gdb: introduce iterator_range, remove next_adapter

I was always a bit confused by next_adapter, because it kind of mixes
the element type and the iterator type.  In reality, it is not much more
than a class that wraps two iterators (begin and end).  However, it
assumes that:

 - you can construct the begin iterator by passing a pointer to the
   first element of the iterable
 - you can default-construct iterator to make the end iterator

I think that by generalizing it a little bit, we can re-use it at more
places.

Rename it to "iterator_range".  I think it describes a bit better: it's
a range made by wrapping a begin and end iterator.  Move it to its own
file, since it's not related to next_iterator anymore.

iterator_range has two constructors.  The variadic one, where arguments
are forwarded to construct the underlying begin iterator.  The end
iterator is constructed through default construction.  This is a
generalization of what we have today.

There is another constructor which receives already constructed begin
and end iterators, useful if the end iterator can't be obtained by
default-construction.  Or, if you wanted to make a range that does not
end at the end of the container, you could pass any iterator as the
"end".

This generalization allows removing some "range" classes, like
all_inferiors_range.  These classes existed only to pass some arguments
when constructing the begin iterator.  With iterator_range, those same
arguments are passed to the iterator_range constructed and then
forwarded to the constructed begin iterator.

There is a small functional difference in how iterator_range works
compared to next_adapter.  next_adapter stored the pointer it received
as argument and constructeur an iterator in the `begin` method.
iterator_range constructs the begin iterator and stores it as a member.
Its `begin` method returns a copy of that iterator.

With just iterator_range, uses of next_adapter<foo> would be replaced
with:

  using foo_iterator = next_iterator<foo>;
  using foo_range = iterator_range<foo_iterator>;

However, I added a `next_range` wrapper as a direct replacement for
next_adapter<foo>.  IMO, next_range is a slightly better name than
next_adapter.

The rest of the changes are applications of this new class.

gdbsupport/ChangeLog:

	* next-iterator.h (class next_adapter): Remove.
	* iterator-range.h: New.

gdb/ChangeLog:

	* breakpoint.h (bp_locations_range): Remove.
	(bp_location_range): New.
	(struct breakpoint) <locations>: Adjust type.
	(breakpoint_range): Use iterator_range.
	(tracepoint_range): Use iterator_range.
	* breakpoint.c (breakpoint::locations): Adjust return type.
	* gdb_bfd.h (gdb_bfd_section_range): Use iterator_range.
	* gdbthread.h (all_threads_safe): Pass argument to
	all_threads_safe_range.
	* inferior-iter.h (all_inferiors_range): Use iterator_range.
	(all_inferiors_safe_range): Use iterator_range.
	(all_non_exited_inferiors_range): Use iterator_range.
	* inferior.h (all_inferiors, all_non_exited_inferiors): Pass
	inferior_list as argument.
	* objfiles.h (struct objfile) <compunits_range>: Remove.
	<compunits>: Return compunit_symtab_range.
	* progspace.h (unwrapping_objfile_iterator)
	<unwrapping_objfile_iterator>: Take parameter by value.
	(unwrapping_objfile_range): Use iterator_range.
	(struct program_space) <objfiles_range>: Define with "using".
	<objfiles>: Adjust.
	<objfiles_safe_range>: Define with "using".
	<objfiles_safe>: Adjust.
	<solibs>: Return so_list_range, define here.
	* progspace.c (program_space::solibs): Remove.
	* psymtab.h (class psymtab_storage) <partial_symtab_iterator>:
	New.
	<partial_symtab_range>: Use iterator_range.
	* solist.h (so_list_range): New.
	* symtab.h (compunit_symtab_range):
	New.
	(symtab_range): New.
	(compunit_filetabs): Change to a function.
	* thread-iter.h (inf_threads_range,
	inf_non_exited_threads_range, safe_inf_threads_range,
	all_threads_safe_range): Use iterator_range.
	* top.h (ui_range): New.
	(all_uis): Use ui_range.

