Built-in bindings reference
In addition to all the primitive types (i32 <=> int32_t), the following common types may be used in the fields of shared structs and the arguments and returns of extern functions.
name in Rust | name in C | restrictions |
---|---|---|
String | rust::String | |
&str | rust::Str | |
&[T] | rust::Slice<const T> | cannot hold opaque C type |
&mut [T] | rust::Slice<T> | cannot hold opaque C type |
CxxString | std::string | cannot be passed by value |
Box<T> | rust::Box<T> | cannot hold opaque C type |
UniquePtr<T> | std::unique_ptr<T> | cannot hold opaque Rust type |
SharedPtr<T> | std::shared_ptr<T> | cannot hold opaque Rust type |
[T; N] | std::array<T, N> | cannot hold opaque C type |
Vec<T> | rust::Vec<T> | cannot hold opaque C type |
CxxVector<T> | std::vector<T> | cannot be passed by value, cannot hold opaque Rust type |
*mut T, *const T | T*, const T* | fn with a raw pointer argument must be declared unsafe to call |
fn(T, U) -> V | rust::Fn<V(T, U)> | only passing from Rust to C is implemented so far |
Result<T> | throw/catch | allowed as return type only |
The C API of the rust
namespace is defined by the include/cxx.h file in
the CXX GitHub repo. You will need to include this header in your C code when
working with those types. When using Cargo and the cxx-build crate, the header
is made available to you at #include "rust/cxx.h"
.
The rust
namespace additionally provides lowercase type aliases of all the
types mentioned in the table, for use in codebases preferring that style. For
example rust::String
, rust::Vec
may alternatively be written rust::string
,
rust::vec
etc.
Pending bindings
The following types are intended to be supported "soon" but are just not implemented yet. I don't expect any of these to be hard to make work but it's a matter of designing a nice API for each in its non-native language.
name in Rust | name in C |
---|---|
BTreeMap<K, V> | tbd |
HashMap<K, V> | tbd |
Arc<T> | tbd |
Option<T> | tbd |
tbd | std::map<K, V> |
tbd | std::unordered_map<K, V> |