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use crate::{CppBox, CppDeletable, DynamicCast, MutRef, Ref, StaticDowncast, StaticUpcast}; use std::ffi::CStr; use std::fmt; use std::ops::{Deref, DerefMut}; use std::os::raw::c_char; /// A mutable pointer to a C++ object (similar to a C++ pointer). /// /// A `MutPtr` may or may not be owned. If you actually own the object, it's recommended to /// convert it to `CppBox` using `to_box` method. /// /// Note that unlike Rust references, `MutPtr` can be freely copied, /// producing multiple mutable pointers to the same object, which is usually necessary /// to do when working with C++ libraries. /// /// `MutPtr` implements operator traits and delegates them /// to the corresponding C++ operators. /// This means that you can use `&ptr + value` to access the object's `operator+`. /// /// `MutPtr` implements `Deref` and `DerefMut`, allowing to call the object's methods /// directly. In addition, methods of the object's first base class are also directly available /// thanks to nested `Deref` implementations. /// /// `MutPtr` can contain a null pointer. `Deref` will panic if attempted to dereference /// a null pointer. /// /// If the object provides an iterator interface through `begin()` and `end()` functions, /// `MutPtr` will implement `IntoIterator`, so you can iterate on it directly. /// /// ### Safety /// /// It's not possible to automatically track the ownership of objects possibly managed by C++ /// libraries. The user must ensure that the object is alive while `MutPtr` exists. Note that /// with `MutPtr`, it's possible to call unsafe C++ code without using any more unsafe Rust code, /// for example, by using operator traits, so care should be taken when exposing /// `MutPtr` in a safe interface. /// /// Null pointers must not be dereferenced. pub struct MutPtr<T>(*mut T); /// Creates another pointer to the same object. impl<T> Clone for MutPtr<T> { fn clone(&self) -> Self { MutPtr(self.0) } } /// Creates another pointer to the same object. impl<T> Copy for MutPtr<T> {} impl<T> fmt::Debug for MutPtr<T> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "MutPtr({:?})", self.0) } } impl<T> MutPtr<T> { /// Creates a `MutPtr` from a raw pointer. /// /// ### Safety /// /// See type level documentation. pub unsafe fn from_raw(ptr: *mut T) -> Self { MutPtr(ptr) } /// Creates a null pointer. /// /// Note that you can also use `NullPtr` to specify a null pointer to a function accepting /// `impl CastInto<MutPtr<_>>`. Unlike `MutPtr`, `NullPtr` is not a generic type, so it will /// not cause type inference issues. /// /// ### Safety /// /// Null pointers must not be dereferenced. See type level documentation. pub unsafe fn null() -> Self { MutPtr(std::ptr::null_mut()) } /// Returns the content as a raw const pointer. pub fn as_raw_ptr(self) -> *const T { self.0 } /// Returns the content as a raw mutable pointer. pub fn as_mut_raw_ptr(self) -> *mut T { self.0 } /// Returns the content as a const `Ptr`. /// /// ### Safety /// /// The operation is safe as long as `self` is valid or null. See type level documentation. pub unsafe fn as_ptr(self) -> Ptr<T> { Ptr::from_raw(self.0) } /// Returns the content as a const `Ref`. Returns `None` if `self` is a null pointer. /// /// ### Safety /// /// The operation is safe as long as `self` is valid or null. See type level documentation. pub unsafe fn as_ref(self) -> Option<Ref<T>> { Ref::from_raw(self.0) } /// Returns the content as a `MutRef`. Returns `None` if `self` is a null pointer. /// /// ### Safety /// /// The operation is safe as long as `self` is valid or null. See type level documentation. pub unsafe fn as_mut_ref(self) -> Option<MutRef<T>> { MutRef::from_raw(self.0) } /// Returns true if the pointer is null. pub fn is_null(self) -> bool { self.0.is_null() } /// Converts the pointer to the base class type `U`. /// /// ### Safety /// /// This operation is safe as long as `self` is valid or null. pub unsafe fn static_upcast<U>(self) -> Ptr<U> where T: StaticUpcast<U>, { StaticUpcast::static_upcast(self.as_ptr()) } /// Converts the pointer to the derived class type `U`. /// /// It's recommended to use `dynamic_cast` instead because it performs a checked conversion. /// /// ### Safety /// /// This operation is safe as long