stack_collections

Stack-allocated collections for Rust: fixed-capacity string and vector types that live entirely on the stack.

Features

• StackString<N>: UTF-8 encoded, fixed-capacity string stored on the stack
• StackVec<T, CAP>: Fixed-capacity vector stored on the stack
• StackArrayString<N, CAP>: Convenience alias for StackVec<StackString<N>, CAP>
• Zero heap allocations
• const fn constructors and many operations
• Comprehensive API with safe and unsafe variants
• Full iterator support including IntoIterator, DoubleEndedIterator, and ExactSizeIterator
• Standard trait implementations: Debug, Display, Clone, Hash, PartialEq, Eq, Ord, etc.
• Write trait implementation for StackString

Usage

Add this to your Cargo.toml:

[dependencies]
stack_collections = "0.3.2"

StackString Example

use stack_collections::StackString;

fn main() {
    let mut stack_string = StackString::<32>::new();
    stack_string.push_str("Hello, ");
    stack_string.push_str("world!");

    println!("String: {}", stack_string);
    println!("Length: {}", stack_string.len());
    println!("Capacity: {}", stack_string.capacity());

    // Pop characters
    while let Some(c) = stack_string.try_pop() {
        println!("Popped: {}", c);
    }
}

StackVec Example

use stack_collections::StackVec;

fn main() {
    let mut vec = StackVec::<i32, 8>::new();

    for i in 1..=5 {
        vec.push(i);
    }

    println!("Vector: {:?}", vec);
    println!("Sum: {}", vec.iter().sum::<i32>());

    vec.retain(|x| *x < 4);
    println!("Numbers less than 4: {:?}", vec);
}

StackArrayString Example

use stack_collections::StackArrayString;

fn main() {
    // StackArrayString is a convenient alias for StackVec<StackString<N>, CAP>
    let mut arr: StackArrayString<16, 4> = StackArrayString::new();

    arr.push("hello".try_into().unwrap());
    arr.push("world".try_into().unwrap());

    assert_eq!(arr.len(), 2);
    assert_eq!(arr.capacity(), 4);
    assert_eq!(arr[0].capacity(), 16);
    assert_eq!(arr[0].as_str(), "hello");
    assert_eq!(arr[1].as_str(), "world");
}

When to Use

Use stack_collections when you:

• Need predictable memory usage without heap allocations
• Know the maximum capacity at compile time
• Want to avoid allocator overhead for small collections
• Are working in no_std environments (note: currently requires std for some traits)
• Need deterministic performance without allocator variance

API Overview

Both StackString and StackVec provide:

• Unchecked variants: push_unchecked, pop_unchecked, etc. for performance-critical code
• Try variants: try_push, try_pop, etc. that return Option instead of panicking
• Standard methods: push, pop, insert, remove, clear, truncate, etc.
• Deref to slice/str: Seamless integration with standard library functions

Safety

This crate uses unsafe internally for performance but exposes a safe API. All unsafe operations are carefully documented and validated. The public API is designed to prevent undefined behavior even when capacity is exceeded (operations will panic or return None instead).

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.