libdw/c++/dwarf_data

/* elfutils::dwarf_data -- internal DWARF data representations in -*- C++ -*-
   Copyright (C) 2009-2010 Red Hat, Inc.
   This file is part of Red Hat elfutils.

   Red Hat elfutils 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; version 2 of the License.

   Red Hat elfutils 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 Red Hat elfutils; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

   In addition, as a special exception, Red Hat, Inc. gives You the
   additional right to link the code of Red Hat elfutils with code licensed
   under any Open Source Initiative certified open source license
   (http://www.opensource.org/licenses/index.php) which requires the
   distribution of source code with any binary distribution and to
   distribute linked combinations of the two.  Non-GPL Code permitted under
   this exception must only link to the code of Red Hat elfutils through
   those well defined interfaces identified in the file named EXCEPTION
   found in the source code files (the "Approved Interfaces").  The files
   of Non-GPL Code may instantiate templates or use macros or inline
   functions from the Approved Interfaces without causing the resulting
   work to be covered by the GNU General Public License.  Only Red Hat,
   Inc. may make changes or additions to the list of Approved Interfaces.
   Red Hat's grant of this exception is conditioned upon your not adding
   any new exceptions.  If you wish to add a new Approved Interface or
   exception, please contact Red Hat.  You must obey the GNU General Public
   License in all respects for all of the Red Hat elfutils code and other
   code used in conjunction with Red Hat elfutils except the Non-GPL Code
   covered by this exception.  If you modify this file, you may extend this
   exception to your version of the file, but you are not obligated to do
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   you must delete this exception statement from your version and license
   this file solely under the GPL without exception.

   Red Hat elfutils is an included package of the Open Invention Network.
   An included package of the Open Invention Network is a package for which
   Open Invention Network licensees cross-license their patents.  No patent
   license is granted, either expressly or impliedly, by designation as an
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#ifndef _ELFUTILS_DWARF_DATA
#define _ELFUTILS_DWARF_DATA	1

#include "dwarf"
#include <cassert>
#include <bitset>

/* This contains common classes/templates used by dwarf_output and dwarf_edit.

   These are implementations of the "boring" components of the dwarf
   object interface.
*/

namespace elfutils
{
  // This is a class only for scoping purposes.
  // It contains no members, only inner classes.
  class dwarf_data
  {
  public:

    // Main container anchoring all the output.
    template<class impl>
    class compile_units_type : public std::list<typename impl::compile_unit>
    {
      friend class subr::create_container;

    protected:
      typedef std::list<typename impl::compile_unit> _base;

      // Constructor copying CUs from input container.
      template<typename input, typename arg_type>
      inline compile_units_type (const input &other, arg_type &arg)
	: _base (subr::argify<input, compile_units_type, arg_type &>
		 (other.begin (), arg),
		 subr::argify<input, compile_units_type, arg_type &>
		 (other.end (), arg))
      {}

    public:
      // Default constructor: an empty container, no CUs.
      inline compile_units_type () {}

      template<typename other_children>
      bool operator== (const other_children &other) const
      {
	return subr::container_equal (*this, other);
      }
      template<typename other_children>
      bool operator!= (const other_children &other) const
      {
	return !(*this == other);
      }
    };

    template<class impl>
    class compile_unit : public impl::debug_info_entry
    {
      friend class subr::create_container;
      friend class impl::compile_units_type;

    protected:
      template<typename input>
      static inline const input &require_cu (const input &cu)
      {
	if (cu.tag () != ::DW_TAG_compile_unit)
	  throw std::runtime_error
	    ("top-level debug_info_entry must be DW_TAG_compile_unit");
	return cu;
      }

      template<typename die_type, typename arg_type>
      inline void set (const die_type &die, arg_type &arg)
      {
	impl::debug_info_entry::set (require_cu (die), arg);
      }

    public:
      explicit inline compile_unit ()
	: impl::debug_info_entry ()
      {
	this->_m_tag = ::DW_TAG_compile_unit;
      }

      inline compile_unit (const compile_unit &other)
	: impl::debug_info_entry (require_cu (other))
      {}

      template<typename input, typename arg_type>
      inline compile_unit (const input &cu, arg_type &arg)
	: impl::debug_info_entry (typename impl::debug_info_entry::pointer (),
				  require_cu (cu), arg)
      {}

      /* Assignment details are up to the base class.
	 We just ensure it's really a compile_unit.  */
      inline compile_unit &
      operator= (const typename impl::debug_info_entry &other)
      {
	impl::debug_info_entry::operator= (require_cu (other));
	return *this;
      }

      // Fetch the CU's DW_AT_stmt_list.
      inline const typename impl::line_info_table &line_info () const
      {
	return this->attributes ().at (::DW_AT_stmt_list).line_info ();
      }

      // Convenience methods for line_info_table sub-containers.
      inline const typename impl::line_table &lines () const
      {
	return line_info ().lines ();
      }

