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

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

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 thrown 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.

Fields

core: R

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

Implementations

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

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.

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

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

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Deserialize this value from the given Serde deserializer. Read more

Return the next random u32. Read more

Return the next random u64. Read more

Fill dest with random data. Read more

Fill dest entirely with random data. Read more

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

Create a new PRNG using the given seed. Read more

Create a new PRNG using a u64 seed. Read more

Create a new PRNG seeded from another Rng. Read more

This is supported on crate feature getrandom only.

Creates a new instance of the RNG seeded via getrandom. Read more

Serialize this value into the given Serde serializer. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Upcast to an RngCore trait object.

Performs the conversion.

Performs the conversion.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.