Start filling hb_shape() in

src/hb-buffer-private.h

@@ -131,6 +131,7 @@ _hb_buffer_allocate_lig_id (hb_buffer_t *buffer);
 #define IN_GLYPH(pos)		(buffer->in_string[(pos)].codepoint)
 #define IN_INFO(pos)		(&buffer->in_string[(pos)])
 #define IN_CURGLYPH()		(buffer->in_string[buffer->in_pos].codepoint)
+#define IN_NEXTGLYPH()		(buffer->in_string[buffer->in_pos + 1].codepoint)
 #define IN_CURINFO()		(&buffer->in_string[buffer->in_pos])
 #define IN_MASK(pos)		(buffer->in_string[(pos)].mask)
 #define IN_LIGID(pos)		(buffer->in_string[(pos)].lig_id)

src/hb-shape.c

@@ -28,6 +28,35 @@
 
 #include "hb-shape.h"
 
+#include "hb-buffer-private.h"
+
+static inline hb_bool_t
+is_variation_selector (hb_codepoint_t unicode)
+{
+  return (unicode >=  0xFE00 && unicode <= 0xFE0F) ||
+	 (unicode >= 0xE0100 && unicode <= 0xE01EF);
+}
+
+static void
+map_glyphs (hb_face_t    *face,
+	    hb_font_t    *font,
+	    hb_buffer_t  *buffer)
+{
+  unsigned int count;
+
+  count = buffer->in_length - 1;
+
+  for (buffer->in_pos = 0; buffer->in_pos < count; buffer->in_pos++) {
+    if (HB_UNLIKELY (is_variation_selector (IN_NEXTGLYPH()))) {
+      IN_CURGLYPH() = hb_font_get_glyph (face, font, IN_CURGLYPH(), IN_NEXTGLYPH());
+      buffer->in_pos++;
+    } else {
+      IN_CURGLYPH() = hb_font_get_glyph (face, font, IN_CURGLYPH(), 0);
+    }
+  }
+  IN_CURGLYPH() = hb_font_get_glyph (face, font, IN_CURGLYPH(), 0);
+}
+
 
 void
 hb_shape (hb_face_t    *face,
@@ -36,5 +65,14 @@ hb_shape (hb_face_t    *face,
 	  hb_feature_t *features,
 	  unsigned int  num_features)
 {
-}
+  /* form_clusters (buffer); */
+  /* do_mirroring (buffer); */
+  /* natural direction analysis */
+  /* OT preprocess */
+
+  map_glyphs (face, font, buffer);
 
+  /* GSUB */
+  /* Default positioning */
+  /* GPOS / kern */
+}