aboutsummaryrefslogtreecommitdiffstats
path: root/util/generic/flags.h
blob: 5898195d7cf12480273764159228a3c01214152f (plain) (blame)
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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
#pragma once

#include <type_traits>

#include <util/system/types.h>
#include <util/generic/typetraits.h>
#include <util/generic/fwd.h>

class IOutputStream;
namespace NPrivate {
    void PrintFlags(IOutputStream& stream, ui64 value, size_t size);
}

/**
 * `TFlags` wrapper provides a type-safe mechanism for storing OR combinations
 * of enumeration values.
 *
 * This class is intended to be used mainly via helper macros. For example:
 * @code
 * class TAligner {
 * public:
 *     enum EOrientation {
 *         Vertical = 1,
 *         Horizontal = 2
 *     };
 *     Y_DECLARE_FLAGS(EOrientations, EOrientation)
 *
 *     // ...
 * };
 *
 * Y_DECLARE_OPERATORS_FOR_FLAGS(TAligner::EOrientations)
 * @endcode
 */
template <class Enum>
class TFlags {
    static_assert(std::is_enum<Enum>::value, "Expecting an enumeration here.");

public:
    using TEnum = Enum;
    using TInt = std::underlying_type_t<Enum>;

    constexpr TFlags(std::nullptr_t = 0)
        : Value_(0)
    {
    }

    constexpr TFlags(Enum value)
        : Value_(static_cast<TInt>(value))
    {
    }

    /* Generated copy/move ctor/assignment are OK. */

    constexpr operator TInt() const {
        return Value_;
    }

    constexpr TInt ToBaseType() const {
        return Value_;
    }

    constexpr static TFlags FromBaseType(TInt value) { 
        return TFlags(TFlag(value));
    } 
 
    constexpr friend TFlags operator|(TFlags l, TFlags r) {
        return TFlags(TFlag(l.Value_ | r.Value_));
    }

    constexpr friend TFlags operator|(TEnum l, TFlags r) {
        return TFlags(TFlag(static_cast<TInt>(l) | r.Value_));
    }

    constexpr friend TFlags operator|(TFlags l, TEnum r) {
        return TFlags(TFlag(l.Value_ | static_cast<TInt>(r)));
    }

    constexpr friend TFlags operator^(TFlags l, TFlags r) {
        return TFlags(TFlag(l.Value_ ^ r.Value_));
    }

    constexpr friend TFlags
    operator^(TEnum l, TFlags r) {
        return TFlags(TFlag(static_cast<TInt>(l) ^ r.Value_));
    }

    constexpr friend TFlags
    operator^(TFlags l, TEnum r) {
        return TFlags(TFlag(l.Value_ ^ static_cast<TInt>(r)));
    }

    constexpr friend TFlags
    operator&(TFlags l, TFlags r) {
        return TFlags(TFlag(l.Value_ & r.Value_));
    }

    constexpr friend TFlags operator&(TEnum l, TFlags r) {
        return TFlags(TFlag(static_cast<TInt>(l) & r.Value_));
    }

    constexpr friend TFlags operator&(TFlags l, TEnum r) {
        return TFlags(TFlag(l.Value_ & static_cast<TInt>(r)));
    }

    constexpr friend bool operator==(TFlags l, TFlags r) {
        return l.Value_ == r.Value_;
    }

    constexpr friend bool operator==(TEnum l, TFlags r) {
        return static_cast<TInt>(l) == r.Value_;
    }

    constexpr friend bool operator==(TFlags l, TEnum r) {
        return l.Value_ == static_cast<TInt>(r);
    }

    constexpr friend bool operator!=(TFlags l, TFlags r) {
        return l.Value_ != r.Value_;
    }

    constexpr friend bool operator!=(TEnum l, TFlags r) {
        return static_cast<TInt>(l) != r.Value_;
    }

    constexpr friend bool operator!=(TFlags l, TEnum r) {
        return l.Value_ != static_cast<TInt>(r);
    }

    TFlags& operator&=(TFlags mask) {
        *this = *this & mask;
        return *this;
    }

    TFlags& operator&=(Enum mask) {
        *this = *this & mask;
        return *this;
    }

    TFlags& operator|=(TFlags flags) {
        *this = *this | flags;
        return *this;
    }

    TFlags& operator|=(Enum flags) {
        *this = *this | flags;
        return *this;
    }

    TFlags& operator^=(TFlags flags) {
        *this = *this ^ flags;
        return *this;
    }

    TFlags& operator^=(Enum flags) {
        *this = *this ^ flags;
        return *this;
    }

    constexpr TFlags operator~() const {
        return TFlags(TFlag(~Value_));
    }

    constexpr bool operator!() const {
        return !Value_;
    }

    constexpr explicit operator bool() const {
        return Value_;
    }

    constexpr bool HasFlags(TFlags flags) const {
        return (Value_ & flags.Value_) == flags.Value_;
    }

    TFlags RemoveFlags(TFlags flags) {
        Value_ &= ~flags.Value_;
        return *this;
    }

    friend IOutputStream& operator<<(IOutputStream& stream, const TFlags& flags) {
        ::NPrivate::PrintFlags(stream, static_cast<ui64>(flags.Value_), sizeof(TInt));
        return stream;
    }

private:
    struct TFlag {
        constexpr TFlag() {
        }
        constexpr explicit TFlag(TInt value)
            : Value(value)
        {
        }

        TInt Value = 0;
    };

    constexpr explicit TFlags(TFlag value)
        : Value_(value.Value)
    {
    }

private:
    TInt Value_;
};

template <class T>
struct TPodTraits<TFlags<T>> {
    enum {
        IsPod = TTypeTraits<T>::IsPod
    };
};

template <class Enum>
struct THash<TFlags<Enum>> {
    size_t operator()(const TFlags<Enum>& flags) const noexcept {
        return THash<typename TFlags<Enum>::TInt>()(flags);
    }
};

/**
 * This macro defines a flags type for the provided enum.
 *
 * @param FLAGS                         Name of the flags type to declare.
 * @param ENUM                          Name of the base enum type to use.
 */
#define Y_DECLARE_FLAGS(FLAGS, ENUM) \
    using FLAGS = TFlags<ENUM>;

/**
 * This macro declares global operator functions for enum base of `FLAGS` type.
 * This way operations on individual enum values will provide a type-safe
 * `TFlags` object.
 *
 * @param FLAGS                         Flags type to declare operator for.
 */
#define Y_DECLARE_OPERATORS_FOR_FLAGS(FLAGS)                           \
    Y_DECLARE_UNUSED                                                   \
    constexpr inline FLAGS operator|(FLAGS::TEnum l, FLAGS::TEnum r) { \
        return FLAGS(l) | r;                                           \
    }                                                                  \
    Y_DECLARE_UNUSED                                                   \
    constexpr inline FLAGS operator~(FLAGS::TEnum value) {             \
        return ~FLAGS(value);                                          \
    }