Move ref<t> into a separate header

This commit is contained in:
Eelco Dolstra 2016-02-23 13:53:31 +01:00
parent 8f71bc33d5
commit c0b7a8a0b5
2 changed files with 69 additions and 59 deletions

67
src/libutil/ref.hh Normal file
View file

@ -0,0 +1,67 @@
#pragma once
#include <memory>
#include <exception>
namespace nix {
/* A simple non-nullable reference-counted pointer. Actually a wrapper
around std::shared_ptr that prevents non-null constructions. */
template<typename T>
class ref
{
private:
std::shared_ptr<T> p;
public:
ref<T>(const ref<T> & r)
: p(r.p)
{ }
explicit ref<T>(const std::shared_ptr<T> & p)
: p(p)
{
if (!p)
throw std::invalid_argument("null pointer cast to ref");
}
T* operator ->() const
{
return &*p;
}
T& operator *() const
{
return *p;
}
operator std::shared_ptr<T> ()
{
return p;
}
template<typename T2>
operator ref<T2> ()
{
return ref<T2>((std::shared_ptr<T2>) p);
}
private:
template<typename T2, typename... Args>
friend ref<T2>
make_ref(Args&&... args);
};
template<typename T, typename... Args>
inline ref<T>
make_ref(Args&&... args)
{
auto p = std::make_shared<T>(std::forward<Args>(args)...);
return ref<T>(p);
}
}

View file

@ -2,6 +2,8 @@
#include "config.h"
#include "ref.hh"
#include <string>
#include <list>
#include <set>
@ -97,63 +99,4 @@ typedef enum {
} Verbosity;
/* A simple non-nullable reference-counted pointer. Actually a wrapper
around std::shared_ptr that prevents non-null constructions. */
template<typename T>
class ref
{
private:
std::shared_ptr<T> p;
public:
ref<T>(const ref<T> & r)
: p(r.p)
{ }
explicit ref<T>(const std::shared_ptr<T> & p)
: p(p)
{
if (!p)
throw std::invalid_argument("null pointer cast to ref");
}
T* operator ->() const
{
return &*p;
}
T& operator *() const
{
return *p;
}
operator std::shared_ptr<T> ()
{
return p;
}
template<typename T2>
operator ref<T2> ()
{
return ref<T2>((std::shared_ptr<T2>) p);
}
private:
template<typename T2, typename... Args>
friend ref<T2>
make_ref(Args&&... args);
};
template<typename T, typename... Args>
inline ref<T>
make_ref(Args&&... args)
{
auto p = std::make_shared<T>(std::forward<Args>(args)...);
return ref<T>(p);
}
}