1 // Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! The implementations of `Rand` for the built-in types.
22 fn rand<R: Rng>(rng: &mut R) -> isize {
23 if isize::BITS == 32 {
24 rng.gen::<i32>() as isize
26 rng.gen::<i64>() as isize
33 fn rand<R: Rng>(rng: &mut R) -> i8 {
40 fn rand<R: Rng>(rng: &mut R) -> i16 {
47 fn rand<R: Rng>(rng: &mut R) -> i32 {
54 fn rand<R: Rng>(rng: &mut R) -> i64 {
61 fn rand<R: Rng>(rng: &mut R) -> usize {
62 if usize::BITS == 32 {
63 rng.gen::<u32>() as usize
65 rng.gen::<u64>() as usize
72 fn rand<R: Rng>(rng: &mut R) -> u8 {
79 fn rand<R: Rng>(rng: &mut R) -> u16 {
86 fn rand<R: Rng>(rng: &mut R) -> u32 {
93 fn rand<R: Rng>(rng: &mut R) -> u64 {
98 macro_rules! float_impls {
99 ($mod_name:ident, $ty:ty, $mantissa_bits:expr, $method_name:ident) => {
101 use {Rand, Rng, Open01, Closed01};
103 const SCALE: $ty = (1u64 << $mantissa_bits) as $ty;
106 /// Generate a floating point number in the half-open
107 /// interval `[0,1)`.
109 /// See `Closed01` for the closed interval `[0,1]`,
110 /// and `Open01` for the open interval `(0,1)`.
112 fn rand<R: Rng>(rng: &mut R) -> $ty {
116 impl Rand for Open01<$ty> {
118 fn rand<R: Rng>(rng: &mut R) -> Open01<$ty> {
119 // add a small amount (specifically 2 bits below
120 // the precision of f64/f32 at 1.0), so that small
121 // numbers are larger than 0, but large numbers
122 // aren't pushed to/above 1.
123 Open01(rng.$method_name() + 0.25 / SCALE)
126 impl Rand for Closed01<$ty> {
128 fn rand<R: Rng>(rng: &mut R) -> Closed01<$ty> {
129 // rescale so that 1.0 - epsilon becomes 1.0
131 Closed01(rng.$method_name() * SCALE / (SCALE - 1.0))
137 float_impls! { f64_rand_impls, f64, 53, next_f64 }
138 float_impls! { f32_rand_impls, f32, 24, next_f32 }
142 fn rand<R: Rng>(rng: &mut R) -> char {
144 const CHAR_MASK: u32 = 0x001f_ffff;
146 // Rejection sampling. About 0.2% of numbers with at most
147 // 21-bits are invalid codepoints (surrogates), so this
148 // will succeed first go almost every time.
149 match char::from_u32(rng.next_u32() & CHAR_MASK) {
159 fn rand<R: Rng>(rng: &mut R) -> bool {
160 rng.gen::<u8>() & 1 == 1
164 macro_rules! tuple_impl {
165 // use variables to indicate the arity of the tuple
166 ($($tyvar:ident),* ) => {
167 // the trailing commas are for the 1 tuple
170 > Rand for ( $( $tyvar ),* , ) {
173 fn rand<R: Rng>(_rng: &mut R) -> ( $( $tyvar ),* , ) {
175 // use the $tyvar's to get the appropriate number of
176 // repeats (they're not actually needed)
189 fn rand<R: Rng>(_: &mut R) -> () { () }
194 tuple_impl!{A, B, C, D}
195 tuple_impl!{A, B, C, D, E}
196 tuple_impl!{A, B, C, D, E, F}
197 tuple_impl!{A, B, C, D, E, F, G}
198 tuple_impl!{A, B, C, D, E, F, G, H}
199 tuple_impl!{A, B, C, D, E, F, G, H, I}
200 tuple_impl!{A, B, C, D, E, F, G, H, I, J}
201 tuple_impl!{A, B, C, D, E, F, G, H, I, J, K}
202 tuple_impl!{A, B, C, D, E, F, G, H, I, J, K, L}
204 impl<T:Rand> Rand for Option<T> {
206 fn rand<R: Rng>(rng: &mut R) -> Option<T> {