GoLadderUtil Namespace Reference

Functions
bool	Ladder (const GoBoard &board, SgPoint prey, SgBlackWhite toPlay, bool fTwoLibIsEscape=false, SgVector< SgPoint > *sequence=0)
	Return whether or not the block at 'prey' can be captured in a ladder when 'toPlay' plays first.
GoLadderStatus	LadderStatus (const GoBoard &bd, SgPoint prey, bool fTwoLibIsEscape=false, SgPoint *toCapture=0, SgPoint *toEscape=0)
	Return whether the block at 'prey' is captured, escaped, or unsettled with regards to capture in a ladder.
bool	IsProtectedLiberty (const GoBoard &bd, SgPoint liberty, SgBlackWhite col, bool &byLadder, bool &isKoCut, bool tryLadder=true)
	Check if this is a chain connection point, or a ko cut point.
bool	IsProtectedLiberty (const GoBoard &bd, SgPoint liberty, SgBlackWhite col)
	Simple form, calls the complex form and ignores bool results.
SgPoint	TryLadder (const GoBoard &bd, SgPoint prey, SgBlackWhite firstPlayer)
	try to escape/capture prey block Possible return values: SG_PASS if already escaped/captured the point to play SG_NULLMOVE in case of failure

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Function Documentation

bool GoLadderUtil::IsProtectedLiberty	(	const GoBoard &	bd,
		SgPoint	liberty,
		SgBlackWhite	col,
		bool &	byLadder,
		bool &	isKoCut,
		bool	tryLadder = true
	)

Check if this is a chain connection point, or a ko cut point.

Try to play there as opponent, then check:

• Suicide
• self removal, self atari
• can be captured by ladder?
• is it a Ko?

Definition at line 615 of file GoLadder.cpp.

References GoModBoard::Board(), GO_MOVEFLAG_SUICIDE, GoBoard::InAtari(), Ladder(), GoBoard::LastMoveInfo(), GoBoard::NumLiberties(), GoBoard::NumStones(), GoBoardUtil::PlayIfLegal(), GoBoard::SetToPlay(), SgOppBW(), GoBoard::TheLiberty(), GoBoard::ToPlay(), and GoBoard::Undo().

Referenced by IsProtectedLiberty().

bool GoLadderUtil::IsProtectedLiberty	(	const GoBoard &	bd,
		SgPoint	liberty,
		SgBlackWhite	col
	)

Simple form, calls the complex form and ignores bool results.

Definition at line 606 of file GoLadder.cpp.

References IsProtectedLiberty().

bool GoLadderUtil::Ladder	(	const GoBoard &	board,
		SgPoint	prey,
		SgBlackWhite	toPlay,
		bool	fTwoLibIsEscape = false,
		SgVector< SgPoint > *	sequence = 0
	)

Return whether or not the block at 'prey' can be captured in a ladder when 'toPlay' plays first.

True means capture, false means escape. If 'sequence' is not 0, return a sequence of moves to capture or escape (need not be the optimal sequence). Return an empty sequence if the prey is already captured or has escaped, without needing to play a move. If the prey can be temporarily removed from the board but can capture back immediately (snapback), return that the prey cannot be captured.

Definition at line 537 of file GoLadder.cpp.

References GoBoard::GetHashCode(), GoBoard::IsValidPoint(), GoLadder::Ladder(), GoBoard::Occupied(), and SG_ASSERT.

Referenced by IsProtectedLiberty(), and TryLadder().

GoLadderStatus GoLadderUtil::LadderStatus	(	const GoBoard &	bd,
		SgPoint	prey,
		bool	fTwoLibIsEscape = false,
		SgPoint *	toCapture = 0,
		SgPoint *	toEscape = 0
	)

Return whether the block at 'prey' is captured, escaped, or unsettled with regards to capture in a ladder.

If it is unsettled, set '*toCapture' and '*toEscape' (if not 0) to the capturing/escaping move to play. Otherwise, leave '*toCapture' and '*toEscape' unchanged. The point at 'prey' must be occupied.

Definition at line 561 of file GoLadder.cpp.

References SgVector< T >::Front(), GoBoard::GetHashCode(), GoBoard::GetStone(), GO_LADDER_CAPTURED, SgVector< T >::IsEmpty(), GoBoard::IsValidPoint(), GoLadder::Ladder(), SgVector< T >::NonEmpty(), GoBoard::Occupied(), SG_ASSERT, SG_PASS, and SgOppBW().

Referenced by GoGtpExtraCommands::CmdLadder().

SgPoint GoLadderUtil::TryLadder	(	const GoBoard &	bd,
		SgPoint	prey,
		SgBlackWhite	firstPlayer
	)

try to escape/capture prey block Possible return values:

• SG_PASS if already escaped/captured
• the point to play
• SG_NULLMOVE in case of failure

Definition at line 677 of file GoLadder.cpp.

References SgVector< T >::Front(), GoBoard::GetStone(), SgVector< T >::IsEmpty(), Ladder(), SG_NULLMOVE, and SG_PASS.