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    //! `static` friendly data structures that don't require dynamic memory allocation
    //!
    //! The core principle behind `heapless` is that its data structures are backed by a *static* memory
    //! allocation. For example, you can think of `heapless::Vec` as an alternative version of
    //! `std::Vec` with fixed capacity and that can't be re-allocated on the fly (e.g. via `push`).
    //!
    //! All `heapless` data structures store their memory allocation *inline* and specify their capacity
    //! via their type parameter `N`. This means that you can instantiate a `heapless` data structure on
    //! the stack, in a `static` variable, or even in the heap.
    //!
    //! ```
    //! use heapless::Vec; // fixed capacity `std::Vec`
    //! use heapless::consts::U8; // type level integer used to specify capacity
    //!
    //! // on the stack
    //! let mut xs: Vec<u8, U8> = Vec::new(); // can hold up to 8 elements
    //! xs.push(42).unwrap();
    //! assert_eq!(xs.pop(), Some(42));
    //!
    //! // in a `static` variable
    //! // (because `const-fn` has not been fully stabilized you need to use the helper structs in
    //! // the `i` module, which must be wrapped in a tuple struct)
    //! static mut XS: Vec<u8, U8> = Vec(heapless::i::Vec::new());
    //!
    //! let xs = unsafe { &mut XS };
    //!
    //! xs.push(42);
    //! assert_eq!(xs.pop(), Some(42));
    //!
    //! // in the heap (though kind of pointless because no reallocation)
    //! let mut ys: Box<Vec<u8, U8>> = Box::new(Vec::new());
    //! ys.push(42).unwrap();
    //! assert_eq!(ys.pop(), Some(42));
    //! ```
    //!
    //! Because they have fixed capacity `heapless` data structures don't implicitly reallocate. This
    //! means that operations like `heapless::Vec.push` are *truly* constant time rather than amortized
    //! constant time with potentially unbounded (depends on the allocator) worst case execution time
    //! (which is bad / unacceptable for hard real time applications).
    //!
    //! `heapless` data structures don't use a memory allocator which means no risk of an uncatchable
    //! Out Of Memory (OOM) condition while performing operations on them. It's certainly possible to
    //! run out of capacity while growing `heapless` data structures, but the API lets you handle this
    //! possibility by returning a `Result` on operations that may exhaust the capacity of the data
    //! structure.
    //!
    //! List of currently implemented data structures:
    //!
    //! - [`BinaryHeap`](binary_heap/struct.BinaryHeap.html) -- priority queue
    //! - [`IndexMap`](struct.IndexMap.html) -- hash table
    //! - [`IndexSet`](struct.IndexSet.html) -- hash set
    //! - [`LinearMap`](struct.LinearMap.html)
    //! - [`Pool`](pool/struct.Pool.html) -- lock-free memory pool
    //! - [`String`](struct.String.html)
    //! - [`Vec`](struct.Vec.html)
    //! - [`mpmc::Q*`](mpmc/index.html) -- multiple producer multiple consumer lock-free queue
    //! - [`spsc::Queue`](spsc/struct.Queue.html) -- single producer single consumer lock-free queue
    //!
    //! # Optional Features
    //!
    //! The `heapless` crate provides the following optional Cargo features:
    //!
    //! - `ufmt-impl`: Implement [`ufmt_write::uWrite`] for `String<N>` and `Vec<u8, N>`
    //!
    //! [`ufmt_write::uWrite`]: https://docs.rs/ufmt-write/
    //!
    //! # Minimum Supported Rust Version (MSRV)
    //!
    //! This crate is guaranteed to compile on stable Rust 1.36 and up with its default set of features.
    //! It *might* compile on older versions but that may change in any new patch release.

    #![cfg_attr(not(test), no_std)]
    #![deny(missing_docs)]
    #![deny(rust_2018_compatibility)]
    #![deny(rust_2018_idioms)]
    #![deny(warnings)]

    pub use binary_heap::BinaryHeap;
    pub use generic_array::typenum::{consts, PowerOfTwo};
    pub use generic_array::ArrayLength;
    pub use histbuf::HistoryBuffer;
    pub use indexmap::{Bucket, FnvIndexMap, IndexMap, Pos};
    pub use indexset::{FnvIndexSet, IndexSet};
    pub use linear_map::LinearMap;
    pub use string::String;
    pub use vec::Vec;

    // NOTE this code was last ported from v0.4.1 of the indexmap crate
    mod histbuf;
    mod indexmap;
    mod indexset;
    mod linear_map;
    mod string;
    mod vec;

    #[cfg(feature = "serde")]
    mod de;
    #[cfg(feature = "serde")]
    mod ser;

    pub mod binary_heap;
    pub mod i;
    #[cfg(all(has_cas, feature = "cas"))]
    pub mod mpmc;
    #[cfg(all(has_cas, feature = "cas"))]
    pub mod pool;
    #[cfg(has_atomics)]
    pub mod spsc;

    #[cfg(feature = "ufmt-impl")]
    mod ufmt;

    mod sealed;