/*!

For Rust-to-Rust ffi,
with a focus on creating libraries loaded at program startup,
and with load-time type-checking.

This library allows defining Rust libraries that can be loaded at runtime,
even if they were built with a different Rust version than the crate that depends on it.

These are some usecases for this library:
    
- Converting a Rust dependency tree from compiling statically into a single binary,
    into one binary (and potentially) many dynamic libraries,
    allowing separate re-compilation on changes.

- Creating a plugin system (without support for unloading).
    
# Features

Currently this library has these features:

- ffi-safe equivalent of trait objects for any combination of a selection of traits.

- Provides ffi-safe alternatives to many standard library types..

- Provides the `StableAbi` trait for asserting that types are ffi-safe.

- Features for building extensible modules and vtables,without breaking ABI compatibility.

- Checking at load-time that the types in the dynamic library have the expected layout,
    allowing for semver compatible changes while checking the layout of types.

- Provides the `StableAbi` derive macro to both assert that the type is ffi compatible,
    and to get the layout of the type at runtime to check that it is still compatible.

# Examples

For **examples** of using `abi_stable` you can look at the crates in the examples directory ,
in the repository for this crate.

To run the examples generally you'll have to build the `*_impl` crate,
then run the `*_user` crate (all `*_user` crates should have a help message and a readme.md).

# Glossary

`interface crate`:the crate that declares the public functions and types that 
are necessary to load the library at runtime.

`ìmplementation crate`:A crate that implements all the functions in the interface crate.

`user crate`:A crate that depends on an `interface crate` and 
loads 1 or more `ìmplementation crate`s for it.

`module`:refers to a struct of function pointers and other static values,
and implement the RootModule trait.
These are declared in the `interface crate`,exported in the `implementation crate`,
and loaded in the `user crate`.

# Rust-to-Rust FFI guidelines.

Types must implement StableAbi to be safely passed through the FFI boundary,
which can be done using the StableAbi derive macro.

These are the kinds of types passed through FFI:

- Value kind:
    The layout of types passed by value must not change in a minor version.
    This is the default kind when deriving StableAbi.

- Opaque kind:
    Types wrapped in `DynTrait<SomePointer<()>,Interface>`,
    whose layout can change in any version of the library,
    and can only be unwrapped back to the original type in the dynamic library/binary 
    that created it.

- [Prefix kind](./docs/prefix_types/index.html):
    Types only accessible through shared references,
    most commonly vtables and modules,
    which can be extended in minor versions while staying ABI compatible.
    by adding fields at the end.

### Declaring enums

Adding variants or fields to a variant is disallowed in minor versions.

To represent non-exhaustive enums without fields it is recommended using structs and associated constants so that it is not UB to keep adding field-less variants in minor versions.

# Extra documentation

- [Unsafe code guidelines](./docs/unsafe_code_guidelines/index.html):<br>
    Describes how to write unsafe code ,relating to this library.

# Macros

- [StableAbi derive macro](./docs/stable_abi_derive/index.html):<br>
    For asserting abi-stability of a type,
    and obtaining the layout of the time at runtime.

- [Prefix-types (using the StableAbi derive macro)
  ](./docs/prefix_types/index.html):<br>
    The method by which *vtables* and *modules* are implemented,
    allowing extending them in minor versions of a library.

*/

#![allow(unused_unsafe)]
#![deny(unused_must_use)]
#![warn(rust_2018_idioms)]

#[macro_use]
extern crate serde_derive;

#[macro_use(StableAbi)]
extern crate abi_stable_derive;


#[doc(inline)]
pub use abi_stable_derive::StableAbi;

#[doc(inline)]
pub use abi_stable_derive::{
    export_sabi_module,
    impl_InterfaceType,
};

#[macro_use]
mod impls;


#[macro_use]
mod macros;


#[cfg(test)]
#[macro_use]
mod test_macros;

#[cfg(test)]
#[macro_use]
mod test_utils;

#[macro_use]
pub mod utils;

#[macro_use]
pub mod const_utils;

#[macro_use]
pub mod traits;


#[macro_use]
pub mod abi_stability;
// pub mod cabi_type;
// pub mod as_proxy;
pub mod erased_types;
// pub mod immovable_wrapper;
pub mod library;
pub mod ignored_wrapper;
pub mod marker_type;
mod multikey_map;
pub mod pointer_trait;
pub mod prefix_type;

#[doc(hidden)]
pub mod return_value_equality;

#[doc(hidden)]
pub mod derive_macro_reexports;
pub mod std_types;


pub mod lazy_static_ref;
pub mod type_level;
pub mod version;

pub mod docs;




/// Miscelaneous items re-exported from core_extensions.
pub mod reexports{
    pub use core_extensions::SelfOps;
}

/*
I am using this static as the `identity` of this dynamic library/executable,
this assumes that private static variables don't get merged between 
Rust dynamic libraries that have a different global allocator.

If the address of this is the same among dynamic libraries that have *different* 
allocators,please create an issue for this.
*/
use std::sync::atomic::AtomicUsize;
static EXECUTABLE_IDENTITY: AtomicUsize = AtomicUsize::new(1);

#[doc(inline)]
pub use crate::{
    abi_stability::StableAbi,
    erased_types::{DynTrait,ImplType, InterfaceType},
};



#[doc(hidden)]
pub mod globals{
    use crate::{
        lazy_static_ref::LazyStaticRef,
        abi_stability::{
            abi_checking::{check_abi_stability_for_ffi},
            stable_abi_trait::AbiInfoWrapper,
        },
        std_types::{RResult,RBoxError},
        utils::leak_value,
    };

    #[repr(C)]
    #[derive(StableAbi)]
    #[sabi(inside_abi_stable_crate)]
    pub struct Globals{
        pub layout_checking:
            extern fn(&'static AbiInfoWrapper,&'static AbiInfoWrapper) -> RResult<(), RBoxError> ,
    }

    impl Globals{
        pub fn new()->&'static Self{
            leak_value(Globals{
                layout_checking:check_abi_stability_for_ffi,
            })
        }
    }

    pub(crate)static GLOBALS:LazyStaticRef<Globals>=LazyStaticRef::new();

    #[inline(never)]
    pub fn initialized_globals()->&'static Globals{
        GLOBALS.init(|| Globals::new() )
    }


    pub type InitializeGlobalsWithFn=
        extern "C" fn(&'static Globals);


    #[inline(never)]
    pub extern fn initialize_globals_with(globs:&'static Globals){
        let _:InitializeGlobalsWithFn=initialize_globals_with;

        GLOBALS.init(|| globs );
    }
}