1/* Copyright (C) 2015-2024 Free Software Foundation, Inc.
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#include "traits.h"
22
23/* Type-safe wrapper for enum flags.  enum flags are enums where the
24   values are bits that are meant to be ORed together.
25
26   This allows writing code like the below, while with raw enums this
27   would fail to compile without casts to enum type at the assignments
28   to 'f':
29
30    enum some_flag
31    {
32       flag_val1 = 1 << 1,
33       flag_val2 = 1 << 2,
34       flag_val3 = 1 << 3,
35       flag_val4 = 1 << 4,
36    };
37    DEF_ENUM_FLAGS_TYPE(enum some_flag, some_flags);
38
39    some_flags f = flag_val1 | flag_val2;
40    f |= flag_val3;
41
42   It's also possible to assign literal zero to an enum flags variable
43   (meaning, no flags), dispensing adding an awkward explicit "no
44   value" value to the enumeration.  For example:
45
46    some_flags f = 0;
47    f |= flag_val3 | flag_val4;
48
49   Note that literal integers other than zero fail to compile:
50
51    some_flags f = 1; // error
52*/
53
54#ifdef __cplusplus
55
56/* Use this to mark an enum as flags enum.  It defines FLAGS_TYPE as
57   enum_flags wrapper class for ENUM, and enables the global operator
58   overloads for ENUM.  */
59#define DEF_ENUM_FLAGS_TYPE(enum_type, flags_type)	\
60  typedef enum_flags<enum_type> flags_type;		\
61  void is_enum_flags_enum_type (enum_type *)
62
63/* To enable the global enum_flags operators for enum, declare an
64   "is_enum_flags_enum_type" overload that has exactly one parameter,
65   of type a pointer to that enum class.  E.g.,:
66
67     void is_enum_flags_enum_type (enum some_flag *);
68
69   The function does not need to be defined, only declared.
70   DEF_ENUM_FLAGS_TYPE declares this.
71
72   A function declaration is preferred over a traits type, because the
73   former allows calling the DEF_ENUM_FLAGS_TYPE macro inside a
74   namespace to define the corresponding enum flags type in that
75   namespace.  The compiler finds the corresponding
76   is_enum_flags_enum_type function via ADL.  */
77
78/* Note that std::underlying_type<enum_type> is not what we want here,
79   since that returns unsigned int even when the enum decays to signed
80   int.  */
81template<int size, bool sign> class integer_for_size { typedef void type; };
82template<> struct integer_for_size<1, 0> { typedef uint8_t type; };
83template<> struct integer_for_size<2, 0> { typedef uint16_t type; };
84template<> struct integer_for_size<4, 0> { typedef uint32_t type; };
85template<> struct integer_for_size<8, 0> { typedef uint64_t type; };
86template<> struct integer_for_size<1, 1> { typedef int8_t type; };
87template<> struct integer_for_size<2, 1> { typedef int16_t type; };
88template<> struct integer_for_size<4, 1> { typedef int32_t type; };
89template<> struct integer_for_size<8, 1> { typedef int64_t type; };
90
91template<typename T>
92struct enum_underlying_type
93{
94  DIAGNOSTIC_PUSH
95  DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION
96  typedef typename
97    integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
98    type;
99  DIAGNOSTIC_POP
100};
101
102namespace enum_flags_detail
103{
104
105/* Private type used to support initializing flag types with zero:
106
107   foo_flags f = 0;
108
109   but not other integers:
110
111   foo_flags f = 1;
112
113   The way this works is that we define an implicit constructor that
114   takes a pointer to this private type.  Since nothing can
115   instantiate an object of this type, the only possible pointer to
116   pass to the constructor is the NULL pointer, or, zero.  */
117struct zero_type;
118
119/* gdb::Requires trait helpers.  */
120template <typename enum_type>
121using EnumIsUnsigned
122  = std::is_unsigned<typename enum_underlying_type<enum_type>::type>;
123template <typename enum_type>
124using EnumIsSigned
125  = std::is_signed<typename enum_underlying_type<enum_type>::type>;
126
127}
128
129template <typename E>
130class enum_flags
131{
132public:
133  typedef E enum_type;
134  typedef typename enum_underlying_type<enum_type>::type underlying_type;
135
136  /* For to_string.  Maps one enumerator of E to a string.  */
137  struct string_mapping
138  {
139    E flag;
140    const char *str;
141  };
142
143  /* Convenience for to_string implementations, to build a
144     string_mapping array.  */
145#define MAP_ENUM_FLAG(ENUM_FLAG) { ENUM_FLAG, #ENUM_FLAG }
146
147public:
148  /* Allow default construction.  */
149  constexpr enum_flags ()
150    : m_enum_value ((enum_type) 0)
151  {}
152
153  /* The default move/copy ctor/assignment do the right thing.  */
154
155  /* If you get an error saying these two overloads are ambiguous,
156     then you tried to mix values of different enum types.  */
157  constexpr enum_flags (enum_type e)
158    : m_enum_value (e)
159  {}
