time-to-botec

main.js (4933B)

---

 /**
 * @license Apache-2.0
 *
 * Copyright (c) 2018 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 isCollection = require( '@stdlib/assert/is-collection' );
 var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
 var isInteger = require( '@stdlib/assert/is-integer' ).isPrimitive;
 var iteratorSymbol = require( '@stdlib/symbol/iterator' );
 
 
 // MAIN //
 
 /**
 * Returns an iterator which iterates over elements in an array-like object according to specified stride parameters.
 *
 * @param {NonNegativeInteger} N - number of values to iterate
 * @param {Collection} src - input value
 * @param {integer} stride - stride length
 * @param {NonNegativeInteger} offset - starting index
 * @param {Function} [mapFcn] - function to invoke for each iterated value
 * @param {*} [thisArg] - execution context
 * @throws {TypeError} first argument must be a nonnegative integer
 * @throws {TypeError} second argument must be an array-like object
 * @throws {TypeError} third argument must be an integer
 * @throws {TypeError} fourth argument must be a nonnegative integer
 * @throws {TypeError} fifth argument must be a function
 * @returns {Iterator} iterator
 *
 * @example
 * var values = [ 1, 2, 3, 4, 5, 6, 7, 8 ];
 *
 * var N = 4;
 * var stride = -2;
 * var offset = 6;
 *
 * var iter = stridedarray2iterator( N, values, stride, offset );
 *
 * var v = iter.next().value;
 * // returns 7
 *
 * v = iter.next().value;
 * // returns 5
 *
 * v = iter.next().value;
 * // returns 3
 *
 * // ...
 */
 function stridedarray2iterator( N, src, stride, offset ) {
 	var thisArg;
 	var iter;
 	var FLG;
 	var fcn;
 	var idx;
 	var i;
 	if ( !isNonNegativeInteger( N ) ) {
 		throw new TypeError( 'invalid argument. First argument must be a nonnegative integer. Value: `' + N + '`.' );
 	}
 	if ( !isCollection( src ) ) {
 		throw new TypeError( 'invalid argument. Second argument must be an array-like object. Value: `' + src + '`.' );
 	}
 	if ( !isInteger( stride ) ) {
 		throw new TypeError( 'invalid argument. Third argument must be an integer. Value: `' + stride + '`.' );
 	}
 	if ( !isNonNegativeInteger( offset ) ) {
 		throw new TypeError( 'invalid argument. Fourth argument must be a nonnegative integer. Value: `' + offset + '`.' );
 	}
 	if ( arguments.length > 4 ) {
 		fcn = arguments[ 4 ];
 		if ( !isFunction( fcn ) ) {
 			throw new TypeError( 'invalid argument. Fifth argument must be a function. Value: `' + fcn + '`.' );
 		}
 		thisArg = arguments[ 5 ];
 	}
 	idx = offset;
 	i = -1;
 
 	// Create an iterator protocol-compliant object:
 	iter = {};
 	if ( fcn ) {
 		setReadOnly( iter, 'next', next1 );
 	} else {
 		setReadOnly( iter, 'next', next2 );
 	}
 	setReadOnly( iter, 'return', end );
 
 	// If an environment supports `Symbol.iterator`, make the iterator iterable:
 	if ( iteratorSymbol ) {
 		setReadOnly( iter, iteratorSymbol, factory );
 	}
 	return iter;
 
 	/**
 	* Returns an iterator protocol-compliant object containing the next iterated value.
 	*
 	* @private
 	* @returns {Object} iterator protocol-compliant object
 	*/
 	function next1() {
 		var v;
 		i += 1;
 		if ( FLG || i >= N ) {
 			return {
 				'done': true
 			};
 		}
 		v = fcn.call( thisArg, src[ idx ], idx, i, src );
 		idx += stride;
 		return {
 			'value': v,
 			'done': false
 		};
 	}
 
 	/**
 	* Returns an iterator protocol-compliant object containing the next iterated value.
 	*
 	* @private
 	* @returns {Object} iterator protocol-compliant object
 	*/
 	function next2() {
 		var v;
 		i += 1;
 		if ( FLG || i >= N ) {
 			return {
 				'done': true
 			};
 		}
 		v = src[ idx ];
 		idx += stride;
 		return {
 			'value': v,
 			'done': false
 		};
 	}
 
 	/**
 	* Finishes an iterator.
 	*
 	* @private
 	* @param {*} [value] - value to return
 	* @returns {Object} iterator protocol-compliant object
 	*/
 	function end( value ) {
 		FLG = true;
 		if ( arguments.length ) {
 			return {
 				'value': value,
 				'done': true
 			};
 		}
 		return {
 			'done': true
 		};
 	}
 
 	/**
 	* Returns a new iterator.
 	*
 	* @private
 	* @returns {Iterator} iterator
 	*/
 	function factory() {
 		if ( fcn ) {
 			return stridedarray2iterator( N, src, stride, offset, fcn, thisArg ); // eslint-disable-line max-len
 		}
 		return stridedarray2iterator( N, src, stride, offset );
 	}
 }
 
 
 // EXPORTS //
 
 module.exports = stridedarray2iterator;