time-to-botec

factory.js (8515B)

---

 /**
 * @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 setReadOnlyAccessor = require( '@stdlib/utils/define-nonenumerable-read-only-accessor' );
 var setReadWriteAccessor = require( '@stdlib/utils/define-nonenumerable-read-write-accessor' );
 var isObject = require( '@stdlib/assert/is-plain-object' );
 var isFunction = require( '@stdlib/assert/is-function' );
 var hasOwnProp = require( '@stdlib/assert/has-own-property' );
 var constantFunction = require( '@stdlib/utils/constant-function' );
 var noop = require( '@stdlib/utils/noop' );
 var randi = require( './../../../base/mt19937' ).factory;
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var isInteger = require( '@stdlib/math/base/assert/is-integer' );
 var typedarray2json = require( '@stdlib/array/to-json' );
 var validate = require( './validate.js' );
 var discreteUniform0 = require( './discrete_uniform.js' );
 
 
 // MAIN //
 
 /**
 * Returns a pseudorandom number generator for generating random numbers draw from a discrete uniform distribution.
 *
 * @param {integer} [a] - minimum support
 * @param {integer} [b] - maximum support
 * @param {Options} [options] - function options
 * @param {PRNG} [options.prng] - pseudorandom number generator which generates uniformly distributed pseudorandom integers
 * @param {PRNGSeedMT19937} [options.seed] - pseudorandom number generator seed
 * @param {PRNGStateMT19937} [options.state] - pseudorandom number generator state
 * @param {boolean} [options.copy=true] - boolean indicating whether to copy a provided pseudorandom number generator state
 * @throws {TypeError} `a` must be an integer
 * @throws {TypeError} `b` must be an integer
 * @throws {RangeError} `a` must be less than `b`
 * @throws {TypeError} options argument must be an object
 * @throws {TypeError} must provide valid options
 * @throws {TypeError} provided PRNG must have a valid `MIN` property
 * @throws {TypeError} provided PRNG must have a valid `MAX` property
 * @throws {Error} must provide a valid state
 * @returns {PRNG} pseudorandom number generator
 *
 * @example
 * var discreteUniform = factory( 1, 10 );
 * var v = discreteUniform();
 * // returns <number>
 *
 * @example
 * var discreteUniform = factory( -30, -1, {
 *     'seed': 297
 * });
 * var v = discreteUniform();
 * // returns <number>
 */
 function factory() {
 	var opts;
 	var rand;
 	var prng;
 	var err;
 	var a;
 	var b;
 
 	if ( arguments.length === 0 ) {
 		rand = randi();
 	} else if ( arguments.length === 1 ) {
 		opts = arguments[ 0 ];
 		if ( !isObject( opts ) ) {
 			throw new TypeError( 'invalid argument. Options argument must be an object. Value: `'+opts+'`.' );
 		}
 		if ( hasOwnProp( opts, 'prng' ) ) {
 			if ( !isFunction( opts.prng ) ) {
 				throw new TypeError( 'invalid option. `prng` option must be a pseudorandom number generator function. Option: `' + opts.prng + '`.' );
 			}
 			rand = opts.prng;
 			if ( !isInteger( rand.MIN ) ) {
 				throw new TypeError( 'invalid option. `prng` option must have a `MIN` property specifying the minimum possible pseudorandom integer value.' );
 			}
 			if ( !isInteger( rand.MAX ) ) {
 				throw new TypeError( 'invalid option. `prng` option must have a `MAX` property specifying the maximum possible pseudorandom integer value.' );
 			}
 		} else {
 			rand = randi( opts );
 		}
 	} else {
 		a = arguments[ 0 ];
 		b = arguments[ 1 ];
 		err = validate( a, b );
 		if ( err ) {
 			throw err;
 		}
 		if ( arguments.length > 2 ) {
 			opts = arguments[ 2 ];
 			if ( !isObject( opts ) ) {
 				throw new TypeError( 'invalid argument. Options argument must be an object. Value: `'+opts+'`.' );
 			}
 			if ( hasOwnProp( opts, 'prng' ) ) {
 				if ( !isFunction( opts.prng ) ) {
 					throw new TypeError( 'invalid option. `prng` option must be a pseudorandom number generator function. Option: `' + opts.prng + '`.' );
 				}
 				rand = opts.prng;
 				if ( !isInteger( rand.MIN ) ) {
 					throw new TypeError( 'invalid option. `prng` option must have a `MIN` property specifying the minimum possible pseudorandom integer value.' );
 				}
 				if ( !isInteger( rand.MAX ) ) {
 					throw new TypeError( 'invalid option. `prng` option must have a `MAX` property specifying the maximum possible pseudorandom integer value.' );
 				}
 			} else {
 				rand = randi( opts );
 			}
 		} else {
 			rand = randi();
 		}
 	}
 	if ( a === void 0 ) {
 		prng = discreteUniform2;
 	} else {
 		prng = discreteUniform1;
 	}
 	setReadOnly( prng, 'NAME', 'discrete-uniform' );
 
