time-to-botec

main.js (9733B)

---

 /**
 * @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 Readable = require( 'readable-stream' ).Readable;
 var isPositiveNumber = require( '@stdlib/assert/is-positive-number' ).isPrimitive;
 var isNumber = require( '@stdlib/assert/is-number' ).isPrimitive;
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var isError = require( '@stdlib/assert/is-error' );
 var copy = require( '@stdlib/utils/copy' );
 var inherit = require( '@stdlib/utils/inherit' );
 var setNonEnumerable = require( '@stdlib/utils/define-nonenumerable-property' );
 var setNonEnumerableReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
 var setReadOnlyAccessor = require( '@stdlib/utils/define-read-only-accessor' );
 var setReadWriteAccessor = require( '@stdlib/utils/define-read-write-accessor' );
 var rlevy = require( './../../../base/levy' ).factory;
 var string2buffer = require( '@stdlib/buffer/from-string' );
 var nextTick = require( '@stdlib/utils/next-tick' );
 var DEFAULTS = require( './defaults.json' );
 var validate = require( './validate.js' );
 var debug = require( './debug.js' );
 
 
 // FUNCTIONS //
 
 /**
 * Returns the PRNG seed.
 *
 * @private
 * @returns {(PRNGSeedMT19937|null)} seed
 */
 function getSeed() {
 	return this._prng.seed; // eslint-disable-line no-invalid-this
 }
 
 /**
 * Returns the PRNG seed length.
 *
 * @private
 * @returns {(PositiveInteger|null)} seed length
 */
 function getSeedLength() {
 	return this._prng.seedLength; // eslint-disable-line no-invalid-this
 }
 
 /**
 * Returns the PRNG state length.
 *
 * @private
 * @returns {(PositiveInteger|null)} state length
 */
 function getStateLength() {
 	return this._prng.stateLength; // eslint-disable-line no-invalid-this
 }
 
 /**
 * Returns the PRNG state size (in bytes).
 *
 * @private
 * @returns {(PositiveInteger|null)} state size (in bytes)
 */
 function getStateSize() {
 	return this._prng.byteLength; // eslint-disable-line no-invalid-this
 }
 
 /**
 * Returns the current PRNG state.
 *
 * @private
 * @returns {(PRNGStateMT19937|null)} current state
 */
 function getState() {
 	return this._prng.state; // eslint-disable-line no-invalid-this
 }
 
 /**
 * Sets the PRNG state.
 *
 * @private
 * @param {PRNGStateMT19937} s - generator state
 * @throws {Error} must provide a valid state
 */
 function setState( s ) {
 	this._prng.state = s; // eslint-disable-line no-invalid-this
 }
 
 /**
 * Implements the `_read` method.
 *
 * @private
 * @param {number} size - number (of bytes) to read
 * @returns {void}
 */
 function read() {
 	/* eslint-disable no-invalid-this */
 	var FLG;
 	var r;
 
 	if ( this._destroyed ) {
 		return;
 	}
 	FLG = true;
 	while ( FLG ) {
 		this._i += 1;
 		if ( this._i > this._iter ) {
 			debug( 'Finished generating pseudorandom numbers.' );
 			return this.push( null );
 		}
 		r = this._prng();
 
 		debug( 'Generated a new pseudorandom number. Value: %d. Iter: %d.', r, this._i );
 
 		if ( this._objectMode === false ) {
 			r = r.toString();
 			if ( this._i === 1 ) {
 				r = string2buffer( r );
 			} else {
 				r = string2buffer( this._sep+r );
 			}
 		}
 		FLG = this.push( r );
 		if ( this._i%this._siter === 0 ) {
 			this.emit( 'state', this.state );
 		}
 	}
 
 	/* eslint-enable no-invalid-this */
 }
 
 /**
 * Gracefully destroys a stream, providing backward compatibility.
 *
 * @private
 * @param {(string|Object|Error)} [error] - error
 * @returns {RandomStream} Stream instance
 */
 function destroy( error ) {
 	/* eslint-disable no-invalid-this */
 	var self;
 	if ( this._destroyed ) {
 		debug( 'Attempted to destroy an already destroyed stream.' );
 		return this;
 	}
 	self = this;
 	this._destroyed = true;
 
 	nextTick( close );
 
 	return this;
 
 	/**
 	* Closes a stream.
 	*
 	* @private
 	*/
 	function close() {
 		if ( error ) {
 			debug( 'Stream was destroyed due to an error. Error: %s.', ( isError( error ) ) ? error.message : JSON.stringify( error ) );
 			self.emit( 'error', error );
 		}
 		debug( 'Closing the stream...' );
 		self.emit( 'close' );
 	}
 
