Add hb_buffer_[sg]et_content_type

And hb_buffer_content_type_t and enum values.

TODO

@@ -91,3 +91,4 @@ Tests to write:
 - hb_cache_t and relatives
 
 - hb_feature_to/from_string
+- hb_buffer_[sg]et_contents

src/hb-buffer-private.hh

@@ -92,6 +92,8 @@ struct hb_buffer_t {
 
   /* Buffer contents */
 
+  hb_buffer_content_type_t content_type;
+
   bool in_error; /* Allocation failed */
   bool have_output; /* Whether we have an output buffer going on */
   bool have_positions; /* Whether we have positions */

src/hb-buffer.cc

@@ -147,6 +147,7 @@ hb_buffer_t::reset (void)
   hb_segment_properties_t default_props = _HB_BUFFER_PROPS_DEFAULT;
   props = default_props;
 
+  content_type = HB_BUFFER_CONTENT_TYPE_INVALID;
   in_error = false;
   have_output = false;
   have_positions = false;
@@ -446,6 +447,9 @@ hb_buffer_t::merge_out_clusters (unsigned int start,
 void
 hb_buffer_t::guess_properties (void)
 {
+  if (unlikely (!len)) return;
+  assert (content_type == HB_BUFFER_CONTENT_TYPE_UNICODE);
+
   /* If script is set to INVALID, guess from buffer contents */
   if (props.script == HB_SCRIPT_INVALID) {
     for (unsigned int i = 0; i < len; i++) {
@@ -564,6 +568,7 @@ hb_buffer_get_empty (void)
     const_cast<hb_unicode_funcs_t *> (&_hb_unicode_funcs_nil),
     _HB_BUFFER_PROPS_DEFAULT,
 
+    HB_BUFFER_CONTENT_TYPE_INVALID,
     true, /* in_error */
     true, /* have_output */
     true  /* have_positions */
@@ -609,6 +614,20 @@ hb_buffer_get_user_data (hb_buffer_t        *buffer,
 }
 
 
+void
+hb_buffer_set_content_type (hb_buffer_t              *buffer,
+			    hb_buffer_content_type_t  content_type)
+{
+  buffer->content_type = content_type;
+}
+
+hb_buffer_content_type_t
+hb_buffer_get_content_type (hb_buffer_t *buffer)
+{
+  return buffer->content_type;
+}
+
+
 void
 hb_buffer_set_unicode_funcs (hb_buffer_t        *buffer,
 			     hb_unicode_funcs_t *unicode)
@@ -849,6 +868,11 @@ hb_buffer_add_utf8 (hb_buffer_t  *buffer,
 		    unsigned int  item_offset,
 		    int           item_length)
 {
+  assert (buffer->content_type == HB_BUFFER_CONTENT_TYPE_UNICODE ||
+	  (!buffer->len && buffer->content_type == HB_BUFFER_CONTENT_TYPE_INVALID));
+  if (unlikely (hb_object_is_inert (buffer)))
+    return;
+  buffer->content_type = HB_BUFFER_CONTENT_TYPE_UNICODE;
 #define UTF_NEXT(S, E, U)	hb_utf8_next (S, E, &(U))
   ADD_UTF (uint8_t);
 #undef UTF_NEXT
@@ -883,6 +907,11 @@ hb_buffer_add_utf16 (hb_buffer_t    *buffer,
 		     unsigned int    item_offset,
 		     int            item_length)
 {
+  assert (buffer->content_type == HB_BUFFER_CONTENT_TYPE_UNICODE ||
+	  (!buffer->len && buffer->content_type == HB_BUFFER_CONTENT_TYPE_INVALID));
+  if (unlikely (hb_object_is_inert (buffer)))
+    return;
+  buffer->content_type = HB_BUFFER_CONTENT_TYPE_UNICODE;
 #define UTF_NEXT(S, E, U)	hb_utf16_next (S, E, &(U))
   ADD_UTF (uint16_t);
 #undef UTF_NEXT
@@ -895,6 +924,11 @@ hb_buffer_add_utf32 (hb_buffer_t    *buffer,
 		     unsigned int    item_offset,
 		     int             item_length)
 {
+  assert (buffer->content_type == HB_BUFFER_CONTENT_TYPE_UNICODE ||
+	  (!buffer->len && buffer->content_type == HB_BUFFER_CONTENT_TYPE_INVALID));
+  if (unlikely (hb_object_is_inert (buffer)))
+    return;
+  buffer->content_type = HB_BUFFER_CONTENT_TYPE_UNICODE;
 #define UTF_NEXT(S, E, U)	((U) = *(S), (S)+1)
   ADD_UTF (uint32_t);
 #undef UTF_NEXT

src/hb-buffer.h

@@ -62,6 +62,12 @@ typedef struct hb_glyph_position_t {
   hb_var_int_t   var;
 } hb_glyph_position_t;
 
+typedef enum {
+  HB_BUFFER_CONTENT_TYPE_INVALID = 0,
+  HB_BUFFER_CONTENT_TYPE_UNICODE,
+  HB_BUFFER_CONTENT_TYPE_GLYPHS
+} hb_buffer_content_type_t;
+
 
 hb_buffer_t *
 hb_buffer_create (void);
@@ -87,6 +93,14 @@ hb_buffer_get_user_data (hb_buffer_t        *buffer,
 			 hb_user_data_key_t *key);
 
 
+void
+hb_buffer_set_content_type (hb_buffer_t              *buffer,
+			    hb_buffer_content_type_t  content_type);
+
+hb_buffer_content_type_t
+hb_buffer_get_content_type (hb_buffer_t *buffer);
+
+
 void
 hb_buffer_set_unicode_funcs (hb_buffer_t        *buffer,
 			     hb_unicode_funcs_t *unicode_funcs);

src/hb-shape.cc

@@ -253,11 +253,16 @@ hb_shape_full (hb_font_t          *font,
   if (unlikely (!buffer->len))
     return true;
 
+  assert (buffer->content_type == HB_BUFFER_CONTENT_TYPE_UNICODE);
+
   buffer->guess_properties ();
 
   hb_shape_plan_t *shape_plan = hb_shape_plan_create_cached (font->face, &buffer->props, features, num_features, shaper_list);
   hb_bool_t res = hb_shape_plan_execute (shape_plan, font, buffer, features, num_features);
   hb_shape_plan_destroy (shape_plan);
+
+  if (res)
+    buffer->content_type = HB_BUFFER_CONTENT_TYPE_GLYPHS;
   return res;
 }