Cache.hh

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/*  Cache

PIRL CVS ID: $Id: Cache.hh,v 1.8 2010/11/11 20:33:13 castalia Exp $

Copyright (C) 2005  Arizona Board of Regents on behalf of the Planetary
Image Research Laboratory, Lunar and Planetary Laboratory at the
University of Arizona.

This library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License, version 2.1,
as published by the Free Software Foundation.

This library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation,
Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
*/
#ifndef _Cache_
#define _Cache_

#include    <iosfwd>

namespace PIRL
{
class Cache
{
public:
/*==============================================================================
    Types:
*/
typedef bool (*Data_Test) (const void*);

/*==============================================================================
    Constants:
*/
static const char* const
    ID;

/*==============================================================================
    Constructors
*/
Cache ();

explicit Cache
    (
    unsigned long   capacity,
    unsigned long   data_margin = 0,
    Data_Test       data_test = NULL
    );

Cache
    (
    unsigned long   capacity,
    std::istream&   source,
    unsigned long   data_margin = 0,
    Data_Test       data_test = NULL
    );

virtual ~Cache ();

private:
//  Copying disallowed:
Cache (const Cache& cache);
Cache& operator= (const Cache& cache);

/*==============================================================================
    Accessors
*/
public:
Cache& source (std::istream& source)
    {Source = &source; return *this;}

std::istream& source () const
    {return *Source;}

unsigned long long bytes_read () const
    {return Bytes_Read;}

Cache& data_margin (unsigned long amount);

unsigned long data_margin () const
    {return
        (Data_Test_Amount &&
        (Data_Test_Amount - 1) > Data_Margin) ?
        (Data_Test_Amount - 1) : Data_Margin;}

Cache& data_test (Data_Test tester, unsigned long data_amount);

Data_Test data_test () const
    {return EOD_Test;}

unsigned long data_test_amount () const
    {return Data_Test_Amount;}

/*==============================================================================
    Manipulators
*/
virtual void drain ();

virtual bool refill (unsigned long max_amount = (unsigned long)-1);

virtual Cache& put (char* data, unsigned long amount);

virtual unsigned long get (char* data, unsigned long amount);

virtual void reset ();

/*==============================================================================
    Cache Management
*/
unsigned long capacity () const
    {return Capacity;}

Cache& capacity (unsigned long amount);

unsigned long amount_used () const
    {return Last - Start;}

unsigned long amount_free () const
    {return End - Last;}

char* start () const
    {return Start;}

Cache& next (char* location)
    {Next = (location > Start) ? location : Start; return *this;}

char* next () const
    {return Next;}

unsigned long amount_consumed () const
    {return Next - Start;}

long amount_remaining () const
    {return Last - Next;}

char* last () const
    {return Last;}

Cache& last (char* location);

void state_report (std::ostream& stream) const;

void state_report () const;

/*==============================================================================
    Data members:
*/
private:
std::istream*
    Source;

unsigned long long
    Bytes_Read;

unsigned long
    Data_Margin;

Data_Test
    EOD_Test;

unsigned long
    Data_Test_Amount;

unsigned long
    Capacity;

//  Cache management pointers:

char*
    Start;
char*
    Next;
char*
    Last;
char*
    End;

};  //  End of Cache class.
}   //  namespace PIRL
#endif