
 * -   If provided a numeric value as an iterator argument, the value is broadcast as an **infinite** iterator which **always** returns the provided value.
 *
 * -   If an iterated value is non-numeric (including `NaN`), the returned iterator returns `NaN`. If non-numeric iterated values are possible, you are advised to provide an iterator which type checks and handles non-numeric values accordingly.
 *
 * -   The length of the returned iterator is equal to the length of the shortest provided iterator. In other words, the returned iterator ends once **one** of the provided iterators ends.
 *
 * -   If an environment supports `Symbol.iterator` and all provided iterators are iterable, the returned iterator is iterable.
 *
 * @param {Iterator} iter0 - first input iterator
 * @param {Iterator} iter1 - second input iterator
 * @param {Function} fcn - function to invoke
 * @param {Options} [options] - options
 * @param {*} [options.invalid=NaN] - return value when an input iterator yields a non-numeric value
 * @throws {TypeError} first argument must be an iterator protocol-compliant object
 * @throws {TypeError} second argument must be an iterator protocol-compliant object
 * @throws {TypeError} third argument must be a function
 * @throws {TypeError} options argument must be an object
 * @throws {TypeError} must provide valid options
 * @returns {Iterator} iterator
 *
 * @example
 * var randu = require( '@stdlib/random/iter/randu' );
 * var copysign = require( '@stdlib/math/base/special/copysign' );
 *
 * var iter = iterMap2( randu(), randu(), copysign );
 *
 * var r = iter.next().value;
 * // returns <number>
 *
 * r = iter.next().value;
 * // returns <number>
 *
 * r = iter.next().value;
 * // returns <number>
 *
 * // ...
 */
 function iterMap2( iter0, iter1, fcn, options ) {
 	var iterators;
 	var values;
 	var types;
 	var niter;
 	var iter;
 	var opts;
 	var FLG;
 	var err;
 	var i;
 
 	niter = 2;
 	values = [ 0.0, 0.0 ];
 
 	iterators = [];
 	types = [];
 	for ( i = 0; i < niter; i++ ) {
 		iterators.push( arguments[ i ] );
 		if ( isIteratorLike( arguments[ i ] ) ) {
 			types.push( 1 );
 		} else if ( isNumber( arguments[ i ] ) ) {
 			types.push( 0 );
 		} else {
 			throw new TypeError( 'invalid argument. Must provide an iterator protocol-compliant object or a number. Argument: `' + i + '`. Value: `' + arguments[ i ] + '`.' );
 		}
 	}
 	if ( !isFunction( fcn ) ) {
 		throw new TypeError( 'invalid argument. Third argument must be a function. Value: `' + fcn + '`.' );
 	}
 	opts = {
 		'invalid': NaN
 	};
 	if ( arguments.length > 3 ) {
 		err = validate( opts, options );
 		if ( err ) {
 			throw err;
 		}
 	}
 	// Create an iterator protocol-compliant object:
 	iter = {};
 	setReadOnly( iter, 'next', next );
 	setReadOnly( iter, 'return', end );
 
 	// If an environment supports `Symbol.iterator` and all provided iterators are iterable, make the iterator iterable:
 	if ( iteratorSymbol ) {
 		for ( i = 0; i < niter; i++ ) {
 			if ( types[ i ] && !isFunction( iterators[ i ][ iteratorSymbol ] ) ) { // eslint-disable-line max-len
 				FLG = true;
 				break;
 			}
 		}
 		if ( !FLG ) {
 			setReadOnly( iter, iteratorSymbol, factory );
 		}
 	}
 	FLG = 0;
 	return iter;
 
 	/**
 	* Returns an iterator protocol-compliant object containing the next iterated value.
 	*
 	* @private
 	* @returns {Object} iterator protocol-compliant object
 	*/
 	function next() {
 		var err;
 		var v;
 		var i;
 		if ( FLG ) {
 			return {
 				'done': true
 			};
 		}
 		FLG = 0;
 		err = 0;
 		for ( i = 0; i < niter; i++ ) {
 			if ( types[ i ] ) {
 				v = iterators[ i ].next();
 				if ( v.done ) {
 					FLG += 1;
 					if ( hasOwnProp( v, 'value' ) ) {
 						if ( typeof v.value === 'number' ) {
 							values[ i ] = v.value;
 						} else {
 							err = 1;
 						}
 						continue;
 					}
 					return {
 						'done': true
 					};
 				}
 				if ( typeof v.value === 'number' ) {
 					values[ i ] = v.value;
 				} else {
 					err = 1;
 				}
 			} else {
 				values[ i ] = iterators[ i ];
 			}
 		}
 		if ( err ) {
 			return {
 				'value': opts.invalid,
 				'done': false
 			};
 		}
 		return {
 			'value': fcn( values[ 0 ], values[ 1 ] ),
 			'done': false
 		};
 	}
 
 	/**
 	* Finishes an iterator.
 	*
 	* @private
 	* @param {*} [value] - value to return
 	* @returns {Object} iterator protocol-compliant object
 	*/
 	function end( value ) {
 		FLG = 1;
 		if ( arguments.length ) {
 			return {
 				'value': value,
 				'done': true
 			};
 		}
 		return {
 			'done': true
 		};
 	}
 
 	/**
 	* Returns a new iterator.
 	*
 	* @private
 	* @returns {Iterator} iterator
 	*/
 	function factory() {
 		var args;
 		var i;
 
 		args = [];
 		for ( i = 0; i < niter; i++ ) {
 			if ( types[ i ] ) {
 				args.push( iterators[ i ][ iteratorSymbol ]() );
 			} else {
 				args.push( iterators[ i ] );
 			}
 		}
 		args.push( fcn, opts );
 		return iterMap2.apply( null, args );
 	}
 }
 
 
 // EXPORTS //
 
 module.exports = iterMap2;