reworked regex directory structure to match boost requirements.

[SVN r9752]

example/snippets/partial_regex_match.cpp

@@ -0,0 +1,46 @@
+#include <string>
+#include <iostream>
+#include <boost/regex.hpp>
+
+boost::regex e("(\\d{3,4})[- ]?(\\d{4})[- ]?(\\d{4})[- ]?(\\d{4})");
+
+bool is_possible_card_number(const std::string& input)
+{
+   //
+   // return false for partial match, true for full match, or throw for
+   // impossible match based on what we have so far...
+   boost::match_results<std::string::const_iterator> what;
+   if(0 == boost::regex_match(input, what, e, boost::match_default | boost::match_partial))
+   {
+      // the input so far could not possibly be valid so reject it:
+      throw std::runtime_error("Invalid data entered - this could not possibly be a valid card number");
+   }
+   // OK so far so good, but have we finished?
+   if(what[0].matched)
+   {
+      // excellent, we have a result:
+      return true;
+   }
+   // what we have so far is only a partial match...
+   return false;
+}
+
+int main(int argc, char* argv[])
+{
+   try{
+      std::string input;
+      std::cin >> input;
+      if(is_possible_card_number(input))
+      {
+         std::cout << "Matched OK..." << std::endl;
+      }
+      else
+         std::cout << "Got a partial match..." << std::endl;
+   }
+   catch(const std::exception& e)
+   {
+      std::cout << e.what() << std::endl;
+   }
+   return 0;
+}
+