160  constexpr enum_flags (enum_flags_detail::zero_type *zero)
161    : m_enum_value ((enum_type) 0)
162  {}
163
164  enum_flags &operator&= (enum_flags e) &
165  {
166    m_enum_value = (enum_type) (m_enum_value & e.m_enum_value);
167    return *this;
168  }
169  enum_flags &operator|= (enum_flags e) &
170  {
171    m_enum_value = (enum_type) (m_enum_value | e.m_enum_value);
172    return *this;
173  }
174  enum_flags &operator^= (enum_flags e) &
175  {
176    m_enum_value = (enum_type) (m_enum_value ^ e.m_enum_value);
177    return *this;
178  }
179
180  /* Delete rval versions.  */
181  void operator&= (enum_flags e) && = delete;
182  void operator|= (enum_flags e) && = delete;
183  void operator^= (enum_flags e) && = delete;
184
185  /* Like raw enums, allow conversion to the underlying type.  */
186  constexpr operator underlying_type () const
187  {
188    return m_enum_value;
189  }
190
191  /* Get the underlying value as a raw enum.  */
192  constexpr enum_type raw () const
193  {
194    return m_enum_value;
195  }
196
197  /* Binary operations involving some unrelated type (which would be a
198     bug) are implemented as non-members, and deleted.  */
199
200  /* Convert this object to a std::string, using MAPPING as
201     enumerator-to-string mapping array.  This is not meant to be
202     called directly.  Instead, enum_flags specializations should have
203     their own to_string function wrapping this one, thus hiding the
204     mapping array from callers.
205
206     Note: this is defined outside the template class so it can use
207     the global operators for enum_type, which are only defined after
208     the template class.  */
209  template<size_t N>
210  std::string to_string (const string_mapping (&mapping)[N]) const;
211
212private:
213  /* Stored as enum_type because GDB knows to print the bit flags
214     neatly if the enum values look like bit flags.  */
215  enum_type m_enum_value;
216};
217
218template <typename E>
219using is_enum_flags_enum_type_t
220  = decltype (is_enum_flags_enum_type (std::declval<E *> ()));
221
222/* Global operator overloads.  */
223
224/* Generate binary operators.  */
225
226#define ENUM_FLAGS_GEN_BINOP(OPERATOR_OP, OP)				\
227									\
228  /* Raw enum on both LHS/RHS.  Returns raw enum type.  */		\
229  template <typename enum_type,						\
230	    typename = is_enum_flags_enum_type_t<enum_type>>		\
231  constexpr enum_type							\
232  OPERATOR_OP (enum_type e1, enum_type e2)				\
233  {									\
234    using underlying = typename enum_flags<enum_type>::underlying_type;	\
235    return (enum_type) (underlying (e1) OP underlying (e2));		\
236  }									\
237									\
238  /* enum_flags on the LHS.  */						\
239  template <typename enum_type,						\
240	    typename = is_enum_flags_enum_type_t<enum_type>>		\
241  constexpr enum_flags<enum_type>					\
242  OPERATOR_OP (enum_flags<enum_type> e1, enum_type e2)			\
243  { return e1.raw () OP e2; }						\
244									\
245  /* enum_flags on the RHS.  */						\
246  template <typename enum_type,						\
247	    typename = is_enum_flags_enum_type_t<enum_type>>		\
248  constexpr enum_flags<enum_type>					\
249  OPERATOR_OP (enum_type e1, enum_flags<enum_type> e2)			\
250  { return e1 OP e2.raw (); }						\
251									\
252  /* enum_flags on both LHS/RHS.  */					\
253  template <typename enum_type,						\
254	    typename = is_enum_flags_enum_type_t<enum_type>>		\
255  constexpr enum_flags<enum_type>					\
256  OPERATOR_OP (enum_flags<enum_type> e1, enum_flags<enum_type> e2)	\
257  { return e1.raw () OP e2.raw (); }					\
258									\
259  /* Delete cases involving unrelated types.  */			\
260									\
261  template <typename enum_type, typename unrelated_type,		\
262	    typename = is_enum_flags_enum_type_t<enum_type>>		\
263  constexpr enum_flags<enum_type>					\
264  OPERATOR_OP (enum_type e1, unrelated_type e2) = delete;		\
265									\
266  template <typename enum_type, typename unrelated_type,		\
267	    typename = is_enum_flags_enum_type_t<enum_type>>		\
268  constexpr enum_flags<enum_type>					\
269  OPERATOR_OP (unrelated_type e1, enum_type e2) = delete;		\
270									\
271  template <typename enum_type, typename unrelated_type,		\
272	    typename = is_enum_flags_enum_type_t<enum_type>>		\
273  constexpr enum_flags<enum_type>					\
274  OPERATOR_OP (enum_flags<enum_type> e1, unrelated_type e2) = delete;	\
275									\
276  template <typename enum_type, typename unrelated_type,		\
277	    typename = is_enum_flags_enum_type_t<enum_type>>		\
278  constexpr enum_flags<enum_type>					\
279  OPERATOR_OP (unrelated_type e1, enum_flags<enum_type> e2) = delete;
280
281/* Generate non-member compound assignment operators.  Only the raw
282   enum versions are defined here.  The enum_flags versions are
283   defined as member functions, simply because it's less code that
284   way.
