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ContentSource.h

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/*
 * Modification History
 *
 * 2002-February-12    Jason Rohrer
 * Created from UML diagram.
 *
 * 2002-March-3    Jason Rohrer
 * Added a virtual destructor.
 *
 * 2002-March-8    Jason Rohrer
 * Added a copy function.
 *
 * 2002-March-9    Jason Rohrer
 * Added a skipContent function.
 * Changed readContent to take an unsigned char buffer.
 *
 * 2002-March-11    Jason Rohrer
 * Added a restart function.
 *
 * 2002-July-23    Jason Rohrer
 * Added a function for clearing the source.
 */



#ifndef CONTENT_SOURCE_INCLUDED
#define CONTENT_SOURCE_INCLUDED






/**
 * Interface for a class that can provide buffers full of content.
 *
 * @author Jason Rohrer
 */
class ContentSource {



    public:



        // present so that virtual deletes work
        virtual ~ContentSource();


        
        /**
         * Gets the number of bytes remaining to be read.
         *
         * @return the number of bytes remaining.
         */
        virtual unsigned long getBytesRemaining(  ) = 0;



        /**
         * Reads a buffer full of content.
         *
         * @param outDestinationBuffer the buffer to place the
         *   read bytes in.  Must be allocated and destroyed by caller.
         * @param inBytesToRead the number of bytes to read
         *   into outDestinationBuffer.
         *
         * @return the number of bytes read successfully.
         */
        virtual int readContent( unsigned char * outDestinationBuffer,
                                 unsigned long inBytesToRead ) = 0;



        /**
         * Skips content.
         *
         * @param inBytesToSkip the number of bytes to skip.
         */
        virtual void skipContent( unsigned long inBytesToSkip )  = 0;



        /**
         * Restarts this content source so that
         * readContent will re-read the first byte.
         */
        virtual void restart() = 0;



        /**
         * Destroys the content underlying this source.
         *
         * For example, if this content source reads from a file on
         * disk, calling clear() on this source will remove the file
         * from the disk.
         *
         * Calling clear() may render a content source unusable.
         */
        virtual void clear() = 0;

        
        
        /**
         * Makes a deep copy of this source.
         *
         * @param a copy of this source.
         *   Must be destroyed by caller.
         */
        virtual ContentSource *copy() = 0;


        
    };



#endif

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