Convert observers to C++

This converts observers from using a special source-generating script
to be plain C++.  This version of the patch takes advantage of C++11
by using std::function and variadic templates; incorporates Pedro's
patches; and renames the header file to "observable.h" (this change
eliminates the need for a clean rebuild).

Note that Pedro's patches used a template lambda in tui-hooks.c, but
this failed to compile on some buildbot instances (presumably due to
differing C++ versions); I replaced this with an ordinary template
function.

Regression tested on the buildbot.

gdb/ChangeLog
2018-03-19  Pedro Alves  <palves@redhat.com>
	    Tom Tromey  <tom@tromey.com>

	* unittests/observable-selftests.c: New file.
	* common/observable.h: New file.
	* observable.h: New file.
	* ada-lang.c, ada-tasks.c, agent.c, aix-thread.c, annotate.c,
	arm-tdep.c, auto-load.c, auxv.c, break-catch-syscall.c,
	breakpoint.c, bsd-uthread.c, cli/cli-interp.c, cli/cli-setshow.c,
	corefile.c, dummy-frame.c, event-loop.c, event-top.c, exec.c,
	extension.c, frame.c, gdbarch.c, guile/scm-breakpoint.c,
	infcall.c, infcmd.c, inferior.c, inflow.c, infrun.c, jit.c,
	linux-tdep.c, linux-thread-db.c, m68klinux-tdep.c,
	mi/mi-cmd-break.c, mi/mi-interp.c, mi/mi-main.c, objfiles.c,
	ppc-linux-nat.c, ppc-linux-tdep.c, printcmd.c, procfs.c,
	python/py-breakpoint.c, python/py-finishbreakpoint.c,
	python/py-inferior.c, python/py-unwind.c, ravenscar-thread.c,
	record-btrace.c, record-full.c, record.c, regcache.c, remote.c,
	riscv-tdep.c, sol-thread.c, solib-aix.c, solib-spu.c, solib.c,
	spu-multiarch.c, spu-tdep.c, stack.c, symfile-mem.c, symfile.c,
	symtab.c, thread.c, top.c, tracepoint.c, tui/tui-hooks.c,
	tui/tui-interp.c, valops.c: Update all users.
	* tui/tui-hooks.c (tui_bp_created_observer)
	(tui_bp_deleted_observer, tui_bp_modified_observer)
	(tui_inferior_exit_observer, tui_before_prompt_observer)
	(tui_normal_stop_observer, tui_register_changed_observer):
	Remove.
	(tui_observers_token): New global.
	(attach_or_detach, tui_attach_detach_observers): New functions.
	(tui_install_hooks, tui_remove_hooks): Use
	tui_attach_detach_observers.
	* record-btrace.c (record_btrace_thread_observer): Remove.
	(record_btrace_thread_observer_token): New global.
	* observer.sh: Remove.
	* observer.c: Rename to observable.c.
	* observable.c (namespace gdb_observers): Define new objects.
	(observer_debug): Move into gdb_observers namespace.
	(struct observer, struct observer_list, xalloc_observer_list_node)
	(xfree_observer_list_node, generic_observer_attach)
	(generic_observer_detach, generic_observer_notify): Remove.
	(_initialize_observer): Update.
	Don't include observer.inc.
	* Makefile.in (generated_files): Remove observer.h, observer.inc.
	(clean mostlyclean): Likewise.
	(observer.h, observer.inc): Remove targets.
	(SUBDIR_UNITTESTS_SRCS): Add observable-selftests.c.
	(COMMON_SFILES): Use observable.c, not observer.c.
	* .gitignore: Remove observer.h.

gdb/doc/ChangeLog
2018-03-19  Tom Tromey  <tom@tromey.com>

	* observer.texi: Remove.

gdb/testsuite/ChangeLog
2018-03-19  Tom Tromey  <tom@tromey.com>

	* gdb.gdb/observer.exp: Remove.

