aboutsummaryrefslogtreecommitdiff
path: root/paludis/util/named_value.hh
blob: b638b2e87deaf839eb39dfd28f02aa50a0dbbd50 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
/* vim: set sw=4 sts=4 et foldmethod=syntax : */

/*
 * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
 *
 * This file is part of the Paludis package manager. Paludis is free software;
 * you can redistribute it and/or modify it under the terms of the GNU General
 * Public License version 2, as published by the Free Software Foundation.
 *
 * Paludis is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef PALUDIS_GUARD_PALUDIS_UTIL_NAMED_VALUE_HH
#define PALUDIS_GUARD_PALUDIS_UTIL_NAMED_VALUE_HH 1

#include <paludis/util/named_value-fwd.hh>
#include <paludis/util/tribool.hh>
#include <utility>
#include <type_traits>
#include <string>

namespace paludis
{
    /**
     * A NamedValue is used to hold a member of type V_ for a class.
     *
     * NamedValue is used to simplify 'plain old data' style classes, and to
     * provide compiler-time-checked named parameters for functions. Use
     * thestruct.themember() and thestruct.themember() = to access the real
     * underlying values.
     *
     * Usually a struct containing NamedValue objects will be constructed using
     * the make_named_values() function. For each NamedValue object,
     * make_named_values() takes a parameter in the form
     * <code>n::whatever_K_is() = the_value</code>.
     *
     * In all cases, NamedValue members are listed in name-sorted order, and
     * the same name is used for K_ and the member name.
     *
     * \ingroup g_oo
     */
    template <typename K_, typename V_>
    class NamedValue
    {
        static_assert(! std::is_reference<V_>::value, "Tried to make a NamedValue hold a reference");

        private:
            V_ _value;

        public:
            typedef K_ KeyType;
            typedef V_ ValueType;

            template <typename T_>
            NamedValue(const NamedValue<K_, T_> & v) :
                _value(v())
            {
            }

            template <typename T_>
            NamedValue(NamedValue<K_, T_> && v) :
                _value(std::move(v()))
            {
            }

            explicit NamedValue(const V_ & v) :
                _value(v)
            {
            }

            explicit NamedValue(V_ && v) :
                _value(v)
            {
            }

            NamedValue(const NamedValue & v) :
                _value(v._value)
            {
            }

            NamedValue(NamedValue && v) :
                _value(std::move(v._value))
            {
            }

            NamedValue & operator=(const NamedValue & v)
            {
                _value = v._value;
                return *this;
            }

            V_ & operator() ()
            {
                return _value;
            }

            const V_ & operator() () const
            {
                return _value;
            }
    };

    /**
     * A Name is used to make the assignment for NamedValue keys work.
     *
     * \ingroup g_oo
     */
    template <typename T_>
    class Name
    {
        public:
            template <typename V_>
            NamedValue<Name<T_>, V_> operator= (const V_ & v) const
            {
                return NamedValue<Name<T_>, V_>(v);
            }

            template <typename V_>
            NamedValue<Name<T_>, typename std::remove_reference<V_>::type> operator= (V_ && v) const
            {
                return NamedValue<Name<T_>, typename std::remove_reference<V_>::type>(v);
            }

            NamedValue<Name<T_>, std::string> operator= (const char * const v) const
            {
                return NamedValue<Name<T_>, std::string>(std::string(v));
            }

            NamedValue<Name<T_>, Tribool> operator= (TriboolIndeterminateValueType) const
            {
                return NamedValue<Name<T_>, Tribool>(Tribool(indeterminate));
            }
    };
}

#endif