355 lines
9.4 KiB
JavaScript
355 lines
9.4 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var Readable = require( 'readable-stream' ).Readable;
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var isPositiveNumber = require( '@stdlib/assert/is-positive-number' ).isPrimitive;
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var isError = require( '@stdlib/assert/is-error' );
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var copy = require( '@stdlib/utils/copy' );
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var inherit = require( '@stdlib/utils/inherit' );
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var setNonEnumerable = require( '@stdlib/utils/define-nonenumerable-property' );
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var setNonEnumerableReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
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var setReadOnlyAccessor = require( '@stdlib/utils/define-read-only-accessor' );
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var setReadWriteAccessor = require( '@stdlib/utils/define-read-write-accessor' );
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var rgamma = require( './../../../base/gamma' ).factory;
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var string2buffer = require( '@stdlib/buffer/from-string' );
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var nextTick = require( '@stdlib/utils/next-tick' );
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var DEFAULTS = require( './defaults.json' );
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var validate = require( './validate.js' );
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var debug = require( './debug.js' );
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// FUNCTIONS //
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/**
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* Returns the PRNG seed.
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*
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* @private
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* @returns {(PRNGSeedMT19937|null)} seed
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*/
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function getSeed() {
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return this._prng.seed; // eslint-disable-line no-invalid-this
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}
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/**
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* Returns the PRNG seed length.
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*
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* @private
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* @returns {(PositiveInteger|null)} seed length
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*/
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function getSeedLength() {
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return this._prng.seedLength; // eslint-disable-line no-invalid-this
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}
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/**
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* Returns the PRNG state length.
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*
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* @private
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* @returns {(PositiveInteger|null)} state length
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*/
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function getStateLength() {
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return this._prng.stateLength; // eslint-disable-line no-invalid-this
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}
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/**
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* Returns the PRNG state size (in bytes).
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*
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* @private
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* @returns {(PositiveInteger|null)} state size (in bytes)
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*/
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function getStateSize() {
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return this._prng.byteLength; // eslint-disable-line no-invalid-this
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}
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/**
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* Returns the current PRNG state.
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*
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* @private
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* @returns {(PRNGStateMT19937|null)} current state
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*/
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function getState() {
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return this._prng.state; // eslint-disable-line no-invalid-this
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}
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/**
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* Sets the PRNG state.
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*
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* @private
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* @param {PRNGStateMT19937} s - generator state
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* @throws {Error} must provide a valid state
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*/
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function setState( s ) {
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this._prng.state = s; // eslint-disable-line no-invalid-this
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}
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/**
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* Implements the `_read` method.
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*
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* @private
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* @param {number} size - number (of bytes) to read
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* @returns {void}
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*/
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function read() {
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/* eslint-disable no-invalid-this */
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var FLG;
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var r;
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if ( this._destroyed ) {
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return;
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}
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FLG = true;
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while ( FLG ) {
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this._i += 1;
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if ( this._i > this._iter ) {
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debug( 'Finished generating pseudorandom numbers.' );
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return this.push( null );
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}
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r = this._prng();
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debug( 'Generated a new pseudorandom number. Value: %d. Iter: %d.', r, this._i );
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if ( this._objectMode === false ) {
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r = r.toString();
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if ( this._i === 1 ) {
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r = string2buffer( r );
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} else {
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r = string2buffer( this._sep+r );
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}
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}
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FLG = this.push( r );
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if ( this._i%this._siter === 0 ) {
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this.emit( 'state', this.state );
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}
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}
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/* eslint-enable no-invalid-this */
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}
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/**
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* Gracefully destroys a stream, providing backward compatibility.
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*
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* @private
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* @param {(string|Object|Error)} [error] - error
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* @returns {RandomStream} Stream instance
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*/
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function destroy( error ) {
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/* eslint-disable no-invalid-this */
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var self;
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if ( this._destroyed ) {
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debug( 'Attempted to destroy an already destroyed stream.' );
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return this;
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}
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self = this;
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this._destroyed = true;
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nextTick( close );
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return this;
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/**
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* Closes a stream.
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*
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* @private
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*/
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function close() {
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if ( error ) {
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debug( 'Stream was destroyed due to an error. Error: %s.', ( isError( error ) ) ? error.message : JSON.stringify( error ) );
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self.emit( 'error', error );
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}
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debug( 'Closing the stream...' );
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self.emit( 'close' );
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}
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/* eslint-enable no-invalid-this */
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}
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// MAIN //
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/**
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* Stream constructor for generating a stream of pseudorandom numbers drawn from a gamma distribution.
