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// DefaultValue.hh
// Copyright (c) 2007 Fluxbox Team (fluxgen at fluxbox dot org)
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
#ifndef FBTK_DEFAULTVALUE_HH
#define FBTK_DEFAULTVALUE_HH
namespace FbTk {
// classes for overriding default values without having to listen for changes
template <typename T>
class DefaultValue {
public:
DefaultValue(const T &def):
m_default(def), m_actual(def), m_use_default(true) { }
inline const T &get() const { return m_use_default ? m_default : m_actual; }
inline void set(const T &val) { m_use_default = false; m_actual = val; }
inline void restoreDefault() { m_use_default = true; }
inline bool isDefault() const { return m_use_default; }
inline DefaultValue<T> &operator =(const T &val) {
set(val); return *this;
}
inline operator T() const { return get(); }
private:
const T &m_default;
T m_actual;
bool m_use_default;
};
// designed for use with built-in types T, thus no need to return references
template <typename T, typename Receiver>
class DefaultAccessor {
public:
typedef T (Receiver:: *Accessor)() const;
DefaultAccessor(const Receiver &r, Accessor a):
m_receiver(r), m_accessor(a), m_actual((r.*a)()),
m_use_default(true) { }
inline const T get() const {
return m_use_default ? (m_receiver.*m_accessor)() : m_actual;
}
inline void set(const T &val) { m_use_default = false; m_actual = val; }
inline void restoreDefault() { m_use_default = true; }
inline bool isDefault() const { return m_use_default; }
inline DefaultAccessor<T, Receiver> &operator =(const T &val) {
set(val); return *this;
}
inline operator T() const { return get(); }
private:
const Receiver &m_receiver;
Accessor m_accessor;
T m_actual;
bool m_use_default;
};
}; // end namespace FbTk
#endif // FBTK_DEFAULTVALUE_HH
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