diff --git a/src/ChineseFilter.hpp b/src/ChineseFilter.hpp
index 621c0ea..c969607 100644
--- a/src/ChineseFilter.hpp
+++ b/src/ChineseFilter.hpp
@@ -6,98 +6,98 @@
 namespace CppJieba
 {
 
-    enum CHAR_TYPE { CHWORD = 0, DIGIT_OR_LETTER = 1};
-    typedef Unicode::const_iterator UniConIter;
-    class ChineseFilter;
-    class ChFilterIterator
-    {
-        public:
-            const Unicode * ptUnico;
-            UniConIter begin;
-            UniConIter end;
-            CHAR_TYPE charType;
-            ChFilterIterator& operator++()
-            {
-                return *this = _get(end);
-            }
-            ChFilterIterator operator++(int)
-            {
-                ChFilterIterator res = *this;
-                *this = _get(end);
-                return res;
-            }
-            bool operator==(const ChFilterIterator& iter)
-            {
-                return begin == iter.begin && end == iter.end;
-            }
-            bool operator!=(const ChFilterIterator& iter)
-            {
-                return !(*this == iter);
-            }
-            ChFilterIterator& operator=(const ChFilterIterator& iter)
-            {
-                ptUnico = iter.ptUnico;
-                begin = iter.begin;
-                end = iter.end;
-                charType = iter.charType;
-                return *this;
-            }
-        
-        public:
-            ChFilterIterator(const Unicode * ptu, UniConIter be, UniConIter en, CHAR_TYPE is):ptUnico(ptu), begin(be), end(en), charType(is){};
-            ChFilterIterator(const Unicode * ptu):ptUnico(ptu){*this = _get(ptUnico->begin());};
-        private:
-            ChFilterIterator(){}
-        private:
-            CHAR_TYPE _charType(uint16_t x)const
-            {
-                if(x < 0x0080)
-                {
-                    return DIGIT_OR_LETTER;
-                }
-                return CHWORD;
-            }
-            ChFilterIterator _get(UniConIter iter)
-            {
-                UniConIter _begin = iter;
-                const UniConIter& _end = ptUnico->end();
-                if(iter == _end)
-                {
-                    return ChFilterIterator(ptUnico, end, end, DIGIT_OR_LETTER);
-                }
-                CHAR_TYPE charType = _charType(*iter);
-                iter ++;
-                while(iter != _end &&charType ==  _charType(*iter))
-                {
-                    iter++;
-                }
-                return ChFilterIterator(ptUnico, _begin, iter, charType);
-            }
+    //enum CHAR_TYPE { CHWORD = 0, DIGIT_OR_LETTER = 1};
+    //typedef Unicode::const_iterator UniConIter;
+    //class ChineseFilter;
+    //class ChFilterIterator
+    //{
+    //    public:
+    //        const Unicode * ptUnico;
+    //        UniConIter begin;
+    //        UniConIter end;
+    //        CHAR_TYPE charType;
+    //        ChFilterIterator& operator++()
+    //        {
+    //            return *this = _get(end);
+    //        }
+    //        ChFilterIterator operator++(int)
+    //        {
+    //            ChFilterIterator res = *this;
+    //            *this = _get(end);
+    //            return res;
+    //        }
+    //        bool operator==(const ChFilterIterator& iter)
+    //        {
+    //            return begin == iter.begin && end == iter.end;
+    //        }
+    //        bool operator!=(const ChFilterIterator& iter)
+    //        {
+    //            return !(*this == iter);
+    //        }
+    //        ChFilterIterator& operator=(const ChFilterIterator& iter)
+    //        {
+    //            ptUnico = iter.ptUnico;
+    //            begin = iter.begin;
+    //            end = iter.end;
+    //            charType = iter.charType;
+    //            return *this;
+    //        }
+    //    
+    //    public:
+    //        ChFilterIterator(const Unicode * ptu, UniConIter be, UniConIter en, CHAR_TYPE is):ptUnico(ptu), begin(be), end(en), charType(is){};
+    //        ChFilterIterator(const Unicode * ptu):ptUnico(ptu){*this = _get(ptUnico->begin());};
+    //    private:
+    //        ChFilterIterator(){}
+    //    private:
+    //        CHAR_TYPE _charType(uint16_t x)const
+    //        {
+    //            if(x < 0x0080)
+    //            {
+    //                return DIGIT_OR_LETTER;
+    //            }
+    //            return CHWORD;
+    //        }
+    //        ChFilterIterator _get(UniConIter iter)
+    //        {
+    //            UniConIter _begin = iter;
+    //            const UniConIter& _end = ptUnico->end();
+    //            if(iter == _end)
+    //            {
+    //                return ChFilterIterator(ptUnico, end, end, DIGIT_OR_LETTER);
+    //            }
+    //            CHAR_TYPE charType = _charType(*iter);
+    //            iter ++;
+    //            while(iter != _end &&charType ==  _charType(*iter))
+    //            {
+    //                iter++;
+    //            }
+    //            return ChFilterIterator(ptUnico, _begin, iter, charType);
+    //        }
 
