This class contains all the ladder-specific stuff. More...

#include <GoLadder.h>

Public Member Functions
	GoLadder ()
int	Ladder (const GoBoard &bd, SgPoint prey, SgBlackWhite toPlay, SgVector< SgPoint > *sequence, bool twoLibIsEscape=false)
	Main ladder routine.
Private Member Functions
bool	CheckMoveOverflow () const
void	InitMaxMoveNumber ()
bool	PointIsAdjToPrey (SgPoint p)
bool	BlockIsAdjToPrey (SgPoint p, int numAdj)
void	MarkStonesAsPrey (SgPoint p, SgVector< SgPoint > *stones=0)
	Marks all stones in the block p as part of the prey.
void	FilterAdjacent (GoPointList &adjBlocks)
	Filter out captured blocks, blocks not in atari, and blocks not adjacent to the prey.
int	PlayHunterMove (int depth, SgPoint move, SgPoint lib1, SgPoint lib2, const GoPointList &adjBlk, SgVector< SgPoint > *sequence)
	Play hunter move and update all the relevant information.
int	PlayPreyMove (int depth, SgPoint move, SgPoint lib1, const GoPointList &adjBlk, SgVector< SgPoint > *sequence)
	Play prey move and update all the relevant information.
bool	IsSnapback (SgPoint prey)
	Check whether the block at 'prey' is caught in a snapback.
int	PreyLadder (int depth, SgPoint lib1, const GoPointList &adjBlk, SgVector< SgPoint > *sequence)
int	HunterLadder (int depth, SgPoint lib1, const GoPointList &adjBlk, SgVector< SgPoint > *sequence)
int	HunterLadder (int depth, SgPoint lib1, SgPoint lib2, const GoPointList &adjBlk, SgVector< SgPoint > *sequence)
void	ReduceToBlocks (GoPointList &stones)
Private Attributes
int	m_maxMoveNumber
	Maximum move number before ladder should be aborted.
GoBoard *	m_bd
SgPointSet	m_partOfPrey
SgBlackWhite	m_preyColor
SgBlackWhite	m_hunterColor
Static Private Attributes
static const int	MAX_LADDER_MOVES = 200
	Maximum number of moves in ladder.

Detailed Description

This class contains all the ladder-specific stuff.

Definition at line 40 of file GoLadder.h.

Constructor & Destructor Documentation

GoLadder::GoLadder ( )

Definition at line 32 of file GoLadder.cpp.

Member Function Documentation

bool GoLadder::BlockIsAdjToPrey	(	SgPoint	p,
		int	numAdj
	)			`[private]`

Definition at line 96 of file GoLadder.cpp.

References GoBoard::IsColor(), m_bd, m_hunterColor, PointIsAdjToPrey(), and SG_ASSERT.

Referenced by FilterAdjacent(), Ladder(), and PreyLadder().

bool GoLadder::CheckMoveOverflow ( ) const [private]

Definition at line 36 of file GoLadder.cpp.

References m_bd, m_maxMoveNumber, and GoBoard::MoveNumber().

Referenced by HunterLadder(), Ladder(), and PreyLadder().

void GoLadder::FilterAdjacent ( GoPointList & adjBlocks ) [private]

Filter out captured blocks, blocks not in atari, and blocks not adjacent to the prey.

The latter are found by checking whether blocks adjacent to the block in question are the prey or not. Does not return the correct blocks if the prey has more than three liberties, but in that case, the prey has escaped anyway.

Definition at line 73 of file GoLadder.cpp.

References BlockIsAdjToPrey(), GoBoard::InAtari(), GoBoard::IsColor(), SgArrayList< SgPoint, SG_MAX_ONBOARD+1 >::Iterator, m_bd, m_hunterColor, SgArrayList< T, SIZE >::PushBack(), and ReduceToBlocks().

Referenced by Ladder(), and PlayPreyMove().

int GoLadder::HunterLadder	(	int	depth,
		SgPoint	lib1,
		SgPoint	lib2,
		const GoPointList &	adjBlk,
		SgVector< SgPoint > *	sequence
	)			`[private]`

Definition at line 308 of file GoLadder.cpp.

