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e2882c85 | 1 | /* Copyright (C) 2015-2018 Free Software Foundation, Inc. |
8d297bbf PA |
2 | |
3 | This file is part of GDB. | |
4 | ||
5 | This program is free software; you can redistribute it and/or modify | |
6 | it under the terms of the GNU General Public License as published by | |
7 | the Free Software Foundation; either version 3 of the License, or | |
8 | (at your option) any later version. | |
9 | ||
10 | This program is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | GNU General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU General Public License | |
16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
17 | ||
18 | #ifndef COMMON_ENUM_FLAGS_H | |
19 | #define COMMON_ENUM_FLAGS_H | |
20 | ||
21 | /* Type-safe wrapper for enum flags. enum flags are enums where the | |
22 | values are bits that are meant to be ORed together. | |
23 | ||
24 | This allows writing code like the below, while with raw enums this | |
25 | would fail to compile without casts to enum type at the assignments | |
26 | to 'f': | |
27 | ||
28 | enum some_flag | |
29 | { | |
30 | flag_val1 = 1 << 1, | |
31 | flag_val2 = 1 << 2, | |
32 | flag_val3 = 1 << 3, | |
33 | flag_val4 = 1 << 4, | |
34 | }; | |
35 | DEF_ENUM_FLAGS_TYPE(enum some_flag, some_flags) | |
36 | ||
37 | some_flags f = flag_val1 | flag_val2; | |
38 | f |= flag_val3; | |
39 | ||
40 | It's also possible to assign literal zero to an enum flags variable | |
41 | (meaning, no flags), dispensing adding an awkward explicit "no | |
42 | value" value to the enumeration. For example: | |
43 | ||
44 | some_flags f = 0; | |
45 | f |= flag_val3 | flag_val4; | |
46 | ||
47 | Note that literal integers other than zero fail to compile: | |
48 | ||
49 | some_flags f = 1; // error | |
50 | */ | |
51 | ||
52 | #ifdef __cplusplus | |
53 | ||
54 | /* Traits type used to prevent the global operator overloads from | |
55 | instantiating for non-flag enums. */ | |
56 | template<typename T> struct enum_flags_type {}; | |
57 | ||
58 | /* Use this to mark an enum as flags enum. It defines FLAGS as | |
59 | enum_flags wrapper class for ENUM, and enables the global operator | |
60 | overloads for ENUM. */ | |
61 | #define DEF_ENUM_FLAGS_TYPE(enum_type, flags_type) \ | |
62 | typedef enum_flags<enum_type> flags_type; \ | |
63 | template<> \ | |
64 | struct enum_flags_type<enum_type> \ | |
65 | { \ | |
66 | typedef enum_flags<enum_type> type; \ | |
67 | } | |
68 | ||
69 | /* Until we can rely on std::underlying type being universally | |
70 | available (C++11), roll our own for enums. */ | |
71 | template<int size, bool sign> class integer_for_size { typedef void type; }; | |
72 | template<> struct integer_for_size<1, 0> { typedef uint8_t type; }; | |
73 | template<> struct integer_for_size<2, 0> { typedef uint16_t type; }; | |
74 | template<> struct integer_for_size<4, 0> { typedef uint32_t type; }; | |
75 | template<> struct integer_for_size<8, 0> { typedef uint64_t type; }; | |
76 | template<> struct integer_for_size<1, 1> { typedef int8_t type; }; | |
77 | template<> struct integer_for_size<2, 1> { typedef int16_t type; }; | |
78 | template<> struct integer_for_size<4, 1> { typedef int32_t type; }; | |
79 | template<> struct integer_for_size<8, 1> { typedef int64_t type; }; | |
80 | ||
81 | template<typename T> | |
82 | struct enum_underlying_type | |
83 | { | |
84 | typedef typename | |
85 | integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type | |
86 | type; | |
87 | }; | |
88 | ||
89 | template <typename E> | |
90 | class enum_flags | |
91 | { | |
92 | public: | |
93 | typedef E enum_type; | |
94 | typedef typename enum_underlying_type<enum_type>::type underlying_type; | |
95 | ||
96 | private: | |