 	/* eslint-enable no-invalid-this */
 }
 
 
 // MAIN //
 
 /**
 * Stream constructor for generating a stream of pseudorandom numbers drawn from a Lévy distribution.
 *
 * @constructor
 * @param {number} mu - mean
 * @param {PositiveNumber} c - scale parameter
 * @param {Options} [options] - stream options
 * @param {boolean} [options.objectMode=false] - specifies whether the stream should operate in object mode
 * @param {(string|null)} [options.encoding=null] - specifies how `Buffer` objects should be decoded to strings
 * @param {NonNegativeNumber} [options.highWaterMark] - specifies the maximum number of bytes to store in an internal buffer before ceasing to generate additional pseudorandom numbers
 * @param {string} [options.sep='\n'] - separator used to join streamed data
 * @param {NonNegativeInteger} [options.iter] - number of iterations
 * @param {PRNG} [options.prng] - pseudorandom number generator which generates uniformly distributed pseudorandom numbers
 * @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
 * @param {PositiveInteger} [options.siter] - number of iterations after which to emit the PRNG state
 * @throws {TypeError} `mu` must be a number
 * @throws {TypeError} `c` must be a positive number
 * @throws {TypeError} options argument must be an object
 * @throws {TypeError} must provide valid options
 * @throws {Error} must provide a valid state
 * @returns {RandomStream} Stream instance
 *
 * @example
 * var inspectStream = require( '@stdlib/streams/node/inspect-sink' );
 *
 * function log( chunk ) {
 *    console.log( chunk.toString() );
 * }
 *
 * var opts = {
 *     'iter': 10
 * };
 *
 * var stream = new RandomStream( 2.0, 5.0, opts );
 *
 * stream.pipe( inspectStream( log )  );
 */
 function RandomStream( mu, c, options ) {
 	var opts;
 	var err;
 	if ( !( this instanceof RandomStream ) ) {
 		if ( arguments.length > 2 ) {
 			return new RandomStream( mu, c, options );
 		}
 		return new RandomStream( mu, c );
 	}
 	if ( !isNumber( mu ) || isnan( mu ) ) {
 		throw new TypeError( 'invalid argument. First argument must be a number primitive and not `NaN`. Value: `'+mu+'`.' );
 	}
 	if ( !isPositiveNumber( c ) ) {
 		throw new TypeError( 'invalid argument. Second argument must be a positive number. Value: `'+c+'`.' );
 	}
 	opts = copy( DEFAULTS );
 	if ( arguments.length > 2 ) {
 		err = validate( opts, options );
 		if ( err ) {
 			throw err;
 		}
 	}
 	// Make the stream a readable stream:
 	debug( 'Creating a readable stream configured with the following options: %s.', JSON.stringify( opts ) );
 	Readable.call( this, opts );
 
 	// Destruction state:
 	setNonEnumerable( this, '_destroyed', false );
 
 	// Cache whether the stream is operating in object mode:
 	setNonEnumerableReadOnly( this, '_objectMode', opts.objectMode );
 
 	// Cache the separator:
 	setNonEnumerableReadOnly( this, '_sep', opts.sep );
 
 	// Cache the total number of iterations:
 	setNonEnumerableReadOnly( this, '_iter', opts.iter );
 
 	// Cache the number of iterations after which to emit the underlying PRNG state:
 	setNonEnumerableReadOnly( this, '_siter', opts.siter );
 
 	// Initialize an iteration counter:
 	setNonEnumerable( this, '_i', 0 );
 
 	// Create the underlying PRNG:
 	setNonEnumerableReadOnly( this, '_prng', rlevy( mu, c, opts ) );
 	setNonEnumerableReadOnly( this, 'PRNG', this._prng.PRNG );
 
 	return this;
 }
 
 /*
 * Inherit from the `Readable` prototype.
 */
 inherit( RandomStream, Readable );
 
 /**
 * PRNG seed.
 *
 * @name seed
 * @memberof RandomStream.prototype
 * @type {(PRNGSeedMT19937|null)}
 */
 setReadOnlyAccessor( RandomStream.prototype, 'seed', getSeed );
 
 /**
 * PRNG seed length.
 *
 * @name seedLength
 * @memberof RandomStream.prototype
 * @type {(PositiveInteger|null)}
 */
 setReadOnlyAccessor( RandomStream.prototype, 'seedLength', getSeedLength );
 
 /**
 * PRNG state getter/setter.
 *
 * @name state
 * @memberof RandomStream.prototype
 * @type {(PRNGStateMT19937|null)}
 * @throws {Error} must provide a valid state
 */
 setReadWriteAccessor( RandomStream.prototype, 'state', getState, setState );
 
 /**
 * PRNG state length.
 *
 * @name stateLength
 * @memberof RandomStream.prototype
 * @type {(PositiveInteger|null)}
 */
 setReadOnlyAccessor( RandomStream.prototype, 'stateLength', getStateLength );
 
 /**
 * PRNG state size (in bytes).
 *
 * @name byteLength
 * @memberof RandomStream.prototype
 * @type {(PositiveInteger|null)}
 */
 setReadOnlyAccessor( RandomStream.prototype, 'byteLength', getStateSize );
 
 /**
 * Implements the `_read` method.
 *
 * @private
 * @name _read
 * @memberof RandomStream.prototype
 * @type {Function}
 * @param {number} size - number (of bytes) to read
 * @returns {void}
 */
 setNonEnumerableReadOnly( RandomStream.prototype, '_read', read );
 
 /**
 * Gracefully destroys a stream, providing backward compatibility.
 *
 * @name destroy
 * @memberof RandomStream.prototype
 * @type {Function}
 * @param {(string|Object|Error)} [error] - error
 * @returns {RandomStream} Stream instance
 */
 setNonEnumerableReadOnly( RandomStream.prototype, 'destroy', destroy );
 
 
 // EXPORTS //
 
 module.exports = RandomStream;