floitsch@google.com
a51dc25968
isUtc is now a getter. Date.hours -> Date.hour Date.minutes -> Date.minute Date.seconds -> Date.second Date.milliseconds -> Date.millisecond Date.fromEpoch -> Date.fromMillisecondsSinceEpoch Date.value -> Date.millisecondsSinceEpoch Date.MON == 1 (up to Date.SUN == 7). Fixes issue 3444, 1985. Review URL: https://chromiumcodereview.appspot.com//10538105 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@8899 260f80e4-7a28-3924-810f-c04153c831b5
110 lines
3.0 KiB
Dart
110 lines
3.0 KiB
Dart
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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// A part of the dart:math library.
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/**
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* A random number generator. The default implementation supplies a stream of
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* pseudo-random bits which is not suitable for cryptographic purposes.
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*/
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interface Random default _Random {
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/**
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* Creates a random-number generator. The optional parameter [seed] is used
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* to initialize the internal state of the generator. The implementation of
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* the random stream can change between releases of the library.
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*
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* Implementation note: The default implementation uses up to 64-bits of seed.
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*/
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Random([int seed]);
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/**
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* Generates a positive random integer uniformly distributed on the range
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* from 0, inclusive, to [max], exclusive.
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*
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* Implementation note: The default implementation supports [max] values
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* between 1 and ((1<<32) - 1) inclusive.
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*/
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int nextInt(int max);
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/**
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* Generates a positive random floating point value uniformly distributed on
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* the range from 0.0, inclusive, to 1.0, exclusive.
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*/
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double nextDouble();
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/**
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* Generates a random boolean value.
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*/
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bool nextBool();
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}
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class _Random implements Random {
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_Random([int seed = null]) {
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if (seed == null) {
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seed = _nextSeed();
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}
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do {
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seed = (seed + 0x5A17) & _MASK_64;
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} while (seed == 0);
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_state = seed;
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}
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// The algorithm used here is Multiply with Carry (MWC) with a Base b = 2^32.
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// http://en.wikipedia.org/wiki/Multiply-with-carry
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// The constant A is selected from "Numerical Recipes 3rd Edition" p.348 B1.
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int _nextInt32() {
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_state = ((_A * (_state & _MASK_32)) + (_state >> 32)) & _MASK_64;
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return _state & _MASK_32;
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}
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int nextInt(int max) {
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if (max <= 0 || max > _POW2_32) {
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throw new IllegalArgumentException("max must be positive and < 2^32:"
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" $max");
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}
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if ((max & -max) == max) {
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// Fast case for powers of two.
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return _nextInt32() & (max - 1);
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}
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var rnd32;
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var result;
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do {
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rnd32 = _nextInt32();
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result = rnd32 % max;
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} while (rnd32 - result + max >= _POW2_32);
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return result;
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}
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double nextDouble() {
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return ((nextInt(1 << (26)) << 27) + nextInt(1 << 27)) / _POW2_53_D;
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}
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bool nextBool() {
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return nextInt(1) == 0;
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}
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static final _MASK_32 = (1 << 32) - 1;
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static final _MASK_64 = (1 << 64) - 1;
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static final _POW2_32 = 1 << 32;
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static final _POW2_53_D = 1.0 * (1 << 53);
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static final _A = 0xffffda61;
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var _state;
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int _nextSeed() {
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if (_prng == null) {
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// TODO(iposva): Use system to get a random seed.
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_prng = new _Random(new Date.now().millisecondsSinceEpoch);
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}
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// Trigger the PRNG once to change the internal state.
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_prng._nextInt32();
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return _prng._state;
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}
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static var _prng = null;
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}
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