Explicit locations: introduce new struct event_location-based API

This patch introduces the new breakpoint/"linespec" API based on
a new struct event_location.  This API currently only supports
traditional linespecs, maintaining the status quo of the code base.
Future patches will add additional functionality for other location
types such as address locations.

gdb/ChangeLog:

	* Makefile.in (SFILES): Add location.c.
	(HFILES_NO_SRCDIR): Add location.h.
	(COMMON_OBS): Add location.o.
	* linespec.c (linespec_lex_to_end): New function.
	* linespec.h (linespec_lex_to_end): Declare.
	* location.c: New file.
	* location.h: New file.

gdb/location.h

@@ -0,0 +1,99 @@
+/* Data structures and API for event locations in GDB.
+   Copyright (C) 2013-2015 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 LOCATIONS_H
+#define LOCATIONS_H 1
+
+struct language_defn;
+struct event_location;
+
+/* An enumeration of the various ways to specify a stop event
+   location (used with create_breakpoint).  */
+
+enum event_location_type
+{
+  /* A traditional linespec.  */
+  LINESPEC_LOCATION
+};
+
+/* Return the type of the given event location.  */
+
+extern enum event_location_type
+  event_location_type (const struct event_location *);
+
+/* Return a string representation of the LOCATION.
+   This function may return NULL for unspecified linespecs,
+   e.g, LOCATION_LINESPEC and addr_string is NULL.
+
+   The result is cached in LOCATION.  */
+
+extern const char *
+  event_location_to_string (struct event_location *location);
+
+/* Create a new linespec location.  The return result is malloc'd
+   and should be freed with delete_event_location.  */
+
+extern struct event_location *
+  new_linespec_location (char **linespec);
+
+/* Return the linespec location (a string) of the given event_location
+   (which must be of type LINESPEC_LOCATION).  */
+
+extern const char *
+  get_linespec_location (const struct event_location *location);
+
+/* Free an event location and any associated data.  */
+
+extern void delete_event_location (struct event_location *location);
+
+/* Make a cleanup to free LOCATION.  */
+
+extern struct cleanup *
+  make_cleanup_delete_event_location (struct event_location *location);
+
+/* Return a copy of the given SRC location.  */
+
+extern struct event_location *
+  copy_event_location (const struct event_location *src);
+
+/* Attempt to convert the input string in *ARGP into an event_location.
+   ARGP is advanced past any processed input.  Returns an event_location
+   (malloc'd) if an event location was successfully found in *ARGP,
+   NULL otherwise.
+
+   This function may call error() if *ARGP looks like properly formed,
+   but invalid, input, e.g., if it is called with missing argument parameters
+   or invalid options.
+
+   The return result must be freed with delete_event_location.  */
+
+extern struct event_location *
+  string_to_event_location (char **argp,
+			    const struct language_defn *langauge);
+
+/* A convenience function for testing for unset locations.  */
+
+extern int event_location_empty_p (const struct event_location *location);
+
+/* Set the location's string representation.  If STRING is NULL, clear
+   the string representation.  */
+
+extern void
+  set_event_location_string (struct event_location *location,
+			     const char *string);
+#endif /* LOCATIONS_H */