1 files changed, 0 insertions, 215 deletions

diff --git a/gdb/observer.c b/gdb/observer.c
deleted file mode 100644
index 3c0ec2a..0000000
--- a/gdb/observer.c
+++ /dev/null
@@ -1,215 +0,0 @@
-/* GDB Notifications to Observers.
-
-   Copyright (C) 2003-2018 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/>.  */
-
-/* An observer is an entity who is interested in being notified when GDB
-   reaches certain states, or certain events occur in GDB.  The entity being
-   observed is called the Subject.  To receive notifications, the observer
-   attaches a callback to the subject.  One subject can have several
-   observers.
-
-   This file implements an internal generic low-level event notification
-   mechanism based on the Observer paradigm described in the book "Design
-   Patterns".  This generic event notification mechansim is then re-used
-   to implement the exported high-level notification management routines
-   for all possible notifications.
-
-   The current implementation of the generic observer provides support
-   for contextual data.  This contextual data is given to the subject
-   when attaching the callback.  In return, the subject will provide
-   this contextual data back to the observer as a parameter of the
-   callback.
-
-   FIXME: The current support for the contextual data is only partial,
-   as it lacks a mechanism that would deallocate this data when the
-   callback is detached.  This is not a problem so far, as this contextual
-   data is only used internally to hold a function pointer.  Later on,
-   if a certain observer needs to provide support for user-level
-   contextual data, then the generic notification mechanism will need
-   need to be enhanced to allow the observer to provide a routine to
-   deallocate the data when attaching the callback.
-
-   This file is currently maintained by hand, but the long term plan
-   if the number of different notifications starts growing is to create
-   a new script (observer.sh) that would generate this file, and the
-   associated documentation.  */
-
-#include "defs.h"
-#include "observer.h"
-#include "command.h"
-#include "gdbcmd.h"
-
-static unsigned int observer_debug;
-static void
-show_observer_debug (struct ui_file *file, int from_tty,
-		     struct cmd_list_element *c, const char *value)
-{
-  fprintf_filtered (file, _("Observer debugging is %s.\n"), value);
-}
-
-/* The internal generic observer.  */
-
-typedef void (generic_observer_notification_ftype) (const void *data,
-						    const void *args);
-
-struct observer
-{
-  generic_observer_notification_ftype *notify;
-  /* No memory management needed for the following field for now.  */
-  void *data;
-};
-
-/* A list of observers, maintained by the subject.  A subject is
-   actually represented by its list of observers.  */
-
-struct observer_list
-{
-  struct observer_list *next;
-  struct observer *observer;
-};
-
-/* Allocate a struct observer_list, intended to be used as a node
-   in the list of observers maintained by a subject.  */
-
-static struct observer_list *
-xalloc_observer_list_node (void)
-{
-  struct observer_list *node = XNEW (struct observer_list);
-
-  node->observer = XNEW (struct observer);
-  return node;
-}
-
-/* The opposite of xalloc_observer_list_node, frees the memory for
-   the given node.  */
-
-static void
-xfree_observer_list_node (struct observer_list *node)
-{
-  xfree (node->observer);
-  xfree (node);
-}
-
-/* Attach the callback NOTIFY to a SUBJECT.  The DATA is also stored,
-   in order for the subject to provide it back to the observer during
-   a notification.  */
-
-static struct observer *
-generic_observer_attach (struct observer_list **subject,
-			 generic_observer_notification_ftype * notify,
-			 void *data)
-{
-  struct observer_list *observer_list = xalloc_observer_list_node ();
-
-  observer_list->next = *subject;
-  observer_list->observer->notify = notify;
-  observer_list->observer->data = data;
-  *subject = observer_list;
-
-  return observer_list->observer;
-}
-
-/* Remove the given OBSERVER from the SUBJECT.  Once detached, OBSERVER
-   should no longer be used, as it is no longer valid.  */
-
-static void
-generic_observer_detach (struct observer_list **subject,
-			 const struct observer *observer)
-{
-  struct observer_list *previous_node = NULL;
-  struct observer_list *current_node = *subject;
-
-  while (current_node != NULL)
-    {
-      if (current_node->observer == observer)
-	{
-	  if (previous_node != NULL)
-	    previous_node->next = current_node->next;
-	  else
-	    *subject = current_node->next;
-	  xfree_observer_list_node (current_node);
-	  return;
-	}
-      previous_node = current_node;
-      current_node = current_node->next;
-    }
-
-  /* We should never reach this point.  However, this should not be
-     a very serious error, so simply report a warning to the user.  */
-  warning (_("Failed to detach observer"));
-}
-
-/* Send a notification to all the observers of SUBJECT.  ARGS is passed to
-   all observers as an argument to the notification callback.  */
-
-static void
-generic_observer_notify (struct observer_list *subject, const void *args)
-{
-  struct observer_list *current_node = subject;
-
-  while (current_node != NULL)
-    {
-      (*current_node->observer->notify) (current_node->observer->data, args);
-      current_node = current_node->next;
-    }
-}
-
-
-/* The following code is only used to unit-test the observers from our
-   testsuite.  DO NOT USE IT within observer.c (or anywhere else for
-   that matter)!  */
-
-/* If we define these variables and functions as `static', the
-   compiler will optimize them out.  */
- 
-int observer_test_first_observer = 0;
-int observer_test_second_observer = 0;
-int observer_test_third_observer = 0;
-
-void
-observer_test_first_notification_function (int arg)
-{
-  observer_test_first_observer++;
-}
-
-void
-observer_test_second_notification_function (int arg)
-{
-  observer_test_second_observer++;
-}
-
-void
-observer_test_third_notification_function (int arg)
-{
-  observer_test_third_observer++;
-}
-
-void
-_initialize_observer (void)
-{
-  add_setshow_zuinteger_cmd ("observer", class_maintenance,
-			     &observer_debug, _("\
-Set observer debugging."), _("\
-Show observer debugging."), _("\
-When non-zero, observer debugging is enabled."),
-			     NULL,
-			     show_observer_debug,
-			     &setdebuglist, &showdebuglist);
-}
-
-#include "observer.inc"