bool GoEyeUtil::CheckInterior(const GoBoard& bd, const SgPointSet& area,
SgBlackWhite opp, bool checkBlocks)
{
bool hasSingleNbPoint = false;
int nuPoints = 0;
for (SgSetIterator it(area); it; ++it)
{
const SgPoint p(*it);
if (bd.IsEmpty(p))
{
int nuNbs = 0;
if (area.Contains(p + SG_NS))
++nuNbs;
if (area.Contains(p - SG_NS))
++nuNbs;
if (area.Contains(p + SG_WE))
++nuNbs;
if (area.Contains(p - SG_WE))
++nuNbs;
if (nuNbs == 1)
hasSingleNbPoint = true;
else if (nuNbs > 2)
return false;
}
else if (p == bd.Anchor(p))
{
if (bd.GetColor(p) != opp)
// if own stones on inside: not a tree shape.
return false;
int nuLibs = bd.NumLiberties(p);
if (nuLibs == 1)
hasSingleNbPoint = true;
else if (checkBlocks && nuLibs > 2)
return false;
}
++nuPoints;
}
return nuPoints == 1 || hasSingleNbPoint;
}
bool GoLadderUtil::IsLadderCaptureMove(const GoBoard& constBd,
SgPoint prey, SgPoint firstMove)
{
SG_ASSERT(constBd.NumLiberties(prey) == 2);
SG_ASSERT(constBd.IsLibertyOfBlock(firstMove, constBd.Anchor(prey)));
GoModBoard mbd(constBd);
GoBoard& bd = mbd.Board();
const SgBlackWhite defender = bd.GetStone(prey);
const SgBlackWhite attacker = SgOppBW(defender);
GoRestoreToPlay r(bd);
bd.SetToPlay(attacker);
if (PlayIfLegal(bd, firstMove, attacker))
{
GoLadder ladder;
bool isCapture = ladder.Ladder(bd, prey, defender,
0, false/*twoLibIsEscape*/
) < 0;
bd.Undo();
return isCapture;
}
else
return false;
}