Change-Id: Ib7a9d2a3547f45f01aa1c6b24536ba159db9b854

16 files changed, 124 insertions, 172 deletions

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index dbbea6b..5cc3743 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -12283,9 +12283,9 @@ breakpoint::~breakpoint ()
 
 /* See breakpoint.h.  */
 
-bp_locations_range breakpoint::locations ()
+bp_location_range breakpoint::locations ()
 {
-  return bp_locations_range (this->loc);
+  return bp_location_range (this->loc);
 }
 
 static struct bp_location *
diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index e40504f..fe68730 100644
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -30,6 +30,8 @@
 #include "gdbsupport/array-view.h"
 #include "gdbsupport/filtered-iterator.h"
 #include "gdbsupport/function-view.h"
+#include "gdbsupport/next-iterator.h"
+#include "gdbsupport/iterator-range.h"
 #include "gdbsupport/refcounted-object.h"
 #include "gdbsupport/safe-iterator.h"
 #include "cli/cli-script.h"
@@ -706,7 +708,7 @@ extern bool target_exact_watchpoints;
 
 /* bp_location linked list range.  */
 
-using bp_locations_range = next_adapter<bp_location>;
+using bp_location_range = next_range<bp_location>;
 
 /* Note that the ->silent field is not currently used by any commands
    (though the code is in there if it was to be, and set_raw_breakpoint
@@ -721,7 +723,7 @@ struct breakpoint
   virtual ~breakpoint ();
 
   /* Return a range of this breakpoint's locations.  */
-  bp_locations_range locations ();
+  bp_location_range locations ();
 
   /* Methods associated with this breakpoint.  */
   const breakpoint_ops *ops = NULL;
@@ -1715,7 +1717,7 @@ using breakpoint_iterator = next_iterator<breakpoint>;
 
 /* Breakpoint linked list range.  */
 
-using breakpoint_range = next_adapter<breakpoint, breakpoint_iterator>;
+using breakpoint_range = iterator_range<breakpoint_iterator>;
 
 /* Return a range to iterate over all breakpoints.  */
 
@@ -1746,7 +1748,7 @@ using tracepoint_iterator
 
 /* Breakpoint linked list range, filtering to only keep tracepoints.  */
 
-using tracepoint_range = next_adapter<breakpoint, tracepoint_iterator>;
+using tracepoint_range = iterator_range<tracepoint_iterator>;
 
 /* Return a range to iterate over all tracepoints.  */
 
diff --git a/gdb/gdb_bfd.h b/gdb/gdb_bfd.h
index d366fc0..156c276 100644
--- a/gdb/gdb_bfd.h
+++ b/gdb/gdb_bfd.h
@@ -23,6 +23,7 @@
 #include "registry.h"
 #include "gdbsupport/byte-vector.h"
 #include "gdbsupport/gdb_ref_ptr.h"
+#include "gdbsupport/iterator-range.h"
 #include "gdbsupport/next-iterator.h"
 
 DECLARE_REGISTRY (bfd);
@@ -208,8 +209,7 @@ gdb_bfd_ref_ptr gdb_bfd_open_from_target_memory (CORE_ADDR addr, ULONGEST size,
        ... use SECT ...
  */
 
-using gdb_bfd_section_iterator = next_iterator<asection>;
-using gdb_bfd_section_range = next_adapter<asection, gdb_bfd_section_iterator>;
+using gdb_bfd_section_range = next_range<asection>;
 
 static inline gdb_bfd_section_range
 gdb_bfd_sections (bfd *abfd)
diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
index 622fa1d..cb3dcc3 100644
--- a/gdb/gdbthread.h
+++ b/gdb/gdbthread.h
@@ -563,7 +563,7 @@ all_non_exited_threads (process_stratum_target *proc_target = nullptr,
 inline all_threads_safe_range
 all_threads_safe ()
 {
-  return {};
+  return all_threads_safe_range (all_threads_iterator::begin_t {});
 }
 
 extern int thread_count (process_stratum_target *proc_target);
diff --git a/gdb/inferior-iter.h b/gdb/inferior-iter.h
index 2ae0a09..f999150 100644
--- a/gdb/inferior-iter.h
+++ b/gdb/inferior-iter.h
@@ -90,6 +90,11 @@ private:
   inferior *m_inf;
 };
 
