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