[API] unicode: rework virtual functions for subclassing

Unicode data providers can now be subclassed, including support for
chain-up.  The interface should now be nicely bindable, as well.

Also fix glib unicode funcs that where broken after hb_script_t
changes.  Nicely caught by the test-unicode.c added in this commit.

src/hb-unicode.h

diff --git a/src/hb-unicode.h b/src/hb-unicode.h
index fb8fe97..792ad54 100644
--- a/src/hb-unicode.h
+++ b/src/hb-unicode.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2009  Red Hat, Inc.
+ * Copyright © 2011 Codethink Limited
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
@@ -22,6 +23,7 @@
  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  *
  * Red Hat Author(s): Behdad Esfahbod
+ * Codethink Author(s): Ryan Lortie
  */
 
 #ifndef HB_UNICODE_H
@@ -39,7 +41,7 @@
 typedef struct _hb_unicode_funcs_t hb_unicode_funcs_t;
 
 hb_unicode_funcs_t *
-hb_unicode_funcs_create (void);
+hb_unicode_funcs_create (hb_unicode_funcs_t *parent_funcs);
 
 hb_unicode_funcs_t *
 hb_unicode_funcs_reference (hb_unicode_funcs_t *ufuncs);
@@ -51,7 +53,7 @@
 hb_unicode_funcs_destroy (hb_unicode_funcs_t *ufuncs);
 
 hb_unicode_funcs_t *
-hb_unicode_funcs_copy (hb_unicode_funcs_t *ufuncs);
+hb_unicode_funcs_get_parent (hb_unicode_funcs_t *ufuncs);
 
 void
 hb_unicode_funcs_make_immutable (hb_unicode_funcs_t *ufuncs);
@@ -63,57 +65,55 @@
  * funcs
  */
 
-
 /* typedefs */
 
-typedef hb_codepoint_t (*hb_unicode_get_mirroring_func_t) (hb_codepoint_t unicode);
-typedef hb_unicode_general_category_t (*hb_unicode_get_general_category_func_t) (hb_codepoint_t unicode);
-typedef hb_script_t (*hb_unicode_get_script_func_t) (hb_codepoint_t unicode);
-typedef unsigned int (*hb_unicode_get_combining_class_func_t) (hb_codepoint_t unicode);
-typedef unsigned int (*hb_unicode_get_eastasian_width_func_t) (hb_codepoint_t unicode);
-
+typedef hb_codepoint_t                (*hb_unicode_get_mirroring_func_t)        (hb_unicode_funcs_t *ufuncs,
+                                                                                 hb_codepoint_t      unicode,
+                                                                                 void               *user_data);
+typedef hb_unicode_general_category_t (*hb_unicode_get_general_category_func_t) (hb_unicode_funcs_t *ufuncs,
+                                                                                 hb_codepoint_t      unicode,
+                                                                                 void               *user_data);
+typedef hb_script_t                   (*hb_unicode_get_script_func_t)           (hb_unicode_funcs_t *ufuncs,
+                                                                                 hb_codepoint_t      unicode,
+                                                                                 void               *user_data);
+typedef unsigned int                  (*hb_unicode_get_combining_class_func_t)  (hb_unicode_funcs_t *ufuncs,
+                                                                                 hb_codepoint_t      unicode,
+                                                                                 void               *user_data);
+typedef unsigned int                  (*hb_unicode_get_eastasian_width_func_t)  (hb_unicode_funcs_t *ufuncs,
+                                                                                 hb_codepoint_t      unicode,
+                                                                                 void               *user_data);
 
 /* setters */
 
 void
 hb_unicode_funcs_set_mirroring_func (hb_unicode_funcs_t *ufuncs,
-				     hb_unicode_get_mirroring_func_t mirroring_func);
+				     hb_unicode_get_mirroring_func_t mirroring_func,
+                                     void *user_data,
+                                     hb_destroy_func_t destroy);
 
 void
 hb_unicode_funcs_set_general_category_func (hb_unicode_funcs_t *ufuncs,
-					    hb_unicode_get_general_category_func_t general_category_func);
+					    hb_unicode_get_general_category_func_t general_category_func,
+                                            void *user_data,
+                                            hb_destroy_func_t destroy);
 
 void
 hb_unicode_funcs_set_script_func (hb_unicode_funcs_t *ufuncs,
-				  hb_unicode_get_script_func_t script_func);
+				  hb_unicode_get_script_func_t script_func,
+                                  void *user_data,
+                                  hb_destroy_func_t destroy);
 
 void
 hb_unicode_funcs_set_combining_class_func (hb_unicode_funcs_t *ufuncs,
-					   hb_unicode_get_combining_class_func_t combining_class_func);
+					   hb_unicode_get_combining_class_func_t combining_class_func,
+                                           void *user_data,
+                                           hb_destroy_func_t destroy);
 
 void
 hb_unicode_funcs_set_eastasian_width_func (hb_unicode_funcs_t *ufuncs,
-					   hb_unicode_get_eastasian_width_func_t eastasian_width_func);
-
-
-/* getters */
-
-/* These never return NULL.  Return fallback defaults instead. */
-
-hb_unicode_get_mirroring_func_t
-hb_unicode_funcs_get_mirroring_func (hb_unicode_funcs_t *ufuncs);
-
-hb_unicode_get_general_category_func_t
-hb_unicode_funcs_get_general_category_func (hb_unicode_funcs_t *ufuncs);
-
-hb_unicode_get_script_func_t
-hb_unicode_funcs_get_script_func (hb_unicode_funcs_t *ufuncs);
-
-hb_unicode_get_combining_class_func_t
-hb_unicode_funcs_get_combining_class_func (hb_unicode_funcs_t *ufuncs);
-
-hb_unicode_get_eastasian_width_func_t
-hb_unicode_funcs_get_eastasian_width_func (hb_unicode_funcs_t *ufuncs);
+					   hb_unicode_get_eastasian_width_func_t eastasian_width_func,
+                                           void *user_data,
+                                           hb_destroy_func_t destroy);
 
 
 /* accessors */