Modula-3 TEXTs are implemented as objects with the methods described below.

INTERFACE TextClass;

CONST Brand = "Text-2.0";

REVEAL
  TEXT = BRANDED Brand OBJECT
  METHODS
    get_info       (VAR i: Info);

    get_char       (i: CARDINAL): CHAR      := GetChar;
    get_wide_char  (i: CARDINAL): WIDECHAR  := GetWideChar;

    get_chars      (VAR a: ARRAY OF CHAR;      start: CARDINAL) := GetChars;
    get_wide_chars (VAR a: ARRAY OF WIDECHAR;  start: CARDINAL) := GetWideChars;
  END;

TYPE
  Info = RECORD
    start  : ADDRESS;  (* non-NIL => string is at [start .. start+length) *)
    length : CARDINAL; (* length of string in characters *)
    wide   : BOOLEAN;  (* => string contains WIDECHARs. *)
  END;
  (* Note: the "start" address may refer to a heap variable, so
     it is only valid as long as it is kept on the stack. *)

PROCEDURE GetChar (t: TEXT;  i: CARDINAL): CHAR;

Returns CHOP(t.get_wide_char (i))

PROCEDURE GetWideChar (t: TEXT;  i: CARDINAL): WIDECHAR;

Returns EXTEND(t.get_char(i))

PROCEDURE GetChars (t: TEXT;  VAR a: ARRAY OF CHAR;  start: CARDINAL);

Returns the result of CHOPing the characters returned by t.get_wide_chars (a, start).

PROCEDURE GetWideChars (t: TEXT;  VAR a: ARRAY OF WIDECHAR;  start: CARDINAL);

Returns the result of EXTENDing the characters returned by t.get_chars (a, start).

END TextClass.

The function CHOP converts a WIDECHAR to a CHAR by dropping the high-order eight bits of the character.

The function EXTEND converts a CHAR to a WIDECHAR by zero-extending the character to a 16-bit value.