NetBSD/usr.bin/menuc/menuc.1

.\"	$NetBSD: menuc.1,v 1.18 2003/06/09 18:48:41 dsl Exp $
.\"
.\" Copyright 1997 Piermont Information Systems Inc.
.\" All rights reserved.
.\"
.\" Written by Philip A. Nelson for Piermont Information Systems Inc.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    must display the following acknowledgement:
.\"      This product includes software developed for the NetBSD Project by
.\"      Piermont Information Systems Inc.
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.Dd May 9, 2003
.Os
.Dt MENUC 1
.Sh NAME
.Nm menuc
.Nd menu compiler
.Sh SYNOPSIS
.Nm
.Op Fl o Ar name
.Ar file
.Sh DESCRIPTION
This implements a curses based menu system.
A source file that describes menus, their options, and how to process
the options is given to
.Nm
and produces both a .c and a .h file that implement the menu system.
The standard base name of the files is
.Pa menu_defs .
The
.Fl o Ar name
can be used to specify a different base name.
.Sh ENVIRONMENT
.Bl -tag -width MENUDEF
.It Ev MENUDEF
Can be set to point to a different set of definition files for
.Nm .
The current location defaults to
.Pa /usr/share/misc .
.El
.Sh MENU DESCRIPTIONS
The input
.Ar file
defines static menus and options for processing those menus.
It also contains comments, initial C code that is required to provide
for definitions and other code necessary for the menu system, and an
option declaration if dynamic menus are requested.
.Pp
Comments may appear anywhere in the input
.Ar file
and are like a space in the input.
They are like C comments starting with
.Em /*
and ending with
.Em */ .
They are unlike C comments in that they may be nested.
A comment does not end until a matching end comment is found.
.Pp
In many places, C code is included in the definition
.Ar file .
All C code is passed verbatim to the C output file.
.Nm
comments do not start in C code and comments in the C code are
passed verbatim to the output.
The C comments are not recognized by
.Nm .
In all cases, C code starts with a left brace
.Pq Em \&{
and ends with the matching right brace
.Pq Em \&} .
It is important to recognize that in code segments, any brace
will be counted, even if it is in a C comment inside the code.
.Pp
The
.Ar file
contains an initial (and optional) code block followed by any
number of menu definition elements in any order.
The initial code block usually contains includes of header files used by
code in the menu code blocks later in the
.Ar file .
If
.Dv USER_MENU_INIT
is #defined, then it will be evaluated before the
rest of the menu is initialised, if it evaluates to a non-zero value
then the initialisation will fail.
The file is free format, so the actual formatting of the input
.Ar file
is to the taste of the programmer.
.Pp
All other C code that will appear in an
.Em action .
This will be specified as
.Aq Em action
in later text.
Such an action will appear as:
.Dl action \*[Lt]opt_endwin\*[Gt] \*[Lt]code\*[Gt]
in the
.Ar file .
The
.Aq Em opt_endwin ,
if present is:
.Dl ( endwin )
and specifies that the curses
.Fn endwin
function should be called before executing the code and
then reinstating the current curses window after the
code has been run.
The
.Aq Em code
is as described above.
.Pp
There are four kinds of menu definition elements.
The first one just declares whether the programmer wants dynamic menus
available.
The default is static menus only.
The static menus are the ones defined by the menu definitions and do not
change at run time.
The dynamic menus provide the programmer with a method to create and
modify menus during the running of the program.
To include dynamic menus, one needs only add the declaration:
.Dl allow dynamic menus ;
The semicolon is required to terminate this declaration.
This declaration may appear anywhere in the
.Ar file ,
but usually appears before any menus are defined.
.Pp
The next element is a code block to execute if the curses
screen can not be successfully initialized.
The declaration
.Dl error code ;
tells the menu system to execute the associated code block
if the initialization fails.
If no code is provided, a default code block is used that prints
.Dl Could not initialize curses.
and exits.
This element may appear anywhere in the
.Ar file
but usually appears before any menus are defined.
.Pp
The next element defines default options for menus.
Each menu is built from a list of options.
These options include the location of the upper left corner of the menu,
whether there is a "box" drawn around the menu, whether the menu is
scrollable, the menu's title, whether shortcut letters are
allowed, whether a standard exit option should be included
in the menu and text associated with the standard exit option.
The general format is:
.Dl default \*[Lt]comma separated option list\*[Gt] ;
The options appear in three forms:
.Dl variable = value
.Dl [no] switch
.Dl variable Ar string
.Pp
