/* DWARF abbrev table

   Copyright (C) 1994-2025 Free Software Foundation, Inc.

   Adapted by Gary Funck (gary@intrepid.com), Intrepid Technology,
   Inc.  with support from Florida State University (under contract
   with the Ada Joint Program Office), and Silicon Graphics, Inc.
   Initial contribution by Brent Benson, Harris Computer Systems, Inc.,
   based on Fred Fish's (Cygnus Support) implementation of DWARF 1
   support.

   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 GDB_DWARF2_ABBREV_H
#define GDB_DWARF2_ABBREV_H

#include "dwarf2.h"
#include "gdbsupport/gdb_obstack.h"
#include "gdbsupport/unordered_set.h"
#include "types.h"

struct attr_abbrev
{
  ENUM_BITFIELD(dwarf_attribute) name : 16;
  ENUM_BITFIELD(dwarf_form) form : 16;

  /* It is valid only if FORM is DW_FORM_implicit_const.  */
  LONGEST implicit_const;
};

/* This data structure holds the information of an abbrev.  */
struct abbrev_info
{
  /* Number identifying abbrev.  */
  unsigned int number;
  /* DWARF tag.  */
  ENUM_BITFIELD (dwarf_tag) tag : 16;
  /* True if the DIE has children.  */
  bool has_children;
  bool interesting;
  /* In Ada, an imported subprogram DIE will be marked as a
     declaration, but will have both a name and a linkage name.  This
     declaration may be the only spot where that name is associated
     with an object, so it has to show up in the index.  But, because
     abbrevs are CU-independent, we can't check the language when
     computing them and instead we keep a separate flag to indicate
     that the scanner should check this DIE.  */
  bool maybe_ada_import;
  unsigned short size_if_constant;
  unsigned short sibling_offset;
  /* Number of attributes.  */
  unsigned short num_attrs;
  /* An array of attribute descriptions, allocated using the struct
     hack.  */
  struct attr_abbrev attrs[1];
};

struct abbrev_table;
using abbrev_table_up = std::unique_ptr<abbrev_table>;

/* Top level data structure to contain an abbreviation table.

   In DWARF version 2, the description of the debugging information is
   stored in a separate .debug_abbrev section.  Before we read any
   dies from a section we read in all abbreviations and install them
   in a hash table.  */

struct abbrev_table
{
  /* Read an abbrev table from the indicated section, at the given
     offset.  The caller is responsible for ensuring that the section
     has already been read.  */

  static abbrev_table_up read (struct dwarf2_section_info *section,
			       sect_offset sect_off);

  /* Look up an abbrev in the table.
     Returns NULL if the abbrev is not found.  */

  const abbrev_info *lookup_abbrev (unsigned int abbrev_number) const
  {
    if (auto iter = m_abbrevs.find (abbrev_number);
	iter != m_abbrevs.end ())
      return *iter;

    return nullptr;
  }

  /* Where the abbrev table came from.
     This is used as a sanity check when the table is used.  */
  const sect_offset sect_off;

  struct dwarf2_section_info *section;

private:

  abbrev_table (sect_offset off, struct dwarf2_section_info *sect)
    : sect_off (off),
      section (sect)
  {}

  DISABLE_COPY_AND_ASSIGN (abbrev_table);

  /* Add an abbreviation to the table.  */
  void add_abbrev (const abbrev_info *abbrev)
  { m_abbrevs.emplace (abbrev); }

  struct abbrev_info_number_eq
  {
    using is_transparent = void;

    bool operator() (unsigned int number,
		     const abbrev_info *abbrev) const noexcept
    { return number == abbrev->number; }

    bool operator() (const abbrev_info *lhs,
		     const abbrev_info *rhs) const noexcept
    { return (*this) (lhs->number, rhs); }
  };

  struct abbrev_info_number_hash
  {
    using is_transparent = void;

    std::size_t operator() (unsigned int number) const noexcept
    { return std::hash<unsigned int> () (number); }

    std::size_t operator() (const abbrev_info *abbrev) const noexcept
    { return (*this) (abbrev->number); }

  };

  /* Hash table of abbrev, identified by their number.  */
  gdb::unordered_set<const abbrev_info *,
  		     abbrev_info_number_hash,
		     abbrev_info_number_eq>
    m_abbrevs;

  /* Storage for the abbrev table.  */
  auto_obstack m_abbrev_obstack;
};

#endif /* GDB_DWARF2_ABBREV_H */