#if 0 // XXX const issues
      inline typename impl::line_info_table &line_info ()
      {
	return this->attributes ()[::DW_AT_stmt_list].line_info ();
      }

      inline typename impl::line_table &lines ()
      {
	return line_info ().lines ();
      }
#endif
    };

    class source_file
    {
    private:
      std::string _m_name;
      ::Dwarf_Word _m_mtime;
      ::Dwarf_Word _m_size;

    public:

      struct hasher
	: public std::unary_function<source_file, size_t>
      {
	size_t operator () (const source_file &v) const
	{
	  size_t hash = 0;
	  subr::hash_combine (hash, v._m_name);
	  subr::hash_combine (hash, v._m_mtime);
	  subr::hash_combine (hash, v._m_size);
	  return hash;
	}
      };

      source_file () : _m_name (), _m_mtime (0), _m_size (0) {}
      source_file (const std::string &n, ::Dwarf_Word m = 0, ::Dwarf_Word s = 0)
	: _m_name (n), _m_mtime (m), _m_size (s) {}
      source_file (const char *n, ::Dwarf_Word m = 0, ::Dwarf_Word s = 0)
	: _m_name (n), _m_mtime (m), _m_size (s) {}

      template<typename file>
      source_file (const file &other)
	: _m_name (other.name ()),
	  _m_mtime (other.mtime ()), _m_size (other.size ()) {}

      template<typename file>
      inline source_file &operator= (const file &other)
      {
	_m_name = other.name ();
	_m_mtime = other.mtime ();
	_m_size = other.size ();
	return *this;
      }
      inline source_file &operator= (const std::string &n)
      {
	_m_name = n;
	_m_mtime = 0;
	_m_size = 0;
	return *this;
      }
      inline source_file &operator= (const char *n)
      {
	_m_name = n;
	_m_mtime = 0;
	_m_size = 0;
	return *this;
      }

      std::string to_string () const;

      inline std::string &name ()
      {
	return _m_name;
      }
      inline const std::string &name () const
      {
	return _m_name;
      }
      inline ::Dwarf_Word &mtime ()
      {
	return _m_mtime;
      }
      inline ::Dwarf_Word mtime () const
      {
	return _m_mtime;
      }
      inline ::Dwarf_Word &size ()
      {
	return _m_size;
      }
      inline ::Dwarf_Word size () const
      {
	return _m_size;
      }

      template<typename other_file>
      bool operator== (const other_file &other) const
      {
	if (mtime () != 0)
	  {
	    ::Dwarf_Word other_mtime = other.mtime ();
	    if (other_mtime != 0 && other_mtime != mtime ())
	      return false;
	  }
	if (size () != 0)
	  {
	    ::Dwarf_Word other_size = other.size ();
	    if (other_size != 0 && other_size != size ())
	      return false;
	  }
	return name () == other.name ();
      }
      template<typename other_file>
      inline bool operator!= (const other_file &other) const
      {
	return !(*this == other);
      }

      // Return a value unique to us while we're in memory.
      inline uintptr_t identity () const
      {
	return (uintptr_t) this;
      }
    };

  private:

    /* This is the common base class for all line_entry<T> instantiations.
       For some reason beyond my ken, std::bitset<flag_count>::reference
       as a return type is rejected by the compiler when used in a template
       class, but not a non-template class.  Go figure.  */
    class line_entry_common
    {
    protected:
      unsigned int _m_line;
      unsigned int _m_column;

      enum flag_bit
	{
	  flag_statement,
	  flag_basic_block,
	  flag_end_sequence,
	  flag_prologue_end,
	  flag_epilogue_begin,
	  flag_count
	};
      std::bitset<flag_count> _m_flags;

    public:
      line_entry_common ()
	: _m_line (0), _m_column (0) {}

      inline unsigned int &line ()
      {
	return _m_line;
      }
      inline unsigned int line () const
      {
	return _m_line;
      }
      inline unsigned int &column ()
      {
	return _m_column;
      }
      inline unsigned int column () const
      {
	return _m_column;
      }

#define _DWARF_EDIT_LE_FLAG(what)			\
      bool what () const				\
      {							\
	return _m_flags[flag_##what];			\
      }							\
      std::bitset<flag_count>::reference what ()	\
      {							\
	return _m_flags[flag_##what];			\
      }
      _DWARF_EDIT_LE_FLAG (statement)
      _DWARF_EDIT_LE_FLAG (basic_block)
      _DWARF_EDIT_LE_FLAG (end_sequence)
      _DWARF_EDIT_LE_FLAG (prologue_end)
      _DWARF_EDIT_LE_FLAG (epilogue_begin)
#undef	_DWARF_EDIT_LE_FLAG
    };

  public:
    /* This holds a line table entry.
       It's parameterized by the source_file representation.  */
    template<typename source_file>
    class line_entry : public line_entry_common
    {
    private:
      ::Dwarf_Addr _m_addr;	// XXX dwfl, reloc
      source_file _m_file;