The variables for the first form are
.Va x ,
.Va y ,
.Va h ,
and
.Va w .
These specify the upper left (x,y) and the
height (h) and width (w) of the menu window.
The upper left is in the curses coordinate system.
If
.Va x
is \-1 the menu window will be centered.
If not specified, the upper left is the upper left of the screen
and the height and width of the menu window is computed
from the menu definition.
.Pp
Options of the second form turn on or off (with the
optional no) features of the menu system.
The
.Va box
option turns on a box around the menu window.
The
.Va exit
option enables the standard exit option in the menus.
The
.Va scrollable
option allows the menu to be scrollable if the
menu window is smaller than the number of menu options.
The
.Va shortcut
option prints a single character shortcut with each menu option.
.Pp
The third sets text variables.
The
.Ar string
can be either a quoted text string or a name #defined to something
suitable for initialising a const char * field.
The variable
.Va title
sets the text title for the menus.
The variable
.Va exitstring
sets the text for the exit menu option and sets the
.Va exit
option.
.Pp
The default declaration may appear multiple times.
Each time, it sets the default values for menu definitions that follow
in the
.Ar file .
In each menu definition, any or all of these default definitions
may be overridden for that menu.
.Pp
The final element is the actual static menu definitions.
The format and order for a menu definition is:
.Bd -ragged -offset indent
menu \*[Lt]name\*[Gt] \*[Lt]options\*[Gt] ;
  \*[Lt]display action\*[Gt]
  \*[Lt]menu items\*[Gt]
  \*[Lt]exit action\*[Gt]
  \*[Lt]help string\*[Gt]
.Ed
.Pp
Names are unquoted strings of alpha-numeric and underscore
characters.
They must start with an alpha character.
In C source, a menu named
.Dq foo
is appears as
.Dq MENU_foo .
(Capitalization is important.)
This is important, because the menu is displayed and processed by
calling the function
.Dl process_menu (MENU_foo) ;
.Pp
The options are a comma separated list of options as in the
.Dq default
declaration.
These override the options from the most recent default declaration.
.Pp
The display action is optional and provides C code to
execute at each and every time the menu is displayed for processing.
If it is included, the format is:
.Dl display \*[Lt]action\*[Gt] ;
.Pp
The bulk of the menu definition is the specification
of the menu items.
The general format of a menu item is:
.Dl option \*[Lt]string\*[Gt], \*[Lt]element_list\*[Gt] ;
The
.Aq Em string
is the text displayed for the menu item, this must be a quoted string
or a name #defined to something that will initialise a const char * field.
There may be an arbitrary number of these items.
(If there are shortcuts in the menu, a practical limit
of 51 should be recognized.
It produces shortcuts a to w, y, z, and A to Z.
x is the shortcut for the exit item.)
.Pp
The
.Aq Em element_list
is a comma separated list of what to do when the item is selected.
They may appear in any order.
.Pp
The first element processed when a menu item
is selected is the associated action.
The next element to be processed is the sub or next menu option.
They are declared as:
.Dl next menu \*[Lt]name\*[Gt]
.Dl sub menu \*[Lt]name\*[Gt]
The difference between these two is that a sub
menu will return to the current menu when exited.
The next menu will just replace the current
menu and when exited, will return to where the
current menu would have gone.
Only one of menu element may be used for each menu item.
Finally, after processing both the action and a sub menu,
the current menu will be exited if the element
.Dl exit
is specified.
.Em Note :
If
.Em exit
is specified, next menu will not work because
the menu system will exit the
.Em current
menu, even if current has been set by
.Em next menu .
.Pp
After all menu items, the final two menu definition
elements may appear.
The exit action is optional and provides C code to
execute in the process of exiting a menu.
If it is included, the format is:
.Dl exit \*[Lt]action\*[Gt] ;
.Pp
The final part of the menu definition is the optional
help string.
The format is:
.Dl help \*[Lt]text\*[Gt] ;
This text is displayed in a full page
help window if the question mark is typed.
The actual help text starts with a left brace
.Pq Em \&{
and ends with the matching right brace
.Pq Em \&} .
The braces are not included in the
help string, but all other characters between
them are included.
Newlines in the code translate to newlines in the help text.
.Sh DYNAMIC MENUS
If requested,
.Nm
supports dynamic menus by allowing the user to create new
menus.
The related definitions for using dynamic menus are:
.Bd -literal
struct menudesc;

typedef
struct menu_ent {
        const char  *opt_name;
        int         opt_menu;
        int         opt_flags;
        int         (*opt_action)(struct menudesc *);
} menu_ent ;

