libdatrie-rs is a libdatrie ported with C2Rust and rewritten into safe Rust.

This project is intended to be a drop in replacement for original libdatrie, except for unexported functions. It has been tested with original libdatrie's test.

Using this library in Rust is possible, but in many places it expects and returns null terminated arrays. There's as_alphachar and ac_to_string adapter provided for &str/String respectively, so at least it should be able to store strings without internal 0 bytes.

The libdatrie FFI interop functions do not have stable interface in Rust and should only be used from FFI or in extern "C" in Rust.

Data types stored in Trie should implement the following traits:

• Default
• TrieSerializable if you want to save from file
• TrieDeserializable if you want to load from file

All these are supported out of the box for i32, Vec and Option<T> of any supporting types.

• std: Enable std. Disable for no_std support. Serialization is not available without std as this library make use of std::io::Cursor (default on)
• cffi: Enable building of C binding (default on, require std)
• ctest: Enable running C compatibility tests. These are the test from original libdatrie copied almost verbatim to ensure that our trie.h is backwards compatible
• bin: Enable building of trietool utility

It is currently unclear whether this library is faster or slower than the original library:

Pros

• All data structure are stack-allocated, reducing memory allocation. Of course, this excludes arrays and types passing through the FFI boundary.
• With generic and inlining, Rust can generate more optimal code than C, which might not inline exported function (even if exported internally) - at least on how it was used to compile original libdatrie.

Cons

• All array sizes are computed in advance (require a loop) while the C version sometimes do not check array size
• All array accesses are bound checked which create overhead
• Some memory access in C use uninitialized memory, but only if the user call things in the wrong order. In the Rust version all data are either initialized (adding initialization cost) or behind Option<> (adding additional checks).
• Serialization code may be slower due to the use of generics

As a derivative work of libdatrie, this package is licensed under the LGPL 2.1 license.