as `self` is valid and it's type is `U` or inherits from `U`, /// of if `self` is a null pointer. pub unsafe fn static_downcast<U>(self) -> Ptr<U> where T: StaticDowncast<U>, { StaticDowncast::static_downcast(self.as_ptr()) } /// Converts the pointer to the derived class type `U`. Returns `None` if the object's type /// is not `U` and doesn't inherit `U`. /// /// ### Safety /// /// This operation is safe as long as `self` is valid or null. pub unsafe fn dynamic_cast<U>(self) -> Ptr<U> where T: DynamicCast<U>, { DynamicCast::dynamic_cast(self.as_ptr()) } /// Converts the pointer to the base class type `U`. /// /// ### Safety /// /// This operation is safe as long as `self` is valid or null. pub unsafe fn static_upcast_mut<U>(self) -> MutPtr<U> where T: StaticUpcast<U>, { StaticUpcast::static_upcast_mut(self) } /// Converts the pointer to the derived class type `U`. /// /// It's recommended to use `dynamic_cast` instead because it performs a checked conversion. /// /// ### Safety /// /// This operation is safe as long as `self` is valid and it's type is `U` or inherits from `U`, /// of if `self` is a null pointer. pub unsafe fn static_downcast_mut<U>(self) -> MutPtr<U> where T: StaticDowncast<U>, { StaticDowncast::static_downcast_mut(self) } /// Converts the pointer to the derived class type `U`. Returns `None` if the object's type /// is not `U` and doesn't inherit `U`. /// /// ### Safety /// /// This operation is safe as long as `self` is valid or null. pub unsafe fn dynamic_cast_mut<U>(self) -> MutPtr<U> where T: DynamicCast<U>, { DynamicCast::dynamic_cast_mut(self) } } impl<T: CppDeletable> MutPtr<T> { /// Converts this pointer to a `CppBox`. Returns `None` if `self` /// is a null pointer. /// /// Use this function to take ownership of the object. This is /// the same as `CppBox::new`. pub unsafe fn to_box(self) -> Option<CppBox<T>> { CppBox::new(self) } } /// Allows to call member functions of `T` and its base classes directly on the pointer. impl<T> Deref for MutPtr<T> { type Target = T; fn deref(&self) -> &T { if self.0.is_null() { panic!("attempted to deref a null MutPtr<T>"); } unsafe { &(*self.0) } } } /// Allows to call member functions of `T` and its base classes directly on the pointer. impl<T> DerefMut for MutPtr<T> { fn deref_mut(&mut self) -> &mut T { if self.0.is_null() { panic!("attempted to deref a null MutPtr<T>"); } unsafe { &mut (*self.0) } } } impl MutPtr<c_char> { /// Creates a `MutPtr<c_char>`, i.e. C++'s `char*` from a `CStr`. /// /// ### Safety /// /// The source `str` must be valid /// while `MutPtr` exists and while /// it's used by the C++ library. /// /// After passing `str` to `MutPtr`, it's unsafe to use `str` and /// any references to the same buffer from Rust because /// the memory can be modified through `MutPtr`. pub unsafe fn from_c_str(str: &CStr) -> Self { Self::from_raw(str.as_ptr() as *mut c_char) } /// Converts `MutPtr<c_char>`, i.e. C++'s `char*` to a `&CStr`. /// /// ### Safety /// /// No guarantees can be made about the validity and lifetime of /// the buffer, since it could be produced by a C++ library. pub unsafe fn to_c_str<'a>(self) -> &'a CStr { CStr::from_ptr(self.0) } } /// A const pointer to a C++ object (similar to a C++ pointer). /// /// A `Ptr` may or may not be owned. If you actually own the object, it's recommended to /// convert it to `CppBox` using `to_box` method. /// /// Note that unlike Rust references, `Ptr` can be freely copied, /// producing multiple pointers to the same object, which is usually necessary /// to do when working with C++ libraries. /// /// `Ptr` implements operator traits and delegates them /// to the corresponding C++ operators. /// This means that you can use `&ptr + value` to access the object's `operator+`. /// /// `Ptr` implements `Deref`, allowing to call the object's methods /// directly. In addition, methods of the object's first base class are also directly available /// thanks to nested `Deref` implementations. /// /// `Ptr` can contain a null pointer. `Deref` will panic if attempted to dereference /// a null pointer. /// /// If the object provides an iterator interface through `begin()` and `end()` functions, /// `Ptr` will implement `IntoIterator`, so you can iterate on it directly. /// /// ### Safety /// /// It's not