-    };
-    class ChineseFilter
-    {
-        private:
-            Unicode _unico;
-        public:
-            typedef ChFilterIterator  iterator;
-        public:
-            ChineseFilter(){};
-            ~ChineseFilter(){};
-        public:
-            bool feed(const string& str)
-            {
-                return TransCode::decode(str, _unico);
-            }
-            iterator begin()
-            {
-                return iterator(&_unico);
-            }
-            iterator end()
-            {
-                return iterator(&_unico, _unico.end(), _unico.end(), DIGIT_OR_LETTER);
-            }
-    };
+    //};
+    //class ChineseFilter
+    //{
+    //    private:
+    //        Unicode _unico;
+    //    public:
+    //        typedef ChFilterIterator  iterator;
+    //    public:
+    //        ChineseFilter(){};
+    //        ~ChineseFilter(){};
+    //    public:
+    //        bool feed(const string& str)
+    //        {
+    //            return TransCode::decode(str, _unico);
+    //        }
+    //        iterator begin()
+    //        {
+    //            return iterator(&_unico);
+    //        }
+    //        iterator end()
+    //        {
+    //            return iterator(&_unico, _unico.end(), _unico.end(), DIGIT_OR_LETTER);
+    //        }
+    //};
     
     /*
      * if char is ascii, count the ascii string's length and return 0;
diff --git a/src/SegmentBase.hpp b/src/SegmentBase.hpp
index 44e4df3..5536047 100644
--- a/src/SegmentBase.hpp
+++ b/src/SegmentBase.hpp
@@ -31,24 +31,56 @@ namespace CppJieba
                     LogError("not inited.");
                     return false;
                 }
-                ChineseFilter filter;
-                filter.feed(str);
-                for(ChineseFilter::iterator it = filter.begin(); it != filter.end(); it++)
+                const char * cstr = str.c_str();
+                uint size = str.size();
+                uint offset = 0;
+                string subs;
+                int ret;
+                uint len;
+                Unicode unico;
+                while(offset < size)
                 {
-                    if(it.charType == CHWORD)
+                    if(-1 == (ret = filterAscii(cstr + offset, size, len)))
                     {
-                        cut(it.begin, it.end, res);
+                        LogFatal("str[%s] illegal.", cstr);
+                        return false;
+                    }
+                    subs.assign(cstr + offset, len);
+                    if(!ret)
+                    {
+                        res.push_back(subs);
                     }
                     else
                     {
-                        string tmp;
-                        if(TransCode::encode(it.begin, it.end, tmp))
+                        unico.clear();
+                        if(!TransCode::decode(subs, unico))
                         {
-                            res.push_back(tmp);
+                            LogFatal("str[%s] decode failed.", subs.c_str());
+                            return false;
                         }
+                        cut(unico.begin(), unico.end(), res);
                     }
+                    offset += len;
                 }
                 return true;
+                //ChineseFilter filter;
+                //filter.feed(str);
+                //for(ChineseFilter::iterator it = filter.begin(); it != filter.end(); it++)
+                //{
+                //    if(it.charType == CHWORD)
+                //    {
+                //        cut(it.begin, it.end, res);
+                //    }
+                //    else
+                //    {
+                //        string tmp;
+                //        if(TransCode::encode(it.begin, it.end, tmp))
+                //        {
+                //            res.push_back(tmp);
+                //        }
+                //    }
+                //}
+                //return true;
             }
 
     };