From a0d01a57a5792268b7dd0c144dfda00e7e171d80 Mon Sep 17 00:00:00 2001
From: aozhiwei <aozhiwe@kingsome.cn>
Date: Tue, 13 Oct 2020 17:16:06 +0800
Subject: [PATCH] 1

---
 a8/strutils.cc | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
 a8/strutils.h  |  2 +-
 2 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/a8/strutils.cc b/a8/strutils.cc
index 37361e8..06c90b6 100644
--- a/a8/strutils.cc
+++ b/a8/strutils.cc
@@ -398,4 +398,60 @@ namespace a8
         return strcmp(s1 ? s1 : "", s2 ? s2 : "");
     }
 
+    size_t GetUtf8Length(const char *str)
+    {
+        static unsigned char utf8_look_for_table[] =
+        {
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+            3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+            4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 1, 1
+        };
+
+        #define UTFLEN(x)  utf8_look_for_table[(x)]
+
+        auto utf8_char_len =
+            [] (char firstByte) -> int
+            {
+                const unsigned char kFirstBitMask = 128; // 1000000
+                const unsigned char kSecondBitMask = 64; // 0100000
+                const unsigned char kThirdBitMask = 32; // 0010000
+                const unsigned char kFourthBitMask = 16; // 0001000
+                const unsigned char kFifthBitMask = 8; // 0000100
+
+                std::string::difference_type offset = 1;
+
+                if (firstByte & kFirstBitMask) { // This means the first byte has a value greater than 127, and so is beyond the ASCII range.
+                    if (firstByte & kThirdBitMask) { // This means that the first byte has a value greater than 224, and so it must be at least a three-octet code point.
+                        if (firstByte & kFourthBitMask) { // This means that the first byte has a value greater than 240, and so it must be a four-octet code point.
+                            offset = 4;
+                        }else{
+                            offset = 3;
+                        }
+                    }else{
+                        offset = 2;
+                    }
+                }
+                return offset;
+            };
+
+        int clen = strlen(str);
+        int len = 0;
+        for (const char *ptr = str;
+             *ptr!=0&&len<clen;
+             len++, ptr+=UTFLEN((unsigned char)*ptr)) ;
+        return len;
+    }
 }
diff --git a/a8/strutils.h b/a8/strutils.h
index 929a586..e63c154 100644
--- a/a8/strutils.h
+++ b/a8/strutils.h
@@ -28,7 +28,7 @@ namespace a8
     std::string IntToFixedString(int val, int n);
     bool ReadStringFromFile(const std::string& filename, std::string& data);
     int SafeStrCmp(const char* s1, const char* s2);
-
+    size_t GetUtf8Length(const char *str);
 }
 
 #endif