Add hb_font_glyph_from/to_string

src/hb-font.cc

diff --git a/src/hb-font.cc b/src/hb-font.cc
index 409b9e8..e5e4af7 100644
--- a/src/hb-font.cc
+++ b/src/hb-font.cc
@@ -200,6 +200,7 @@
   if (font->parent)
     return hb_font_get_glyph_name (font->parent, glyph, name, size);
 
+  if (size) *name = '\0';
   return false;
 }
 
@@ -410,10 +411,7 @@
 			hb_codepoint_t glyph,
 			char *name, unsigned int size)
 {
-  hb_bool_t ret = font->get_glyph_name (glyph, name, size);
-  if (!ret)
-    snprintf (name, size, "gid%u", glyph);
-  return ret;
+  return font->get_glyph_name (glyph, name, size);
 }
 
 hb_bool_t
@@ -490,6 +488,24 @@
   return font->get_glyph_contour_point_for_origin (glyph, point_index, direction, x, y);
 }
 
+/* Generates gidDDD if glyph has no name. */
+void
+hb_font_glyph_to_string (hb_font_t *font,
+			 hb_codepoint_t glyph,
+			 char *s, unsigned int size)
+{
+  font->glyph_to_string (glyph, s, size);
+}
+
+/* Parses gidDDD and uniUUUU strings automatically. */
+hb_bool_t
+hb_font_glyph_from_string (hb_font_t *font,
+			   const char *s, int len, /* -1 means nul-terminated */
+			   hb_codepoint_t *glyph)
+{
+  return font->glyph_from_string (s, len, glyph);
+}
+
 
 /*
  * hb_face_t