rust/src/libcore/rand.rs
2013-01-10 21:24:08 -08:00

558 lines
14 KiB
Rust

// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Random number generation
// NB: transitional, de-mode-ing.
#[forbid(deprecated_mode)];
#[forbid(deprecated_pattern)];
use int;
use prelude::*;
use str;
use task;
use u32;
use uint;
use util;
use vec;
#[allow(non_camel_case_types)] // runtime type
enum rctx {}
#[abi = "cdecl"]
extern mod rustrt {
unsafe fn rand_seed() -> ~[u8];
unsafe fn rand_new() -> *rctx;
unsafe fn rand_new_seeded2(&&seed: ~[u8]) -> *rctx;
unsafe fn rand_next(c: *rctx) -> u32;
unsafe fn rand_free(c: *rctx);
}
/// A random number generator
pub trait Rng {
/// Return the next random integer
fn next() -> u32;
}
/// A value with a particular weight compared to other values
pub type Weighted<T> = { weight: uint, item: T };
/// Extension methods for random number generators
impl Rng {
/// Return a random int
fn gen_int() -> int {
self.gen_i64() as int
}
/**
* Return an int randomly chosen from the range [start, end),
* failing if start >= end
*/
fn gen_int_range(start: int, end: int) -> int {
assert start < end;
start + int::abs(self.gen_int() % (end - start))
}
/// Return a random i8
fn gen_i8() -> i8 {
self.next() as i8
}
/// Return a random i16
fn gen_i16() -> i16 {
self.next() as i16
}
/// Return a random i32
fn gen_i32() -> i32 {
self.next() as i32
}
/// Return a random i64
fn gen_i64() -> i64 {
(self.next() as i64 << 32) | self.next() as i64
}
/// Return a random uint
fn gen_uint() -> uint {
self.gen_u64() as uint
}
/**
* Return a uint randomly chosen from the range [start, end),
* failing if start >= end
*/
fn gen_uint_range(start: uint, end: uint) -> uint {
assert start < end;
start + (self.gen_uint() % (end - start))
}
/// Return a random u8
fn gen_u8() -> u8 {
self.next() as u8
}
/// Return a random u16
fn gen_u16() -> u16 {
self.next() as u16
}
/// Return a random u32
fn gen_u32() -> u32 {
self.next()
}
/// Return a random u64
fn gen_u64() -> u64 {
(self.next() as u64 << 32) | self.next() as u64
}
/// Return a random float in the interval [0,1]
fn gen_float() -> float {
self.gen_f64() as float
}
/// Return a random f32 in the interval [0,1]
fn gen_f32() -> f32 {
self.gen_f64() as f32
}
/// Return a random f64 in the interval [0,1]
fn gen_f64() -> f64 {
let u1 = self.next() as f64;
let u2 = self.next() as f64;
let u3 = self.next() as f64;
const scale : f64 = (u32::max_value as f64) + 1.0f64;
return ((u1 / scale + u2) / scale + u3) / scale;
}
/// Return a random char
fn gen_char() -> char {
self.next() as char
}
/**
* Return a char randomly chosen from chars, failing if chars is empty
*/
fn gen_char_from(chars: &str) -> char {
assert !chars.is_empty();
self.choose(str::chars(chars))
}
/// Return a random bool
fn gen_bool() -> bool {
self.next() & 1u32 == 1u32
}
/// Return a bool with a 1 in n chance of true
fn gen_weighted_bool(n: uint) -> bool {
if n == 0u {
true
} else {
self.gen_uint_range(1u, n + 1u) == 1u
}
}
/**
* Return a random string of the specified length composed of A-Z,a-z,0-9
*/
fn gen_str(len: uint) -> ~str {
let charset = ~"ABCDEFGHIJKLMNOPQRSTUVWXYZ\
abcdefghijklmnopqrstuvwxyz\
0123456789";
let mut s = ~"";
let mut i = 0u;
while (i < len) {
s = s + str::from_char(self.gen_char_from(charset));
i += 1u;
}
move s
}
/// Return a random byte string of the specified length
fn gen_bytes(len: uint) -> ~[u8] {
do vec::from_fn(len) |_i| {
self.gen_u8()
}
}
/// Choose an item randomly, failing if values is empty
fn choose<T:Copy>(values: &[T]) -> T {
self.choose_option(values).get()
}