References SgPointUtil::AreAdjacent(), CheckMoveOverflow(), SgArrayList< T, SIZE >::IsEmpty(), m_bd, m_hunterColor, GoBoard::NumEmptyNeighbors(), GoBoard::Play(), PlayHunterMove(), PreyLadder(), SgVector< T >::PushBack(), SgVector< T >::SwapWith(), and GoBoard::Undo().

int GoLadder::HunterLadder	(	int	depth,
		SgPoint	lib1,
		const GoPointList &	adjBlk,
		SgVector< SgPoint > *	sequence
	)			`[private]`

Definition at line 295 of file GoLadder.cpp.

References CheckMoveOverflow(), SgVector< T >::SetTo(), and SG_UNUSED().

Referenced by Ladder(), and PlayPreyMove().

void GoLadder::InitMaxMoveNumber ( ) [private]

Definition at line 41 of file GoLadder.cpp.

References GO_MAX_NUM_MOVES, m_bd, m_maxMoveNumber, MAX_LADDER_MOVES, and GoBoard::MoveNumber().

Referenced by Ladder().

bool GoLadder::IsSnapback ( SgPoint prey ) [private]

Check whether the block at 'prey' is caught in a snapback.

Snapback means that it can be captured, but it's only a single stone, and the prey can capture right back.

Definition at line 519 of file GoLadder.cpp.

References GoBoard::GetStone(), GoBoard::InAtari(), GoBoard::IsSingleStone(), m_bd, GoBoardUtil::PlayIfLegal(), SgOppBW(), and GoBoard::Undo().

Referenced by Ladder().

int GoLadder::Ladder	(	const GoBoard &	bd,
		SgPoint	prey,
		SgBlackWhite	toPlay,
		SgVector< SgPoint > *	sequence,
		bool	twoLibIsEscape = `false`
	)

Main ladder routine.

twoLibIsEscape: if prey is to play and has two libs, does it count as an immediate escape, or shall we keep trying to capture?

Returns:: Positive value if ladder is good for prey, negative, if good for hunter.

Definition at line 395 of file GoLadder.cpp.

References GoBoardUtil::AdjacentStones(), BlockIsAdjToPrey(), GoModBoard::Board(), CheckMoveOverflow(), SgPointSet::Clear(), SgVector< T >::Clear(), SgVector< T >::Concat(), FilterAdjacent(), GoBoard::GetStone(), HunterLadder(), InitMaxMoveNumber(), GoBoard::IsColor(), IsSnapback(), SgArrayList< SgPoint, SG_MAX_ONBOARD+1 >::Iterator, m_bd, m_hunterColor, m_partOfPrey, m_preyColor, MarkStonesAsPrey(), GoBoardUtil::NeighborsOfColor(), GoBoard::NumLiberties(), GoBoard::Occupied(), GoBoardUtil::PlayIfLegal(), PreyLadder(), SgVector< T >::PushBack(), ReduceToBlocks(), SgVector< T >::Reverse(), SG_ASSERT, SG_EMPTY, SgOppBW(), and GoBoard::Undo().

Referenced by GoLadderUtil::Ladder(), and GoLadderUtil::LadderStatus().

void GoLadder::MarkStonesAsPrey	(	SgPoint	p,
		SgVector< SgPoint > *	stones = `0`
	)			`[private]`

Marks all stones in the block p as part of the prey.

If 'stones' is not 0, then append the stones to the existing list.

Definition at line 52 of file GoLadder.cpp.

References SgPointSet::Include(), GoBoard::IsValidPoint(), m_bd, m_partOfPrey, GoBoard::Occupied(), SgVector< T >::PushBack(), and SG_ASSERT.

Referenced by Ladder(), and PlayPreyMove().

int GoLadder::PlayHunterMove	(	int	depth,
		SgPoint	move,
		SgPoint	lib1,
		SgPoint	lib2,
		const GoPointList &	adjBlk,
		SgVector< SgPoint > *	sequence
	)			`[private]`