+/* A range adapter that makes it possible to iterate over all
+   inferiors with range-for.  */
+
+using all_inferiors_range = iterator_range<all_inferiors_iterator>;
+
 /* Filter for filtered_iterator.  Filters out exited inferiors.  */
 
 struct exited_inferior_filter
@@ -106,21 +111,10 @@ using all_non_exited_inferiors_iterator
   = filtered_iterator<all_inferiors_iterator, exited_inferior_filter>;
 
 /* A range adapter that makes it possible to iterate over all
-   inferiors with range-for.  */
-struct all_inferiors_range
-{
-  all_inferiors_range (process_stratum_target *proc_target = nullptr)
-    : m_filter_target (proc_target)
-  {}
+   non-exited inferiors with range-for.  */
 
-  all_inferiors_iterator begin () const
-  { return all_inferiors_iterator (m_filter_target, inferior_list); }
-  all_inferiors_iterator end () const
-  { return all_inferiors_iterator (); }
-
-private:
-  process_stratum_target *m_filter_target;
-};
+using all_non_exited_inferiors_range
+  = iterator_range<all_non_exited_inferiors_iterator>;
 
 /* Iterate over all inferiors, safely.  */
 
@@ -131,51 +125,6 @@ using all_inferiors_safe_iterator
    inferiors with range-for "safely".  I.e., it is safe to delete the
    currently-iterated inferior.  */
 
-struct all_inferiors_safe_range
-{
-  explicit all_inferiors_safe_range (process_stratum_target *filter_target)
-    : m_filter_target (filter_target)
-  {}
-
-  all_inferiors_safe_range ()
-    : m_filter_target (nullptr)
-  {}
-
-  all_inferiors_safe_iterator begin () const
-  {
-    return (all_inferiors_safe_iterator
-	    (all_inferiors_iterator (m_filter_target, inferior_list)));
-  }
-
-  all_inferiors_safe_iterator end () const
-  { return all_inferiors_safe_iterator (); }
-
-private:
-  /* The filter.  */
-  process_stratum_target *m_filter_target;
-};
-
-/* A range adapter that makes it possible to iterate over all
-   non-exited inferiors with range-for.  */
-
-struct all_non_exited_inferiors_range
-{
-  explicit all_non_exited_inferiors_range (process_stratum_target *filter_target)
-    : m_filter_target (filter_target)
-  {}
-
-  all_non_exited_inferiors_range ()
-    : m_filter_target (nullptr)
-  {}
-
-  all_non_exited_inferiors_iterator begin () const
-  { return all_non_exited_inferiors_iterator (m_filter_target, inferior_list); }
-  all_non_exited_inferiors_iterator end () const
-  { return all_non_exited_inferiors_iterator (); }
-
-private:
-  /* The filter.  */
-  process_stratum_target *m_filter_target;
-};
+using all_inferiors_safe_range = iterator_range<all_inferiors_safe_iterator>;
 
 #endif /* !defined (INFERIOR_ITER_H) */
diff --git a/gdb/inferior.h b/gdb/inferior.h
index f61b588..c63990a 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -681,7 +681,7 @@ all_inferiors_safe ()
 inline all_inferiors_range
 all_inferiors (process_stratum_target *proc_target = nullptr)
 {
-  return all_inferiors_range (proc_target);
+  return all_inferiors_range (proc_target, inferior_list);
 }
 
 /* Return a range that can be used to walk over all inferiors with PID
@@ -690,7 +690,7 @@ all_inferiors (process_stratum_target *proc_target = nullptr)
 inline all_non_exited_inferiors_range
 all_non_exited_inferiors (process_stratum_target *proc_target = nullptr)
 {
-  return all_non_exited_inferiors_range (proc_target);
+  return all_non_exited_inferiors_range (proc_target, inferior_list);
 }
 
 /* Prune away automatically added inferiors that aren't required
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index 766c4b4..55be1bf 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -445,14 +445,12 @@ public:
 
   DISABLE_COPY_AND_ASSIGN (objfile);
 
-  typedef next_adapter<struct compunit_symtab> compunits_range;
-
   /* A range adapter that makes it possible to iterate over all
      compunits in one objfile.  */
 
-  compunits_range compunits ()
+  compunit_symtab_range compunits ()
   {
-    return compunits_range (compunit_symtabs);
+    return compunit_symtab_range (compunit_symtabs);
   }
 
