Trivial ROT13 encoding/decoding

Utils/rot13_codecvt.cpp

@@ -0,0 +1,63 @@
+///////////////////////////////////////////
+//
+// $Id$
+//
+///////////////////////////////////////////
+
+#include "rot13_codecvt.h"
+
+static unsigned char table[]={0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,78,79,80,81,82,83,84,85,86,87,88,89,90,65,66,67,68,69,70,71,72,73,74,75,76,77,91,92,93,94,95,96,110,111,112,113,114,115,116,117,118,119,120,121,122,97,98,99,100,101,102,103,104,105,106,107,108,109,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255};
+
+rot13_codecvt::~rot13_codecvt()
+{
+} // ~rot13_codecvt
+
+std::codecvt_base::result rot13_codecvt::rot13(const char* from,
+               const char* from_end,
+               const char*& from_next,
+               char* to,
+               char* to_limit,
+               char*& to_next) const
+{
+  from_next = from;
+  to_next = to;
+
+  while((to_next != to_limit) && (from_next != from_end) )
+    *to_next++ = table[*from_next++];
+
+  return (from_next == from_end) ? std::codecvt_base::ok : std::codecvt_base::partial; 
+} // rot13
+
+std::codecvt_base::result rot13_codecvt::do_unshift(state_t& state,
+                            char* to,
+                            char* /* to_limit */,
+                            char*& to_next) const
+{
+  to_next = to;
+  return codecvt_base::ok;
+} // do_unshift
+
+int rot13_codecvt::do_encoding() const throw()
+{
+  return 0;
+} // do_encoding
+
+bool rot13_codecvt::do_always_noconv() const throw()
+{
+  return false;
+} // do_always_noconv
+
+int rot13_codecvt::do_length(const state_t&,
+                        const char* from,
+                        const char* end,
+                        size_t max) const
+{
+  return std::max<int>(end - from, max);
+} // do_length
+
+int rot13_codecvt::do_max_length() const throw()
+{
+  return 1;
+} // do_max_length
+
+// end of file

Utils/rot13_codecvt.h

@@ -0,0 +1,62 @@
+#ifndef ARABICA_UTILS_ROT13_CODECVT_H
+#define ARABICA_UTILS_ROT13_CODECVT_H
+///////////////////////////////////////////
+//
+// $Id$
+//
+///////////////////////////////////////////
+
+#include <locale>
+
+class rot13_codecvt : public std::codecvt<char, char, std::char_traits<char>::state_type>
+{
+public:
+  typedef std::char_traits<char>::state_type state_t;
+
+protected:
+  virtual ~rot13_codecvt();
+
+  virtual result do_out(state_t& state,
+                        const char* from,
+                        const char* from_end,
+                        const char*& from_next,
+                        char* to,
+                        char* to_limit,
+                        char*& to_next) const 
+      { return rot13(from, from_end, from_next, to, to_limit, to_next); }
+
+  virtual result do_in(state_t& state,
+                       const char* from,
+                       const char* from_end,
+                       const char*& from_next,
+                       char* to,
+                       char* to_limit,
+                       char*& to_next) const
+      { return rot13(from, from_end, from_next, to, to_limit, to_next); }
+
+  virtual result do_unshift(state_t&  state,
+                       char* to,
+                       char* to_limit,
+                       char*& to_next) const;
+
+  virtual int do_encoding() const throw();
+
+  virtual bool do_always_noconv() const throw();
+
+  virtual int do_length(const state_t&,
+                        const char* from,
+                        const char* end,
+                        size_t max) const;
+
+  virtual int do_max_length() const throw();
+
+private:
+  result rot13(const char* from,
+               const char* from_end,
+               const char*& from_next,
+               char* to,
+               char* to_limit,
+               char*& to_next) const;
+}; // class rot13_codecvt
+
+#endif