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.

2 files changed, 38 insertions, 66 deletions

diff --git a/gdb/common/format.c b/gdb/common/format.c
index 8cb1551..95cb805 100644
--- a/gdb/common/format.c
+++ b/gdb/common/format.c
@@ -20,17 +20,13 @@
 #include "common-defs.h"
 #include "format.h"
 
-struct format_piece *
-parse_format_string (const char **arg)
+format_pieces::format_pieces (const char **arg)
 {
   const char *s;
   char *f, *string;
   const char *prev_start;
   const char *percent_loc;
   char *sub_start, *current_substring;
-  struct format_piece *pieces;
-  int next_frag;
-  int max_pieces;
   enum argclass this_argclass;
 
   s = *arg;
@@ -100,12 +96,7 @@ parse_format_string (const char **arg)
   /* Need extra space for the '\0's.  Doubling the size is sufficient.  */
 
   current_substring = (char *) xmalloc (strlen (string) * 2 + 1000);
-
-  max_pieces = strlen (string) + 2;
-
-  pieces = XNEWVEC (struct format_piece, max_pieces);
-
-  next_frag = 0;
+  m_storage.reset (current_substring);
 
   /* Now scan the string for %-specs and see what kinds of args they want.
      argclass classifies the %-specs so we can give printf-type functions
@@ -135,9 +126,7 @@ parse_format_string (const char **arg)
 	current_substring += f - 1 - prev_start;
 	*current_substring++ = '\0';
 
-	pieces[next_frag].string = sub_start;
-	pieces[next_frag].argclass = literal_piece;
-	next_frag++;
+	m_pieces.emplace_back (sub_start, literal_piece);
 
 	percent_loc = f - 1;
 
@@ -343,9 +332,7 @@ parse_format_string (const char **arg)
 
 	prev_start = f;
 
-	pieces[next_frag].string = sub_start;
-	pieces[next_frag].argclass = this_argclass;
-	next_frag++;
+	m_pieces.emplace_back (sub_start, this_argclass);
       }
 
   /* Record the remainder of the string.  */
@@ -356,44 +343,5 @@ parse_format_string (const char **arg)
   current_substring += f - prev_start;
   *current_substring++ = '\0';
 
-  pieces[next_frag].string = sub_start;
-  pieces[next_frag].argclass = literal_piece;
-  next_frag++;
-
-  /* Record an end-of-array marker.  */
-
-  pieces[next_frag].string = NULL;
-  pieces[next_frag].argclass = literal_piece;
-
-  return pieces;
+  m_pieces.emplace_back (sub_start, literal_piece);
 }
-
-void
-free_format_pieces (struct format_piece *pieces)
-{
-  if (!pieces)
-    return;
-
-  /* We happen to know that all the string pieces are in the block
-     pointed to by the first string piece.  */
-  if (pieces[0].string)
-    xfree (pieces[0].string);
-
-  xfree (pieces);
-}
-
-void
-free_format_pieces_cleanup (void *ptr)
-{
-  struct format_piece **location = (struct format_piece **) ptr;
-
-  if (location == NULL)
-    return;
-
-  if (*location != NULL)
-    {
-      free_format_pieces (*location);
-      *location = NULL;
-    }
-}
-
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 */