285
286   Note we delete operators that would allow e.g.,
287
288     "enum_type | 1" or "enum_type1 | enum_type2"
289
290   because that would allow a mistake like :
291     enum flags1 { F1_FLAGS1 = 1 };
292     enum flags2 { F2_FLAGS2 = 2 };
293     enum flags1 val;
294     switch (val) {
295       case F1_FLAGS1 | F2_FLAGS2:
296     ...
297
298   If you really need to 'or' enumerators of different flag types,
299   cast to integer first.
300*/
301#define ENUM_FLAGS_GEN_COMPOUND_ASSIGN(OPERATOR_OP, OP)			\
302  /* lval reference version.  */					\
303  template <typename enum_type,						\
304	    typename = is_enum_flags_enum_type_t<enum_type>>		\
305  constexpr enum_type &							\
306  OPERATOR_OP (enum_type &e1, enum_type e2)				\
307  { return e1 = e1 OP e2; }						\
308									\
309  /* rval reference version.  */					\
310  template <typename enum_type,						\
311	    typename = is_enum_flags_enum_type_t<enum_type>>		\
312  void									\
313  OPERATOR_OP (enum_type &&e1, enum_type e2) = delete;			\
314									\
315  /* Delete compound assignment from unrelated types.  */		\
316									\
317  template <typename enum_type, typename other_enum_type,		\
318	    typename = is_enum_flags_enum_type_t<enum_type>>		\
319  constexpr enum_type &							\
320  OPERATOR_OP (enum_type &e1, other_enum_type e2) = delete;		\
321									\
322  template <typename enum_type, typename other_enum_type,		\
323	    typename = is_enum_flags_enum_type_t<enum_type>>		\
324  void									\
325  OPERATOR_OP (enum_type &&e1, other_enum_type e2) = delete;
326
327ENUM_FLAGS_GEN_BINOP (operator|, |)
328ENUM_FLAGS_GEN_BINOP (operator&, &)
329ENUM_FLAGS_GEN_BINOP (operator^, ^)
330
331ENUM_FLAGS_GEN_COMPOUND_ASSIGN (operator|=, |)
332ENUM_FLAGS_GEN_COMPOUND_ASSIGN (operator&=, &)
333ENUM_FLAGS_GEN_COMPOUND_ASSIGN (operator^=, ^)
334
335/* Allow comparison with enum_flags, raw enum, and integers, only.
336   The latter case allows "== 0".  As side effect, it allows comparing
337   with integer variables too, but that's not a common mistake to
338   make.  It's important to disable comparison with unrelated types to
339   prevent accidentally comparing with unrelated enum values, which
340   are convertible to integer, and thus coupled with enum_flags
341   conversion to underlying type too, would trigger the built-in 'bool
342   operator==(unsigned, int)' operator.  */
343
344#define ENUM_FLAGS_GEN_COMP(OPERATOR_OP, OP)				\
345									\
346  /* enum_flags OP enum_flags */					\
347									\
348  template <typename enum_type>						\
349  constexpr bool							\
350  OPERATOR_OP (enum_flags<enum_type> lhs, enum_flags<enum_type> rhs)	\
351  { return lhs.raw () OP rhs.raw (); }					\
352									\
353  /* enum_flags OP other */						\
354									\
355  template <typename enum_type>						\
356  constexpr bool							\
357  OPERATOR_OP (enum_flags<enum_type> lhs, enum_type rhs)		\
358  { return lhs.raw () OP rhs; }						\
359									\
360  template <typename enum_type>						\
361  constexpr bool							\
362  OPERATOR_OP (enum_flags<enum_type> lhs, int rhs)			\
363  { return lhs.raw () OP rhs; }						\
364									\
365  template <typename enum_type, typename U>				\
366  constexpr bool							\
367  OPERATOR_OP (enum_flags<enum_type> lhs, U rhs) = delete;		\
368									\
369  /* other OP enum_flags */						\
370									\
371  template <typename enum_type>						\
372  constexpr bool							\
373  OPERATOR_OP (enum_type lhs, enum_flags<enum_type> rhs)		\
374  { return lhs OP rhs.raw (); }						\
375									\
376  template <typename enum_type>						\
377  constexpr bool							\
378  OPERATOR_OP (int lhs, enum_flags<enum_type> rhs)			\
379  { return lhs OP rhs.raw (); }						\
380									\
381  template <typename enum_type, typename U>				\
382  constexpr bool							\
