PkmnLib_rs/src/ffi/mod.rs

/// The foreign function interfaces for the dynamic data
mod dynamic_data;
/// The foreign function interfaces for that static data
mod static_data;

/// Helper type for clearer functions.
type OwnedPtr<T> = *mut T;
/// Helper type for clearer functions.
type BorrowedPtr<T> = *const T;

/// Generates a basic getter foreign function interface.
macro_rules! ffi_arc_getter {
    (
        $type:ty, $func:ident, $returns: ty
    ) => {
        paste::paste! {
            #[no_mangle]
            extern "C" fn [< $type:snake _ $func >](ptr: ExternPointer<Arc<$type>>) -> $returns {
                ptr.as_ref().$func()
            }
        }
    };
}

/// Generates a basic getter foreign function interface.
macro_rules! ffi_arc_dyn_getter {
    (
        $type:ty, $func:ident, $returns: ty
    ) => {
        paste::paste! {
            #[no_mangle]
            extern "C" fn [< $type:snake _ $func >](ptr: ExternPointer<Arc<dyn $type>>) -> $returns {
                ptr.as_ref().$func()
            }
        }
    };
}

/// Generates a basic getter foreign function interface where the return type is a [`crate::StringKey`].
macro_rules! ffi_arc_stringkey_getter {
    (
        $type:ty, $func:ident
    ) => {
        paste::paste! {
            #[no_mangle]
            extern "C" fn [< $type:lower _ $func >](ptr: ExternPointer<Arc<dyn $type>>) -> OwnedPtr<c_char> {
                std::ffi::CString::new(ptr.as_ref().$func().str()).unwrap().into_raw()
            }
        }
    };
}

/// Generates a foreign function interface for a vec. This generates a length function, and a getter.
macro_rules! ffi_vec_value_getters {
    (
        $name:ident, $type:ty, $func:ident, $returns: ty
    ) => {
        paste::paste! {
            #[no_mangle]
            extern "C" fn [< $name:lower _ $func _length>](ptr: ExternPointer<Arc<$type>>) -> usize {
                ptr.as_ref().$func().len()
            }
            #[no_mangle]
            extern "C" fn [< $name:lower _ $func _get>](ptr: ExternPointer<Arc<$type>>, index: usize) -> $returns {
                *ptr.as_ref().$func().get(index).unwrap()
            }
        }
    };
}

/// Generates a foreign function interface for a vec of [`crate::StringKey`]. This generates a
/// length function, and a getter.
macro_rules! ffi_vec_stringkey_getters {
    (
        $type:ty, $func:ident
    ) => {
        paste::paste! {
            #[no_mangle]
            extern "C" fn [< $type:lower _ $func _length>](ptr: ExternPointer<Arc<dyn $type>>) -> usize {
                ptr.as_ref().$func().len()
            }
            #[no_mangle]
            extern "C" fn [< $type:lower _ $func _get>](ptr: ExternPointer<Arc<dyn $type>>, index: usize) -> OwnedPtr<c_char> {
                CString::new(ptr.as_ref().$func().get(index).unwrap().str()).unwrap().into_raw()
            }
        }
    };
}

use crate::{ValueIdentifiable, ValueIdentifier};
pub(self) use ffi_arc_dyn_getter;
pub(self) use ffi_arc_getter;
pub(self) use ffi_arc_stringkey_getter;
pub(self) use ffi_vec_stringkey_getters;
pub(self) use ffi_vec_value_getters;
use std::ffi::{c_char, CString};
use std::mem::transmute;
use std::sync::Arc;

/// Helper utility class to wrap a pointer for extern functions.
#[repr(C)]
pub(self) struct ExternPointer<T: ?Sized> {
    /// The wrapped pointer.
    ptr: *mut T,
}

impl<T: ?Sized> ExternPointer<T> {
    /// Get the internal pointer as reference.
    pub(self) fn as_ref(&self) -> &T {
        unsafe {
            self.ptr
                .as_ref()
                .unwrap_or_else(|| panic!("Given pointer of type '{}' was null", std::any::type_name::<T>()))
        }
    }
    /// Get the internal pointer as mutable reference.
    pub(self) fn as_mut(&mut self) -> &mut T {
        unsafe {
            self.ptr
                .as_mut()
                .unwrap_or_else(|| panic!("Given pointer of type '{}' was null", std::any::type_name::<T>()))
        }
    }
}

