redAcore/CharBufferCore.h

/*
 * CharBufferCore.h
 *
 *  Created on: 18 May 2016
 *      Author: wentzelc
 */

#ifndef REDACORE_CHARBUFFERCORE_H_
#define REDACORE_CHARBUFFERCORE_H_

// Standard C/C++ Libraries
/* none */

// redA Libraries
/* none */

//---------------------------------------------------------------------------

/** Shift and Rolling buffer class
 *
 * Char Buffer:
 *   Virtual definition of core parameters and buffer interface
 *
 * Shifting buffer:
 *   Data is either set at start of buffer or appended to buffer
 *   Start of buffered data is always at beginning of buffer
 *   Never rolls over (option to over overwrite if data longer than buffer)
 *   Shifts unsused data to left when clearing used data
 *   Always zero terminates buffer
 *   Can look directly at buffer
 *
 * Rolling buffer:
 *   Data is continuosly assigned to buffer
 *   Start of buffer is tracked by references (can be anywhere)
 *   Data rolls over to start of buffer if end of buffer reached (option to overwrite start)
 *   Data is never shifted/moved inside buffer, only references are adjusted
 *   Never zero terminates buffer
 *   Can only look at data by copying (stitching) to another buffer
 */

//---------------------------------------------------------------------------

class CCharBuffer
{
protected:
    // Buffer Definition
    char        * Buffer;   // Memory allocated to buffer
    const int   BufSize;    // Size of allocated buffer
    int         BufLen;     // Total unread characters in buffer

    // Temporary output buffer
    char    * OutBuffer;    // Temporary output buffer for "stitched" (rollover) data

public:
    // Life Cycle
    CCharBuffer( int BufferSize );
    virtual ~CCharBuffer();

    // Direct Operations
    virtual int Reset();                                                            // Clear buffer and reset all pointers to start of buffer

    // Reading from buffer
    virtual char PeekChar( int Pos = 0 ) = 0;                                       // Return one character from buffer (do not remove from buffer
    virtual int  PeekDirect( char ** Data, int PeekPos = 0 ) = 0;                   // Return contiguous data pointer direct to buffer (continguous data couont returned)
    virtual int  Peek( char ** Data, int PeekPos = 0, int MaxLen = -1 ) = 0;        // Return stiched data copied to temporary output buffer
    virtual int  PeekCopy( char ** Data, int PeekPos = 0, int MaxLen = -1 ) = 0;    // Return stiched data copied to supplied pointer (create if not exist)

    virtual bool FindStr( const char * SearchStr, int SearchLen, int &FoundPos, int StartPos = 0 ) = 0;   // Search buffer directly

    // Change data on buffer
    virtual int Push( bool Overwrite, const char * Data, int Len = -1 ) = 0;        // Add Bytes to the end of the buffer
    virtual int Clear( int ClearLen = -1 ) = 0;                                     // Clear Bytes from start of buffer

    virtual int Pop( char ** Data, int MaxLen = -1 );                               // Read and remove bytes from start of buffer
    virtual int PopCopy( char ** Data, int MaxLen = -1 );                           // Same as Pop() except it returns a copy of the bytes in a new pointer

    // File operations
    virtual int ReadFromFD( int Handle, int MaxRead = -1, bool Overwrite = false ) = 0;     // Read directly from file descriptor into buffer (speed advantage)
    virtual int WriteToFD( int Handle, int MaxWrite = -1 ) = 0;                             // Write directly to file descriptor from buffer (speed advantage)

    // Miscellaneous
    int Size()        { return BufSize; };                                          // Returns number of total size of buffer (used and empty)
    int Len()         { return BufLen; };                                           // Returns number of bytes stored in buffer
};

//---------------------------------------------------------------------------

class CRollingBuffer : public CCharBuffer
{
protected:
    // Buffer pointers
    int     BufStart;       // First unread characters in buffer
    int     BufEnd;         // Next write position for new data (End of unread data + 1)

public:
    // Life Cycle
    CRollingBuffer( int BufferSize );
    virtual ~CRollingBuffer() {};

    // Direct Operations
    virtual int Reset();

    // Reading from buffer
    virtual char PeekChar( int Pos = 0 );
    virtual int  PeekDirect( char ** Data, int PeekPos = 0 );
    virtual int  Peek( char ** Data, int PeekPos = 0, int MaxLen = -1 );
    virtual int  PeekCopy( char ** Data, int PeekPos = 0, int MaxLen = -1 );

    virtual bool FindStr( const char * SearchStr, int SearchLen, int &FoundPos, int StartPos = 0 );

    // Change data on buffer
    virtual int Push( bool Overwrite, const char * Data, int Len = -1 );
    virtual int Clear( int ClearLen = -1 );

    // File operations
    virtual int ReadFromFD( int Handle, int MaxRead = -1, bool Overwrite = false );
    virtual int WriteToFD( int Handle, int MaxWrite = -1 );
};
//---------------------------------------------------------------------------

class CShiftBuffer : public CCharBuffer
{
public:
    // Life Cycle
    CShiftBuffer( int BufferSize );
    virtual ~CShiftBuffer() {};

    // Reading from buffer
    virtual char PeekChar( int Pos = 0 );
    virtual int  PeekDirect( char ** Data, int PeekPos = 0 );
    virtual int  Peek( char ** Data, int PeekPos = 0, int MaxLen = -1 );
    virtual int  PeekCopy( char ** Data, int PeekPos = 0, int MaxLen = -1 );

    virtual bool FindStr( const char * SearchStr, int SearchLen, int &FoundPos, int StartPos = 0 );

    // Change data on buffer
    virtual int Push( bool Overwrite, const char * Data, int Len = -1 );
    virtual int Clear( int ClearLen = -1 );

    // File operations
    virtual int ReadFromFD( int Handle, int MaxRead = -1, bool Overwrite = false );
    virtual int WriteToFD( int Handle, int MaxWrite = -1 );
};
//---------------------------------------------------------------------------

#endif /* REDACORE_CHARBUFFERCORE_H_ */