org.moyoman.module.ladder.ladderimpl
Class LadderImpl

java.lang.Object
  |
  +--org.moyoman.module.Module
        |
        +--org.moyoman.module.ladder.ladderimpl.LadderImpl

All Implemented Interfaces:

Cloneable, Component, Ladder, ModuleInterface, Serializable

public class LadderImpl

extends Module

implements Ladder

This module implements the Ladder interface. This module is meant to be both a working Ladder module and a demonstration of how to write a search based module.

Currently, this module is stateless, that is, ladders are read out after each move even though the last move may not have changed ladders which were already present. Caching of results should result in a marked performance improvement.

See Also:

Serialized Form

Field Summary

private static DebugType[]	dt The debug types which this module produces.
private boolean	isGenerated This is true after generateMove() but before makeMove() is called.
private Board	lastBoard The current Board module.
private Groups	lastGroups The current Groups module.
private MoveDescriptorForest	mdf The sequence of best play for the various ladders on the board.
private static ModuleType[]	mt The modules upon which this module depends.
private HashMap	results The key is a SingleGroup object, and the value is a LadderInfo object.
private RatedMove[]	rm The moves suggested by this module.

Fields inherited from class org.moyoman.module.Module

Fields inherited from interface org.moyoman.module.ladder.Ladder

CONFIDENCE

Constructor Summary

LadderImpl(GameId id, ModuleName name)
Create a new LadderImpl object.

Method Summary

private void	calculateLadder(Scheduler sch, MoveDescriptorForest mdf, LadderInfo li, SingleGroup sg, MoveDescriptor last) This method adds two moves to a ladder per invocation.
private LadderInfo	calculateLadder(SingleGroup sg) Calculate ladder information for a single group.
private Set	calculateLadderBreakers(SingleGroup sg, MoveDescriptorForest mdf) Find all moves which are ladder breakers for the given group.
private Set	calculateLadderThreats(SingleGroup sg, MoveDescriptorForest mdf) Find all moves which are ladder breakers for the given group.
boolean	canGroupPotentiallyBeCaught(SingleGroup sg) Return true if the group is in a potential ladder and would be caught if the opponent moves first.
Object	clone() Clone the module.
Stone[]	createLadder(SingleGroup sg) Get the stones which would put the group into a ladder.
void	generateMove(Module[] modules) Generate moves based on the ladders and potential ladders on the board.
Debug[]	getDebugInformation(DebugType[] types) Return Debug objects based on the current analysis of the board.
DebugType[]	getDebugTypes() Get the debug types that this module supports.
Set	getLadderBreakers(SingleGroup sg) Get all stones which would break the ladder on the group and allow it to escape.
Set	getLadderThreats(SingleGroup sg) Get all stones which would threaten to capture the ladder.
RatedMove[]	getMoves() Get the moves rated by this module.
private short	getPathLength(MoveDescriptorForest forest, MoveDescriptor md, short len) Return the shortest path length of the ladder from this point.
ModuleType[]	getRequiredModuleList() Get the module types used by this module.
SingleGroup[]	groupsInLadder() Get all of the groups which are currently in a ladder.
SingleGroup[]	groupsInPotentialLadder() Get all of the groups which could be put in a ladder if the opponent moves next.
boolean	isGroupCaught(SingleGroup sg) Determine if the group in the ladder can be captured.
boolean	isInLadder(SingleGroup sg) Determine if the group is in a ladder.
boolean	isInPotentialLadder(SingleGroup sg) Determine if the group is in a potential ladder.
private int	libCount(Point pt, Color escapeColor)
void	makeMove(Move move, Module[] modules) Update this module with the current move.
private void	onePairAnalysis(Point attackerPt, Point escaperPt, Scheduler sch, MoveDescriptorForest mdf, LadderInfo li, SingleGroup sg, MoveDescriptor last) Add two moves to the ladder.
private SingleGroup	refresh(SingleGroup sg) Return the corresponding SingleGroup object from the current lastGroups.
short	totalMovesToCapture(SingleGroup sg) Return the total number of moves to capture the group.

Methods inherited from class org.moyoman.module.Module

checkTime, create, createHelper, debug, error, error, fatal, fatal, getAllHelpers, getHelper, getId, getKomi, getModule, getModuleName, getScheduler, information, setTime, warning, warning

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.moyoman.module.ModuleInterface

getScheduler

Field Detail

mt

private static ModuleType[] mt

The modules upon which this module depends.

dt

private static DebugType[] dt

The debug types which this module produces.

rm

private RatedMove[] rm

The moves suggested by this module.

isGenerated

private boolean isGenerated

This is true after generateMove() but before makeMove() is called.

lastBoard

private Board lastBoard

The current Board module.

lastGroups

private Groups lastGroups

The current Groups module.

results

private HashMap results

The key is a SingleGroup object, and the value is a LadderInfo object.

mdf

private MoveDescriptorForest mdf

The sequence of best play for the various ladders on the board.

