C++ Mathematical Expression Library (ExprTk)  http://www.partow.net/programming/exprtk/index.html

exprtk.hpp

diff --git a/exprtk.hpp b/exprtk.hpp
index 6043aa6..670eda9 100644
--- a/exprtk.hpp
+++ b/exprtk.hpp
@@ -586,55 +586,40 @@
                              const typename std::iterator_traits<Iterator>::value_type& zero_or_more,
                              const typename std::iterator_traits<Iterator>::value_type& zero_or_one)
       {
-         if (0 == std::distance(data_begin,data_end))
-         {
-            return false;
-         }
-
          Iterator d_itr = data_begin;
          Iterator p_itr = pattern_begin;
-         Iterator c_itr = data_begin;
-         Iterator m_itr = data_begin;
 
-         while ((data_end != d_itr) && (zero_or_more != (*p_itr)))
+         while ((p_itr != pattern_end) && (d_itr != data_end))
          {
-            if ((!Compare::cmp((*p_itr),(*d_itr))) && (zero_or_one != (*p_itr)))
+            if (zero_or_more == *p_itr)
             {
-               return false;
-            }
-
-            ++p_itr;
-            ++d_itr;
-         }
-
-         while (data_end != d_itr)
-         {
-            if (zero_or_more == (*p_itr))
-            {
-               if (pattern_end == (++p_itr))
+               while ((p_itr != pattern_end) && (*p_itr == zero_or_more || *p_itr == zero_or_one))
                {
-                  return true;
+                  ++p_itr;
                }
 
-               m_itr = p_itr;
-               c_itr = d_itr;
-               ++c_itr;
-            }
-            else if ((Compare::cmp((*p_itr),(*d_itr))) || (zero_or_one == (*p_itr)))
-            {
-               ++p_itr;
+               if (p_itr == pattern_end)
+                  return true;
+
+               const typename std::iterator_traits<Iterator>::value_type c = *(p_itr++);
+
+               while ((d_itr != data_end) && !Compare::cmp(c,*d_itr))
+               {
+                  ++d_itr;
+               }
+
                ++d_itr;
             }
-            else
+            else if ((*p_itr == zero_or_one) || Compare::cmp(*p_itr, *d_itr))
             {
-               p_itr = m_itr;
-               d_itr = c_itr++;
+               ++d_itr;
+               ++p_itr;
             }
+            else
+               return false;
          }
 
-         while ((p_itr != pattern_end) && (zero_or_more == (*p_itr))) { ++p_itr; }
-
-         return (p_itr == pattern_end);
+         return (d_itr == data_end) && (p_itr == pattern_end);
       }
 
       inline bool wc_match(const std::string& wild_card,