   /* A range adapter that makes it possible to iterate over all
diff --git a/gdb/progspace.c b/gdb/progspace.c
index ebbc784..e3cc692 100644
--- a/gdb/progspace.c
+++ b/gdb/progspace.c
@@ -215,14 +215,6 @@ program_space::remove_objfile (struct objfile *objfile)
 
 /* See progspace.h.  */
 
-next_adapter<struct so_list>
-program_space::solibs () const
-{
-  return next_adapter<struct so_list> (this->so_list);
-}
-
-/* See progspace.h.  */
-
 void
 program_space::exec_close ()
 {
diff --git a/gdb/progspace.h b/gdb/progspace.h
index 7906847..fb348ca 100644
--- a/gdb/progspace.h
+++ b/gdb/progspace.h
@@ -25,6 +25,7 @@
 #include "gdb_bfd.h"
 #include "gdbsupport/gdb_vecs.h"
 #include "registry.h"
+#include "solist.h"
 #include "gdbsupport/next-iterator.h"
 #include "gdbsupport/safe-iterator.h"
 #include <list>
@@ -59,8 +60,8 @@ public:
   typedef typename objfile_list::iterator::iterator_category iterator_category;
   typedef typename objfile_list::iterator::difference_type difference_type;
 
-  unwrapping_objfile_iterator (const objfile_list::iterator &iter)
-    : m_iter (iter)
+  unwrapping_objfile_iterator (objfile_list::iterator iter)
+    : m_iter (std::move (iter))
   {
   }
 
@@ -89,29 +90,7 @@ private:
 
 /* A range that returns unwrapping_objfile_iterators.  */
 
-struct unwrapping_objfile_range
-{
-  typedef unwrapping_objfile_iterator iterator;
-
-  unwrapping_objfile_range (objfile_list &ol)
-    : m_list (ol)
-  {
-  }
-
-  iterator begin () const
-  {
-    return iterator (m_list.begin ());
-  }
-
-  iterator end () const
-  {
-    return iterator (m_list.end ());
-  }
-
-private:
-
-  objfile_list &m_list;
-};
+using unwrapping_objfile_range = iterator_range<unwrapping_objfile_iterator>;
 
 /* A program space represents a symbolic view of an address space.
    Roughly speaking, it holds all the data associated with a
@@ -222,7 +201,7 @@ struct program_space
      a program space.  */
   ~program_space ();
 
-  typedef unwrapping_objfile_range objfiles_range;
+  using objfiles_range = unwrapping_objfile_range;
 
   /* Return an iterable object that can be used to iterate over all
      objfiles.  The basic use is in a foreach, like:
@@ -230,10 +209,12 @@ struct program_space
      for (objfile *objf : pspace->objfiles ()) { ... }  */
   objfiles_range objfiles ()
   {
-    return unwrapping_objfile_range (objfiles_list);
+    return objfiles_range
+      (unwrapping_objfile_iterator (objfiles_list.begin ()),
+       unwrapping_objfile_iterator (objfiles_list.end ()));
   }
 
-  typedef basic_safe_range<objfiles_range> objfiles_safe_range;
+  using objfiles_safe_range = basic_safe_range<objfiles_range>;
 
   /* An iterable object that can be used to iterate over all objfiles.
      The basic use is in a foreach, like:
@@ -244,7 +225,10 @@ struct program_space
      deleted during iteration.  */
   objfiles_safe_range objfiles_safe ()
   {
-    return objfiles_safe_range (objfiles_list);
+    return objfiles_safe_range
+      (objfiles_range
+	 (unwrapping_objfile_iterator (objfiles_list.begin ()),
+	  unwrapping_objfile_iterator (objfiles_list.end ())));
   }
 
   /* Add OBJFILE to the list of objfiles, putting it just before
@@ -270,7 +254,8 @@ struct program_space
      program space.  Use it like:
 
      for (so_list *so : pspace->solibs ()) { ... }  */
-  next_adapter<struct so_list> solibs () const;
+  so_list_range solibs () const
+  { return so_list_range (this->so_list); }
 