Constructor Detail

LadderImpl

public LadderImpl(GameId id,
                  ModuleName name)
           throws InternalErrorException

Create a new LadderImpl object.

Parameters:

id - The id of this player.

name - The name of this module.

Throws:

InternalErrorException - Thrown if the operation fails for any reason.

Method Detail

refresh

private SingleGroup refresh(SingleGroup sg)
                     throws NoSuchDataException

Return the corresponding SingleGroup object from the current lastGroups.

Parameters:

sg - A SingleGroup object.

Returns:

A SingleGroup object corresponding to the sg parameter which is contained by lastGroups.

Throws:

NoSuchDataException - Thrown if there is no single group corresponding to the sg parameter.

isInLadder

public boolean isInLadder(SingleGroup sg)

Determine if the group is in a ladder.

Specified by:

isInLadder in interface Ladder

Parameters:

sg - The SingleGroup in question.

Returns:

true if the group is in a ladder, or false.

isInPotentialLadder

public boolean isInPotentialLadder(SingleGroup sg)

Determine if the group is in a potential ladder. A potential ladder is defined as a situation where the opponent can put the group in a ladder if a stone is not added to the group.

Specified by:

isInPotentialLadder in interface Ladder

Parameters:

sg - The SingleGroup in question.

Returns:

true if the group is in a potential ladder, or false.

groupsInLadder

public SingleGroup[] groupsInLadder()

Get all of the groups which are currently in a ladder. It does not matter if the ladders work or not.

Specified by:

groupsInLadder in interface Ladder

Returns:

An array of SingleGroup objects.

groupsInPotentialLadder

public SingleGroup[] groupsInPotentialLadder()

Get all of the groups which could be put in a ladder if the opponent moves next. It does not matter if the ladders would work or not.

Specified by:

groupsInPotentialLadder in interface Ladder

Returns:

An array of SingleGroup objects.

isGroupCaught

public boolean isGroupCaught(SingleGroup sg)
                      throws IllegalArgumentException

Determine if the group in the ladder can be captured.

Specified by:

isGroupCaught in interface Ladder

Returns:

true if the group is caught, or false if it can escape.

Throws:

IllegalArgumentException - Thrown if isInLadder(sg) would return false.

canGroupPotentiallyBeCaught

public boolean canGroupPotentiallyBeCaught(SingleGroup sg)

Return true if the group is in a potential ladder and would be caught if the opponent moves first. The method returns false otherwise, even if the group is actually in a ladder.

Specified by:

canGroupPotentiallyBeCaught in interface Ladder

Parameters:

sg - The SingleGroup in question.

Returns:

true if the group is in a potential ladder and can be caught.

getLadderBreakers

public Set getLadderBreakers(SingleGroup sg)
                      throws IllegalArgumentException

Get all stones which would break the ladder on the group and allow it to escape. These stones are returned regardless of whether the ladder currently works or not.

Specified by:

getLadderBreakers in interface Ladder

Parameters:

sg - The group in question.

Returns:

An array of Stone objects.

Throws:

IllegalArgumentException - Thrown if isInLadder(sg) would return false.

getLadderThreats

public Set getLadderThreats(SingleGroup sg)
                     throws IllegalArgumentException

Get all stones which would threaten to capture the ladder. These stones are returned regardless of whether the ladder currently works or not.

Specified by:

getLadderThreats in interface Ladder

Parameters:

sg - The group in question.

Returns:

An array of Stone objects.

Throws:

IllegalArgumentException - Thrown if isInLadder(sg) would return false.

createLadder

public Stone[] createLadder(SingleGroup sg)
                     throws IllegalArgumentException

Get the stones which would put the group into a ladder. The group must already be in a potential ladder, so playing any of the stones returned would put the group in a ladder.

Specified by:

createLadder in interface Ladder

Parameters:

sg - The group in question.

Returns:

An array of Stone objects.

Throws:

IllegalArgumentException - Thrown if the group is not in a potential ladder.

totalMovesToCapture

public short totalMovesToCapture(SingleGroup sg)
                          throws IllegalArgumentException

Return the total number of moves to capture the group. The count includes moves by both sides. If there are branches, then the smallest number of moves which results in a capture is used.

Specified by:

totalMovesToCapture in interface Ladder

Parameters:

sg - The group in question.

Returns:

A short which is the smallest number of moves to capture.

Throws:

IllegalArgumentException - Thrown if the group is not in a ladder or potential ladder, or if the group cannot be captured.

getPathLength

private short getPathLength(MoveDescriptorForest forest,
                            MoveDescriptor md,
                            short len)
                     throws IllegalArgumentException

Return the shortest path length of the ladder from this point. This method calls itself recursively to walk the ladder.

Parameters:

forest - The sequences of the ladder.

md - The current position of the ladder being analyzed.

len - The length of the ladder to this position.