    public:

      struct hasher
	: public std::unary_function<line_entry, size_t>
      {
	size_t operator () (const line_entry &v) const
	{
	  size_t hash = 0;
	  subr::hash_combine (hash, v._m_addr);
	  subr::hash_combine (hash, v._m_file);
	  subr::hash_combine (hash, v._m_line);
	  subr::hash_combine (hash, v._m_column);
	  return hash;
	}
      };

      line_entry (::Dwarf_Addr addr)
	: line_entry_common (), _m_addr (addr), _m_file ()
      {}

      template<typename entry>
      line_entry (const entry &other)
	: line_entry_common (), _m_addr (0), _m_file ()
      {
	*this = other;
      }

      template<typename entry>
      line_entry &operator= (const entry &other)
      {
	_m_addr = other.address ();
	_m_file = other.file ();
	_m_line = other.line ();
	_m_column = other.column ();
	statement () = other.statement ();
	basic_block () = other.basic_block ();
	end_sequence () = other.end_sequence ();
	prologue_end () = other.prologue_end ();
	epilogue_begin () = other.epilogue_begin ();
	return *this;
      }

      inline ::Dwarf_Addr &address ()
      {
	return _m_addr;
      }
      inline ::Dwarf_Addr address () const
      {
	return _m_addr;
      }
      inline source_file &file ()
      {
	return _m_file;
      }
      inline const source_file &file () const
      {
	return _m_file;
      }

      template<typename entry>
      bool operator< (const entry &other) const
      {
	return address () < other.address ();
      }
      template<typename entry>
      bool operator> (const entry &other) const
      {
	return address () > other.address ();
      }
      template<typename entry>
      bool operator<= (const entry &other) const
      {
	return address () <= other.address ();
      }
      template<typename entry>
      bool operator>= (const entry &other) const
      {
	return address () >= other.address ();
      }

      template<typename entry>
      inline bool operator== (const entry &other) const
      {
	return (address () == other.address ()
		&& line () == other.line ()
		&& column () == other.column ()
		&& statement () == other.statement ()
		&& basic_block () == other.basic_block ()
		&& end_sequence () == other.end_sequence ()
		&& prologue_end () == other.prologue_end ()
		&& epilogue_begin () == other.epilogue_begin ()
		&& file () == other.file ());
      }
      template<typename entry>
      inline bool operator!= (const entry &other) const
      {
	return !(*this == other);
      }
    };

    /* This holds a line table.
       It's parameterized by the line_entry representation.  */
    template<typename line_entry>
    class line_table : public std::vector<line_entry>
    {
    private:
      typedef std::vector<line_entry> _base;

    public:
      typedef typename _base::size_type size_type;
      typedef typename _base::difference_type difference_type;
      typedef typename _base::value_type value_type;
      typedef typename _base::iterator iterator;
      typedef typename _base::const_iterator const_iterator;

      struct hasher : public subr::container_hasher<line_table> {};

      line_table () {}

      template<typename table>
      line_table (const table &other) : _base (other.begin (), other.end ()) {}

      std::string to_string () const;

      template<typename table>
      inline bool operator== (const table &other) const
      {
	return (_base::size () == other.size ()
		&& subr::container_equal (*this, other));
      }
      template<typename table>
      inline bool operator!= (const table &other) const
      {
	return !(*this == other);
      }

      // Look up by matching address.
      iterator find (::Dwarf_Addr);
      const_iterator find (::Dwarf_Addr) const;
    };

    /* This holds the entirety of line information.
       The line_table is all there actually is.  */
    template<typename line_table>
    class line_info_table
    {
    private:
      line_table _m_lines;

    public:
      struct hasher : public std::unary_function<line_info_table, size_t>
      {
	inline size_t operator () (const line_info_table &info) const
	{
	  return subr::hash_this (info._m_lines);
	}
      };

      inline line_info_table () {}

      template<typename table>
      inline line_info_table (const table &other)
	: _m_lines (other.lines ())
      {}

      template<typename table>
      inline line_info_table &operator= (const table &other)
      {
	_m_lines = line_table (other.lines ());
	return *this;
      }

      std::string to_string () const;

      inline line_table &lines ()
      {
	return _m_lines;
      }
      inline const line_table &lines () const
      {
	return _m_lines;
      }

      template<typename table>
      inline bool operator== (const table &other) const
      {
	return lines () == other.lines ();
      }
      template<typename table>
      inline bool operator!= (const table &other) const
      {
	return !(*this == other);
      }
    };

    class dwarf_enum
      : private std::pair< ::Dwarf_Word, unsigned int>
    {
    private:
      typedef std::pair< ::Dwarf_Word, unsigned int> _base;

    protected:
      inline dwarf_enum ()
	: _base (0, 0)
      {}

    public:
      friend class subr::base_hasher<dwarf_enum, _base>;
      typedef subr::base_hasher<dwarf_enum, _base> hasher;

      inline dwarf_enum (unsigned int attr, unsigned int value)
	: _base (value, attr)
      {}

      template<typename constant>
      inline dwarf_enum (const constant &other)
	: _base (static_cast<unsigned int> (other), other.which ())
      {}

