vipunen/patched_sdk/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.

part of dart.math;

/**
 * A generator of random bool, int, or double values.
 *
 * The default implementation supplies a stream of
 * pseudo-random bits that are not suitable for cryptographic purposes.
 *
 * Use the Random.secure() constructor for cryptographic
 * purposes.
 */
abstract 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.
   */
  factory Random([int seed = -1]) {
    var state = _Random._setupSeed((seed == -1) ? _Random._nextSeed() : seed);
    // Crank a couple of times to distribute the seed bits a bit further.
    return new _Random._withState(state)
      .._nextState()
      .._nextState()
      .._nextState()
      .._nextState();
  }

  /**
   * Creates a cryptographically secure random number generator.
   *
   * If the program cannot provide a cryptographically secure
   * source of random numbers, it throws an [UnsupportedError].
   */
  factory Random.secure() {
    return new _SecureRandom();
  }

  /**
   * Generates a non-negative random integer uniformly distributed in the range
   * from 0, inclusive, to [max], exclusive.
   *
   * Implementation note: The default implementation supports [max] values
   * between 1 and (1<<32) inclusive.
   */
  int nextInt(int max);

  /**
   * Generates a non-negative random floating point value uniformly distributed
   * in the range from 0.0, inclusive, to 1.0, exclusive.
   */
  double nextDouble();

  /**
   * Generates a random boolean value.
   */
  bool nextBool();
}