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use crate::ops::{Begin, BeginMut, End, EndMut, Increment, Indirection}; use crate::vector_ops::{Data, DataMut, Size}; use crate::{ cpp_iter, CppBox, CppDeletable, CppIterator, DynamicCast, Ref, StaticDowncast, StaticUpcast, }; use std::ops::Deref; use std::{fmt, slice}; /// A 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>(*mut 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 as *mut T) } /// Creates a null pointer. /// /// Note that accessing the content of a null `Ptr` through `Deref` /// will result in a panic. /// /// 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_mut()) } /// Returns the content as a raw const pointer. pub fn as_mut_raw_ptr(self) -> *mut T { self.0 as *mut T } /// 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 a reference to the value. Returns `None` if the pointer is null. /// /// ### Safety /// /// `self` must be valid. /// The content must not be read or modified through other ways while the returned reference /// exists.See type level documentation. pub unsafe fn as_raw_ref<'a>(self) -> Option<&'a T> { self.as_ref().map(|r| r.as_raw_ref()) } /// Returns a mutable reference to the value. Returns `None` if the pointer is null. /// /// ### Safety /// /// `self` must be valid. /// The content must not be read or modified through other ways while the returned reference /// exists.See type level documentation. pub unsafe fn as_mut_raw_ref<'a>(self) -> Option<&'a mut T> { self.as_ref().map(|r| r.as_mut_raw_ref()) } /// 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) } } impl<V, T> Ptr<V> where V: Data<Output = *const T> + Size, { /// Returns the content of the object as a slice, based on `data()` and `size()` methods. /// /// # Safety /// /// The caller must make sure `self` contains a valid pointer. The content must /// not be read or modified through other ways while the returned slice exists. /// This function /// may invoke arbitrary foreign code, so no safety guarantees can be made. pub unsafe fn as_slice<'a>(self) -> &'a [T] { let ptr = self.data(); let size = self.size(); slice::from_raw_parts(ptr, size) } } impl<V, T> Ptr<V> where V: DataMut<Output = *mut T> + Size, { /// Returns the content of the vector as a mutable slice, /// based on `data()` and `size()` methods. /// /// # Safety /// /// The caller must make sure `self` contains a valid pointer. The content must /// not be read or modified through other ways while the returned slice exists. /// This function /// may invoke arbitrary foreign code, so no safety guarantees can be made. pub unsafe fn as_mut_slice<'a>(self) -> &'a mut [T] { let ptr = self.data_mut(); let size = self.size(); slice::from_raw_parts_mut(ptr, size) } } impl<T, T1, T2> Ptr<T> where T: Begin<Output = CppBox<T1>> + End<Output = CppBox<T2>>, T1: CppDeletable + PartialEq<Ref<T2>> + Increment + Indirection, T2: CppDeletable, { /// Returns an iterator over the content of the object, /// based on `begin()` and `end()` methods. /// /// # Safety /// /// The caller must make sure `self` contains a valid pointer. The content must /// not be read or modified through other ways while the returned slice exists. /// This function /// may invoke arbitrary foreign code, so no safety guarantees can be made. pub unsafe fn iter(self) -> CppIterator<T1, T2> { cpp_iter(self.begin(), self.end()) } } impl<T, T1, T2> Ptr<T> where T: BeginMut<Output = CppBox<T1>> + EndMut<Output = CppBox<T2>>, T1: CppDeletable + PartialEq<Ref<T2>> + Increment + Indirection, T2: CppDeletable, { /// Returns a mutable iterator over the content of the object, /// based on `begin()` and `end()` methods. /// /// # Safety /// /// The caller must make sure `self` contains a valid pointer. The content must /// not be read or modified through other ways while the returned slice exists. /// This function /// may invoke arbitrary foreign code, so no safety guarantees can be made. pub unsafe fn iter_mut(self) -> CppIterator<T1, T2> { cpp_iter(self.begin_mut(), self.end_mut()) } } /// Allows to call member functions of `T` and its base classes directly on the pointer. /// /// Panics if the pointer is null. 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) } } } impl<T: CppDeletable> Ptr<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`. /// /// # Safety /// /// See type level documentation. See also `CppBox::new` documentation. pub unsafe fn to_box(self) -> Option<CppBox<T>> { CppBox::new(self) } } /// A null pointer. /// /// `NullPtr` implements `CastInto<Ptr<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 i = 42; unsafe { let ptr: Ptr<i32> = Ptr::from_raw(&i); assert_eq!(*ptr, 42); } }