diff options
Diffstat (limited to 'butl/const-ptr')
-rw-r--r-- | butl/const-ptr | 80 |
1 files changed, 0 insertions, 80 deletions
diff --git a/butl/const-ptr b/butl/const-ptr deleted file mode 100644 index 2790253..0000000 --- a/butl/const-ptr +++ /dev/null @@ -1,80 +0,0 @@ -// file : butl/const-ptr -*- C++ -*- -// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd -// license : MIT; see accompanying LICENSE file - -#ifndef BUTL_CONST_PTR -#define BUTL_CONST_PTR - -#include <cstddef> // nullptr_t - -namespace butl -{ - // Const-propagating pointer. - // - // It has the semantics of a raw pointer except that it passes on its own - // const-ness to the pointed-to object. In other words, if you have a const - // instance of this pointer, then you can only obtain a const raw pointer to - // the underlying object. It is normally used as a data member, for example: - // - // struct tree - // { - // const_ptr<tree> left; - // const_ptr<tree> right; - // - // void modify (); - // }; - // - // tree* x = ...; - // const tree* y = ...; - // - // x.left->modify (); // Ok. - // y.left->modify (); // Error. - // - // Note that due to this semantics, copy construction/assignment requires - // a non-const instance of const_ptr. - // - // Note that this type is standard layout (which means we can reinterpret - // it as a raw pointer). - // - // Known drawbacks/issues: - // - // 1. Cannot do static_cast<mytree*> (x.left). - // - template <typename T> - class const_ptr - { - public: - const_ptr () = default; - explicit const_ptr (T* p): p_ (p) {} - const_ptr (std::nullptr_t): p_ (nullptr) {} - - const_ptr& operator= (T* p) {p_ = p; return *this;} - const_ptr& operator= (std::nullptr_t) {p_ = nullptr; return *this;} - - template <class T1> explicit const_ptr (T1* p): p_ (p) {} - template <class T1> const_ptr (const_ptr<T1>& p): p_ (p.p_) {} - - template <class T1> const_ptr& operator= (T1* p) {p_ = p; return *this;} - template <class T1> const_ptr& operator= (const_ptr<T1>& p) { - p_ = p.p_; return *this;} - - T* operator-> () {return p_;} - const T* operator-> () const {return p_;} - - T& operator* () {return *p_;} - const T& operator* () const {return *p_;} - - operator T* () {return p_;} - operator const T* () const {return p_;} - - explicit operator bool () const {return p_ != nullptr;} - - T* get () {return p_;} - const T* get () const {return p_;} - - private: - T* p_; - }; -} - -#endif // BUTL_CONST_PTR |