From bb73334a110add062915d67ca61d21897415f1d5 Mon Sep 17 00:00:00 2001
From: David Malcolm <dmalcolm@redhat.com>
Date: Tue, 5 Jun 2018 11:50:02 -0400
Subject: [PATCH 16/56] FIXME: Add gdb's enum-flags.h as-is

---
 include/enum-flags.h | 215 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 215 insertions(+)
 create mode 100644 include/enum-flags.h

diff --git a/include/enum-flags.h b/include/enum-flags.h
new file mode 100644
index 0000000..82568a5
--- /dev/null
+++ b/include/enum-flags.h
@@ -0,0 +1,215 @@
+/* Copyright (C) 2015-2018 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef COMMON_ENUM_FLAGS_H
+#define COMMON_ENUM_FLAGS_H
+
+/* Type-safe wrapper for enum flags.  enum flags are enums where the
+   values are bits that are meant to be ORed together.
+
+   This allows writing code like the below, while with raw enums this
+   would fail to compile without casts to enum type at the assignments
+   to 'f':
+
+    enum some_flag
+    {
+       flag_val1 = 1 << 1,
+       flag_val2 = 1 << 2,
+       flag_val3 = 1 << 3,
+       flag_val4 = 1 << 4,
+    };
+    DEF_ENUM_FLAGS_TYPE(enum some_flag, some_flags);
+
+    some_flags f = flag_val1 | flag_val2;
+    f |= flag_val3;
+
+   It's also possible to assign literal zero to an enum flags variable
+   (meaning, no flags), dispensing adding an awkward explicit "no
+   value" value to the enumeration.  For example:
+
+    some_flags f = 0;
+    f |= flag_val3 | flag_val4;
+
+   Note that literal integers other than zero fail to compile:
+
+    some_flags f = 1; // error
+*/
+
+#ifdef __cplusplus
+
+/* Traits type used to prevent the global operator overloads from
+   instantiating for non-flag enums.  */
+template<typename T> struct enum_flags_type {};
+
+/* Use this to mark an enum as flags enum.  It defines FLAGS as
+   enum_flags wrapper class for ENUM, and enables the global operator
+   overloads for ENUM.  */
+#define DEF_ENUM_FLAGS_TYPE(enum_type, flags_type)	\
+  typedef enum_flags<enum_type> flags_type;		\
+  template<>						\
+  struct enum_flags_type<enum_type>			\
+  {							\
+    typedef enum_flags<enum_type> type;			\
+  }
+
+/* Until we can rely on std::underlying type being universally
+   available (C++11), roll our own for enums.  */
+template<int size, bool sign> class integer_for_size { typedef void type; };
+template<> struct integer_for_size<1, 0> { typedef uint8_t type; };
+template<> struct integer_for_size<2, 0> { typedef uint16_t type; };
+template<> struct integer_for_size<4, 0> { typedef uint32_t type; };
+template<> struct integer_for_size<8, 0> { typedef uint64_t type; };
+template<> struct integer_for_size<1, 1> { typedef int8_t type; };
+template<> struct integer_for_size<2, 1> { typedef int16_t type; };
+template<> struct integer_for_size<4, 1> { typedef int32_t type; };
+template<> struct integer_for_size<8, 1> { typedef int64_t type; };
+
+template<typename T>
+struct enum_underlying_type
+{
+  typedef typename
+    integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
+    type;
+};
+
+template <typename E>
+class enum_flags
+{
+public:
+  typedef E enum_type;
+  typedef typename enum_underlying_type<enum_type>::type underlying_type;
+
+private:
+  /* Private type used to support initializing flag types with zero:
+
+       foo_flags f = 0;
+
+     but not other integers:
+
+       foo_flags f = 1;
+
+     The way this works is that we define an implicit constructor that
+     takes a pointer to this private type.  Since nothing can
+     instantiate an object of this type, the only possible pointer to
+     pass to the constructor is the NULL pointer, or, zero.  */
+  struct zero_type;
+
+  underlying_type
+  underlying_value () const
+  {
+    return m_enum_value;
+  }
+
+public:
+  /* Allow default construction.  */
+  enum_flags ()
+    : m_enum_value ((enum_type) 0)
+  {}
+
+  /* If you get an error saying these two overloads are ambiguous,
+     then you tried to mix values of different enum types.  */
+  enum_flags (enum_type e)
+    : m_enum_value (e)
+  {}
+  enum_flags (struct enum_flags::zero_type *zero)
+    : m_enum_value ((enum_type) 0)
+  {}
+
+  enum_flags &operator&= (enum_type e)
+  {
+    m_enum_value = (enum_type) (underlying_value () & e);
+    return *this;
+  }
+  enum_flags &operator|= (enum_type e)
+  {
+    m_enum_value = (enum_type) (underlying_value () | e);
+    return *this;
+  }
+  enum_flags &operator^= (enum_type e)
+  {
+    m_enum_value = (enum_type) (underlying_value () ^ e);
+    return *this;
+  }
+
+  operator enum_type () const
+  {
+    return m_enum_value;
+  }
+
+  enum_flags operator& (enum_type e) const
+  {
+    return (enum_type) (underlying_value () & e);
+  }
+  enum_flags operator| (enum_type e) const
+  {
+    return (enum_type) (underlying_value () | e);
+  }
+  enum_flags operator^ (enum_type e) const
+  {
+    return (enum_type) (underlying_value () ^ e);
+  }
+  enum_flags operator~ () const
+  {
+    return (enum_type) ~underlying_value ();
+  }
+
+private:
+  /* Stored as enum_type because GDB knows to print the bit flags
+     neatly if the enum values look like bit flags.  */
+  enum_type m_enum_value;
+};
+
+/* Global operator overloads.  */
+
+template <typename enum_type>
+typename enum_flags_type<enum_type>::type
+operator& (enum_type e1, enum_type e2)
+{
+  return enum_flags<enum_type> (e1) & e2;
+}
+
+template <typename enum_type>
+typename enum_flags_type<enum_type>::type
+operator| (enum_type e1, enum_type e2)
+{
+  return enum_flags<enum_type> (e1) | e2;
+}
+
+template <typename enum_type>
+typename enum_flags_type<enum_type>::type
+operator^ (enum_type e1, enum_type e2)
+{
+  return enum_flags<enum_type> (e1) ^ e2;
+}
+
+template <typename enum_type>
+typename enum_flags_type<enum_type>::type
+operator~ (enum_type e)
+{
+  return ~enum_flags<enum_type> (e);
+}
+
+#else /* __cplusplus */
+
+/* In C, the flags type is just a typedef for the enum type.  */
+
+#define DEF_ENUM_FLAGS_TYPE(enum_type, flags_type) \
+  typedef enum_type flags_type
+
+#endif /* __cplusplus */
+
+#endif /* COMMON_ENUM_FLAGS_H */
-- 
1.8.5.3

