mirror of
https://github.com/XRPLF/rippled.git
synced 2025-11-20 02:55:50 +00:00
96 lines
2.4 KiB
Objective-C
96 lines
2.4 KiB
Objective-C
//------------------------------------------------------------------------------
|
|
/*
|
|
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.
|
|
*/
|
|
//==============================================================================
|
|
|
|
#ifndef BEAST_SAFEBOOL_H_INCLUDED
|
|
#define BEAST_SAFEBOOL_H_INCLUDED
|
|
|
|
namespace beast {
|
|
|
|
namespace detail {
|
|
|
|
class SafeBoolBase
|
|
{
|
|
private:
|
|
void disallowed () const { }
|
|
|
|
public:
|
|
void allowed () const { }
|
|
|
|
protected:
|
|
typedef void (SafeBoolBase::*boolean_t) () const;
|
|
|
|
SafeBoolBase () { }
|
|
SafeBoolBase (SafeBoolBase const&) { }
|
|
SafeBoolBase& operator= (SafeBoolBase const&)
|
|
{
|
|
return *this;
|
|
}
|
|
~SafeBoolBase () { }
|
|
};
|
|
|
|
}
|
|
|
|
/** Safe evaluation of class as `bool`.
|
|
|
|
This allows a class to be safely evaluated as a bool without the usual
|
|
harmful side effects of the straightforward operator conversion approach.
|
|
To use it, derive your class from SafeBool and implement `asBoolean()` as:
|
|
|
|
@code
|
|
|
|
bool asBoolean () const;
|
|
|
|
@endcode
|
|
|
|
Ideas from http://www.artima.com/cppsource/safebool.html
|
|
|
|
@class SafeBool
|
|
*/
|
|
template <typename T = void>
|
|
class SafeBool : public detail::SafeBoolBase
|
|
{
|
|
public:
|
|
operator detail::SafeBoolBase::boolean_t () const
|
|
{
|
|
return (static_cast <T const*> (this))->asBoolean ()
|
|
? &SafeBoolBase::allowed : 0;
|
|
}
|
|
|
|
protected:
|
|
~SafeBool () { }
|
|
};
|
|
|
|
template <typename T, typename U>
|
|
void operator== (SafeBool <T> const& lhs, SafeBool <U> const& rhs)
|
|
{
|
|
lhs.disallowed ();
|
|
}
|
|
|
|
template <typename T, typename U>
|
|
void operator!= (SafeBool <T> const& lhs, SafeBool <U> const& rhs)
|
|
{
|
|
lhs.disallowed ();
|
|
}
|
|
|
|
}
|
|
|
|
#endif
|
|
|
|
|