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Add weak_fn

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This commit is contained in:
Vinnie Falco
2014-11-08 09:40:17 -08:00
parent ef57b3954c
commit 3d7c6f831c
3 changed files with 322 additions and 0 deletions
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1
beast/utility/Utility.unity.cpp
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@@ -33,4 +33,5 @@
#include <beast/utility/tests/Journal.test.cpp> #include <beast/utility/tests/Journal.test.cpp>
#include <beast/utility/tests/static_initializer.test.cpp> #include <beast/utility/tests/static_initializer.test.cpp>
#include <beast/utility/tests/tagged_integer.test.cpp> #include <beast/utility/tests/tagged_integer.test.cpp>
#include <beast/utility/tests/weak_fn.test.cpp>
#include <beast/utility/tests/Zero.test.cpp> #include <beast/utility/tests/Zero.test.cpp>

146
beast/utility/tests/weak_fn.test.cpp Normal file
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@@ -0,0 +1,146 @@
//------------------------------------------------------------------------------
/*
This file is part of Beast: https://github.com/vinniefalco/Beast
Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
#include <beast/weak_fn.h>
#include <beast/unit_test/suite.h>
namespace beast {
class weak_fn_test : public beast::unit_test::suite
{
public:
struct T
{
bool& called_;
explicit
T (bool& called)
: called_(called)
{
}
void
fv()
{
called_ = true;
}
void
fi(int i)
{
called_ = true;
}
void
fis(int, std::string)
{
called_ = true;
}
int
fri()
{
called_ = true;
return 2;
}
};
void
run()
{
{
bool called = false;
auto const p = std::make_shared<T>(called);
std::bind(weak_fn(&T::fv, p))();
expect(called);
}
{
bool called = false;
auto p = std::make_shared<T>(called);
auto call = std::bind(weak_fn(&T::fv, p));
p.reset();
call();
expect(! called);
}
{
bool called = false;
auto p = std::make_shared<T>(called);
std::bind(weak_fn(&T::fi, p), 1)();
expect(called);
}
{
bool called = false;
auto p = std::make_shared<T>(called);
std::bind(weak_fn(&T::fi, p),
std::placeholders::_1)(1);
expect(called);
}
{
bool called = false;
auto p = std::make_shared<T>(called);
std::bind(weak_fn(&T::fis, p),
1, std::placeholders::_1)("foo");
expect(called);
}
{
bool called = false;
auto p = std::make_shared<T>(called);
try
{
std::bind(weak_fn(&T::fis, p, throw_if_invalid<>()),
1, std::placeholders::_1)("foo");
p.reset();
fail();
}
catch(std::bad_weak_ptr const&)
{
expect(! called);
}
}
{
bool called = false;
auto p = std::make_shared<T>(called);
expect(std::bind(weak_fn(&T::fri, p))() == 2);
expect(called);
}
{
bool called = false;
auto p = std::make_shared<T>(called);
auto call = std::bind(weak_fn(&T::fv, p,
[&called]()
{
called = true;
}));
p.reset();
call();
expect(called);
}
}
};
BEAST_DEFINE_TESTSUITE(weak_fn,asio,beast);
}

175
beast/weak_fn.h Normal file
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@@ -0,0 +1,175 @@
//------------------------------------------------------------------------------
/*
This file is part of Beast: https://github.com/vinniefalco/Beast
Copyright 2014, Vinnie Falco <vinnie.falco@gmail.com>
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
#ifndef BEAST_WEAK_FN_H_INCLUDED
#define BEAST_WEAK_FN_H_INCLUDED
#include <beast/utility/empty_base_optimization.h>
#include <memory>
// Original version:
// http://lists.boost.org/Archives/boost/att-189469/weak_fn.hpp
//
// This work was adapted from source code with this copyright notice:
//
// weak_fun.hpp
//
// Copyright (c) 2009 Artyom Beilis
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
namespace beast {
// Policy throws if weak pointer is expired
template <class V = void>
struct throw_if_invalid
{
V operator()() const
{
throw std::bad_weak_ptr();
}
};
// Policy returns a value if weak pointer is expired
template <class V>
struct return_default_if_invalid
{
return_default_if_invalid()
: def_value_()
{ }
return_default_if_invalid(V def_value)
: def_value_(def_value)
{ }
V operator()() const
{
return def_value_;
}
private:
V def_value_;
};
// Policy does nothing if weak pointer is expired
template <class V>
struct ignore_if_invalid
{
V operator()() const
{
return V();
}
};
template <class V>
using default_invalid_policy = ignore_if_invalid<V>;
namespace detail {
template <class T, class R, class Policy, class... Args>
class weak_binder
: private beast::empty_base_optimization<Policy>
{
private:
typedef R (T::*member_type)(Args...);
using pointer_type = std::weak_ptr<T>;
using shared_type = std::shared_ptr<T>;
member_type member_;
pointer_type object_;
public:
using result_type = R;
weak_binder (member_type member,
Policy policy, pointer_type object)
: empty_base_optimization<Policy>(std::move(policy))
, member_(member)
, object_(object)
{ }
R operator()(Args... args)
{
if(auto p = object_.lock())
return ((*p).*member_)(args...);
return this->member()();
}
};
} // detail
/** Returns a callback that can be used with std::bind and a weak_ptr.
When called, it tries to lock weak_ptr to get a shared_ptr. If successful,
it calls given member function with given arguments. If not successful,
the policy functor is called. Built-in policies are:
ignore_if_invalid does nothing
throw_if_invalid throws `bad_weak_ptr`
return_default_if_invalid returns a chosen value
Example:
struct Foo {
void bar(int i) {
std::cout << i << std::endl;
}
};
struct do_something {
void operator()() {
std::cout << "outdated reference" << std::endl;
}
};
int main()
{
std::shared_ptr<Foo> sp(new Foo());
std::weak_ptr<Foo> wp(sp);
std::bind(weak_fn(&Foo::bar, wp), _1)(1);
sp.reset();
std::bind(weak_fn(&Foo::bar, wp), 1)();
std::bind(weak_fn(&Foo::bar, wp, do_something()), 1)();
}
*/
/** @{ */
template <class T, class R, class Policy, class... Args>
detail::weak_binder<T, R, Policy, Args...>
weak_fn (R (T::*member)(Args...), std::shared_ptr<T> p,
Policy policy)
{
return detail::weak_binder<T, R,
Policy, Args...>(member, policy, p);
}
template <class T, class R, class... Args>
detail::weak_binder<T, R, default_invalid_policy<R>, Args...>
weak_fn (R (T::*member)(Args...), std::shared_ptr<T> p)
{
return detail::weak_binder<T, R,
default_invalid_policy<R>, Args...>(member,
default_invalid_policy<R>{}, p);
}
/** @} */
} // beast
#endif