coder_strbuf_adapter.h

A Library of Efficient Data Types and Algorithms,封装了常用的ADT及其相关算法的软件包

/*******************************************************************************
+
+  LEDA 4.5  
+
+
+  coder_strbuf_adapter.h
+
+
+  Copyright (c) 1995-2004
+  by Algorithmic Solutions Software GmbH
+  All rights reserved.
+ 
*******************************************************************************/

// $Revision: 1.16 $  $Date: 2004/02/23 14:16:08 $

#ifndef _LEDA_CODER_STRBUF_ADAPTER_H
#define _LEDA_CODER_STRBUF_ADAPTER_H

#if !defined(LEDA_ROOT_INCL_ID)
#define LEDA_ROOT_INCL_ID 450355
#include <LEDA/PREAMBLE.h>
#endif

#include <LEDA/string.h>

#include <LEDA/impl/coder_base.h>

#ifdef __mipspro__
#define LEDA_COMPRESSION_WA4
#endif

#if (_MSC_VER >= 1300)
#define LEDA_COMPRESSION_WA7
#endif

LEDA_BEGIN_NAMESPACE

// work-around for Microsoft .NET
#ifdef LEDA_COMPRESSION_WA7
class local_streambuf : public streambuf {};
#define LEDA_STREAMBUF local_streambuf
#else
#define LEDA_STREAMBUF streambuf
#endif

/// coder_strbuf_adapter ////////////////////////////////////////////////////////////////////

class __exportC coder_strbuf_adapter : public LEDA_STREAMBUF {
public:
	typedef coder_base::byte   byte;
	typedef coder_base::uint32 uint32;
	enum { DefaultBufSize = 4, StreamBlocked = coder_base::StreamBlocked };

public:
	coder_strbuf_adapter(coder_base* coder = 0, bool own_coder = false, 
						 streambuf* strbuf = 0, bool own_strbuf = false, 
						 uint32 buf_size = DefaultBufSize);
	virtual ~coder_strbuf_adapter();

	coder_base* get_coder() const { return pCoder; }
	void set_coder(coder_base* coder, bool own_coder = false);

	streambuf* get_encoded_stream() const { return pEncodedStream; }
	void set_encoded_stream(streambuf* stream, bool own_stream = false);
	void set_encoded_file(const char* file_name, ios::openmode mode);

	void sputEOF();

	virtual void reset(); // same state as the default ctor, but keeps coder and BufferSize

	bool fail() const { return State == s_error; }

protected:
	enum state { s_init, s_encoding_first_pass, s_encoding_later_pass, s_decoding, 
		         s_finished, s_finalized, s_error };

protected:
	// the following function should be called in the destructor of a derived class
	// (It has to be called if the virtual function sync() is overwritten!)
	void finalize();

	void error(const char* err_msg = 0);

	virtual streambuf* create_internal_stream(string filename);
	virtual void destroy_internal_stream(streambuf* int_stream, string filename);

	virtual void observe_state_change(state new_state) {}

	// the following functions are inherited from streambuf
	virtual int overflow(int c); // called when put-buffer buffer full  (puts the character to the stream)
	virtual int underflow();     // called when get-buffer buffer empty (gets a character from stream, but doesn' point past it)
	virtual int uflow();		 // called when get-buffer buffer empty (gets a character from stream, and points past it)
	virtual streampos seekoff(streamoff off, ios::seekdir way, ios::openmode which);
	virtual streampos seekpos(streampos sp, ios::openmode which);
	virtual streambuf* setbuf(char*, streamsize) { return 0; } // do not allow to change buffer

#ifdef LEDA_COMPRESSION_WA4
	virtual streamsize xsgetn(char* buffer, streamsize count);
#endif

#ifdef LEDA_COMPRESSION_WA1
// work-around for MSVC 6.0 and CXX 5.1 (alpha) and HPUX aCC (see also LEDA/PREAMBLE.h)
public:
	virtual streampos seekpos(streampos sp, int mode) { return seekpos(sp, ios::openmode(mode)); }
    virtual streampos seekoff(streamoff off, ios::seek_dir way, int mode) { return seekoff(off, way, ios::openmode(mode)); }
// Observe: sync must be public below!
#endif
	virtual int sync(); // used to flush buffers

private:
	void set_state(state new_state);

	void start_encoding();
	void encode_internal_buffer();

	void start_decoding();
	int  decode_into_internal_buffer();

private:
	state       State;
	char*		InternalBuffer;
	uint32		BufferSize;
	char		TinyBuffer[4];
	coder_base*	pCoder;
	streambuf*	pEncodedStream;
	bool        OwnCoder;
	bool        OwnEncodedStream;
	bool		SignalEof;
	int			NumOverFlowChars;

	streambuf*  pStreamForBuffering;
	string		TmpFileName;
};

#ifdef LEDA_COMPRESSION_WA7
#undef LEDA_STREAMBUF
#endif

#if LEDA_ROOT_INCL_ID == 450355
#undef LEDA_ROOT_INCL_ID
#include <LEDA/POSTAMBLE.h>
#endif

LEDA_END_NAMESPACE

#endif