383  OPERATOR_OP (U lhs, enum_flags<enum_type> rhs) = delete;
384
385ENUM_FLAGS_GEN_COMP (operator==, ==)
386ENUM_FLAGS_GEN_COMP (operator!=, !=)
387
388/* Unary operators for the raw flags enum.  */
389
390/* We require underlying type to be unsigned when using operator~ --
391   if it were not unsigned, undefined behavior could result.  However,
392   asserting this in the class itself would require too many
393   unnecessary changes to usages of otherwise OK enum types.  */
394template <typename enum_type,
395	  typename = is_enum_flags_enum_type_t<enum_type>,
396	  typename
397	    = gdb::Requires<enum_flags_detail::EnumIsUnsigned<enum_type>>>
398constexpr enum_type
399operator~ (enum_type e)
400{
401  using underlying = typename enum_flags<enum_type>::underlying_type;
402  return (enum_type) ~underlying (e);
403}
404
405template <typename enum_type,
406	  typename = is_enum_flags_enum_type_t<enum_type>,
407	  typename = gdb::Requires<enum_flags_detail::EnumIsSigned<enum_type>>>
408constexpr void operator~ (enum_type e) = delete;
409
410template <typename enum_type,
411	  typename = is_enum_flags_enum_type_t<enum_type>,
412	  typename
413	    = gdb::Requires<enum_flags_detail::EnumIsUnsigned<enum_type>>>
414constexpr enum_flags<enum_type>
415operator~ (enum_flags<enum_type> e)
416{
417  using underlying = typename enum_flags<enum_type>::underlying_type;
418  return (enum_type) ~underlying (e);
419}
420
421template <typename enum_type,
422	  typename = is_enum_flags_enum_type_t<enum_type>,
423	  typename = gdb::Requires<enum_flags_detail::EnumIsSigned<enum_type>>>
424constexpr void operator~ (enum_flags<enum_type> e) = delete;
425
426/* Delete operator<< and operator>>.  */
427
428template <typename enum_type, typename any_type,
429	  typename = is_enum_flags_enum_type_t<enum_type>>
430void operator<< (const enum_type &, const any_type &) = delete;
431
432template <typename enum_type, typename any_type,
433	  typename = is_enum_flags_enum_type_t<enum_type>>
434void operator<< (const enum_flags<enum_type> &, const any_type &) = delete;
435
436template <typename enum_type, typename any_type,
437	  typename = is_enum_flags_enum_type_t<enum_type>>
438void operator>> (const enum_type &, const any_type &) = delete;
439
440template <typename enum_type, typename any_type,
441	  typename = is_enum_flags_enum_type_t<enum_type>>
442void operator>> (const enum_flags<enum_type> &, const any_type &) = delete;
443
444template<typename E>
445template<size_t N>
446std::string
447enum_flags<E>::to_string (const string_mapping (&mapping)[N]) const
448{
449  enum_type flags = raw ();
450  std::string res = hex_string (flags);
451  res += " [";
452
453  bool need_space = false;
454  for (const auto &entry : mapping)
455    {
456      if ((flags & entry.flag) != 0)
457	{
458	  /* Work with an unsigned version of the underlying type,
459	     because if enum_type's underlying type is signed, op~
460	     won't be defined for it, and, bitwise operations on
461	     signed types are implementation defined.  */
462	  using uns = typename std::make_unsigned<underlying_type>::type;
463	  flags &= (enum_type) ~(uns) entry.flag;
464
465	  if (need_space)
466	    res += " ";
467	  res += entry.str;
468
469	  need_space = true;
470	}
471    }
472
473  /* If there were flags not included in the mapping, print them as
474     a hex number.  */
475  if (flags != 0)
476    {
477      if (need_space)
478	res += " ";
479      res += hex_string (flags);
480    }
481
482  res += "]";
483
484  return res;
485}
486
487#else /* __cplusplus */
488
489/* In C, the flags type is just a typedef for the enum type.  */
490
491#define DEF_ENUM_FLAGS_TYPE(enum_type, flags_type) \
492  typedef enum_type flags_type
493
494#endif /* __cplusplus */
495
496#endif /* COMMON_ENUM_FLAGS_H */
497