/* For opt_menu */
#define OPT_NOMENU -1

/* For opt_flags */
#define OPT_SUB    1
#define OPT_ENDWIN 2
#define OPT_EXIT   4

typedef
struct menudesc {
        const char  *title;
        int         y, x;
        int         h, w;
        int         mopt;
        int         numopts;
        int         cursel;
        int         topline;
        menu_ent    *opts;
        WINDOW      *mw;
        const char  *helpstr;
        const char  *exitstr;
        void       (*post_act)(struct menudesc *, void *);
        void       (*exit_act)(struct menudesc *, void *);
} menudesc ;

/* defines for mopt field. */
#define MC_NOEXITOPT 1
#define MC_NOBOX 2
#define MC_SCROLL 4
#define MC_NOSHORTCUT 8
#define MC_NOCLEAR 16

int new_menu (char * title, menu_ent * opts, int numopts,
        int x, int y, int h, int w, int mopt,
        void (*post_act)(struct menudesc *, void *),
        void (*exit_act)(struct menudesc *, void *), char *help);

void free_menu (int menu_no);
.Ed
.Pp
The
.Ar title
is the title displayed at the top of the menu.
The
.Ar opts
is an array of menu entry definitions that has
.Ar numopts
elements.
The programmer must build this array and
fill in all of the fields before processing calling
.Fn process_menu
for the new menu.
The fields of the
.Ar opts
may change at any time.
For example,
.Em opt_name
may change as a result of selecting that option.
When the menu is redisplayed, the new text is printed.
Arguments,
.Ar x , y , h ,
and
.Ar w
are the same as the options in the menu description.
.Ar mopt
is the boolean options.
Note, box, exit and shortcuts are enabled by default.
You need to add option flags to turn them off or turn on scrollable menus.
The options
.Ar post_act ,
and
.Ar exit_act
are function pointers to the the display action and the exit
action.
If they are
.Dv NULL ,
no call will be made.
And finally,
.Ar help
is the text to display in a help screen.
A
.Dv NULL
help pointer will disable the help feature for the menu.
.Sh FILES
.Bl -item -width /usr/share/misc/menu_sys.def
.It
.Pa /usr/share/misc/menu_sys.def
.El
.Sh EXAMPLES
The following is a simple menu definition file.
It is complete in that the output of
.Nm
may be compiled into a complete program.
For example, if the following was in a file called
.Pa example.mc ,
an executable program could be produced by the following commands.
.Bd -literal -offset indent
menuc -o example example.mc
cc -o example example.c -lcurses
.Ed
A much more complete example is available with the source
distribution in a subdirectory called
.Em testm .
.Bd -literal
/* This is an example menu definition file for menuc. */

{
#include \*[Lt]stdio.h\*[Gt]
#include \*[Lt]unistd.h\*[Gt]

/* Main program! This is often in a different file. */
int
main()
  {
    process_menu (MENU_main);
    endwin();
    return 0;
  }

/* Example initialize function! */
void
init_main()
  {
  }
}

default x=20, y=10, box, scrollable, exit;

error action {
   fprintf (stderr, "Example Menu: Could not initialize curses.");
   exit(1);
};

menu main, title "Main Menu", no exit, no shortcut;
   display action { init_main(); };
   option "Option 1",
      action (endwin) {
        printf ("That was option 1!");
        sleep(3);
      };
   option "Sub Menu", sub menu othermenu;
   option "Next Menu", next menu othermenu;
   option "Quit", exit;
   help {
This is a simple help screen for an example menu definition file.
};

menu othermenu, title "Sub/Next Menu", x=5, y=5, no box;
   option "Do Nothing!", action { };
.Ed
.Sh AUTHORS
.An Philip A. Nelson
for Piermont Information Systems Inc.
Initial ideas for this were developed and implemented in Pascal at the
Leiden University, Netherlands, in the summer of 1980.