Copyright (C) 1989-1992, Digital Equipment Corporation 
 All rights reserved. 
 See the file COPYRIGHT for a full description. 
 Last modified on Fri Jul  9 21:30:41 PDT 1993 by mhb    
      modified on Fri Jun 11 23:03:17 PDT 1993 by meehan 
 modified on Fri Mar 27 02:14:10 1992 by steveg 

{\em Resources\/} are arbitrary texts that are associated with applications. Resources can be bundled into an application using the m3bundle facility. They may also be found in the file system.

This interface supports retrieval of resources using a {\em search path}. A search path is a list of elements; each element is either a Pathname.T that refers to a directory, or a Bundle.T, typically created by m3bundle.


IMPORT RefList, Rd, Thread;

TYPE Path = RefList.T; (* of Pathname.T or Bundle.T *)


PROCEDURE Open (name: TEXT; path: Path): Rd.T
  RAISES {NotFound};
If name is an absolute pathname, then look for name in the file system: A reader is returned if
is successeful; otherwise an exception is raised. If name is not an absolute pathname, then search each element of path, from front to back, for the first occurrence of the resource called name and return a reader on the resource. If the path element is a pathname p, then a reader is returned if
      FileRd.Open(Pathname.Join (p, name, NIL))
is successful. If the path element is a bundle b, a reader is returned if
      TextRd.New(Bundle.Get(b, name))
is successful. The NotFound exception is raised if no element of path yields a successful reader on name. It is a checked runtime error if path contains an element that is neither a pathname nor a bundle.

PROCEDURE Get (name: TEXT; path: Path): TEXT
  RAISES {NotFound, Rd.Failure, Thread.Alerted};
A convenience procedure to retrieve the contents of the resource name as a TEXT.
 The procedure Get is logically equivalent to
       VAR rd := Open(name, path);
           RETURN Rd.GetText(rd, LAST(CARDINAL))
The implementation is slightly more efficient, because it takes advantage of Bundle.Get procedure which returns the contents of the bundle element as a TEXT. The Rd.Failure exception is raised if Rd.GetText or Rd.Close report a problem. The Thread.Alerted can be raised by the call to Rd.GetText.

PROCEDURE BuildPath (a1, a2, a3, a4: REFANY := NIL): Path;
Build a Path from the non-NIL elements. Each element must be either a Bundle.T or a TEXT. If it is a TEXT, it is assumed to be the pathname of a directory, unless it starts with a dollar sign, in which case it is assumed to be an environment variable whose value is the name of a directory; the value is retrieved using Env.Get. It is a checked runtime error if the pathname is not valid.

END Rsrc.