 	// If we are provided an "external" PRNG, we don't support getting or setting PRNG state, as we'd need to check for compatible state value types, etc, entailing considerable complexity.
 	if ( opts && opts.prng ) {
 		setReadOnly( prng, 'seed', null );
 		setReadOnly( prng, 'seedLength', null );
 		setReadWriteAccessor( prng, 'state', constantFunction( null ), noop );
 		setReadOnly( prng, 'stateLength', null );
 		setReadOnly( prng, 'byteLength', null );
 		setReadOnly( prng, 'toJSON', constantFunction( null ) );
 		setReadOnly( prng, 'PRNG', rand );
 	} else {
 		setReadOnlyAccessor( prng, 'seed', getSeed );
 		setReadOnlyAccessor( prng, 'seedLength', getSeedLength );
 		setReadWriteAccessor( prng, 'state', getState, setState );
 		setReadOnlyAccessor( prng, 'stateLength', getStateLength );
 		setReadOnlyAccessor( prng, 'byteLength', getStateSize );
 		setReadOnly( prng, 'toJSON', toJSON );
 		setReadOnly( prng, 'PRNG', rand );
 	}
 	return prng;
 
 	/**
 	* Returns the PRNG seed.
 	*
 	* @private
 	* @returns {PRNGSeedMT19937} seed
 	*/
 	function getSeed() {
 		return rand.seed;
 	}
 
 	/**
 	* Returns the PRNG seed length.
 	*
 	* @private
 	* @returns {PositiveInteger} seed length
 	*/
 	function getSeedLength() {
 		return rand.seedLength;
 	}
 
 	/**
 	* Returns the PRNG state length.
 	*
 	* @private
 	* @returns {PositiveInteger} state length
 	*/
 	function getStateLength() {
 		return rand.stateLength;
 	}
 
 	/**
 	* Returns the PRNG state size (in bytes).
 	*
 	* @private
 	* @returns {PositiveInteger} state size (in bytes)
 	*/
 	function getStateSize() {
 		return rand.byteLength;
 	}
 
 	/**
 	* Returns the current pseudorandom number generator state.
 	*
 	* @private
 	* @returns {PRNGStateMT19937} current state
 	*/
 	function getState() {
 		return rand.state;
 	}
 
 	/**
 	* Sets the pseudorandom number generator state.
 	*
 	* @private
 	* @param {PRNGStateMT19937} s - generator state
 	* @throws {Error} must provide a valid state
 	*/
 	function setState( s ) {
 		rand.state = s;
 	}
 
 	/**
 	* Serializes the pseudorandom number generator as a JSON object.
 	*
 	* ## Notes
 	*
 	* -   `JSON.stringify()` implicitly calls this method when stringifying a PRNG.
 	*
 	* @private
 	* @returns {Object} JSON representation
 	*/
 	function toJSON() {
 		var out = {};
 		out.type = 'PRNG';
 		out.name = prng.NAME;
 		out.state = typedarray2json( rand.state );
 		if ( a === void 0 ) {
 			out.params = [];
 		} else {
 			out.params = [ a, b ];
 		}
 		return out;
 	}
 
 	/**
 	* Returns a pseudorandom number drawn from a discrete uniform distribution with minimum support `a` and maximum support `b`.
 	*
 	* @private
 	* @returns {integer} pseudorandom number
 	*
 	* @example
 	* var v = discreteUniform1();
 	* // returns <number>
 	*/
 	function discreteUniform1() {
 		return discreteUniform0( rand, a, b );
 	}
 
 	/**
 	* Returns a pseudorandom number drawn from a discrete uniform distribution with minimum support `a` and maximum support `b`.
 	*
 	* @private
 	* @param {integer} a - minimum support
 	* @param {integer} b - maximum support
 	* @returns {integer} pseudorandom number
 	*
 	* @example
 	* var v = discreteUniform2( 1, 10 );
 	* // returns <number>
 	*
 	* @example
 	* var v = discreteUniform2( 1, 0 );
 	* // returns NaN
 	*/
 	function discreteUniform2( a, b ) {
 		if (
 			isnan( a ) ||
 			isnan( b ) ||
 			!isInteger( a ) ||
 			!isInteger( b ) ||
 			a > b
 		) {
 			return NaN;
 		}
 		return discreteUniform0( rand, a, b );
 	}
 }
 
 
 // EXPORTS //
 
 module.exports = factory;