97 | /* Private type used to support initializing flag types with zero: | |
98 | ||
99 | foo_flags f = 0; | |
100 | ||
101 | but not other integers: | |
102 | ||
103 | foo_flags f = 1; | |
104 | ||
105 | The way this works is that we define an implicit constructor that | |
106 | takes a pointer to this private type. Since nothing can | |
107 | instantiate an object of this type, the only possible pointer to | |
108 | pass to the constructor is the NULL pointer, or, zero. */ | |
109 | struct zero_type; | |
110 | ||
111 | underlying_type | |
112 | underlying_value () const | |
113 | { | |
114 | return m_enum_value; | |
115 | } | |
116 | ||
117 | public: | |
1b90b139 | 118 | /* Allow default construction. */ |
8d297bbf | 119 | enum_flags () |
1b90b139 | 120 | : m_enum_value ((enum_type) 0) |
8d297bbf PA |
121 | {} |
122 | ||
8d297bbf PA |
123 | /* If you get an error saying these two overloads are ambiguous, |
124 | then you tried to mix values of different enum types. */ | |
125 | enum_flags (enum_type e) | |
126 | : m_enum_value (e) | |
127 | {} | |
128 | enum_flags (struct enum_flags::zero_type *zero) | |
129 | : m_enum_value ((enum_type) 0) | |
130 | {} | |
131 | ||
132 | enum_flags &operator&= (enum_type e) | |
133 | { | |
134 | m_enum_value = (enum_type) (underlying_value () & e); | |
135 | return *this; | |
136 | } | |
137 | enum_flags &operator|= (enum_type e) | |
138 | { | |
139 | m_enum_value = (enum_type) (underlying_value () | e); | |
140 | return *this; | |
141 | } | |
142 | enum_flags &operator^= (enum_type e) | |
143 | { | |
144 | m_enum_value = (enum_type) (underlying_value () ^ e); | |
145 | return *this; | |
146 | } | |
147 | ||
148 | operator enum_type () const | |
149 | { | |
150 | return m_enum_value; | |
151 | } | |
152 | ||
153 | enum_flags operator& (enum_type e) const | |
154 | { | |
155 | return (enum_type) (underlying_value () & e); | |
156 | } | |
157 | enum_flags operator| (enum_type e) const | |
158 | { | |
159 | return (enum_type) (underlying_value () | e); | |
160 | } | |
161 | enum_flags operator^ (enum_type e) const | |
162 | { | |
163 | return (enum_type) (underlying_value () ^ e); | |
164 | } | |
165 | enum_flags operator~ () const | |
166 | { | |
167 | return (enum_type) ~underlying_value (); | |
168 | } | |
169 | ||
170 | private: | |
171 | /* Stored as enum_type because GDB knows to print the bit flags | |
172 | neatly if the enum values look like bit flags. */ | |
173 | enum_type m_enum_value; | |
174 | }; | |
175 | ||
176 | /* Global operator overloads. */ | |
177 | ||
178 | template <typename enum_type> | |
179 | typename enum_flags_type<enum_type>::type | |
180 | operator& (enum_type e1, enum_type e2) | |
181 | { | |
182 | return enum_flags<enum_type> (e1) & e2; | |
183 | } | |
184 | ||
185 | template <typename enum_type> | |
186 | typename enum_flags_type<enum_type>::type | |
187 | operator| (enum_type e1, enum_type e2) | |
188 | { | |
189 | return enum_flags<enum_type> (e1) | e2; | |
190 | } | |
191 | ||
192 | template <typename enum_type> | |
193 | typename enum_flags_type<enum_type>::type | |
194 | operator^ (enum_type e1, enum_type e2) | |
195 | { | |
196 | return enum_flags<enum_type> (e1) ^ e2; | |
197 | } | |
198 | ||
199 | template <typename enum_type> | |
200 | typename enum_flags_type<enum_type>::type | |
201 | operator~ (enum_type e) | |
202 | { | |
203 | return ~enum_flags<enum_type> (e); | |
204 | } | |
205 | ||
206 | #else /* __cplusplus */ | |
207 | ||
208 | /* In C, the flags type is just a typedef for the enum type. */ | |
209 | ||
210 | #define DEF_ENUM_FLAGS_TYPE(enum_type, flags_type) \ | |
211 | typedef enum_type flags_type | |
212 | ||
213 | #endif /* __cplusplus */ | |
214 | ||
215 | #endif /* COMMON_ENUM_FLAGS_H */ |