Struct Bump

Source

pub struct Bump { /* private fields */ }

Expand description

Single-chunk bump arena. See the module-level docs.

§Examples

use arena_lib::Bump;

let mut bump = Bump::with_capacity(64);
let a = bump.alloc(7_u32);
let b = bump.alloc(42_u32);
assert_eq!(*a, 7);
assert_eq!(*b, 42);

// Resetting clears the offset; capacity is retained.
bump.reset();
assert_eq!(bump.allocated_bytes(), 0);

Implementations§

Source §

impl Bump

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pub fn new() -> Self

Creates an empty bump arena that can satisfy only zero-sized allocations.

Use Bump::with_capacity for any non-trivial use.

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pub fn with_capacity(capacity: usize) -> Self

Creates a bump arena backed by a fixed-size chunk of capacity bytes.

capacity is the upper bound on the byte footprint of every allocation made against this arena before Bump::reset is called. Account for alignment padding in addition to raw value size.

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pub fn chunk_capacity(&self) -> usize

Total capacity of the underlying chunk, in bytes.

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pub fn allocated_bytes(&self) -> usize

Bytes consumed since the most recent Bump::reset (or since construction).

Includes alignment padding.

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pub fn alloc<T>(&self, value: T) -> &mut T

Allocates value and returns a unique reference to it.

Panics if the chunk does not have room for value (after alignment padding). Use Bump::try_alloc for an explicit fallible variant.

§Examples

use arena_lib::Bump;

let bump = Bump::with_capacity(16);
let n = bump.alloc(123_u32);
assert_eq!(*n, 123);

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pub fn try_alloc<T>(&self, value: T) -> Result<&mut T>

Allocates value, returning Ok(&mut T) on success or Error::CapacityExceeded if the chunk is full.

The returned &mut T borrows from &self because the Bump owns the underlying chunk and hands out non-overlapping regions per call — the same pattern used by bumpalo::Bump::alloc.

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pub fn reset(&mut self)

Resets the arena, marking every prior allocation as discarded.

Capacity is retained. Destructors of previously allocated values are not run (see the module-level docs for the Drop policy). Taking &mut self ensures no outstanding references survive across the call.