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

exprtk.hpp

@@ -192,6 +192,45 @@ namespace exprtk
          return result;
       }
 
+      inline bool is_hex_digit(const std::string::value_type digit)
+      {
+         return (('0' <= digit) && (digit <= '9')) ||
+                (('A' <= digit) && (digit <= 'F')) ||
+                (('a' <= digit) && (digit <= 'f')) ;
+      }
+
+      inline unsigned char hex_to_bin(unsigned char h)
+      {
+         if (('0' <= h) && (h <= '9'))
+            return (h - '0');
+         else
+            return (std::toupper(h) - 'A');
+      }
+
+      template <typename Iterator>
+      inline void parse_hex(Iterator& itr, Iterator end, std::string::value_type& result)
+      {
+         if (
+              (end !=  (itr    )) &&
+              (end !=  (itr + 1)) &&
+              (end !=  (itr + 2)) &&
+              (end !=  (itr + 3)) &&
+              ('0' == *(itr    )) &&
+              (
+                ('x' == *(itr + 1)) ||
+                ('X' == *(itr + 1))
+              ) &&
+              (is_hex_digit(*(itr + 2))) &&
+              (is_hex_digit(*(itr + 3)))
+            )
+         {
+            result = hex_to_bin(*(itr + 2)) << 4 | hex_to_bin(*(itr + 3));
+            itr += 3;
+         }
+         else
+            result = '\0';
+      }
+
       inline void cleanup_escapes(std::string& s)
       {
          std::string::iterator itr1 = s.begin();
@@ -214,6 +253,9 @@ namespace exprtk
                      case 'n' : (*itr1) = '\n'; break;
                      case 'r' : (*itr1) = '\r'; break;
                      case 't' : (*itr1) = '\t'; break;
+                     case '0' : parse_hex(itr1,end,(*itr1));
+                                removal_count += 3;
+                                break;
                   }
 
                   continue;
@@ -2362,7 +2404,31 @@ namespace exprtk
                      break;
                }
                else if (escaped)
+               {
+                  if (!is_end(s_itr_) && ('0' == *(s_itr_)))
+                  {
+                     if (
+                          is_end(s_itr_ + 1) ||
+                          is_end(s_itr_ + 2) ||
+                          is_end(s_itr_ + 3) ||
+                          (
+                            ('x' != *(s_itr_ + 1)) &&
+                            ('X' != *(s_itr_ + 1))
+                          ) ||
+                          (!details::is_hex_digit(*(s_itr_ + 2))) ||
+                          (!details::is_hex_digit(*(s_itr_ + 3)))
+                        )
+                     {
+                        t.set_error(token::e_err_string,initial_itr,s_itr_,base_itr_);
+                        token_list_.push_back(t);
+                        return;
+                     }
+                     else
+                        s_itr_ += 3;
+                  }
+
                   escaped = false;
+               }
 
                ++s_itr_;
             }

exprtk_test.cpp

@@ -2237,7 +2237,13 @@ inline bool run_test02()
                               test_ab<T>("(a[3:9] := b); (a == '012ABCDE89');", "0123456789","ABCDE"     ,T(1.0)),
                               test_ab<T>("(a[3:9] := b); (a == '012ABCDEF9');", "0123456789","ABCDEF"    ,T(1.0)),
                               test_ab<T>("(a[r1 / r0:r2] := b[3:b[] - r3]);  (a == '012ABCDE89');", "0123456789","xyzABCDEFGHIJxyz",T(1.0)),
-                              test_ab<T>("(a[r0:r2 + 1]  := b[r3:b[] - r3]); (a == '01ABCDEFG9');", "0123456789","xyzABCDEFGHIJxyz",T(1.0))
+                              test_ab<T>("(a[r0:r2 + 1]  := b[r3:b[] - r3]); (a == '01ABCDEFG9');", "0123456789","xyzABCDEFGHIJxyz",T(1.0)),
+                              test_ab<T>("'\\0x30\\0x31\\0x32\\0x33\\0x34\\0x35\\0x36\\0x37\\0x38\\0x39' == '0123456789'","","",T(1.0)),
+                              test_ab<T>("'abc\\0x30\\0x31\\0x32\\0x33xyz' == 'abc0123xyz'"       ,"","",T(1.0)),
+                              test_ab<T>("'\\0x30\\n\\0x31\\n\\0x32\\n\\0x33' == '0\\n1\\n2\\n3'" ,"","",T(1.0)),
+                              test_ab<T>("('\\0x30' + '') == '0'"                                 ,"","",T(1.0)),
+                              test_ab<T>("('\\0x30' + '\\0x31\\0x32') == '012'"                   ,"","",T(1.0)),
+                              test_ab<T>("('\\0x30' + '\\0x31\\0x32' + '\\0x33\\0x34\\0x35') == '012345'" ,"","",T(1.0))
                            };
 
    static const std::size_t test_list_size = sizeof(test_list) / sizeof(test_ab<T>);
@@ -2246,6 +2252,7 @@ inline bool run_test02()
    for (std::size_t r = 0; r < rounds; ++r)
    {
       bool result = true;
+
       for (std::size_t i = 0; i < test_list_size; ++i)
       {
          test_ab<T>& test = const_cast<test_ab<T>&>(test_list[i]);

readme.txt

@@ -1881,9 +1881,10 @@ into account when using Exprtk:
       ('\n', '\r', '\t', '\b', '\v', '\f')
 
  (13) Strings may be comprised of any combination of letters, digits
-      or special characters including (~!@#$%^&*()[]|=+ ,./?<>;:"`~_),
+      special characters including (~!@#$%^&*()[]|=+ ,./?<>;:"`~_) or
-      and must be enclosed with single-quotes.
+      hexadecimal escaped sequences (eg: \0x30) and must be enclosed
-      eg: 'Frankly my dear, 1 do n0t give a damn!'
+      with single-quotes.
+      eg: 'Frankly my dear, \0x49 do n0t give a damn!'
 
  (14) User defined  normal functions  can have  up to  20 parameters,
       where as  user defined  generic-functions and  vararg-functions