      // Return the DW_AT_* indicating which enum this value belongs to.
      inline unsigned int which () const
      {
	return this->second;
      }

      inline operator unsigned int () const
      {
	return this->first;
      }

      inline dwarf_enum &operator= (::Dwarf_Word value)
      {
	this->first = value;
	return *this;
      }

      inline dwarf_enum &operator= (const dwarf_enum& other)
      {
	if (this->second == 0)
	  {
	    throw std::logic_error ("dwarf_enum default constructed");
	    this->second = other.second;
	  }
	else if (this->second != other.second)
	  throw std::runtime_error
	    ("cannot assign dwarf_constant () from "
	     + dwarf::attributes::name (other.second) + "to "
	     + dwarf::attributes::name (this->second));

	this->first = other.first;
	return *this;
      }

      template<typename constant>
      inline dwarf_enum &operator= (const constant& other)
      {
	return *this = dwarf_enum (other.which (), other);
      }

      std::string to_string () const;

      const char *identifier () const;
      const char *name () const;

      template<typename constant>
      inline bool operator== (const constant &other) const
      {
	return (static_cast<unsigned int> (*this)
		== static_cast<unsigned int> (other));
      }
      template<typename constant>
      inline bool operator!= (const constant &other) const
      {
	return !(*this == other);
      }
    };

    // Same as set<pair<Dwarf_Addr, Dwarf_Addr>>.
    typedef dwarf::arange_list range_list;

    class location_attr
      : public std::map<dwarf::location_attr::key_type, std::vector<uint8_t> >
    {
    private:
      typedef std::map<dwarf::location_attr::key_type,
		       std::vector<uint8_t> > _base;

      template<typename pair>
      struct nonempty : public std::unary_function<pair, bool>
      {
	inline bool operator () (const pair &x)
	{
	  return !x.second.empty ();
	}
      };

    public:
      typedef _base::size_type size_type;
      typedef _base::difference_type difference_type;
      typedef _base::key_type key_type;
      typedef _base::mapped_type mapped_type;
      typedef _base::value_type value_type;
      typedef _base::iterator iterator;
      typedef _base::const_iterator const_iterator;

      struct hasher : public subr::container_hasher<location_attr> {};

      inline location_attr () : _base () {}
      inline location_attr (const location_attr &other)
	: _base (static_cast<const _base &> (other)) {}
      template<typename loc>
      inline location_attr (const loc &other) : _base ()
      {
	*this = other;
      }

      template<typename loc>
      inline location_attr &operator= (const loc &other)
      {
	clear ();
	if (other.empty ())
	  ;
	else if (other.is_list ())
	  for (typename loc::const_iterator i = other.begin ();
	       i != other.end ();
	       ++i)
	    {
	      const typename loc::mapped_type &x = (*i).second;
	      (*this)[(*i).first] = mapped_type (x.begin (), x.end ());
	    }
	else
	  {
	    mapped_type v = other.location ();
	    (*this)[key_type (0, -1)] = v;
	  }
	return *this;
      }

      inline bool is_list () const
      {
	if (empty ())
	  return false;
	if (size () > 1)
	  return true;

	const key_type &elt = begin ()->first;
	return !(elt.first == 0 && elt.second == (Dwarf_Addr) -1);
      }

      inline mapped_type &location ()
      {
	if (empty ())
	  return (*this)[key_type (0, -1)];

	value_type &v = *begin ();
	if (v.first.first != 0 || v.first.second != (Dwarf_Addr) -1
	    || size () > 1)
	  throw std::runtime_error ("location is list, not single location");

	return v.second;
      }
      inline const mapped_type &location () const
      {
	if (size () == 1)
	  {
	    const value_type &v = *begin ();
	    if (v.first.first == 0 && v.first.second == (Dwarf_Addr) -1)
	      return v.second;
	  }
	throw std::runtime_error ("location is list, not single location");
      }

      template<typename other_attr>
      bool operator== (const other_attr &other) const
      {
	if (empty ())
	  return (other.empty ()
		  || std::find_if (other.begin (), other.end (),
				   nonempty<typename other_attr::value_type> ()
				   ) == other.end ());
	if (!is_list ())
	  return (!other.is_list () && !other.empty ()
		  && subr::container_equal (location (), other.location ()));

	return other.is_list () && subr::container_equal (*this, other);
      }
      template<typename other_attr>
      inline bool operator!= (const other_attr &other) const
      {
	return !(*this == other);
      }

      std::string to_string () const;
    };

    template<typename impl, bool alloc_values = true>
    struct value
    {
      struct value_dispatch
      {
	virtual ~value_dispatch () {}
      };

      typedef value_dispatch value_cell_type;

      static const bool delete_value = alloc_values;

