[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/commands.cc

@@ -0,0 +1,79 @@
+#include "dbg-lib/commands.h"
+#include "persistent-data/block.h"
+
+#include <boost/lexical_cast.hpp>
+#include <stdexcept>
+
+using namespace dbg;
+using namespace persistent_data;
+using namespace std;
+
+//----------------------------------------------------------------
+
+namespace {
+	class hello : public dbg::command {
+		virtual void exec(dbg::strings const &args, ostream &out) {
+			out << "Hello, world!" << endl;
+		}
+	};
+
+	class exit_handler : public dbg::command {
+	public:
+		exit_handler(command_interpreter::ptr interpreter)
+			: interpreter_(interpreter) {
+		}
+
+		virtual void exec(dbg::strings const &args, ostream &out) {
+			out << "Goodbye!" << endl;
+			interpreter_->exit_main_loop();
+		}
+
+	private:
+		command_interpreter::ptr interpreter_;
+	};
+
+	class block_handler : public dbg::command {
+	public:
+		block_handler(block_manager::ptr bm, block_dumper::ptr dumper)
+			: bm_(bm), dumper_(dumper) {
+		}
+
+		virtual void exec(dbg::strings const &args, ostream &out) {
+			if (args.size() != 2)
+				throw runtime_error("incorrect number of arguments");
+
+			block_address block = boost::lexical_cast<block_address>(args[1]);
+
+			// no checksum validation for debugging purpose
+			block_manager::read_ref rr = bm_->read_lock(block);
+
+			dumper_->show(rr, out);
+		}
+
+	private:
+		block_manager::ptr bm_;
+		block_dumper::ptr dumper_;
+	};
+}
+
+//----------------------------------------------------------------
+
+command::ptr
+dbg::create_hello_handler()
+{
+	return command::ptr(new hello());
+}
+
+command::ptr
+dbg::create_exit_handler(command_interpreter::ptr interp)
+{
+	return command::ptr(new exit_handler(interp));
+}
+
+command::ptr
+dbg::create_block_handler(block_manager::ptr bm, block_dumper::ptr dumper)
+{
+	return command::ptr(new block_handler(bm, dumper));
+}
+
+//----------------------------------------------------------------