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*
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* @constructor
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* @param {PositiveNumber} alpha - shape parameter
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* @param {PositiveNumber} beta - rate parameter
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* @param {Options} [options] - stream options
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* @param {boolean} [options.objectMode=false] - specifies whether the stream should operate in object mode
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* @param {(string|null)} [options.encoding=null] - specifies how `Buffer` objects should be decoded to strings
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* @param {NonNegativeNumber} [options.highWaterMark] - specifies the maximum number of bytes to store in an internal buffer before ceasing to generate additional pseudorandom numbers
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* @param {string} [options.sep='\n'] - separator used to join streamed data
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* @param {NonNegativeInteger} [options.iter] - number of iterations
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* @param {PRNG} [options.prng] - pseudorandom number generator which generates uniformly distributed pseudorandom numbers
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* @param {PRNGSeedMT19937} [options.seed] - pseudorandom number generator seed
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* @param {PRNGStateMT19937} [options.state] - pseudorandom number generator state
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* @param {boolean} [options.copy=true] - boolean indicating whether to copy a provided pseudorandom number generator state
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* @param {PositiveInteger} [options.siter] - number of iterations after which to emit the PRNG state
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* @throws {TypeError} `alpha` must be a positive number
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* @throws {TypeError} `beta` must be a positive number
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* @throws {TypeError} options argument must be an object
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* @throws {TypeError} must provide valid options
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* @throws {Error} must provide a valid state
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* @returns {RandomStream} Stream instance
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*
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* @example
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* var inspectStream = require( '@stdlib/streams/node/inspect-sink' );
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*
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* function log( chunk ) {
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* console.log( chunk.toString() );
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* }
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*
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* var opts = {
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* 'iter': 10
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* };
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*
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* var stream = new RandomStream( 2.0, 5.0, opts );
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*
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* stream.pipe( inspectStream( log ) );
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*/
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function RandomStream( alpha, beta, options ) {
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var opts;
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var err;
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if ( !( this instanceof RandomStream ) ) {
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if ( arguments.length > 2 ) {
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return new RandomStream( alpha, beta, options );
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}
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return new RandomStream( alpha, beta );
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}
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if ( !isPositiveNumber( alpha ) ) {
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throw new TypeError( 'invalid argument. First argument must be a positive number. Value: `'+alpha+'`.' );
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}
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if ( !isPositiveNumber( beta ) ) {
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throw new TypeError( 'invalid argument. Second argument must be a positive number. Value: `'+beta+'`.' );
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}
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opts = copy( DEFAULTS );
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if ( arguments.length > 2 ) {
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err = validate( opts, options );
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if ( err ) {
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throw err;
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}
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}
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// Make the stream a readable stream:
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debug( 'Creating a readable stream configured with the following options: %s.', JSON.stringify( opts ) );
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Readable.call( this, opts );
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// Destruction state:
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setNonEnumerable( this, '_destroyed', false );
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// Cache whether the stream is operating in object mode:
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setNonEnumerableReadOnly( this, '_objectMode', opts.objectMode );
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// Cache the separator:
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setNonEnumerableReadOnly( this, '_sep', opts.sep );
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// Cache the total number of iterations:
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setNonEnumerableReadOnly( this, '_iter', opts.iter );
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// Cache the number of iterations after which to emit the underlying PRNG state:
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setNonEnumerableReadOnly( this, '_siter', opts.siter );
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// Initialize an iteration counter:
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setNonEnumerable( this, '_i', 0 );
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// Create the underlying PRNG:
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setNonEnumerableReadOnly( this, '_prng', rgamma( alpha, beta, opts ) );
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setNonEnumerableReadOnly( this, 'PRNG', this._prng.PRNG );
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return this;
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}
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/*
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* Inherit from the `Readable` prototype.
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*/
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inherit( RandomStream, Readable );
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/**
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* PRNG seed.
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*
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* @name seed
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* @memberof RandomStream.prototype
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* @type {(PRNGSeedMT19937|null)}
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*/
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setReadOnlyAccessor( RandomStream.prototype, 'seed', getSeed );
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/**
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* PRNG seed length.
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*
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* @name seedLength
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* @memberof RandomStream.prototype
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* @type {(PositiveInteger|null)}
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*/
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setReadOnlyAccessor( RandomStream.prototype, 'seedLength', getSeedLength );
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/**
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* PRNG state getter/setter.
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*
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* @name state
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* @memberof RandomStream.prototype
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* @type {(PRNGStateMT19937|null)}
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* @throws {Error} must provide a valid state
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*/
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setReadWriteAccessor( RandomStream.prototype, 'state', getState, setState );
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/**
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* PRNG state length.
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*
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* @name stateLength
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* @memberof RandomStream.prototype
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* @type {(PositiveInteger|null)}
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*/
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setReadOnlyAccessor( RandomStream.prototype, 'stateLength', getStateLength );
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/**
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* PRNG state size (in bytes).
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*
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* @name byteLength
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* @memberof RandomStream.prototype
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* @type {(PositiveInteger|null)}
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*/
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setReadOnlyAccessor( RandomStream.prototype, 'byteLength', getStateSize );
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/**
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* Implements the `_read` method.
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*
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* @private
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* @name _read
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* @memberof RandomStream.prototype
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* @type {Function}
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* @param {number} size - number (of bytes) to read
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* @returns {void}
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*/
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setNonEnumerableReadOnly( RandomStream.prototype, '_read', read );
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/**
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* Gracefully destroys a stream, providing backward compatibility.
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*
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* @name destroy
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* @memberof RandomStream.prototype
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* @type {Function}
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* @param {(string|Object|Error)} [error] - error
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* @returns {RandomStream} Stream instance
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*/
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setNonEnumerableReadOnly( RandomStream.prototype, 'destroy', destroy );
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// EXPORTS //
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module.exports = RandomStream;
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