      template<typename flavor>
      static inline flavor &
      variant (flavor *&, const value_dispatch *&)
      {
	assert (!alloc_values);
	throw std::logic_error ("can't happen!");
      }

      template<typename flavor>
      static inline flavor &
      variant (flavor *&result, value_dispatch *&value)
      {
	assert (alloc_values);
	if (value == NULL)
	 {
	   result = new flavor;
	   value = result;
	   return *result;
	 }
	result = dynamic_cast<flavor *> (value);
	if (result == NULL)
	  throw std::runtime_error ("wrong value type");
	return *result;
      }

      template<typename arg_type>
      struct maker
      {
	inline explicit maker (const arg_type &) {}

	template<typename flavor, typename input>
	static inline void
	make (value_dispatch *&v, flavor *&result,
	      int /*whatattr*/, const input &x, arg_type &arg)
	{
	  assert (alloc_values);
	  v = result = new flavor (x, arg);
	}
      };

      template<typename arg_type>
      static inline maker<arg_type> make (arg_type &arg)
      {
	return maker<arg_type> (arg);
      }

      struct value_string : public value_dispatch, public std::string
      {
	typedef std::tr1::hash<std::string> hasher;

	inline value_string () {}

	template<typename string, typename arg_type>
	inline value_string (const string &s, arg_type &)
	  : std::string (s)
	{}

	template<typename string>
	inline value_string (const string &s)
	  : std::string (s)
	{}

	std::string to_string () const
	{
	  std::string result ("\"");
	  result += *this;
	  result += "\"";
	  return result;
	}
      };

      struct value_identifier : public value_string
      {
	inline value_identifier () {}

	template<typename id, typename arg_type>
	inline value_identifier (const id &s, arg_type &arg)
	  : value_string (s, arg)
	{}

	template<typename id>
	inline value_identifier (const id &s)
	  : value_string (s)
	{}
      };

      struct value_reference : public value_dispatch
      {
	typedef typename impl::debug_info_entry::pointer value_type;
	value_type ref;

	// Default constructor: reference to nowhere, invalid.
	inline value_reference ()
	  : ref ()
	{}

	/* This is only kosher for a pointer into the same dwarf_edit
	   object.  This is what plain assignment does.  This just uses
	   this pointer, rather than translating it from another file
	   into this one (which requires a tracker).  */
	inline value_reference (const value_type &i, subr::nothing &)
	  : ref (i)
	{}

	template<typename iter, typename tracker>
	inline value_reference (const iter &i, tracker &t)
	  : ref ()		// Invalid until t.finish ().
	{
	  t.refer (&ref, i);
	}
      };

      struct value_flag : public value_dispatch
      {
	bool flag;

	inline value_flag (bool t = true)
	  : flag (t)
	{}

	template<typename arg_type>
	inline value_flag (bool t, arg_type &)
	  : flag (t)
	{}
      };

      struct value_address : public value_dispatch
      {
	// XXX dwfl, reloc
	::Dwarf_Addr addr;

	inline value_address (::Dwarf_Addr x = 0)
	  : addr (x)
	{}

	template<typename arg_type>
	inline value_address (::Dwarf_Addr x, arg_type &)
	  : addr (x)
	{}

	struct hasher : public std::unary_function<value_address, size_t>
	{
	  inline size_t operator () (const value_address &c) const
	  {
	    return c.addr;
	  }
	};

	inline operator ::Dwarf_Addr () const
	{
	  return addr;
	}

	inline bool operator== (::Dwarf_Addr x) const
	{
	  return addr == x;
	}
      };

      struct value_rangelistptr : public value_dispatch, public range_list
      {
	inline value_rangelistptr () {}

	template<typename list, typename arg_type>
	inline value_rangelistptr (const list &other, arg_type &)
	  : range_list (other)
	{}

	template<typename list>
	inline value_rangelistptr (const list &other)
	  : range_list (other)
	{}
      };

      struct value_lineptr : public value_dispatch, public impl::line_info_table
      {
	inline value_lineptr () {}

	template<typename table, typename arg_type>
	inline value_lineptr (const table &other, arg_type &)
	  : impl::line_info_table (other)
	{}
      };

      struct value_constant : public value_dispatch
      {
	union
	{
	  ::Dwarf_Word word;
	  ::Dwarf_Sword sword;
	};

	inline value_constant (::Dwarf_Word value = 0)
	  : word (value)
	{}

	template<typename arg_type>
	inline value_constant (::Dwarf_Word x, arg_type &)
	  : word (x)
	{}

	struct hasher : public std::unary_function<value_constant, size_t>
	{
	  inline size_t operator () (const value_constant &c) const
	  {
	    return c.word;
	  }
	};

	inline operator ::Dwarf_Word () const
	{
	  return word;
	}

	inline bool operator== (::Dwarf_Word x) const
	{
	  return word == x;
	}
      };

