[dbg] Pull out common code into dbg-lib

- Modularize common routines
- Extract the block_dumper interface for displaying blocks
- Remove inheritance from show_traits

dbg-lib/command_interpreter.cc

@@ -0,0 +1,88 @@
+#include "dbg-lib/command_interpreter.h"
+
+using namespace dbg;
+using namespace std;
+
+//----------------------------------------------------------------
+
+namespace {
+	class command_interpreter_impl : public command_interpreter {
+	public:
+		typedef std::shared_ptr<command_interpreter> ptr;
+
+		command_interpreter_impl(std::istream &in, std::ostream &out)
+			: in_(in),
+			  out_(out),
+			  exit_(false) {
+		}
+
+		void register_command(std::string const &str, command::ptr cmd) {
+			commands_.insert(make_pair(str, cmd));
+		}
+
+		void enter_main_loop() {
+			while (!exit_)
+				do_once();
+		}
+
+		void exit_main_loop() {
+			exit_ = true;
+		}
+
+	private:
+		void do_once();
+
+		std::istream &in_;
+		std::ostream &out_;
+		std::map <std::string, command::ptr> commands_;
+		bool exit_;
+	};
+
+	//--------------------------------
+
+	strings read_input(std::istream &in)
+	{
+		using namespace boost::algorithm;
+
+		std::string input;
+		getline(in, input);
+
+		strings toks;
+		split(toks, input, is_any_of(" \t"), token_compress_on);
+
+		return toks;
+	}
+}
+
+//----------------------------------------------------------------
+
+void command_interpreter_impl::do_once()
+{
+	if (in_.eof())
+		throw runtime_error("input closed");
+
+	out_ << "> ";
+	strings args = read_input(in_);
+
+	std::map<std::string, command::ptr>::iterator it;
+	it = commands_.find(args[0]);
+	if (it == commands_.end())
+		out_ << "Unrecognised command" << endl;
+	else {
+		try {
+			it->second->exec(args, out_);
+		} catch (std::exception &e) {
+			cerr << e.what() << endl;
+		}
+	}
+}
+
+//----------------------------------------------------------------
+
+command_interpreter::ptr
+dbg::create_command_interpreter(std::istream &in, std::ostream &out)
+{
+	return command_interpreter::ptr(new command_interpreter_impl(in, out));
+}
+
+//----------------------------------------------------------------