Separate face source code from font

Makes documentation / introspection easier.
diff --git a/src/hb-face-private.hh b/src/hb-face-private.hh
new file mode 100644
index 0000000..b33be0e
--- /dev/null
+++ b/src/hb-face-private.hh
@@ -0,0 +1,108 @@
+/*
+ * Copyright © 2009  Red Hat, Inc.
+ * Copyright © 2011  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Red Hat Author(s): Behdad Esfahbod
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_FACE_PRIVATE_HH
+#define HB_FACE_PRIVATE_HH
+
+#include "hb-private.hh"
+
+#include "hb-font.h"
+#include "hb-object-private.hh"
+#include "hb-shaper-private.hh"
+#include "hb-shape-plan-private.hh"
+
+
+/*
+ * hb_face_t
+ */
+
+struct hb_face_t {
+  hb_object_header_t header;
+  ASSERT_POD ();
+
+  hb_bool_t immutable;
+
+  hb_reference_table_func_t  reference_table_func;
+  void                      *user_data;
+  hb_destroy_func_t          destroy;
+
+  unsigned int index;
+  mutable unsigned int upem;
+  mutable unsigned int num_glyphs;
+
+  struct hb_shaper_data_t shaper_data;
+
+  struct plan_node_t {
+    hb_shape_plan_t *shape_plan;
+    plan_node_t *next;
+  } *shape_plans;
+
+
+  inline hb_blob_t *reference_table (hb_tag_t tag) const
+  {
+    hb_blob_t *blob;
+
+    if (unlikely (!this || !reference_table_func))
+      return hb_blob_get_empty ();
+
+    blob = reference_table_func (/*XXX*/const_cast<hb_face_t *> (this), tag, user_data);
+    if (unlikely (!blob))
+      return hb_blob_get_empty ();
+
+    return blob;
+  }
+
+  inline HB_PURE_FUNC unsigned int get_upem (void) const
+  {
+    if (unlikely (!upem))
+      load_upem ();
+    return upem;
+  }
+
+  inline unsigned int get_num_glyphs (void) const
+  {
+    if (unlikely (num_glyphs == (unsigned int) -1))
+      load_num_glyphs ();
+    return num_glyphs;
+  }
+
+  private:
+  HB_INTERNAL void load_upem (void) const;
+  HB_INTERNAL void load_num_glyphs (void) const;
+};
+
+extern HB_INTERNAL const hb_face_t _hb_face_nil;
+
+#define HB_SHAPER_DATA_CREATE_FUNC_EXTRA_ARGS
+#define HB_SHAPER_IMPLEMENT(shaper) HB_SHAPER_DATA_PROTOTYPE(shaper, face);
+#include "hb-shaper-list.hh"
+#undef HB_SHAPER_IMPLEMENT
+#undef HB_SHAPER_DATA_CREATE_FUNC_EXTRA_ARGS
+
+
+#endif /* HB_FACE_PRIVATE_HH */