           menu_driver - command-processing loop of the menu system

## SYNOPSIS

           #include <menu.h>
           int menu_driver(MENU *menu, int c);

## DESCRIPTION

           Once a menu has been posted (displayed), you should funnel
           input events to it through menu_driver.  This routine  has
           two  major input cases; either the input is a menu naviga-
           tion request or it's a  printable  ASCII  character.   The
           menu driver requests are as follows:

           REQ_LEFT_ITEM
                Move left to an item.

           REQ_RIGHT_ITEM
                Move right to an item.

           REQ_UP_ITEM
                Move up to an item.

           REQ_DOWN_ITEM
                Move down to an item.

           REQ_SCR_ULINE
                Scroll up a line.

           REQ_SCR_DLINE
                Scroll down a line.

           REQ_SCR_DPAGE
                Scroll down a page.

           REQ_SCR_UPAGE
                Scroll up a page.

           REQ_FIRST_ITEM
                Move to the first item.

           REQ_LAST_ITEM
                Move to the last item.

           REQ_NEXT_ITEM
                Move to the next item.

           REQ_PREV_ITEM
                Move to the previous item.

           REQ_TOGGLE_ITEM
                Select/deselect an item.

                Clear the menu pattern buffer.

           REQ_BACK_PATTERN
                Delete   the  previous  character  from  the  pattern
                buffer.

           REQ_NEXT_MATCH
                Move to the next item matching the pattern match.

           REQ_PREV_MATCH
                Move to the previous item matching the pattern match.

           If the second argument is a printable ASCII character, the
           code appends it to the pattern buffer and attempts to move
           to the next item matching the new pattern.  If there is no
           such match, menu_driver returns E_NO_MATCH and deletes the
           appended character from the buffer.

           If  the  second  argument  is one of the above pre-defined
           requests, the corresponding action is performed.

           If the second argument is neither printable ASCII nor  one
           of  the above pre-defined menu requests, the drive assumes
           it  is  an  application-specific   command   and   returns
           E_UNKNOWN_COMMAND.  Application-defined commands should be
           defined relative to  MAX_COMMAND,  the  maximum  value  of
           these pre-defined requests.

## RETURN VALUE

           menu_driver return one of the following error codes:

           E_OK The routine succeeded.

           E_SYSTEM_ERROR
                System error occurred (see errno).

           E_BAD_ARGUMENT
                Routine  detected  an incorrect or out-of-range argu-
                ment.

           E_BAD_STATE
                Routine was called from an initialization or termina-
                tion function.

           E_NOT_POSTED
                The menu has not been posted.

           E_UNKNOWN_COMMAND
                The menu driver code saw an unknown request code.

           E_NO_MATCH
                Character failed to match.
                The menu driver could not process the request.

## SEE ALSO

           curses(3X), menu(3X).

## NOTES

           The header file <menu.h> automatically includes the header
           files <curses.h>.

## PORTABILITY

           These routines emulate the System V  menu  library.   They
           were not supported on Version 7 or BSD versions.

## AUTHORS

           Juergen  Pfeifer.   Manual  pages  and  adaptation for new
           curses by Eric S. Raymond.