possible to automatically track the ownership of objects possibly managed by C++ /// libraries. The user must ensure that the object is alive while `Ptr` exists. Note that /// with `Ptr`, it's possible to call unsafe C++ code without using any more unsafe Rust code, /// for example, by using operator traits, so care should be taken when exposing /// `Ptr` in a safe interface. /// /// Null pointers must not be dereferenced. pub struct Ptr<T>(*const T); /// Creates another pointer to the same object. impl<T> Clone for Ptr<T> { fn clone(&self) -> Self { Ptr(self.0) } } /// Creates another pointer to the same object. impl<T> Copy for Ptr<T> {} impl<T> fmt::Debug for Ptr<T> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "Ptr({:?})", self.0) } } impl<T> Ptr<T> { /// Creates a `Ptr` from a raw pointer. /// /// ### Safety /// /// See type level documentation. pub unsafe fn from_raw(ptr: *const T) -> Self { Ptr(ptr) } /// Creates a null pointer. /// /// Note that you can also use `NullPtr` to specify a null pointer to a function accepting /// `impl CastInto<Ptr<_>>`. Unlike `Ptr`, `NullPtr` is not a generic type, so it will /// not cause type inference issues. /// /// ### Safety /// /// Null pointers must not be dereferenced. See type level documentation. pub unsafe fn null() -> Self { Ptr(std::ptr::null()) } /// Returns the content as a raw const pointer. pub fn as_raw_ptr(self) -> *const T { self.0 } /// Returns the content as a const `Ref`. Returns `None` if `self` is a null pointer. /// /// ### Safety /// /// The operation is safe as long as `self` is valid or null. See type level documentation. pub unsafe fn as_ref(self) -> Option<Ref<T>> { Ref::from_raw(self.0) } /// Returns true if the pointer is null. pub fn is_null(self) -> bool { self.0.is_null() } /// Converts the pointer to the base class type `U`. /// /// ### Safety /// /// This operation is safe as long as `self` is valid or null. pub unsafe fn static_upcast<U>(self) -> Ptr<U> where T: StaticUpcast<U>, { StaticUpcast::static_upcast(self) } /// Converts the pointer to the derived class type `U`. /// /// It's recommended to use `dynamic_cast` instead because it performs a checked conversion. /// /// ### Safety /// /// This operation is safe as long as `self` is valid and it's type is `U` or inherits from `U`, /// of if `self` is a null pointer. pub unsafe fn static_downcast<U>(self) -> Ptr<U> where T: StaticDowncast<U>, { StaticDowncast::static_downcast(self) } /// Converts the pointer to the derived class type `U`. Returns `None` if the object's type /// is not `U` and doesn't inherit `U`. /// /// ### Safety /// /// This operation is safe as long as `self` is valid or null. pub unsafe fn dynamic_cast<U>(self) -> Ptr<U> where T: DynamicCast<U>, { DynamicCast::dynamic_cast(self) } } /// Allows to call member functions of `T` and its base classes directly on the pointer. impl<T> Deref for Ptr<T> { type Target = T; fn deref(&self) -> &T { if self.0.is_null() { panic!("attempted to deref a null Ptr<T>"); } unsafe { &(*self.0) } } } /// Allows to call member functions of `T` and its base classes directly on the pointer. impl Ptr<c_char> { /// Creates a `Ptr<c_char>`, i.e. C++'s `const char*` from a `CStr`. /// /// ### Safety /// /// The source `str` must be valid /// while `Ptr` exists and while /// it's used by the C++ library. /// /// After passing `str` to `Ptr`, it's unsafe to use `str` and /// any references to the same buffer from Rust because /// the memory can be modified through `Ptr`. pub unsafe fn from_c_str(str: &CStr) -> Self { Self::from_raw(str.as_ptr()) } /// Converts `Ptr<c_char>`, i.e. C++'s `const char*` to a `&CStr`. /// /// ### Safety /// /// No guarantees can be made about the validity and lifetime of /// the buffer, since it could be produced by a C++ library. pub unsafe fn to_c_str<'a>(self) -> &'a CStr { CStr::from_ptr(self.0) } } /// A null pointer. /// /// `NullPtr` implements `CastInto<Ptr<T>>` and `CastInto<MutPtr<T>>`, so it can be /// passed as argument to functions accepting pointers. It's possible to use `Ptr::null()` /// as well, but that would require a type annotation. pub struct NullPtr; #[test] fn ptr_deref() { let mut i = 42; unsafe { let ptr: MutPtr<i32> = MutPtr::from_raw(&mut i as *mut i32); assert_eq!(*ptr, 42); } }