The Stream Filter archetecture is finished, it's actually much cooler than I

had anticipated, and much cleaner.  I'll have to add some documentation to it,
because it's not really obvious how any of it fits together from the outset,
although I have to say that the bzip2 test program is the easiest general bzip2
compression program I've ever made...it just goes :)

Decompression in Bu::BZip2 isn't finished yet, but that's ok, it's coming soon.

1 files changed, 59 insertions, 0 deletions

diff --git a/src/filter.h b/src/filter.h
new file mode 100644
index 0000000..b068206
--- /dev/null
+++ b/src/filter.h
@@ -0,0 +1,59 @@
+#ifndef FILTER_H
+#define FILTER_H
+
+#include <stdint.h>
+
+#include "bu/stream.h"
+
+namespace Bu
+{
+        /**
+         * Data filter base class.  Each data filter should contain a read and write
+         * section.  Effectively, the write applies the filter, the read un-applies
+         * the filter, if possible.  For example, BZip2 is a filter that compresses
+         * on write and decompresses on read.  All bi-directional filters should
+         * follow:  x == read( write( x ) ) (byte-for-byte comparison)
+         *
+         * Also, all returned buffers should be owned by the filter, and deleted
+         * when the filter is deleted.  This means that the output of a read or
+         * write operation must be used before the next call to read or write or the
+         * data will be destroyed.  Also, the internal buffer may be changed or
+         * recreated between calls, so always get a new pointer from a call to
+         * read or write.
+         *
+         * The close function can also return data, so make sure to check for it,
+         * many filters such as compression filters will buffer data until they have
+         * enough to create a compression block, in these cases the leftover data
+         * will be returned by close.
+         */
+        class Filter : public Bu::Stream
+        {
+        public:
+                Filter( Bu::Stream &rNext );
+                virtual ~Filter();
+
+                virtual void start()=0;
+                virtual void stop()=0;
+                virtual void close();
+                virtual long tell();
+                virtual void seek( long offset );
+                virtual void setPos( long pos );
+                virtual void setPosEnd( long pos );
+                virtual bool isEOS();
+
+                virtual bool canRead();
+                virtual bool canWrite();
+                virtual bool canSeek();
+
+                virtual bool isBlocking();
+                virtual void setBlocking( bool bBlocking=true );
+
+        protected:
+                Bu::Stream &rNext;
+
+        private:
+
+        };
+}
+
+#endif