Returns:

The shortest path through the ladder.

Throws:

IllegalArgumentException - Thrown if the group is not in a ladder or potential ladder, or if the group cannot be captured.

generateMove

public void generateMove(Module[] modules)
                  throws InternalErrorException

Generate moves based on the ladders and potential ladders on the board.

Specified by:

generateMove in class Module

Parameters:

modules - The modules which this module uses.

Throws:

InternalErrorException - Thrown if the module fails for any reason.

getDebugInformation

public Debug[] getDebugInformation(DebugType[] types)

Return Debug objects based on the current analysis of the board. The following debug objects are returned:

• Forest - Shows the sequences of moves for all ladders and potential ladders.
• Continuous - Shows rated moves for the last player.
• Discrete - Shows ladder threats and breakers for the current player.
• Discrete - Shows ladder threats and breakers for the opponent player.

Specified by:

getDebugInformation in class Module

Parameters:

types - The types of debug objects that the caller can use.

Returns:

An array of Debug objects.

getDebugTypes

public DebugType[] getDebugTypes()

Get the debug types that this module supports.

Specified by:

getDebugTypes in class Module

Returns:

An array of DebugType objects.

getMoves

public RatedMove[] getMoves()

Get the moves rated by this module.

Specified by:

getMoves in interface ModuleInterface

Specified by:

getMoves in class Module

Returns:

An array of RatedMove objects.

getRequiredModuleList

public ModuleType[] getRequiredModuleList()

Get the module types used by this module.

Specified by:

getRequiredModuleList in class Module

Returns:

An array of ModuleType objects.

makeMove

public void makeMove(Move move,
                     Module[] modules)
              throws InternalErrorException

Update this module with the current move.

Specified by:

makeMove in class Module

Parameters:

move - The last move made.

modules - The modules that this module uses.

Throws:

InternalErrorException - Thrown if the module fails for any reason.

calculateLadder

private LadderInfo calculateLadder(SingleGroup sg)

Calculate ladder information for a single group. This method calculates the information from scratch, without using any information from previous stages of the game.

Parameters:

sg - The SingleGroup in question.

Returns:

a LadderInfo object containing information about this group, or null if the group is not in a ladder.

calculateLadder

private void calculateLadder(Scheduler sch,
                             MoveDescriptorForest mdf,
                             LadderInfo li,
                             SingleGroup sg,
                             MoveDescriptor last)

This method adds two moves to a ladder per invocation. It and onePairAnalysis() recursively call each other until the ladder is completely read out. On entry, the single group has two or less liberties, and it is the attackers turn to move. If either or both of the two possible ataris followed by the escaper playing on the other liberty results in the single group having 2 or less liberties, then it is added to the sequence of moves. Sequences terminate upon the escaping group being captured or having 3 or more liberties.

Parameters:

sch - The Scheduler which represents the state of the board being analyzed.

mdf - The sequences of moves found so far.

li - The LadderInfo object with the results so far.

sg - The single group which is trying to be caught in the ladder.

onePairAnalysis

private void onePairAnalysis(Point attackerPt,
                             Point escaperPt,
                             Scheduler sch,
                             MoveDescriptorForest mdf,
                             LadderInfo li,
                             SingleGroup sg,
                             MoveDescriptor last)

Add two moves to the ladder. On entry, the group under attack has two liberties and it is the attackers turn.

Parameters:

escaperPt - The point on which the escaper is to play after the attackers move.

sch - The Scheduler object representing the current position being analyzed.

mdf - The sequence of moves in the ladder.

li - The LadderInfo object.

sg - The group under attack.

last - The last position analyzed so far.

calculateLadderBreakers

private Set calculateLadderBreakers(SingleGroup sg,
                                    MoveDescriptorForest mdf)

Find all moves which are ladder breakers for the given group. Ladder breakers are found up until the ladder branches. Once the ladder branches, no moves are returned from beyond that point. This method does not currently find all ladder breakers, but finds the vast majority of them.

Parameters:

sg - The group in question.

mdf - The sequences of moves for the ladder.

Returns:

A Set which contains all of the stones which are ladder breakers.

libCount

private int libCount(Point pt,
                     Color escapeColor)

calculateLadderThreats

private Set calculateLadderThreats(SingleGroup sg,
                                   MoveDescriptorForest mdf)

Find all moves which are ladder breakers for the given group.

Parameters:

sg - The group in question.

mdf - The sequences of moves for the ladder.

Returns:

A Set which contains all of the stones which are ladder breakers.

clone

public Object clone()

Description copied from interface: ModuleInterface

Clone the module. This method overrides the one in Object. Cloning modules is an important requirement for the system to function correctly. The derived class of Module must override this method. It may be as straightforward as calling super.clone(). Consult any Java textbook for more details. If you are not sure, ask for help.

Specified by:

clone in interface ModuleInterface

Overrides:

clone in class Module

Returns:

The cloned Module object.