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(* StrIO.mod provides simple string input output routines.
Copyright (C) 2001-2025 Free Software Foundation, Inc.
Contributed by Gaius Mulley <gaius.mulley@southwales.ac.uk>.
This file is part of GNU Modula-2.
GNU Modula-2 is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GNU Modula-2 is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. *)
IMPLEMENTATION MODULE StrIO ;
FROM ASCII IMPORT cr, nul, lf, bel, del, bs, nak, etb, ff, eof ;
FROM StdIO IMPORT Read, Write ;
FROM libc IMPORT isatty ;
VAR
IsATTY: BOOLEAN ; (* Is default input from the keyboard? *)
(*
WriteLn - writes a carriage return and a newline
character.
*)
PROCEDURE WriteLn ;
BEGIN
Echo(cr) ;
Write(lf)
END WriteLn ;
(*
ReadString - reads a sequence of characters into a string.
Line editing accepts Del, Ctrl H, Ctrl W and
Ctrl U.
*)
PROCEDURE ReadString (VAR a: ARRAY OF CHAR) ;
VAR
n ,
high : CARDINAL ;
ch : CHAR ;
BEGIN
high := HIGH(a) ;
n := 0 ;
REPEAT
Read(ch) ;
IF (ch=del) OR (ch=bs)
THEN
IF n=0
THEN
Write(bel)
ELSE
Erase ;
DEC(n)
END
ELSIF ch=nak (* Ctrl U *)
THEN
WHILE n>0 DO
Erase ;
DEC(n)
END
ELSIF ch=etb (* Ctrl W *)
THEN
IF n=0
THEN
Echo(bel)
ELSIF AlphaNum(a[n-1])
THEN
REPEAT
Erase ;
DEC(n)
UNTIL (n=0) OR (NOT AlphaNum(a[n-1]))
ELSE
Erase ;
DEC(n)
END
ELSIF n<=high
THEN
IF (ch=cr) OR (ch=lf)
THEN
a[n] := nul ;
INC(n)
ELSIF ch=ff
THEN
a[0] := ch ;
IF high>0
THEN
a[1] := nul
END ;
ch := cr
ELSIF ch>=' '
THEN
Echo(ch) ;
a[n] := ch ;
INC(n)
ELSIF ch=eof
THEN
a[n] := ch ;
INC(n) ;
ch := cr;
IF n<=high
THEN
a[n] := nul
END
END
ELSIF ch#cr
THEN
Echo(bel)
END
UNTIL (ch=cr) OR (ch=lf)
END ReadString ;
(*
WriteString - writes a string to the default output.
*)
PROCEDURE WriteString (a: ARRAY OF CHAR) ;
VAR
n ,
high : CARDINAL ;
BEGIN
high := HIGH(a) ;
n := 0 ;
WHILE (n <= high) AND (a[n] # nul) DO
Write(a[n]) ;
INC(n)
END
END WriteString ;
(*
Erase - writes a backspace, space and backspace to remove the
last character displayed.
*)
PROCEDURE Erase ;
BEGIN
Echo(bs) ;
Echo(' ') ;
Echo(bs)
END Erase ;
(*
Echo - echos the character, ch, onto the output channel if IsATTY
is true.
*)
PROCEDURE Echo (ch: CHAR) ;
BEGIN
IF IsATTY
THEN
Write(ch)
END
END Echo ;
(*
AlphaNum- returns true if character, ch, is an alphanumeric character.
*)
PROCEDURE AlphaNum (ch: CHAR) : BOOLEAN ;
BEGIN
RETURN ((ch>='a') AND (ch<='z')) OR
((ch>='A') AND (ch<='Z')) OR
((ch>='0') AND (ch<='9'))
END AlphaNum ;
BEGIN
(* IsATTY := isatty() *)
IsATTY := FALSE
END StrIO.
|
