factor/library/io/stream.factor

! Copyright (C) 2003, 2005 Slava Pestov.
! See http://factor.sf.net/license.txt for BSD license.
IN: io
USING: errors generic kernel lists math namespaces sequences
strings ;

SYMBOL: stdio

! Stream protocol.
GENERIC: stream-flush      ( stream -- )
GENERIC: stream-auto-flush ( stream -- )
GENERIC: stream-readln     ( stream -- string )
GENERIC: stream-read       ( count stream -- string )
GENERIC: stream-read1      ( stream -- char/f )
GENERIC: stream-write-attr ( string style stream -- )
GENERIC: stream-close      ( stream -- )
GENERIC: set-timeout       ( timeout stream -- )

: stream-write ( string stream -- )
    f swap stream-write-attr ;

: stream-print ( string stream -- )
    [ stream-write ] keep
    [ "\n" swap stream-write ] keep
    stream-auto-flush ;

: (stream-copy) ( in out -- )
    4096 pick stream-read [
        over stream-write (stream-copy)
    ] [
        2drop
    ] ifte* ;

: stream-copy ( in out -- )
    [ 2dup (stream-copy) ]
    [ >r stream-close stream-close r> [ rethrow ] when* ] catch ;

! Think '/dev/null'.
TUPLE: null-stream ;
M: null-stream stream-flush drop ;
M: null-stream stream-auto-flush drop ;
M: null-stream stream-readln drop f ;
M: null-stream stream-read 2drop f ;
M: null-stream stream-read1 drop f ;
M: null-stream stream-write-attr 3drop ;
M: null-stream stream-close drop ;

! Sometimes, we want to have a delegating stream that uses stdio
! words.
TUPLE: wrapper-stream scope ;

C: wrapper-stream ( stream -- stream )
    2dup set-delegate [
        >r <namespace> [ stdio set ] extend r>
        set-wrapper-stream-scope
    ] keep ;

: with-wrapper ( stream quot -- )
    >r wrapper-stream-scope r> bind ;

! Standard actions protocol for presentations output to
! attributed streams.
: <actions> ( path alist -- alist )
    #! For each element of the alist, change the value to
    #! path " " value
    [ uncons >r swap " " r> append3 cons ] map-with ;