/// Choose Some(item) randomly, returning None if values is empty
fn choose_option<T:Copy>(values: &[T]) -> Option<T> {
if values.is_empty() {
None
} else {
Some(values[self.gen_uint_range(0u, values.len())])
}
}
/**
* Choose an item respecting the relative weights, failing if the sum of
* the weights is 0
*/
fn choose_weighted<T: Copy>(v : &[Weighted<T>]) -> T {
self.choose_weighted_option(v).get()
}
/**
* Choose Some(item) respecting the relative weights, returning none if
* the sum of the weights is 0
*/
fn choose_weighted_option<T:Copy>(v: &[Weighted<T>]) -> Option<T> {
let mut total = 0u;
for v.each |item| {
total += item.weight;
}
if total == 0u {
return None;
}
let chosen = self.gen_uint_range(0u, total);
let mut so_far = 0u;
for v.each |item| {
so_far += item.weight;
if so_far > chosen {
return Some(item.item);
}
}
util::unreachable();
}
/**
* Return a vec containing copies of the items, in order, where
* the weight of the item determines how many copies there are
*/
fn weighted_vec<T:Copy>(v: &[Weighted<T>]) -> ~[T] {
let mut r = ~[];
for v.each |item| {
for uint::range(0u, item.weight) |_i| {
r.push(item.item);
}
}
move r
}
/// Shuffle a vec
fn shuffle<T:Copy>(values: &[T]) -> ~[T] {
let mut m = vec::from_slice(values);
self.shuffle_mut(m);
move m
}
/// Shuffle a mutable vec in place
fn shuffle_mut<T>(values: &[mut T]) {
let mut i = values.len();
while i >= 2u {
// invariant: elements with index >= i have been locked in place.
i -= 1u;
// lock element i in place.
vec::swap(values, i, self.gen_uint_range(0u, i + 1u));
}
}
}
struct RandRes {
c: *rctx,
drop {
unsafe {
rustrt::rand_free(self.c);
}
}
}
fn RandRes(c: *rctx) -> RandRes {
RandRes {
c: c
}
}
impl @RandRes: Rng {
fn next() -> u32 {
unsafe {
return rustrt::rand_next((*self).c);
}
}
}
/// Create a new random seed for seeded_rng
pub fn seed() -> ~[u8] {
unsafe {
rustrt::rand_seed()
}
}
/// Create a random number generator with a system specified seed
pub fn Rng() -> Rng {
unsafe {
@RandRes(rustrt::rand_new()) as Rng
}
}
/**
* Create a random number generator using the specified seed. A generator
* constructed with a given seed will generate the same sequence of values as
* all other generators constructed with the same seed. The seed may be any
* length.
*/
pub fn seeded_rng(seed: &~[u8]) -> Rng {
unsafe {
@RandRes(rustrt::rand_new_seeded2(*seed)) as Rng
}
}
type XorShiftState = {
mut x: u32,
mut y: u32,
mut z: u32,
mut w: u32
};
impl XorShiftState: Rng {
fn next() -> u32 {
let x = self.x;
let mut t = x ^ (x << 11);
self.x = self.y;
self.y = self.z;
self.z = self.w;
let w = self.w;
self.w = w ^ (w >> 19) ^ (t ^ (t >> 8));
self.w
}
}
pub pure fn xorshift() -> Rng {
// constants taken from http://en.wikipedia.org/wiki/Xorshift
seeded_xorshift(123456789u32, 362436069u32, 521288629u32, 88675123u32)
}
pub pure fn seeded_xorshift(x: u32, y: u32, z: u32, w: u32) -> Rng {
{mut x: x, mut y: y, mut z: z, mut w: w} as Rng
}
// used to make space in TLS for a random number generator
fn tls_rng_state(_v: @RandRes) {}
/**
* Gives back a lazily initialized task-local random number generator,
* seeded by the system. Intended to be used in method chaining style, ie
* task_rng().gen_int().
*/
pub fn task_rng() -> Rng {
let r : Option<@RandRes>;
unsafe {
r = task::local_data::local_data_get(tls_rng_state);
}
match r {
None => {
unsafe {
let rng = @RandRes(rustrt::rand_new());
task::local_data::local_data_set(tls_rng_state, rng);
rng as Rng
}
}
Some(rng) => rng as Rng
}
}
/**
* Returns a random uint, using the task's based random number generator.