   /* Close and clear exec_bfd.  If we end up with no target sections
      to read memory from, this unpushes the exec_ops target.  */
diff --git a/gdb/psymtab.h b/gdb/psymtab.h
index 522ccf3..7cd3e95 100644
--- a/gdb/psymtab.h
+++ b/gdb/psymtab.h
@@ -104,7 +104,7 @@ public:
 
   void install_psymtab (partial_symtab *pst);
 
-  typedef next_adapter<struct partial_symtab> partial_symtab_range;
+  using partial_symtab_range = next_range<partial_symtab>;
 
   /* A range adapter that makes it possible to iterate over all
      psymtabs in one objfile.  */
diff --git a/gdb/solist.h b/gdb/solist.h
index d44e6f4..6033751 100644
--- a/gdb/solist.h
+++ b/gdb/solist.h
@@ -163,6 +163,8 @@ struct target_so_ops
   void (*handle_event) (void);
 };
 
+using so_list_range = next_range<so_list>;
+
 /* Free the memory associated with a (so_list *).  */
 void free_so (struct so_list *so);
 
diff --git a/gdb/symtab.h b/gdb/symtab.h
index 471ae9e..fd8dd62 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -33,6 +33,7 @@
 #include "gdbsupport/gdb_optional.h"
 #include "gdbsupport/gdb_string_view.h"
 #include "gdbsupport/next-iterator.h"
+#include "gdbsupport/iterator-range.h"
 #include "completer.h"
 #include "gdb-demangle.h"
 
@@ -1521,6 +1522,8 @@ struct compunit_symtab
   struct compunit_symtab *user;
 };
 
+using compunit_symtab_range = next_range<compunit_symtab>;
+
 #define COMPUNIT_OBJFILE(cust) ((cust)->objfile)
 #define COMPUNIT_FILETABS(cust) ((cust)->filetabs)
 #define COMPUNIT_DEBUGFORMAT(cust) ((cust)->debugformat)
@@ -1536,13 +1539,13 @@ struct compunit_symtab
 /* A range adapter to allowing iterating over all the file tables
    within a compunit.  */
 
-struct compunit_filetabs : public next_adapter<struct symtab>
+using symtab_range = next_range<symtab>;
+
+static inline symtab_range
+compunit_filetabs (compunit_symtab *cu)
 {
-  compunit_filetabs (struct compunit_symtab *cu)
-    : next_adapter<struct symtab> (cu->filetabs)
-  {
-  }
-};
+  return symtab_range (cu->filetabs);
+}
 
 /* Return the primary symtab of CUST.  */
 
diff --git a/gdb/thread-iter.h b/gdb/thread-iter.h
index 8530986..098af0f 100644
--- a/gdb/thread-iter.h
+++ b/gdb/thread-iter.h
@@ -170,43 +170,24 @@ using safe_inf_threads_iterator
 /* A range adapter that makes it possible to iterate over all threads
    of an inferior with range-for.  */
 
-using inf_threads_range
-  = next_adapter<thread_info, inf_threads_iterator>;
+using inf_threads_range = iterator_range<inf_threads_iterator>;
 
 /* A range adapter that makes it possible to iterate over all
    non-exited threads of an inferior with range-for.  */
 
 using inf_non_exited_threads_range
-  = next_adapter<thread_info, inf_non_exited_threads_iterator>;
+  = iterator_range<inf_non_exited_threads_iterator>;
 
 /* A range adapter that makes it possible to iterate over all threads
    of an inferior with range-for, safely.  */
 
-using safe_inf_threads_range
-  = next_adapter<thread_info, safe_inf_threads_iterator>;
-
-/* A range adapter that makes it possible to iterate over all threads
-   of all inferiors with range-for.  */
-
-struct all_threads_range
-{
-  all_threads_iterator begin () const
-  { return all_threads_iterator (all_threads_iterator::begin_t {}); }
-  all_threads_iterator end () const
-  { return all_threads_iterator (); }
-};
+using safe_inf_threads_range = iterator_range<safe_inf_threads_iterator>;
 
 /* A range adapter that makes it possible to iterate over all threads
    with range-for "safely".  I.e., it is safe to delete the
    currently-iterated thread.  */
 