      struct value_constant_block : public value_dispatch,
				    public std::vector<uint8_t>
      {
	typedef subr::hash<std::vector<uint8_t> > hasher;

	inline value_constant_block () {}

	template<typename block, typename arg_type>
	inline value_constant_block (const block &b, arg_type &)
	  : std::vector<uint8_t> (b.begin (), b.end ())
	{}

	template<typename block>
	inline value_constant_block (const block &b)
	  : std::vector<uint8_t> (b.begin (), b.end ())
	{}
      };

      struct value_dwarf_constant : public value_dispatch, public dwarf_enum
      {
	inline value_dwarf_constant () {}

	template<typename constant>
	inline value_dwarf_constant (const constant &other)
	  : dwarf_enum (other)
	{}

	template<typename constant, typename arg_type>
	inline value_dwarf_constant (const constant &other, arg_type &)
	  : dwarf_enum (other)
	{}
      };

      struct value_source_file : public value_dispatch, public source_file
      {
	inline value_source_file () {}

	template<typename file, typename arg_type>
	inline value_source_file (const file &other, arg_type &)
	  : source_file (other)
	{}

	template<typename file>
	inline value_source_file (const file &other)
	  : source_file (other)
	{}
      };

      struct value_source_line : public value_dispatch
      {
	unsigned int n;

	inline value_source_line (unsigned int x = 0)
	  : n (x)
	{}

	template<typename arg_type>
	inline value_source_line (unsigned int m, arg_type &)
	  : n (m)
	{}

	struct hasher : public std::unary_function<value_source_line, size_t>
	{
	  inline size_t operator () (const value_source_line &c) const
	  {
	    return c.n;
	  }
	};

	inline operator unsigned int () const
	{
	  return n;
	}

	inline bool operator== (unsigned int x) const
	{
	  return n == x;
	}
      };

      class value_source_column : public value_source_line
      {
      };

      struct value_macptr : public value_dispatch {};

      struct value_location : public value_dispatch, public location_attr
      {
	inline value_location () {}

	template<typename loc, typename arg_type>
	inline value_location (const loc &other, arg_type &)
	  : location_attr (other)
	{}

	template<typename loc>
	inline value_location (const loc &other)
	  : location_attr (other)
	{}
      };
    };

    // Forward decl.
    template<class impl, typename v = value<impl> > class attributes_type;

    template<class impl, typename vw = value<impl> >
    class attr_value
    {
      friend class attributes_type<impl, vw>;
      friend class value<impl>;

    protected:
      typename vw::value_cell_type *_m_value;
      typedef typename impl::debug_info_entry::pointer die_ptr;

      template<typename value, typename arg_type = subr::nothing>
      struct init
      {
	inline init (attr_value *av, int whatattr,
		     const value &other, arg_type &arg)
	{
	  do_init (av, whatattr, other, arg);
	}

	inline init (attr_value *av, int whatattr, const value &other)
	{
	  arg_type dummy;
	  do_init (av, whatattr, other, dummy);
	}

	static inline void do_init (attr_value *av, int whatattr,
				    const value &other, arg_type &arg)
	{
	  switch (other.what_space ())
	    {
#define _DWARF_DATA_AV_MAKE(flavor, fetch)				      \
	      case dwarf::VS_##flavor:					      \
		{							      \
		  typename vw::value_##flavor *p;			      \
		  vw::make (arg)	      				      \
		    .make (av->_m_value, p, whatattr, other.fetch (), arg);   \
		}							      \
	      break

	      _DWARF_DATA_AV_MAKE (identifier, identifier);
	      _DWARF_DATA_AV_MAKE (string, string);
	      _DWARF_DATA_AV_MAKE (flag, flag);
	      _DWARF_DATA_AV_MAKE (rangelistptr, ranges);
	      _DWARF_DATA_AV_MAKE (lineptr, line_info);
	      _DWARF_DATA_AV_MAKE (address, address);
	      _DWARF_DATA_AV_MAKE (source_line, source_line);
	      _DWARF_DATA_AV_MAKE (source_file, source_file);
	      _DWARF_DATA_AV_MAKE (dwarf_constant, dwarf_constant);
	      _DWARF_DATA_AV_MAKE (reference, reference);
	      _DWARF_DATA_AV_MAKE (location, location);
	      //_DWARF_DATA_AV_MAKE (macptr, macros); 	XXX

	    case dwarf::VS_constant:
	      if (other.constant_is_integer ())
		{
		  typename vw::value_constant *p;
		  vw::make (arg).make (av->_m_value, p, whatattr,
				       other.constant (), arg);
		}
	      else
		{
		  typename vw::value_constant_block *p;
		  vw::make (arg).make (av->_m_value, p, whatattr,
				       other.constant_block (), arg);
		}
	      break;

	    default:
	    case dwarf::VS_discr_list:
	      throw std::runtime_error ("XXX unimplemented");

#undef _DWARF_DATA_AV_MAKE
	    }
	}
      };

      // This is kosher only when freshly default-constructed.
      template<typename value, typename arg_type>
      inline void set (int whatattr, const value &other, arg_type &arg)
      {
	assert (_m_value == NULL);
	init<value, arg_type> me (this, whatattr, other, arg);
      }

      template<typename flavor>
      inline flavor &const_variant () const
      {
	flavor *p = dynamic_cast<flavor *> (_m_value);
	if (p == NULL)
	  throw std::runtime_error (_m_value != NULL ? "wrong value type"
				    : "uninitialized attr_value (const?)");
	return *p;
      }

      template<typename flavor>
      inline const flavor &variant () const
      {
	return const_variant<const flavor> ();
      }

      template<typename flavor>
      inline flavor &variant ()
      {
	flavor *p;
	return vw::variant (p, _m_value);
      }

      template<typename value>
      inline attr_value &copy (const value &other)
      {
	if (_m_value != NULL)
	  {
	    delete _m_value;
	    _m_value = NULL;
	  }
	init<value> me (this, 0, other);
	return *this;
      }

    public:
      attr_value (const attr_value &other)
	: _m_value (NULL)
      {
	if (other._m_value != NULL)
	  init<attr_value> me (this, 0, other);
      }

      inline attr_value ()
	: _m_value (NULL)
      {}

      ~attr_value ()
      {
	if (vw::delete_value && _m_value != NULL)
	  delete _m_value;
      }

      template<typename value>
      inline attr_value &operator= (const value &other)
      {
	return copy (other);
      }

      /* This is the same as the generic template one,
	 but we have to define it explicitly to override
	 the default assignment operator.  */
      inline attr_value &operator= (const attr_value &other)
      {
	return copy (other);
      }

      dwarf::value_space what_space () const;
      inline std::string to_string () const;

      inline const bool &flag () const
      {
	return variant<typename vw::value_flag> ().flag;
      }

      inline bool &flag ()
      {
	return variant<typename vw::value_flag> ().flag;
      }

      // XXX dwfl, reloc
      inline const ::Dwarf_Addr &address () const
      {
	return variant<typename vw::value_address> ().addr;
      }

      // XXX dwfl, reloc
      inline ::Dwarf_Addr &address ()
      {
	return variant<typename vw::value_address> ().addr;
      }

      inline const die_ptr &reference () const
      {
	return variant<typename vw::value_reference> ().ref;
      }

      inline die_ptr &reference ()
      {
	return variant<typename vw::value_reference> ().ref;
      }

      inline const location_attr &location () const
      {
	return static_cast<const location_attr &>
	  (variant<typename vw::value_location> ());
      }

      inline location_attr &location ()
      {
	return static_cast<location_attr &>
	  (variant<typename vw::value_location> ());
      }

      inline const std::string &string () const
      {
	if (dynamic_cast<const typename vw::value_source_file *> (_m_value))
	  return source_file ().name ();
	return static_cast<const std::string &>
	  (variant<typename vw::value_string> ());
      }

      inline std::string &string ()
      {
	if (dynamic_cast<const typename vw::value_source_file *> (_m_value))
	  return source_file ().name ();
	return static_cast<std::string &>
	  (variant<typename vw::value_string> ());
      }

      inline const std::string &identifier () const
      {
	return static_cast<const std::string &>
	  (variant<typename vw::value_identifier> ());
      }

      inline std::string &identifier ()
      {
	return static_cast<std::string &>
	  (variant<typename vw::value_identifier> ());
      }

      inline const typename impl::source_file &source_file () const
      {
	return static_cast<const typename impl::source_file &>
	  (variant<typename vw::value_source_file> ());
      }

      inline typename impl::source_file &source_file ()
      {
	return static_cast<typename impl::source_file &>
	  (variant<typename vw::value_source_file> ());
      }

      inline const unsigned int &source_line () const
      {
	return variant<typename vw::value_source_line> ().n;
      }

      inline unsigned int &source_line ()
      {
	return variant<typename vw::value_source_line> ().n;
      }

      inline const unsigned int &source_column () const
      {
	return variant<typename vw::value_source_column> ().n;
      }

      inline unsigned int &source_column ()
      {
	return variant<typename vw::value_source_column> ().n;
      }

      inline const ::Dwarf_Word &constant () const
      {
	return variant<typename vw::value_constant> ().word;
      }

      inline ::Dwarf_Word &constant ()
      {
	return variant<typename vw::value_constant> ().word;
      }

      inline const ::Dwarf_Sword &signed_constant () const
      {
	return variant<typename vw::value_constant> ().sword;
      }

      inline ::Dwarf_Sword &signed_constant ()
      {
	return variant<typename vw::value_constant> ().sword;
      }

      inline const std::vector<uint8_t> &constant_block () const
      {
	return static_cast<const std::vector<uint8_t> &>
	  (variant<typename vw::value_constant_block> ());
      }

      inline std::vector<uint8_t> &constant_block ()
      {
	return static_cast<std::vector<uint8_t> &>
	  (variant<typename vw::value_constant_block> ());
      }

      inline const typename impl::dwarf_enum &dwarf_constant () const
      {
	return variant<typename vw::value_dwarf_constant> ();
      }

      inline typename impl::dwarf_enum &dwarf_constant ()
      {
	return variant<typename vw::value_dwarf_constant> ();
      }

      inline bool constant_is_integer () const
      {
	return (dynamic_cast<const typename vw::value_constant *> (_m_value)
		!= NULL);
      }

      inline const typename impl::range_list &ranges () const
      {
	return static_cast<const range_list &>
	  (variant<const typename vw::value_rangelistptr> ());
      }

      inline typename impl::range_list &ranges ()
      {
	return static_cast<range_list &>
	  (variant<typename vw::value_rangelistptr> ());
      }

      inline const typename impl::line_info_table &line_info () const
      {
	return static_cast<const typename impl::line_info_table &>
	  (variant<const typename vw::value_lineptr> ());
      }

      inline typename impl::line_info_table &line_info ()
      {
	return static_cast<typename impl::line_info_table &>
	  (variant<typename vw::value_lineptr> ());
      }

      // macptr

      template<typename value>
      inline bool operator== (const value &other) const
      {
	const dwarf::value_space what = what_space ();
	if (likely (other.what_space () == what))
	  switch (what)
	    {
	    case dwarf::VS_identifier:
	      return identifier () == other.identifier ();
	    case dwarf::VS_string:
	      return string () == other.string ();
	    case dwarf::VS_reference:
	      return reference () == other.reference ();
	    case dwarf::VS_flag:
	      return flag () == other.flag ();
	    case dwarf::VS_rangelistptr:
	      return ranges () == other.ranges ();
	    case dwarf::VS_lineptr:
	      return line_info () == other.line_info ();
	    case dwarf::VS_constant:
	      if (constant_is_integer ())
		return (other.constant_is_integer ()
			&& constant () == other.constant ());
	      return (!other.constant_is_integer ()
		      && constant_block () == other.constant_block ());
	    case dwarf::VS_source_file:
	      return source_file () == other.source_file ();
	    case dwarf::VS_source_line:
	      return source_line () == other.source_line ();
	    case dwarf::VS_source_column:
	      return source_column () == other.source_column ();
	    case dwarf::VS_address:
	      return address () == other.address ();
	    case dwarf::VS_location:
	      return location () == other.location ();
	    case dwarf::VS_dwarf_constant:
	      return dwarf_constant () == other.dwarf_constant ();
#if 0
	    case dwarf::VS_macptr:
	      return macptr () == other.macptr ();
#endif
	    default:
	    case dwarf::VS_discr_list:
	      throw std::runtime_error ("XXX unimplemented");
	    }
	return false;
      }
      template<typename value>
      inline bool operator!= (const value &other) const
      {
	return !(*this == other);
      }
    };

    template<class impl, typename v>
    class attributes_type
      : public std::map<int, typename impl::attr_value>
    {
      friend class impl::me;
    protected:
      typedef std::map<int, typename impl::attr_value> base_type;

      inline attributes_type () {}

      template<typename iter>
      inline attributes_type (const iter &from, const iter &to)
	: base_type (from, to)
      {}

      template<typename input, typename arg_type>
      inline void set (const input &other, arg_type &c)
      {
	for (typename input::const_iterator attr = other.begin ();
	     attr != other.end ();
	     ++attr)
	  (*this)[(*attr).first].set ((*attr).first, (*attr).second, c);
      }

    public: // XXX should be protected

      /* We don't use the base_type (begin, end) iterator constructor here
	 for good reason.  The ref-maker needs to collect back-pointers
	 into our mapped_value (attr_value) objects.  It would not fly to
	 have that done in a temporary attr_value object that gets copied
	 into the map cell by assignment.  We must make sure that when a
	 value_reference is constructed, it is really the one sitting in
	 our map that the ref-maker will want to update later.  */
      template<typename input, typename arg_type>
      inline attributes_type (const input &other, arg_type &c)
	: base_type ()
      {
	set (other, c);
      }

    public:
      typedef typename base_type::key_type key_type;
      typedef typename base_type::value_type value_type;
      typedef typename base_type::mapped_type mapped_type;

      static inline bool ordered ()
      {
	return true;
      }

      template<typename attrs>
      inline operator attrs () const
      {
	return attrs (base_type::begin (), base_type::end ());
      }
    };

  };

  // Explicit specializations.
  template<>
  std::string to_string<dwarf_data::dwarf_enum> (const dwarf_data::dwarf_enum&);
  inline std::string dwarf_data::dwarf_enum::to_string () const
  {
    return elfutils::to_string (*this); // Use that.
  }

  template<class impl, typename v>
  inline std::string dwarf_data::attr_value<impl, v>::to_string () const
  {
    return elfutils::to_string (*this); // Use that.
  }

};

#endif