[][src]Struct rand_core::block::BlockRng

pub struct BlockRng<R: BlockRngCore + ?Sized> {
    pub core: R,
    // some fields omitted

A wrapper type implementing RngCore for some type implementing BlockRngCore with u32 array buffer; i.e. this can be used to implement a full RNG from just a generate function.

The core field may be accessed directly but the results buffer may not. PRNG implementations can simply use a type alias (pub type MyRng = BlockRng<MyRngCore>;) but might prefer to use a wrapper type (pub struct MyRng(BlockRng<MyRngCore>);); the latter must re-implement RngCore but hides the implementation details and allows extra functionality to be defined on the RNG (e.g. impl MyRng { fn set_stream(...){...} }).

BlockRng has heavily optimized implementations of the RngCore methods reading values from the results buffer, as well as calling BlockRngCore::generate directly on the output array when fill_bytes / try_fill_bytes is called on a large array. These methods also handle the bookkeeping of when to generate a new batch of values.

No whole generated u32 values are thown away and all values are consumed in-order. next_u32 simply takes the next available u32 value. next_u64 is implemented by combining two u32 values, least significant first. fill_bytes and try_fill_bytes consume a whole number of u32 values, converting each u32 to a byte slice in little-endian order. If the requested byte length is not a multiple of 4, some bytes will be discarded.

See also BlockRng64 which uses u64 array buffers. Currently there is no direct support for other buffer types.

For easy initialization BlockRng also implements SeedableRng.


core: R

The core part of the RNG, implementing the generate function.


impl<R: BlockRngCore> BlockRng<R>[src]

pub fn new(core: R) -> BlockRng<R>[src]

Create a new BlockRng from an existing RNG implementing BlockRngCore. Results will be generated on first use.

pub fn index(&self) -> usize[src]

Get the index into the result buffer.

If this is equal to or larger than the size of the result buffer then the buffer is "empty" and generate() must be called to produce new results.

pub fn reset(&mut self)[src]

Reset the number of available results. This will force a new set of results to be generated on next use.

pub fn generate_and_set(&mut self, index: usize)[src]

Generate a new set of results immediately, setting the index to the given value.

Trait Implementations

impl<R: Clone + BlockRngCore + ?Sized> Clone for BlockRng<R> where
    R::Results: Clone

impl<R: BlockRngCore + CryptoRng> CryptoRng for BlockRng<R>[src]

impl<R: BlockRngCore + Debug> Debug for BlockRng<R>[src]

impl<R: BlockRngCore<Item = u32>> RngCore for BlockRng<R> where
    <R as BlockRngCore>::Results: AsRef<[u32]> + AsMut<[u32]>, 

impl<R: BlockRngCore + SeedableRng> SeedableRng for BlockRng<R>[src]

type Seed = R::Seed

Seed type, which is restricted to types mutably-dereferencable as u8 arrays (we recommend [u8; N] for some N). Read more

Auto Trait Implementations

impl<R: ?Sized> RefUnwindSafe for BlockRng<R> where
    R: RefUnwindSafe,
    <R as BlockRngCore>::Results: RefUnwindSafe

impl<R: ?Sized> Send for BlockRng<R> where
    R: Send,
    <R as BlockRngCore>::Results: Send

impl<R: ?Sized> Sync for BlockRng<R> where
    R: Sync,
    <R as BlockRngCore>::Results: Sync

impl<R: ?Sized> Unpin for BlockRng<R> where
    R: Unpin,
    <R as BlockRngCore>::Results: Unpin

impl<R: ?Sized> UnwindSafe for BlockRng<R> where
    R: UnwindSafe,
    <R as BlockRngCore>::Results: UnwindSafe

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized

impl<T> Borrow<T> for T where
    T: ?Sized

impl<T> BorrowMut<T> for T where
    T: ?Sized

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 

impl<T> ToOwned for T where
    T: Clone

type Owned = T

The resulting type after obtaining ownership.

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.