*/
pub fn random() -> uint {
task_rng().gen_uint()
}
#[cfg(test)]
pub mod tests {
use debug;
use option::{None, Option, Some};
use rand;
#[test]
pub fn rng_seeded() {
let seed = rand::seed();
let ra = rand::seeded_rng(&seed);
let rb = rand::seeded_rng(&seed);
assert ra.gen_str(100u) == rb.gen_str(100u);
}
#[test]
pub fn rng_seeded_custom_seed() {
// much shorter than generated seeds which are 1024 bytes
let seed = ~[2u8, 32u8, 4u8, 32u8, 51u8];
let ra = rand::seeded_rng(&seed);
let rb = rand::seeded_rng(&seed);
assert ra.gen_str(100u) == rb.gen_str(100u);
}
#[test]
pub fn rng_seeded_custom_seed2() {
let seed = ~[2u8, 32u8, 4u8, 32u8, 51u8];
let ra = rand::seeded_rng(&seed);
// Regression test that isaac is actually using the above vector
let r = ra.next();
error!("%?", r);
assert r == 890007737u32 // on x86_64
|| r == 2935188040u32; // on x86
}
#[test]
pub fn gen_int_range() {
let r = rand::Rng();
let a = r.gen_int_range(-3, 42);
assert a >= -3 && a < 42;
assert r.gen_int_range(0, 1) == 0;
assert r.gen_int_range(-12, -11) == -12;
}
#[test]
#[should_fail]
#[ignore(cfg(windows))]
pub fn gen_int_from_fail() {
rand::Rng().gen_int_range(5, -2);
}
#[test]
pub fn gen_uint_range() {
let r = rand::Rng();
let a = r.gen_uint_range(3u, 42u);
assert a >= 3u && a < 42u;
assert r.gen_uint_range(0u, 1u) == 0u;
assert r.gen_uint_range(12u, 13u) == 12u;
}
#[test]
#[should_fail]
#[ignore(cfg(windows))]
pub fn gen_uint_range_fail() {
rand::Rng().gen_uint_range(5u, 2u);
}
#[test]
pub fn gen_float() {
let r = rand::Rng();
let a = r.gen_float();
let b = r.gen_float();
log(debug, (a, b));
}
#[test]
pub fn gen_weighted_bool() {
let r = rand::Rng();
assert r.gen_weighted_bool(0u) == true;
assert r.gen_weighted_bool(1u) == true;
}
#[test]
pub fn gen_str() {
let r = rand::Rng();
log(debug, r.gen_str(10u));
log(debug, r.gen_str(10u));
log(debug, r.gen_str(10u));
assert r.gen_str(0u).len() == 0u;
assert r.gen_str(10u).len() == 10u;
assert r.gen_str(16u).len() == 16u;
}
#[test]
pub fn gen_bytes() {
let r = rand::Rng();
assert r.gen_bytes(0u).len() == 0u;
assert r.gen_bytes(10u).len() == 10u;
assert r.gen_bytes(16u).len() == 16u;
}
#[test]
pub fn choose() {
let r = rand::Rng();
assert r.choose([1, 1, 1]) == 1;
}
#[test]
pub fn choose_option() {
let r = rand::Rng();
let x: Option<int> = r.choose_option([]);
assert x.is_none();
assert r.choose_option([1, 1, 1]) == Some(1);
}
#[test]
pub fn choose_weighted() {
let r = rand::Rng();
assert r.choose_weighted(~[{weight: 1u, item: 42}]) == 42;
assert r.choose_weighted(~[
{weight: 0u, item: 42},
{weight: 1u, item: 43}
]) == 43;
}
#[test]
pub fn choose_weighted_option() {
let r = rand::Rng();
assert r.choose_weighted_option(~[{weight: 1u, item: 42}]) ==
Some(42);
assert r.choose_weighted_option(~[
{weight: 0u, item: 42},
{weight: 1u, item: 43}
]) == Some(43);
let v: Option<int> = r.choose_weighted_option([]);
assert v.is_none();
}
#[test]
pub fn weighted_vec() {
let r = rand::Rng();
let empty: ~[int] = ~[];
assert r.weighted_vec(~[]) == empty;
assert r.weighted_vec(~[
{weight: 0u, item: 3u},
{weight: 1u, item: 2u},
{weight: 2u, item: 1u}
]) == ~[2u, 1u, 1u];
}
#[test]
pub fn shuffle() {
let r = rand::Rng();
let empty: ~[int] = ~[];
assert r.shuffle(~[]) == empty;
assert r.shuffle(~[1, 1, 1]) == ~[1, 1, 1];
}
#[test]
pub fn task_rng() {
let r = rand::task_rng();
r.gen_int();
assert r.shuffle(~[1, 1, 1]) == ~[1, 1, 1];
assert r.gen_uint_range(0u, 1u) == 0u;
}
#[test]
pub fn random() {
// not sure how to test this aside from just getting a number
let _n : uint = rand::random();
}
}
// Local Variables:
// mode: rust;
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End: