Cleanup of math sources.

lib/math/random.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // A part of the dart:math library.
 
 /**
  * A random number generator. The default implementation supplies a stream of
  * pseudo-random bits which is not suitable for cryptographic purposes.
  */
-interface Random default _Random {
-  /** 
+class Random {
+  /**
    * Creates a random-number generator. The optional parameter [seed] is used
    * to initialize the internal state of the generator. The implementation of
    * the random stream can change between releases of the library.
    *
    * Implementation note: The default implementation uses up to 64-bits of seed.
    */
-  Random([int seed]);
+  external factory Random([int seed]);
 
-  /** 
+  /**
    * Generates a positive random integer uniformly distributed on the range
    * from 0, inclusive, to [max], exclusive.
    *
    * Implementation note: The default implementation supports [max] values
    * between 1 and ((1<<32) - 1) inclusive.
    */
-  int nextInt(int max);
+  abstract int nextInt(int max);
 
-  /** 
+  /**
    * Generates a positive random floating point value uniformly distributed on
    * the range from 0.0, inclusive, to 1.0, exclusive.
    */
-  double nextDouble();
+  abstract double nextDouble();
 
-  /** 
+  /**
    * Generates a random boolean value.
    */
-  bool nextBool();
+  abstract bool nextBool();
 }
-
-class _Random implements Random {
-
-  _Random([int seed = null]) {
-    if (seed == null) {
-      seed = _nextSeed();
-    }
-    do {
-      seed = (seed + 0x5A17) & _MASK_64;
-    } while (seed == 0);
-    _state = seed;
-  }
-
-  // The algorithm used here is Multiply with Carry (MWC) with a Base b = 2^32.
-  // http://en.wikipedia.org/wiki/Multiply-with-carry
-  // The constant A is selected from "Numerical Recipes 3rd Edition" p.348 B1.
-  int _nextInt32() {
-    _state = ((_A * (_state & _MASK_32)) + (_state >> 32)) & _MASK_64;
-    return _state & _MASK_32;
-  }
-
-  int nextInt(int max) {
-    if (max <= 0 || max > _POW2_32) {
-      throw new IllegalArgumentException("max must be positive and < 2^32:"
-                                         " $max");
-    }
-    if ((max & -max) == max) {
-      // Fast case for powers of two.
-      return _nextInt32() & (max - 1);
-    }
-    
-    var rnd32;
-    var result;
-    do {
-      rnd32 = _nextInt32();
-      result = rnd32 % max;
-    } while (rnd32 - result + max >= _POW2_32);
-    return result;
-  }
-
-  double nextDouble() {
-    return ((nextInt(1 << (26)) << 27) + nextInt(1 << 27)) / _POW2_53_D;
-  }
-
-  bool nextBool() {
-    return nextInt(1) == 0;
-  }
-
-  static final _MASK_32 = (1 << 32) - 1;
-  static final _MASK_64 = (1 << 64) - 1;
-  static final _POW2_32 = 1 << 32;
-  static final _POW2_53_D = 1.0 * (1 << 53);
-
-  static final _A = 0xffffda61;
-
-  var _state;
-
-  int _nextSeed() {
-    if (_prng == null) {
-      // TODO(iposva): Use system to get a random seed.
-      _prng = new _Random(new Date.now().millisecondsSinceEpoch);
-    }
-    // Trigger the PRNG once to change the internal state.
-    _prng._nextInt32();
-    return _prng._state;
-  }
-
-  static var _prng = null;
-}