DEFINITION MODULE Strings;
(* Note: truncation of strings may occur if the user does not provide
   large enough variables to contain the result of the operation.
*)

(* Strings are of type ARRAY OF CHAR, and their length is the size
   of the array, unless a 0-byte occurs in the string to indicate the
   end of the string.
*)

PROCEDURE Assign(source: ARRAY OF CHAR; VAR dest: ARRAY OF CHAR);
(* Assign string source to dest
*)

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.
*)

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.
*)

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.
*)

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].
*)

PROCEDURE Concat(s1, s2: ARRAY OF CHAR; VAR result: ARRAY OF CHAR);
(* Concatenate two strings.
*)

PROCEDURE Length(str: ARRAY OF CHAR): CARDINAL;
(* Return number of characters in str.
*)

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.
*)

END Strings.