wyvern.kernel.motion
Class PushCommand

java.lang.Object
  wyvern.kernel.motion.PushCommand

All Implemented Interfaces:

BuiltInCommand, Command

public class PushCommand

extends java.lang.Object

implements BuiltInCommand

This command implements pushing objects around. It shares some of the semantics of movement, including the complex checks for whether the agent can move into the destination square, which is why it's in the kernel.

Version:

1.0, Jun 06, 1998

Author:

Steve Yegge

Nested Class Summary

class

PushCommand.PushEvent Inner class for encapsulating a Push event.

Method Summary

void	addCommands(java.util.Map commands, CommandList list) Adds known commands.
CommandEvent	createEvent(CommandEvent initial) Creates a PushEvent from scratch.
CommandEvent	createFromMove(MoveEvent move, Point target, GameObject pushable, Predicate pp) Mogrifies a MoveEvent into a PushEvent.
boolean	execute(CommandEvent event) Executes the push.
static PushCommand	getImpl()
boolean	knowsCommand(java.lang.String cmd) Returns 'true' for handling "push".

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getImpl

public static PushCommand getImpl()

addCommands

public void addCommands(java.util.Map commands,
                        CommandList list)

Adds known commands.

Specified by:

addCommands in interface BuiltInCommand

Parameters:

commands - a Map whose keys are commands, and whose values are Commands that handle those commands.

list - the CommandList the Command is being added to.

knowsCommand

public boolean knowsCommand(java.lang.String cmd)

Returns 'true' for handling "push".

Specified by:

knowsCommand in interface Command

Parameters:

cmd - the entire command string, including arguments

Returns:

true if we want to handle the command

createEvent

public CommandEvent createEvent(CommandEvent initial)

Creates a PushEvent from scratch. Called when someone commanded a Commandable to "push {something}".

Specified by:

createEvent in interface Command

Parameters:

initial - the CommandEvent that started this push. It's a generic event used to hold the command arguments.

Returns:

a CommandEvent subclass encapsulating this command's execution parameters and state. It should copy in the fields from the passed-in event.

createFromMove

public CommandEvent createFromMove(MoveEvent move,
                                   Point target,
                                   GameObject pushable,
                                   Predicate pp)

Mogrifies a MoveEvent into a PushEvent. Called by the ContactManager when it discovers that something pushable is in the way of the move. This method was separated from the createEvent method because in 99+% of all pushes originate as moves, and we don't want to have to re-check all the preconditions.

Parameters:

move - the MoveEvent in whose destination list the ContactManager found a pushable object.

target - the map location of the pushable object

pushable - the pushable object we found

pp - a PropertyPredicate instance that checks for "pushable"

execute

public boolean execute(CommandEvent event)

Executes the push.

Specified by:

execute in interface Command

Parameters:

event - the PushEvent to execute

Returns:

true if push succeeded, else false