/// Helper utility class to give both the pointer and identifier to a FFI.
#[repr(C)]
pub(self) struct IdentifiablePointer<T> {
    /// The wrapped pointer.
    pub ptr: *const T,
    /// The identifier of the pointer.
    pub id: usize,
}

impl<T> Clone for IdentifiablePointer<T> {
    fn clone(&self) -> Self {
        Self {
            id: self.id,
            ptr: self.ptr,
        }
    }
}

impl<T> Copy for IdentifiablePointer<T> {}

impl<T> IdentifiablePointer<T> {
    /// Creates a new IdentifiablePointer.
    pub(self) fn new(ptr: *const T, id: ValueIdentifier) -> Self {
        unsafe { Self { ptr, id: transmute(id) } }
    }
}

impl<T> From<*mut T> for ExternPointer<T> {
    fn from(ptr: *mut T) -> Self {
        ExternPointer { ptr }
    }
}

impl<T: ValueIdentifiable + ?Sized> From<Arc<T>> for IdentifiablePointer<Arc<T>> {
    fn from(v: Arc<T>) -> Self {
        let id = v.value_identifier().value();
        Self {
            ptr: Box::into_raw(Box::new(v)),
            id,
        }
    }
}

impl<T: ValueIdentifiable + ?Sized> From<Option<Arc<T>>> for IdentifiablePointer<Arc<T>> {
    fn from(v: Option<Arc<T>>) -> Self {
        if let Some(v) = v {
            let id = unsafe { transmute(v.value_identifier()) };
            Self {
                ptr: Box::into_raw(Box::new(v)),
                id,
            }
        } else {
            IdentifiablePointer::none()
        }
    }
}

impl<T: ValueIdentifiable + ?Sized> From<Box<T>> for IdentifiablePointer<Box<T>> {
    fn from(v: Box<T>) -> Self {
        let id = unsafe { transmute(v.value_identifier()) };
        Self {
            ptr: Box::into_raw(Box::new(v)),
            id,
        }
    }
}

impl<T: ValueIdentifiable + ?Sized> From<&Box<T>> for IdentifiablePointer<Box<T>> {
    fn from(v: &Box<T>) -> Self {
        let id = unsafe { transmute(v.value_identifier()) };
        Self {
            ptr: v as *const Box<T>,
            id,
        }
    }
}

impl<T: ValueIdentifiable + ?Sized> From<Option<Box<T>>> for IdentifiablePointer<Box<T>> {
    fn from(v: Option<Box<T>>) -> Self {
        if let Some(v) = v {
            let id = unsafe { transmute(v.value_identifier()) };
            Self {
                ptr: Box::into_raw(Box::new(v)),
                id,
            }
        } else {
            IdentifiablePointer::none()
        }
    }
}

impl<T: ValueIdentifiable + ?Sized> From<&Option<Box<T>>> for IdentifiablePointer<Box<T>> {
    fn from(v: &Option<Box<T>>) -> Self {
        if let Some(v) = v {
            let id = unsafe { transmute(v.value_identifier()) };
            unsafe {
                Self {
                    ptr: *Box::into_raw(Box::new(v as *const Box<T>)),
                    id,
                }
            }
        } else {
            IdentifiablePointer::none()
        }
    }
}

impl<T: ValueIdentifiable> From<Box<T>> for IdentifiablePointer<T> {
    fn from(v: Box<T>) -> Self {
        let id = unsafe { transmute(v.value_identifier()) };
        Self {
            ptr: Box::into_raw(v),
            id,
        }
    }
}

impl<T: ValueIdentifiable> From<*const T> for IdentifiablePointer<T> {
    fn from(v: *const T) -> Self {
        let id = unsafe { transmute(v.as_ref().unwrap().value_identifier()) };
        Self { ptr: v, id }
    }
}

impl<T> IdentifiablePointer<T> {
    /// Returns an identifiable pointer with null as pointer, and 0 as identifier.
    pub fn none() -> Self {
        Self {
            ptr: std::ptr::null(),
            id: Default::default(),
        }
    }
}

/// Helper utility class to give either the data or an error to a FFI.
#[repr(C)]
union ResultUnion<T: Copy> {
    /// If the result is ok, this contains the value.
    ok: T,
    /// If the result is an error, this contains the error message.
    err: OwnedPtr<c_char>,
}

/// The result of a FFI call that can either be an error or a value.
#[repr(C)]
pub struct NativeResult<T: Copy> {
    /// If the result is ok, this is 1, otherwise 0.
    ok: u8,
    /// The value or error.
    value: ResultUnion<T>,
}

impl<T: Copy> NativeResult<T> {
    /// Creates a new NativeResult with the given value.
    pub fn ok(value: T) -> Self {
        Self {
            ok: 1,
            value: ResultUnion { ok: value },
        }
    }
    /// Creates a new NativeResult with the given error.
    pub fn err(err: anyhow::Error) -> Self {
        Self {
            ok: 0,
            value: ResultUnion {
                err: CString::new(err.to_string()).unwrap().into_raw(),
            },
        }
    }
}

impl<T: Copy> From<anyhow::Result<T>> for NativeResult<T> {
    fn from(value: anyhow::Result<T>) -> Self {
        match value {
            Ok(v) => Self::ok(v),
            Err(e) => Self::err(e),
        }
    }
}

impl<T: Copy> From<T> for NativeResult<T> {
    fn from(value: T) -> Self {
        Self::ok(value)
    }
}