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(* StrLib.mod provides string manipulation procedures.
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 StrLib ;
FROM ASCII IMPORT nul, tab ;
(*
StrConCat - combines a and b into c.
*)
PROCEDURE StrConCat (a: ARRAY OF CHAR; b: ARRAY OF CHAR; VAR c: ARRAY OF CHAR) ;
VAR
Highb,
Highc,
i, j : CARDINAL ;
BEGIN
Highb := StrLen(b) ;
Highc := HIGH(c) ;
StrCopy(a, c) ;
i := StrLen(c) ;
j := 0 ;
WHILE (j<Highb) AND (i<=Highc) DO
c[i] := b[j] ;
INC(i) ;
INC(j)
END ;
IF i<=Highc
THEN
c[i] := nul
END
END StrConCat ;
(*
StrLess - returns TRUE if string, a, alphabetically occurs before
string, b.
*)
PROCEDURE StrLess (a, b: ARRAY OF CHAR) : BOOLEAN ;
VAR
Higha,
Highb,
i : CARDINAL ;
BEGIN
Higha := StrLen(a) ;
Highb := StrLen(b) ;
i := 0 ;
WHILE (i<Higha) AND (i<Highb) DO
IF a[i]<b[i]
THEN
RETURN( TRUE )
ELSIF a[i]>b[i]
THEN
RETURN( FALSE )
END ;
(* must be equal, move on to next character *)
INC(i)
END ;
RETURN( Higha<Highb ) (* substrings are equal so we go on length *)
END StrLess ;
PROCEDURE StrEqual (a, b: ARRAY OF CHAR) : BOOLEAN ;
VAR
i,
higha,
highb: CARDINAL ;
BEGIN
higha := HIGH(a) ;
highb := HIGH(b) ;
i := 0 ;
WHILE (i<=higha) AND (i<=highb) AND (a[i]#nul) AND (b[i]#nul) DO
IF a[i]#b[i]
THEN
RETURN( FALSE )
END ;
INC(i)
END ;
RETURN NOT (((i<=higha) AND (a[i]#nul)) OR
((i<=highb) AND (b[i]#nul)))
END StrEqual ;
PROCEDURE StrLen (a: ARRAY OF CHAR) : CARDINAL ;
VAR
High,
Len : CARDINAL ;
BEGIN
Len := 0 ;
High := HIGH(a) ;
WHILE (Len<=High) AND (a[Len]#nul) DO
INC(Len)
END ;
RETURN( Len )
END StrLen ;
(*
StrCopy - copy string src into string dest providing dest is large enough.
If dest is smaller than a then src then the string is truncated when
dest is full. Add a nul character if there is room in dest.
*)
PROCEDURE StrCopy (src: ARRAY OF CHAR ; VAR dest: ARRAY OF CHAR) ;
VAR
HighSrc,
HighDest,
n : CARDINAL ;
BEGIN
n := 0 ;
HighSrc := StrLen (src) ;
HighDest := HIGH (dest) ;
WHILE (n < HighSrc) AND (n <= HighDest) DO
dest[n] := src[n] ;
INC (n)
END ;
IF n <= HighDest
THEN
dest[n] := nul
END
END StrCopy ;
(*
IsSubString - returns true if b is a subcomponent of a.
*)
PROCEDURE IsSubString (a, b: ARRAY OF CHAR) : BOOLEAN ;
VAR
i, j,
LengthA,
LengthB: CARDINAL ;
BEGIN
LengthA := StrLen(a) ;
LengthB := StrLen(b) ;
i := 0 ;
IF LengthA>LengthB
THEN
WHILE i<=LengthA-LengthB DO
j := 0 ;
WHILE (j<LengthB) AND (a[i+j]=b[j]) DO
INC(j)
END ;
IF j=LengthB
THEN
RETURN( TRUE )
ELSE
INC(i)
END
END
END ;
RETURN( FALSE )
END IsSubString ;
(*
IsWhite - returns TRUE if, ch, is a space or a tab.
*)
PROCEDURE IsWhite (ch: CHAR) : BOOLEAN ;
BEGIN
RETURN( (ch=' ') OR (ch=tab) )
END IsWhite ;
(*
StrRemoveWhitePrefix - copies string, into string, b, excluding any white
space infront of a.
*)
PROCEDURE StrRemoveWhitePrefix (a: ARRAY OF CHAR; VAR b: ARRAY OF CHAR) ;
VAR
i, j,
higha, highb: CARDINAL ;
BEGIN
i := 0 ;
j := 0 ;
higha := StrLen(a) ;
highb := HIGH(b) ;
WHILE (i<higha) AND IsWhite(a[i]) DO
INC(i)
END ;
WHILE (i<higha) AND (j<=highb) DO
b[j] := a[i] ;
INC(i) ;
INC(j)
END ;
IF j<=highb
THEN
b[j] := nul
END
END StrRemoveWhitePrefix ;
END StrLib.
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