-struct all_threads_safe_range
-{
-  all_threads_safe_iterator begin () const
-  { return all_threads_safe_iterator (all_threads_iterator::begin_t {}); }
-  all_threads_safe_iterator end () const
-  { return all_threads_safe_iterator (); }
-};
+using all_threads_safe_range = iterator_range<all_threads_safe_iterator>;
 
 /* A range adapter that makes it possible to iterate over all threads
    that match a PTID filter with range-for.  */
diff --git a/gdb/top.h b/gdb/top.h
index 56bd06c..ef88ca0 100644
--- a/gdb/top.h
+++ b/gdb/top.h
@@ -204,11 +204,13 @@ public:
 #define SWITCH_THRU_ALL_UIS()		\
   for (switch_thru_all_uis stau_state; !stau_state.done (); stau_state.next ())
 
+using ui_range = next_range<ui>;
+
 /* An adapter that can be used to traverse over all UIs.  */
 static inline
-next_adapter<ui> all_uis ()
+ui_range all_uis ()
 {
-  return next_adapter<ui> (ui_list);
+  return ui_range (ui_list);
 }
 
 /* Register the UI's input file descriptor in the event loop.  */
diff --git a/gdbsupport/iterator-range.h b/gdbsupport/iterator-range.h
new file mode 100644
index 0000000..2a718e6
--- /dev/null
+++ b/gdbsupport/iterator-range.h
@@ -0,0 +1,60 @@
+/* A range adapter that wraps begin / end iterators.
+   Copyright (C) 2021 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 GDBSUPPORT_ITERATOR_RANGE_H
+#define GDBSUPPORT_ITERATOR_RANGE_H
+
+/* A wrapper that allows using ranged for-loops on a range described by two
+   iterators.  */
+
+template <typename IteratorType>
+struct iterator_range
+{
+  using iterator = IteratorType;
+
+  /* Create an iterator_range using BEGIN as the begin iterator.
+
+     Assume that the end iterator can be default-constructed.  */
+  template <typename... Args>
+  iterator_range (Args &&...args)
+    : m_begin (std::forward<Args> (args)...)
+  {}
+
+  /* Create an iterator range using explicit BEGIN and END iterators.  */
+  template <typename... Args>
+  iterator_range (IteratorType begin, IteratorType end)
+    : m_begin (std::move (begin)), m_end (std::move (end))
+  {}
+
+  /* Need these as the variadic constructor would be a better match
+     otherwise.  */
+  iterator_range (iterator_range &) = default;
+  iterator_range (const iterator_range &) = default;
+  iterator_range (iterator_range &&) = default;
+
+  IteratorType begin () const
+  { return m_begin; }
+
+  IteratorType end () const
+  { return m_end; }
+
+private:
+  IteratorType m_begin, m_end;
+};
+
+#endif /* GDBSUPPORT_ITERATOR_RANGE_H */
diff --git a/gdbsupport/next-iterator.h b/gdbsupport/next-iterator.h
index 5017524..72b241e 100644
--- a/gdbsupport/next-iterator.h
+++ b/gdbsupport/next-iterator.h
@@ -19,6 +19,8 @@
 #ifndef COMMON_NEXT_ITERATOR_H
 #define COMMON_NEXT_ITERATOR_H
 
+#include "gdbsupport/iterator-range.h"
+
 /* An iterator that uses the 'next' field of a type to iterate.  This
    can be used with various GDB types that are stored as linked
    lists.  */
@@ -70,33 +72,9 @@ private:
   T *m_item;
 };
 
-/* A range adapter that allows iterating over a linked list.  */
-
-template<typename T, typename Iterator = next_iterator<T>>
-class next_adapter
-{
-public:
-
-  explicit next_adapter (T *item)
-    : m_item (item)
-  {
-  }
-
-  using iterator = Iterator;
-
-  iterator begin () const
-  {
-    return iterator (m_item);
-  }
-
-  iterator end () const
-  {
-    return iterator ();
-  }
+/* A convenience wrapper to make a range type around a next_iterator.  */
 
-private:
-
-  T *m_item;
-};
+template <typename T>
+using next_range = iterator_range<next_iterator<T>>;
 
 #endif /* COMMON_NEXT_ITERATOR_H */