infocom/compilers/inform6/examples/contributions/echo.inf

!***************************************************************************
!**
!** Test For Echo
!**
!** This short Inform "game" gives an example of using the BeforeParsing()
!** entry point to simulate a room where commands are echoed back to
!** the player, much like Zork I's Loud Room.
!** 
!** Users are free to use this code anyway they like, and may modify it to 
!** suit their needs. 
!** 
!** John Menichelli (menichel@cox.net)
!** 
!***************************************************************************

Constant Story "Test For Echo";

Constant Headline "^A sample game (with apologies to Rush) 
					by John Menichelli^^";

Release 1;

Include "Parser";

Include "Verblib";

!***************************************************************************
!** 
!** The Loud Room has the attribute "general" when the echo effect has
!** been canceled.
!** 
!***************************************************************************

Object LoudRoom "Loud Room"
 with 	name   "Loud Room",
  		description [;
        	print "This is a large room with a ceiling which cannot be
			detected from the ground. A narrow passage leads east and west. ";
        
	        if (self has general)
    	    	"The room is eerie in its quietness.";
        	else
        		"The room is deafeningly loud with an undetermined
            	rushing sound. The sound seems to reverberate from
            	all of the walls, making it difficult even to think.";
 		],
 e_to	EastRoom,
 w_to	WestRoom,
 has 	light;

!***************************************************************************
!**
!** The obligatory platinum bar which can't be picked up until the echo
!** effect has been canceled.
!**
!***************************************************************************
 
Object -> PlatBar "platinum bar"
 with	name "platinum" "bar",
;
 
Object EastRoom "East Room"
 with 	name "East Room",
  		description "This is a room with an exit to the west.",
 w_to 	LoudRoom,
 has 	light;

 Object WestRoom "West Room"
 with 	name "West Room",
  		description "This is a room with an exit to the east.",
 e_to 	LoudRoom,
 has 	light;

 
[ BeforeParsing ;
	if (player notin LoudRoom) rfalse;

	if (player in LoudRoom && LoudRoom has general) rfalse;

	! Allow certain system verbs

	if (parse-->1 == 'restore' or 'restart' or 'save' or 'q//' or 'quit') rfalse;
	
	! Test for east or west movement and allow it

	if (parse-->1 == 'go' && (parse-->3 == 'e//' || parse-->3 == 'w//')) rfalse;

	if (parse-->1 == 'go' && (parse-->3 == 'east' || parse-->3 == 'west')) rfalse;

	if (parse-->1 == 'go' && parse->1 == 1) rfalse;
	
	if (parse-->1 == 'e//' or 'w//') rfalse;
	
	if (parse-->1 == 'east' or 'west') rfalse;

	! "Bug" response

	if (parse-->1 == 'bug') rfalse;

	! Print the last word in the input stream twice

	PrintRawInputWord(parse->1);
	print " ";
	PrintRawInputWord(parse->1);
	print " ...^";

	! Test for the word "echo" and cause it's effect
	! Gives the Loud Room general and cancels the echo effect

	if (parse-->1 == 'echo')
	{
		print "^The acoustics of the room change subtly.^^";
		give LoudRoom general;
		parse->1 = 1;
		parse-->1 = 'cth';
		<< Examine LoudRoom >>;
	}

	! Modify the parse table and continue execution. This prevents returning
	! a response to the command the player types.

	else
	{
		parse->1 = 1;
		parse-->1 = 'cth';
	}
];

!***************************************************************************
!**
!** Print word num from the raw input stream
!**
!***************************************************************************

[ PrintRawInputWord num i ;
	! Print non-dictionary word
  	for (i = 0: i < WordLength(num): i++) 
    	print (char) WordAddress(num)->i;
];

!***************************************************************************
!**
!**  Initialise
!**
!***************************************************************************

[Initialise ;

	location = EastRoom;
];

Include "Grammar";

[ EchoSub ;
	"echo echo ...";
];

Verb 'echo'
	*	->	Echo;

!***************************************************************************
!**
!** Dummy action when no response is desired. "Cth" was chosen because 
!** it's not a command most players would use. This is a crude hack; if 
!** anyone knows a better way, please let me know.
!** 
!***************************************************************************

[ CthSub ;
];

Verb 'cth'
	*	->	Cth;

[ BugSub ;
	"That's only your opinion.";
];

Verb 'bug'
	*	->	Bug;