(* Copyright (C) 1989, Digital Equipment Corporation           *)
(* All rights reserved.                                        *)
(* See the file COPYRIGHT for a full description.              *)

(* Last modified on Fri Apr  6 10:18:34 1990 by muller         *)


MODULE TextRd;

IMPORT Rd, RdClass, Text;
FROM Thread IMPORT Alerted;
FROM Rd IMPORT Failure, Error;

REVEAL
  T = Rd.T BRANDED "TextRd.T version 0.0" OBJECT
        text: Text.T;
        len:  INTEGER; END;

CONST
  BuffSize = 500;

PROCEDURE New (t: Text.T): T =
  BEGIN
    RETURN (NEW (T, st := 0, lo := 0, cur := 0, hi := 0,
         buff := NEW (REF ARRAY OF CHAR , BuffSize),
         closed := FALSE, seekable := FALSE, intermittent := TRUE,
         seek := Seek, length := Length, close := Close,
         text := t, len := Text.Length (t)));
  END New;

PROCEDURE Seek (rd: T; <*UNUSED*> dontBlock: BOOLEAN): RdClass.SeekResult 
     RAISES {Failure, Alerted, Error} =
  VAR
    thisTime: INTEGER;
  BEGIN
    IF rd.cur # rd.hi THEN
      RAISE Failure ("Impossible! A bug in Rd or TextRd"); END;
    IF rd.len <= rd.cur THEN
      RETURN RdClass.SeekResult.Eof; END;
    thisTime := MIN (NUMBER (rd.buff^), rd.len);
    Text.SetChars (rd.buff^, Text.Sub (rd.text, rd.cur, thisTime));
    rd.lo := rd.cur;
    rd.hi := rd.lo + thisTime;
    RETURN RdClass.SeekResult.Ready;
  END Seek;

PROCEDURE Length (rd: T): CARDINAL RAISES {Failure, Alerted, Error} =
  BEGIN
    RETURN Text.Length (rd.text);
  END Length;

PROCEDURE Close (rd: T) RAISES {Failure, Alerted, Error} =
  BEGIN
    rd.buff := NIL;
    rd.text := NIL;
  END Close;

BEGIN
END TextRd.