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1// DefaultValue.hh
2// Copyright (c) 2007 Fluxbox Team (fluxgen at fluxbox dot org)
3//
4// Permission is hereby granted, free of charge, to any person obtaining a
5// copy of this software and associated documentation files (the "Software"),
6// to deal in the Software without restriction, including without limitation
7// the rights to use, copy, modify, merge, publish, distribute, sublicense,
8// and/or sell copies of the Software, and to permit persons to whom the
9// Software is furnished to do so, subject to the following conditions:
10//
11// The above copyright notice and this permission notice shall be included in
12// all copies or substantial portions of the Software.
13//
14// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
19// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
20// DEALINGS IN THE SOFTWARE.
21
22#ifndef FBTK_DEFAULTVALUE_HH
23#define FBTK_DEFAULTVALUE_HH
24
25namespace FbTk {
26
27// classes for overriding default values without having to listen for changes
28template <typename T>
29class DefaultValue {
30public:
31 DefaultValue(const T &def):
32 m_default(def), m_actual(def), m_use_default(true) { }
33
34 inline const T &get() const { return m_use_default ? m_default : m_actual; }
35 inline void set(const T &val) { m_use_default = false; m_actual = val; }
36 inline void restoreDefault() { m_use_default = true; }
37 inline void isDefault() const { return m_use_default; }
38
39 inline DefaultValue<T> &operator =(const T &val) {
40 set(val); return *this;
41 }
42
43 inline operator T() const { return get(); }
44
45private:
46 const T &m_default;
47 T m_actual;
48 bool m_use_default;
49};
50
51// designed for use with built-in types T, thus no need to return references
52template <typename T, typename Receiver>
53class DefaultAccessor {
54public:
55 typedef T (Receiver:: *Accessor)() const;
56 DefaultAccessor(const Receiver &r, Accessor a):
57 m_receiver(r), m_accessor(a), m_actual((r.*a)()),
58 m_use_default(true) { }
59
60 inline const T get() const {
61 return m_use_default ? (m_receiver.*m_accessor)() : m_actual;
62 }
63 inline void set(const T &val) { m_use_default = false; m_actual = val; }
64 inline void restoreDefault() { m_use_default = true; }
65 inline void isDefault() const { return m_use_default; }
66
67 inline DefaultAccessor<T, Receiver> &operator =(const T &val) {
68 set(val); return *this;
69 }
70
71 inline operator T() const { return get(); }
72
73private:
74 const Receiver &m_receiver;
75 Accessor &m_accessor;
76 T m_actual;
77 bool m_use_default;
78};
79
80}; // end namespace FbTk
81
82#endif // FBTK_DEFAULTVALUE_HH