1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124

//! `static_cast` and `dynamic_cast`.

use crate::{MutPtr, Ptr};

/// Converts a class pointer to a base class pointer.
///
/// A null pointer is always converted to a null pointer.
/// Otherwise, the provided pointer must be valid.
///
/// It's recommended to perform the conversion by calling `static_upcast` and
/// `static_upcast_mut` methods on pointer types (`CppBox`, `Ptr`, `MutPtr`, `Ref`, `MutRef`)
/// instead of importing the trait directly.
///
/// Provides access to C++ `static_cast` conversion from derived class to base class.
/// The conversion in opposite direction can be done with `StaticDowncast`.
///
/// If `T1` class is derived (in C++) from `T2` class (directly or indirectly),
/// `StaticUpcast<T2>` is implemented for `T1`.
/// The implementation is generated by `ritual` automatically.
///
/// Note that Rust functions associated with this trait have runtime overhead.
/// In C++, `static_cast` is usually a no-op if there is no multiple inheritance,
/// and multiple inheritance requires pointer adjustment. However, Rust compiler
/// and `ritual` do not have any information about these implementation details,
/// so all calls of `static_cast` are wrapper in FFI functions.
pub trait StaticUpcast<T>: Sized {
    /// Convert type of a const pointer.
    ///
    /// ### Safety
    ///
    /// This operation is safe as long as `ptr` is either valid or null.
    unsafe fn static_upcast(ptr: Ptr<Self>) -> Ptr<T>;
    /// Convert type of a mutable pointer.
    ///
    /// ### Safety
    ///
    /// This operation is safe as long as `ptr` is either valid or null.
    unsafe fn static_upcast_mut(ptr: MutPtr<Self>) -> MutPtr<T>;
}

impl<T> StaticUpcast<T> for T {
    unsafe fn static_upcast(ptr: Ptr<T>) -> Ptr<T> {
        ptr
    }

    unsafe fn static_upcast_mut(ptr: MutPtr<T>) -> MutPtr<T> {
        ptr
    }
}

/// Converts a class pointer to a base class pointer without a runtime check.
///
/// A null pointer is always converted to a null pointer.
/// Otherwise, the provided pointer must be valid and point to the object of the specified type.
///
/// It's generally safer to use `DynamicCast` instead because it performs a checked conversion.
/// This trait should only be used if the type of the object is known.
///
/// It's recommended to perform the conversion by calling `static_downcast` and
/// `static_downcast_mut` methods on pointer types (`CppBox`, `Ptr`, `MutPtr`, `Ref`, `MutRef`)
/// instead of importing the trait directly.
///
/// Provides access to C++ `static_cast` conversion from base class to derived class.
/// The conversion in opposite direction can be done with `StaticUpcast`.
///
/// If `T1` class is derived (in C++) from `T2` class (directly or indirectly),
/// `StaticDowncast<T1>` is implemented for `T2`.
/// The implementation is generated by `ritual` automatically.
///
/// Note that Rust functions associated with this trait have runtime overhead.
/// In C++, `static_cast` is usually a no-op if there is no multiple inheritance,
/// and multiple inheritance requires pointer adjustment. However, Rust compiler
/// and `ritual` do not have any information about these implementation details,
/// so all calls of `static_cast` are wrapper in FFI functions.
pub trait StaticDowncast<T>: Sized {
    /// Convert type of a const pointer.
    ///
    /// ### Safety
    ///
    /// This operation is safe as long as `ptr` is either null or points to an object
    /// of the `T` class or a class inherited by `T`.
    unsafe fn static_downcast(ptr: Ptr<Self>) -> Ptr<T>;
    /// Convert type of a mutable pointer.
    ///
    /// ### Safety
    ///
    /// This operation is safe as long as `ptr` is either null or points to an object
    /// of the `T` class or a class inherited by `T`.
    unsafe fn static_downcast_mut(ptr: MutPtr<Self>) -> MutPtr<T>;
}

/// Converts a class pointer to a base class pointer.
///
/// A null pointer is always converted to a null pointer.
/// If the object can't be converted to the requested type, a null pointer is returned.
///
/// It's recommended to perform the conversion by calling `dynamic_cast` and
/// `dynamic_cast_mut` methods on pointer types (`CppBox`, `Ptr`, `MutPtr`, `Ref`, `MutRef`)
/// instead of importing the trait directly.
///
/// Provides access to C++ `dynamic_cast` conversion from base class to derived class.
/// The conversion in opposite direction can be done with `StaticUpcast`.
///
/// If `T1` class is derived (in C++) from `T2` class (directly or indirectly),
/// `DynamicCast<T1>` is implemented for `T2`.
/// The implementation is generated by `ritual` automatically.
pub trait DynamicCast<T>: Sized {
    /// Convert type of a const pointer.
    ///
    /// Returns a null pointer if the object doesn't have the requested type.
    ///
    /// ### Safety
    ///
    /// This operation is safe as long as `ptr` is either valid or null.
    unsafe fn dynamic_cast(ptr: Ptr<Self>) -> Ptr<T>;
    /// Convert type of a mutable pointer.
    ///
    /// Returns a null pointer if the object doesn't have the requested type.
    ///
    /// ### Safety
    ///
    /// This operation is safe as long as `ptr` is either valid or null.
    unsafe fn dynamic_cast_mut(ptr: MutPtr<Self>) -> MutPtr<T>;
}