#ifndef CPPCMS_COPY_FILTER_H

#define CPPCMS_COPY_FILTER_H

#include <booster/streambuf.h>

#include <booster/noncopyable.h>

#include <booster/hold_ptr.h>

#include <cppcms/defs.h>

#include <list>

#include <ostream>

namespace cppcms {

///

/// \brief Copy the output stream part - "tee" filter

///

/// This simple class designed to "copy" all the output that comes to the stream

/// to internal buffer and the stream itself and return the copied data on detaching

/// the filter.

///

/// It is very useful to use with caching, for example:

///

/// \code

/// std::string frame;

/// if(cache().fetch_frame("key",frame)) {

/// out() << frame;

/// }

/// else {

/// cppcms::copy_filter tee(out());

/// ...

/// // generate something heavy

/// ...

/// cache().store_frame("key",tee.detach());

/// }

/// \endcode

///

class CPPCMS_API copy_filter : public booster::noncopyable {

public:

///

/// Create a filter copying all output to internal buffer

///

copy_filter(std::ostream &output);

///

/// When destroyed, if the stream wasn't detached aborts coping the data,

/// making it exception safe.

///

~copy_filter();

///

/// Stop the coping process and return all collected data as string.

///

std::string detach();

private:

class tee_device;

struct data;

booster::hold_ptr<data> d;

booster::streambuf copy_buffer_;

std::ostream &output_;

std::ostream real_output_stream_;

std::list<std::string> data_;

bool detached_;

};

} // cppcms

#endif