--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tango/tango/io/model/IConduit.d	Fri Jan 11 17:57:40 2008 +0100
@@ -0,0 +1,248 @@
+/*******************************************************************************
+
+        copyright:      Copyright (c) 2004 Kris Bell. All rights reserved
+
+        license:        BSD style: $(LICENSE)
+
+        version:        Initial release: March 2004      
+                        Outback release: December 2006
+        
+        author:         Kris
+
+*******************************************************************************/
+
+module tango.io.model.IConduit;
+
+public import tango.io.model.IBuffer;
+
+/*******************************************************************************
+
+        Conduits provide virtualized access to external content, and 
+        represent things like files or Internet connections. Conduits 
+        expose a pair of streams, are modelled by tango.io.model.IConduit, 
+        and are implemented via classes such as FileConduit & SocketConduit. 
+        
+        Additional kinds of conduit are easy to construct: one either 
+        subclasses tango.io.Conduit, or implements tango.io.model.IConduit. 
+        A conduit typically reads and writes from/to an IBuffer in large 
+        chunks, typically the entire buffer. Alternatively, one can invoke 
+        input.read(dst[]) and/or output.write(src[]) directly.
+
+*******************************************************************************/
+
+interface IConduit : InputStream, OutputStream
+{
+        /***********************************************************************
+
+                Return the input stream
+
+        ***********************************************************************/
+        
+        abstract InputStream input ();
+
+        /***********************************************************************
+
+                Return the output stream
+
+        ***********************************************************************/
+        
+        abstract OutputStream output ();
+
+        /***********************************************************************
+        
+                Return a preferred size for buffering conduit I/O
+
+        ***********************************************************************/
+
+        abstract uint bufferSize (); 
+                     
+        /***********************************************************************
+        
+                Return the name of this conduit
+
+        ***********************************************************************/
+
+        abstract char[] toString (); 
+                     
+        /***********************************************************************
+
+                Is the conduit alive?
+
+        ***********************************************************************/
+
+        abstract bool isAlive ();
+
+        /***********************************************************************
+                
+                Release external resources
+
+        ***********************************************************************/
+
+        abstract void detach ();
+
+        /***********************************************************************
+
+                Throw a generic IO exception with the provided msg
+
+        ***********************************************************************/
+
+        abstract void error (char[] msg);
+
+        /***********************************************************************
+
+                Models the ability to seek within a conduit
+
+        ***********************************************************************/
+
+        interface Seek
+        {
+                /***************************************************************
+        
+                        The anchor positions supported by seek()
+
+                ***************************************************************/
+
+                enum Anchor     {
+                                Begin   = 0,
+                                Current = 1,
+                                End     = 2,
+                                };
+
+                /***************************************************************
+                
+                        Move the file position to the given offset from the 
+                        provided anchor point, and return adjusted position.
+
+                ***************************************************************/
+
+                long seek (long offset, Anchor anchor = Anchor.Begin);
+        }
+}
+
+
+/*******************************************************************************
+
+        Describes how to make an IO entity usable with selectors
+        
+*******************************************************************************/
+
+interface ISelectable
+{      
+        typedef int Handle = -1;        /// opaque OS file-handle        
+
+        /***********************************************************************
+
+                Models a handle-oriented device. 
+
+                TODO: figure out how to avoid exposing this in the general
+                case
+
+        ***********************************************************************/
+
+        Handle fileHandle ();
+}
+
+
+/*******************************************************************************
+        
+        The common attributes of streams
+
+*******************************************************************************/
+
+interface IOStream 
+{
+        enum : uint 
+        {
+                Eof = uint.max /// the End-of-Flow identifer
+        }
+
+        /***********************************************************************
+        
+                Return the host conduit
+
+        ***********************************************************************/
+
+        IConduit conduit ();
+
+                          
+        /***********************************************************************
+        
+                Close the input
+
+        ***********************************************************************/
+
+        void close ();               
+}
+
+
+/*******************************************************************************
+        
+        The Tango input stream
+
+*******************************************************************************/
+
+interface InputStream : IOStream
+{
+        /***********************************************************************
+        
+                Read from conduit into a target array. The provided dst 
+                will be populated with content from the conduit. 
+
+                Returns the number of bytes read, which may be less than
+                requested in dst. Eof is returned whenever an end-of-flow 
+                condition arises.
+
+        ***********************************************************************/
+
+        uint read (void[] dst);               
+                        
+        /***********************************************************************
+        
+                Clear any buffered content
+
+        ***********************************************************************/
+
+        InputStream clear ();               
+}
+
+
+/*******************************************************************************
+        
+        The Tango output stream
+
+*******************************************************************************/
+
+interface OutputStream : IOStream
+{
+        /***********************************************************************
+        
+                Write to conduit from a source array. The provided src
+                content will be written to the conduit.
+
+                Returns the number of bytes written from src, which may
+                be less than the quantity provided. Eof is returned when 
+                an end-of-flow condition arises.
+
+        ***********************************************************************/
+
+        uint write (void[] src);     
+        
+        /***********************************************************************
+
+                Transfer the content of another conduit to this one. Returns
+                a reference to this class, and throws IOException on failure.
+
+        ***********************************************************************/
+
+        OutputStream copy (InputStream src);
+                          
+        /***********************************************************************
+        
+                Purge buffered content
+
+        ***********************************************************************/
+
+        OutputStream flush ();               
+}
+
+