source: trunk/minix/lib/ack/libm2/Strings.mod@ 20

(*
  (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
  See the copyright notice in the ACK home directory, in the file "Copyright".
*)

(*$R-*)
IMPLEMENTATION MODULE Strings;
(*
  Module:       String manipulations
  Author:       Ceriel J.H. Jacobs
  Version:      $Header: /cvsup/minix/src/lib/ack/libm2/Strings.mod,v 1.1 2005/10/10 15:27:46 beng Exp $
*)

  PROCEDURE Assign(source: ARRAY OF CHAR; VAR dest: ARRAY OF CHAR);
  (* Assign string source to dest
  *)
  VAR   i: CARDINAL;
        max: CARDINAL;
  BEGIN
        max := HIGH(source);
        IF HIGH(dest) < max THEN max := HIGH(dest); END;
        i := 0;
        WHILE (i <= max) AND (source[i] # 0C) DO
                dest[i] := source[i];
                INC(i);
        END;
        IF i < HIGH(dest) THEN dest[i] := 0C; END;
  END Assign;

  PROCEDURE Insert(substr: ARRAY OF CHAR; VAR str: ARRAY OF CHAR; inx: CARDINAL);
  (* Insert the string substr into str, starting at str[inx].
     If inx is equal to or greater than Length(str) then substr is appended
     to the end of str.
  *)
  VAR   sublen, length, i: CARDINAL;
  BEGIN
        sublen := Length(substr);
        IF sublen = 0 THEN RETURN; END;
        length := Length(str);
        IF inx > length THEN inx := length; END;
        i := length;
        IF i + sublen  - 1 > HIGH(str) THEN i := HIGH(str); END;
        WHILE i > inx DO
                str[i+sublen-1] := str[i-1];
                DEC(i);
        END;
        FOR i := 0 TO sublen - 1 DO
                IF i + inx <= HIGH(str) THEN
                        str[i + inx] := substr[i];
                ELSE
                        RETURN;
                END;
        END;
        IF length + sublen <= HIGH(str) THEN
                str[length + sublen] := 0C;
        END;
  END Insert;

  PROCEDURE Delete(VAR str: ARRAY OF CHAR; inx, len: CARDINAL);
  (* Delete len characters from str, starting at str[inx].
     If inx >= Length(str) then nothing happens.
     If there are not len characters to delete, characters to the end of the
     string are deleted.
  *)
  VAR   length: CARDINAL;
  BEGIN
        IF len = 0 THEN RETURN; END;
        length := Length(str);
        IF inx >= length THEN RETURN; END;
        WHILE inx + len < length DO
                str[inx] := str[inx + len];
                INC(inx);
        END;
        str[inx] := 0C;
  END Delete;

  PROCEDURE Pos(substr, str: ARRAY OF CHAR): CARDINAL;
  (* Return the index into str of the first occurrence of substr.
     Pos returns a value greater than HIGH(str) of no occurrence is found.
  *)
  VAR   i, j, max, subl: CARDINAL;
  BEGIN
        max := Length(str);
        subl := Length(substr);
        IF subl > max THEN RETURN HIGH(str) + 1; END;
        IF subl = 0 THEN RETURN 0; END;
        max := max - subl;
        FOR i := 0 TO max DO
                j := 0;
                WHILE (j <= subl-1) AND (str[i+j] = substr[j]) DO
                        INC(j);
                END;
                IF j = subl THEN RETURN i; END;
        END;
        RETURN HIGH(str) + 1;
  END Pos;

  PROCEDURE Copy(str: ARRAY OF CHAR;
                 inx, len: CARDINAL;
                 VAR result: ARRAY OF CHAR);
  (* Copy at most len characters from str into result, starting at str[inx].
  *)
  VAR   i: CARDINAL;
  BEGIN
        IF Length(str) <= inx THEN RETURN END;
        i := 0;
        LOOP
                IF i > HIGH(result) THEN RETURN; END;
                IF len = 0 THEN EXIT; END;
                IF inx > HIGH(str) THEN EXIT; END;
                result[i] := str[inx];
                INC(i); INC(inx); DEC(len);
        END;
        IF i <= HIGH(result) THEN result[i] := 0C; END;
  END Copy;

  PROCEDURE Concat(s1, s2: ARRAY OF CHAR; VAR result: ARRAY OF CHAR);
  (* Concatenate two strings.
  *)
  VAR   i, j: CARDINAL;
  BEGIN
        i := 0;
        WHILE (i <= HIGH(s1)) AND (s1[i] # 0C) DO
                IF i > HIGH(result) THEN RETURN END;
                result[i] := s1[i];
                INC(i);
        END;
        j := 0;
        WHILE (j <= HIGH(s2)) AND (s2[j] # 0C) DO
                IF i > HIGH(result) THEN RETURN END;
                result[i] := s2[j];
                INC(i);
                INC(j);
        END;
        IF i <= HIGH(result) THEN result[i] := 0C; END;
  END Concat;

  PROCEDURE Length(str: ARRAY OF CHAR): CARDINAL;
  (* Return number of characters in str.
  *)
  VAR i: CARDINAL;
  BEGIN
        i := 0;
        WHILE (i <= HIGH(str)) DO
                IF str[i] = 0C THEN RETURN i; END;
                INC(i);
        END;
        RETURN i;
  END Length;

  PROCEDURE CompareStr(s1, s2: ARRAY OF CHAR): INTEGER;
  (* Compare two strings, return -1 if s1 < s2, 0 if s1 = s2, and 1 if s1 > s2.
  *)
  VAR   i: CARDINAL;
        max: CARDINAL;
  BEGIN
        max := HIGH(s1);
        IF HIGH(s2) < max THEN max := HIGH(s2); END;
        i := 0;
        WHILE (i <= max) DO
                IF s1[i] < s2[i] THEN RETURN -1; END;
                IF s1[i] > s2[i] THEN RETURN 1; END;
                IF s1[i] = 0C THEN RETURN 0; END;
                INC(i);
        END;
        IF (i <= HIGH(s1)) AND (s1[i] # 0C) THEN RETURN 1; END;
        IF (i <= HIGH(s2)) AND (s2[i] # 0C) THEN RETURN -1; END;
        RETURN 0;
  END CompareStr;

END Strings.