gm2-libs/Scan (The GNU Modula-2 Compiler)

#### 4.1.39 gm2-libs/Scan ¶

    DEFINITION MODULE Scan ;

    (* Provides a primitive symbol fetching from input.
       Symbols are delimited by spaces and tabs.
       Limitation only allows one source file at
       a time to deliver symbols.  *)

    EXPORT QUALIFIED GetNextSymbol, WriteError,
                     OpenSource, CloseSource,
                     TerminateOnError, DefineComments ;

    (* OpenSource - opens a source file for reading.                  *)

    PROCEDURE OpenSource (a: ARRAY OF CHAR) : BOOLEAN ;

    (* CloseSource - closes the current source file from reading.     *)

    PROCEDURE CloseSource ;

    (* GetNextSymbol gets the next source symbol and returns it in a. *)

    PROCEDURE GetNextSymbol (VAR a: ARRAY OF CHAR) ;

    (* WriteError writes a message, a, under the source line, which   *)
    (* attempts to pinpoint the Symbol at fault.                      *)

    PROCEDURE WriteError (a: ARRAY OF CHAR) ;

    (*
       TerminateOnError - exits with status 1 if we call WriteError.
    *)

    PROCEDURE TerminateOnError ;

    (*
       DefineComments - defines the start of comments within the source
                        file.

                        The characters in Start define the comment start
                        and characters in End define the end.
                        The BOOLEAN eoln determine whether the comment
                        is terminated by end of line. If eoln is TRUE
                        then End is ignored.

                        If this procedure is never called then no comments
                        are allowed.
    *)

    PROCEDURE DefineComments (Start, End: ARRAY OF CHAR; eoln: BOOLEAN) ;

    END Scan.