C++-ify parse_format_string

This replaces parse_format_string with a class, removing some
constructors along the way.  While doing this, I found that one
argument to gen_printf is unused, so I removed it.

Also, I am not completely sure, but the use of `release' in
maint_agent_printf_command and parse_cmd_to_aexpr seems like it may
leak expressions.

Regression tested by the buildbot.

ChangeLog
2017-12-08  Tom Tromey  <tom@tromey.com>

	* printcmd.c (ui_printf): Update.  Use std::vector.
	* common/format.h (struct format_piece): Add constructor.
	<string>: Now const.
	(class format_pieces): New class.
	(parse_format_string, free_format_pieces)
	(free_format_pieces_cleanup): Remove.
	* common/format.c (format_pieces::format_pieces): Rename from
	parse_format_string.  Update.
	(free_format_pieces, free_format_pieces_cleanup): Remove.
	* breakpoint.c (parse_cmd_to_aexpr): Update.  Use std::vector.
	* ax-gdb.h (gen_printf): Remove argument.
	* ax-gdb.c (gen_printf): Remove "frags" argument.
	(maint_agent_printf_command): Update.  Use std::vector.

gdbserver/ChangeLog
2017-12-08  Tom Tromey  <tom@tromey.com>

	* ax.c (ax_printf): Update.

1 files changed, 33 insertions, 9 deletions

diff --git a/gdb/common/format.h b/gdb/common/format.h
index f3a94b8..dd083f9 100644
--- a/gdb/common/format.h
+++ b/gdb/common/format.h
@@ -48,22 +48,46 @@ enum argclass
 
 struct format_piece
 {
-  char *string;
+  format_piece (const char *str, enum argclass argc)
+    : string (str),
+      argclass (argc)
+  {
+  }
+
+  const char *string;
   enum argclass argclass;
 };
 
-/* Return an array of printf fragments found at the given string, and
-   rewrite ARG with a pointer to the end of the format string.  */
+class format_pieces
+{
+public:
+
+  format_pieces (const char **arg);
+  ~format_pieces () = default;
+
+  DISABLE_COPY_AND_ASSIGN (format_pieces);
 
-extern struct format_piece *parse_format_string (const char **arg);
+  format_piece &operator[] (size_t index)
+  {
+    return m_pieces[index];
+  }
 
-/* Given a pointer to an array of format pieces, free any memory that
-   would have been allocated by parse_format_string.  */
+  typedef std::vector<format_piece>::iterator iterator;
 
-extern void free_format_pieces (struct format_piece *frags);
+  iterator begin ()
+  {
+    return m_pieces.begin ();
+  }
 
-/* Freeing, cast as a cleanup.  */
+  iterator end ()
+  {
+    return m_pieces.end ();
+  }
 
-extern void free_format_pieces_cleanup (void *);
+private:
+
+  std::vector<format_piece> m_pieces;
+  gdb::unique_xmalloc_ptr<char> m_storage;
+};
 
 #endif /* COMMON_FORMAT_H */