TextReader.i3
Copyright (c) 2000 California Institute of Technology
All rights reserved.
Department of Computer Science
Pasadena, CA 91125.
Author: Mika Nystrom <mika@cs.caltech.edu>
pushback portion: Karl Papadantonakis <kp@caltech.edu>
Permission to use, copy, modify, and distribute this software
and its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
copies. The California Institute of Technology makes no representations
about the suitability of this software for any purpose. It is
provided as is without express or implied warranty. Export of this
software outside of the United States of America may require an
export license.
$Id: TextReader.i3.html,v 1.3 2010-04-29 17:17:55 wagner Exp $
INTERFACE TextReader;
IMPORT TextList, Rd;
IMPORT Thread;
Think ``strtok''. A TextReader.T is initialized with
txtRd := NEW(TextReader.T).init(string);
Tokens may be parsed out by passing in a delimiter,
as follows:
VAR
txt : TEXT;
BEGIN
WHILE txtRd.next(" ,.", txt) DO
( parse txt )
END
END
To get the rest of the line, pass ``'' as the delims.
It is a checked run-time error to pass NIL as the delims or as line.
EXCEPTION
NoMore;
TYPE
T <: Public;
All the methods of a TextReader.T leave the reader in a state
to parse further untouched tokens.
Public = OBJECT METHODS
next(delims : TEXT; VAR chunk : TEXT; skipNulls := FALSE) : BOOLEAN;
get next word before delims from reader. If skipNulls is TRUE,
zero-length strings are never returned. Return value is TRUE
if call succeeded. If nothing was left, call fails, and returns
FALSE.
nextS(READONLY delims : SET OF CHAR;
VAR chunk : TEXT; skipNulls := FALSE) : BOOLEAN;
next actually calls nextS.
nextE(delims : TEXT; skipNulls := FALSE) : TEXT RAISES { NoMore };
same as next, except failure is signalled thru an exception
init(line : TEXT) : T;
initialize a new TextReader.T
initFromRd(rd : Rd.T) : T RAISES { Rd.Failure, Thread.Alerted };
initialize from an Rd.T. rd must eventually end (to allow in-memory
implementations)
isEmpty() : BOOLEAN;
probe a TextReader.T
shatter(listDelims : TEXT;
endDelims : TEXT; skipNulls := FALSE) : TextList.T;
tokenize a line into TEXT tokens until EOT or an endDelim.
It is a checked runtime error for there to be an overlap between
listDelims and endDelims
pushBack(t: TEXT);
insert t before remaining unread TEXT. t must end in
delimiter(s) if the next call to next is not to run past the
end of t. Current implementation may or may not insert an
extra invisible delimiter after t in some cases. This will not
be seen if skipNulls is always TRUE and t always ends in a
delimiter anyway.
END;
END TextReader.