--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/enigma/rotor.cpp	Thu Jun 21 21:05:26 2012 -0500
@@ -0,0 +1,54 @@
+// Copyright (C) 2012 by Brian Neal.
+// This file is part of Cpp-Enigma, the Enigma Machine simulation.
+// Cpp-Enigma is released under the MIT License (see License.txt).
+//
+// rotor.cpp - Implementation file for the rotor class.
+
+#include <set>
+#include <array>
+#include <algorithm>
+#include "rotor.h"
+
+using namespace enigma;
+
+namespace
+{
+   const char* const ucase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+   const std::set<char> ucase_set(ucase, ucase + 26);
+}
+
+rotor::rotor(const char* name, const char* wiring, int ring_setting, const char* stepping)
+ : rotor_name(name),
+   wiring_str(wiring),
+   ring_setting(ring_setting),
+   pos(0),
+   rotations(0)
+{
+   // check wiring length
+   if (wiring_str.size() != 26)
+   {
+      throw rotor_error("invalid wiring length");
+   }
+
+   // ensure wiring contains only uppercase letters & every char must appear
+   // exactly once:
+
+   std::array<int, 26> letter_counts {{ 0 }};
+   for (int i = 0; i < 26; ++i)
+   {
+      const char c(wiring_str[i]);
+
+      if (ucase_set.find(c) == ucase_set.end())
+      {
+         throw rotor_error("invalid wiring");
+      }
+      ++letter_counts[c - 'A'];
+   }
+
+   if (std::find_if(letter_counts.begin(),
+                    letter_counts.end(),
+                    [](int n) { return n != 1; }) != letter_counts.end())
+   {
+      throw rotor_error("invalid wiring; duplicate letter");
+   }
+}