*** empty log message ***

diff --git a/MText.cs b/MText.cs
index 477d7e6..cd9b9db 100644 (file)
--- a/MText.cs
+++ b/MText.cs
@@ -48,6 +48,7 @@ namespace M17N.Core
     private MTextPlist plist;
 
     private static UTF8Encoding utf8 = new UTF8Encoding ();
+    private static UTF32Encoding utf32 = new UTF8Encoding ();
 
     public MText ()
     {
@@ -58,24 +59,84 @@ namespace M17N.Core
 
     public MText (byte[] str)
     {
-      cache_pos = cache_idx = 0;
-      plist = null;          
       sb = new StringBuilder (utf8.GetString (str));
     }
 
     public MText (String str)
     {
-      cache_pos = cache_idx = 0;
-      plist = null;          
       sb = new StringBuilder (str);
     }
 
+    private static int inc_idx (int i)
+    {
+      return ((sb[i] >= 0xD800 && sb[i] < 0xDC00)
+             ? i + 2 : i + 1);
+    }
+
+    private static int dec_idx (int i)
+    {
+      return ((sb[i - 1] >= 0xDC00 && sb[i - 1] < 0xE000)
+             ? i - 2 : i - 1);
+    }
+
+    private static int pos_to_idx (int pos)
+    {
+      int p, i;
+      bool forward;
+
+      if (pos < cache_pos)
+       {
+         if (cache_pos == cache_idx)
+           return cache_idx;
+         if (pos < cache_pos - pos)
+           {
+             p = i = 0;
+             forward = true;
+           }
+         else
+           {
+             p = cache_pos; i = cache_idx;
+             forward = false;
+           }
+       }
+      else
+       {
+         if (nchars - cache_pos == sb.Length - cache_idx)
+           return (cache_idx + pos - cache_pos);
+         if (pos - cache_pos < nchars - pos)
+           {
+             p = char_pos; i = char_idx;
+             forward = true;
+           }
+         else
+           {
+             p = nchars; i = sb.Length;
+             forward = false;
+           }
+       }
+      if (forward)
+       for (; p < pos; i = inc_idx (i), p++);
+      else
+       for (; p > pos; i = dec_idx (i), p--);
+      cache_pos = p;
+      cache_idx = i;
+      return i;
+    }
+
     public int this[int i]
     {
-      set { this.sb[i] = (char) value; }
+      set {
+       if (i != cache_pos)
+         i = pos_to_idx (i);
+       if (value < 0x10000)
+         this.sb[i] = (char) value;
+       else
+         {
+           
+         }
+      }
       get { return this.sb[i]; }
     }
-  }
 
   public class MTextProperty
   {