Add hb_utf_strlen()

Speeds up UTF-8 parsing by calling strlen().

src/hb-buffer.cc

@@ -30,9 +30,6 @@
 #include "hb-buffer-private.hh"
 #include "hb-utf-private.hh"
 
-#include <string.h>
-
-
 
 #ifndef HB_DEBUG_BUFFER
 #define HB_DEBUG_BUFFER (HB_DEBUG+0)
@@ -812,14 +809,8 @@ hb_buffer_add_utf (hb_buffer_t  *buffer,
   if (unlikely (hb_object_is_inert (buffer)))
     return;
 
-  if (text_length == -1) {
-    text_length = 0;
-    const T *p = (const T *) text;
-    while (*p) {
-      text_length++;
-      p++;
-    }
-  }
+  if (text_length == -1)
+    text_length = hb_utf_strlen (text);
 
   if (item_length == -1)
     item_length = text_length - item_offset;

src/hb-utf-private.hh

@@ -72,6 +72,12 @@ hb_utf_next (const uint8_t *text,
   }
 }
 
+static inline unsigned int
+hb_utf_strlen (const uint8_t *text)
+{
+  return strlen ((const char *) text);
+}
+
 
 /* UTF-16 */
 
@@ -97,6 +103,14 @@ hb_utf_next (const uint16_t *text,
   return text;
 }
 
+static inline unsigned int
+hb_utf_strlen (const uint16_t *text)
+{
+  unsigned int l = 0;
+  while (*text++) l++;
+  return l;
+}
+
 
 /* UTF-32 */
 
@@ -109,5 +123,13 @@ hb_utf_next (const uint32_t *text,
   return text + 1;
 }
 
+static inline unsigned int
+hb_utf_strlen (const uint32_t *text)
+{
+  unsigned int l = 0;
+  while (*text++) l++;
+  return l;
+}
+
 
 #endif /* HB_UTF_PRIVATE_HH */