Files
ab_glyph_rasterizer
addr2line
adler
andrew
approx
arrayvec
ash
atom
backtrace
bitflags
byteorder
calloop
cfg_if
colorful
conrod_core
conrod_derive
conrod_example_shared
conrod_gfx
conrod_glium
conrod_piston
conrod_rendy
conrod_vulkano
conrod_wgpu
conrod_winit
copyless
copypasta
crossbeam
crossbeam_channel
crossbeam_deque
crossbeam_epoch
crossbeam_queue
crossbeam_utils
daggy
dlib
downcast_rs
draw_state
either
fixedbitset
float
fnv
futures
futures_channel
futures_core
futures_executor
futures_io
futures_macro
futures_sink
futures_task
futures_util
async_await
future
io
lock
sink
stream
task
fxhash
getrandom
gfx
gfx_backend_empty
gfx_backend_vulkan
gfx_core
gfx_descriptor
gfx_hal
gfx_memory
gimli
glium
glutin
glutin_egl_sys
glutin_glx_sys
graphics
half
hibitset
inplace_it
input
instant
interpolation
iovec
itoa
lazy_static
lazycell
libc
libloading
line_drawing
linked_hash_map
lock_api
log
maybe_uninit
memchr
memmap
memoffset
miniz_oxide
mio
mio_extras
naga
net2
nix
nom
num
num_bigint
num_complex
num_cpus
num_integer
num_iter
num_rational
num_traits
object
once_cell
ordered_float
ordermap
osmesa_sys
owned_ttf_parser
parking_lot
parking_lot_core
percent_encoding
petgraph
pin_project
pin_project_internal
pin_project_lite
pin_utils
ppv_lite86
proc_macro2
proc_macro_hack
proc_macro_nested
quote
rand
rand_chacha
rand_core
raw_window_handle
read_color
relevant
rendy
rendy_chain
rendy_command
rendy_core
rendy_descriptor
rendy_factory
rendy_frame
rendy_graph
rendy_init
rendy_memory
rendy_mesh
rendy_resource
rendy_shader
rendy_texture
rendy_wsi
rustc_demangle
rustc_hash
rusttype
ryu
same_file
scoped_tls
scopeguard
serde
serde_derive
serde_json
shaderc
shaderc_sys
shared_library
slab
smallvec
smithay_client_toolkit
smithay_clipboard
spirv_headers
stb_truetype
syn
takeable_option
texture
thiserror
thiserror_impl
thread_profiler
time
tracing
tracing_core
ttf_parser
typed_arena
unicode_xid
vecmath
viewport
vk_sys
void
vulkano
buffer
command_buffer
descriptor
device
framebuffer
image
instance
memory
pipeline
query
swapchain
sync
vulkano_shaders
walkdir
wayland_client
wayland_commons
wayland_cursor
wayland_egl
wayland_protocols
wayland_sys
wgpu
wgpu_core
wgpu_types
winit
x11
x11_clipboard
x11_dl
xcb
xcursor
xdg
xml
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
// Copyright 2018 Developers of the Rand project.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Mock random number generator

use rand_core::{impls, Error, RngCore};

/// A simple implementation of `RngCore` for testing purposes.
///
/// This generates an arithmetic sequence (i.e. adds a constant each step)
/// over a `u64` number, using wrapping arithmetic. If the increment is 0
/// the generator yields a constant.
///
/// ```
/// use rand::Rng;
/// use rand::rngs::mock::StepRng;
///
/// let mut my_rng = StepRng::new(2, 1);
/// let sample: [u64; 3] = my_rng.gen();
/// assert_eq!(sample, [2, 3, 4]);
/// ```
#[derive(Debug, Clone)]
pub struct StepRng {
    v: u64,
    a: u64,
}

impl StepRng {
    /// Create a `StepRng`, yielding an arithmetic sequence starting with
    /// `initial` and incremented by `increment` each time.
    pub fn new(initial: u64, increment: u64) -> Self {
        StepRng {
            v: initial,
            a: increment,
        }
    }
}

impl RngCore for StepRng {
    #[inline]
    fn next_u32(&mut self) -> u32 {
        self.next_u64() as u32
    }

    #[inline]
    fn next_u64(&mut self) -> u64 {
        let result = self.v;
        self.v = self.v.wrapping_add(self.a);
        result
    }

    #[inline]
    fn fill_bytes(&mut self, dest: &mut [u8]) {
        impls::fill_bytes_via_next(self, dest);
    }

    #[inline]
    fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
        self.fill_bytes(dest);
        Ok(())
    }
}