public static List<List<MoveDesc>> Run(AnalysisNode starting_node,
INodeGenerator node_generator, uint fullmove_depth)
{
Debug.Assert(starting_node != null && starting_node.Position != null);
Debug.Assert(node_generator != null);
Debug.Assert(fullmove_depth > 0);
List<List<MoveDesc>> result = null;
// Run recursive function, which finds all forced mates
// This call erases all nodes (except root), which do not
// lead to a forced checkmate. So, if there is (are) forced mate(s)
// then the remaining tree nodes give us an answer
if (FindMateRecursive(starting_node, node_generator, fullmove_depth)
&& !starting_node.IsLeaf)
{
result = new List<List<MoveDesc>>();
foreach (var child in starting_node.Children)
{
CollectAllVariations(child, new List<MoveDesc>(), result);
}
Debug.Assert(result.Count > 0);
}
return result;
}
public float Evaluate(AnalysisNode node, IPersonality personality)
{
m_white_data.Init(node.Position);
m_black_data.Init(node.Position);
ulong white_good_cells = 0;
ulong black_good_cells = 0;
float white_value = m_white_data.m_material;
float black_value = m_black_data.m_material;
// TODO - if not endgame..
white_good_cells = CentralSquares;
black_good_cells = CentralSquares;
// TODO - create arrays for pawns, we need them anyway
var white_pieces = node.Position.GetPieces(Players.White);
var black_pieces = node.Position.GetPieces(Players.Black);
var white_good_cells_count = CountGoodCells(white_good_cells,
Players.White, white_pieces);
var black_good_cells_count = CountGoodCells(black_good_cells,
Players.Black, black_pieces);
// TODO - consider here optimistic and pessimistic players
white_value += 0.05f * white_good_cells_count;
black_value += 0.05f * black_good_cells_count;
// TODO - do more
return white_value - black_value;
}
// TODO - consider removing
//public Fingerprint Fingerprint { get; set; }
public AnalysisNode(AnalysisNode parent, Position.Position p, Move m)
{
Debug.Assert(p != null);
Parent = parent;
// Must init ParentMove before Position
m_parent_move = m;
Position = p;
Children = null;
IsWhiteToMove = p.IsWhiteToMove;
}
private static bool FindMateRecursive(AnalysisNode starting_node,
INodeGenerator nodes_generator, uint fullmove_depth)
{
Debug.Assert(fullmove_depth > 0);
if (fullmove_depth == 1)
{
nodes_generator.GenerateAllChildren(starting_node, 1);
// Release all children nodes except checkmate nodes
nodes_generator.ReleaseChildren(x =>
{
if (x.Position.IsInCheck)
{
nodes_generator.GenerateAllChildren(x, 1);
return !x.Position.IsCheckmate;
}
return true;
},
starting_node);
}
else
{
nodes_generator.GenerateAllChildren(starting_node, 2);
foreach (var my_move in starting_node.Children)
{
bool is_skip = false;
foreach (var her_move in my_move.Children)
{
if (!FindMateRecursive(her_move, nodes_generator,
fullmove_depth - 1))
{
// My opponent can avoid being checkmated
is_skip = true;
break;
}
}
if (is_skip)
{
nodes_generator.ReleaseChildren(my_move);
}
}
// Erase all children except checkmate nodes or move sequences
// that lead to a force mate
nodes_generator.ReleaseChildren(x =>
{
return !x.Position.IsCheckmate && x.Children == null;
},
starting_node);
}
return starting_node.Children != null;
}
public static void Evaluate(AnalysisNode root)
{
for (int i = 0; i < root.Children.Count; ++i)
{
var child = root.Children[i];
if (child.Children != null)
Evaluate(child);
}
var best_child = GetBestChild(root);
if (best_child != null)
{
root.MinmaxEvaluation = best_child.MinmaxEvaluation;
}
}
private static void CollectAllVariations(AnalysisNode current_node,
List<MoveDesc> current_parents, List<List<MoveDesc>> variations)
{
var new_parents = new List<MoveDesc>(current_parents.Count + 1);
new_parents.AddRange(current_parents);
new_parents.Add(current_node.ParentMove.ToMoveDesc(current_node.Position));
if (current_node.Children == null || current_node.Children.Count == 0)
{
// Leaf node
variations.Add(new List<MoveDesc>(new_parents));
}
else
{
foreach (var child in current_node.Children)
{
CollectAllVariations(child, new_parents, variations);
}
}
}
public static AnalysisNode GetBestChild(AnalysisNode root)
{
int best_index = -1;
if (root.IsWhiteToMove)
{
float best_evaluation = float.MinValue;
// Return the child with the greatest evaluation
for (int i = 0; i < root.Children.Count; ++i)
{
var child = root.Children[i];
if (child.IsLeaf && child.HasStaticEvaluation)
{
child.MinmaxEvaluation = child.StaticEvaluation;
}
if (child.HasMinmaxEvaluation
&& child.MinmaxEvaluation > best_evaluation)
{
best_index = i;
best_evaluation = child.MinmaxEvaluation;
}
}
}
else
{
// Return the child with the lowest evaluation
float best_evaluation = float.MaxValue;
for (int i = 0; i < root.Children.Count; ++i)
{
var child = root.Children[i];
if (child.IsLeaf && child.HasStaticEvaluation)
{
child.MinmaxEvaluation = child.StaticEvaluation;
}
if (child.HasMinmaxEvaluation
&& child.MinmaxEvaluation < best_evaluation)
{
best_index = i;
best_evaluation = child.MinmaxEvaluation;
}
}
}
return best_index == -1 ? null : root.Children[best_index];
}
/// <summary>
/// Erases all children nodes which satisfy the specified condition
/// WARNING: this method is not thread-safe, run it in parallel only
/// for nodes in non-overlapping subtrees
/// </summary>
public void ReleaseChildren(Predicate<AnalysisNode> condition,
AnalysisNode subtree_root)
{
if (subtree_root.Children == null)
{
return;
}
List<AnalysisNode> new_children = null;
foreach (var child in subtree_root.Children)
{
if (condition(child))
{
ReleaseNode(child);
}
else
{
if (new_children == null)
{
new_children = new List<AnalysisNode>(
subtree_root.Children.Count);
}
new_children.Add(child);
}
}
if (new_children == null
|| (new_children.Count != subtree_root.Children.Count))
{
subtree_root.IsSomeChildrenErased = true;
subtree_root.SetChildrenList(new_children);
}
}
public void UpdateBestLine(AnalysisNode root_node, bool report)
{
if (root_node == null || root_node.Children == null
|| root_node.Children.Count == 0)
{
m_best_line = null;
Evaluation = 0;
}
else
{
m_best_line = new List<MoveDesc>(64);
Evaluation = root_node.HasMinmaxEvaluation ?
root_node.MinmaxEvaluation : 0f;
var cur_node = MinMax.GetBestChild(root_node);
while (cur_node != null)
{
m_best_line.Add(cur_node.GetParentMoveDesc());
cur_node = cur_node.Children != null
&& cur_node.Children.Count > 0
? MinMax.GetBestChild(cur_node) : null;
}
// Just in case there are no evaluated nodes
if (m_best_line.Count == 0)
{
m_best_line.Add(root_node.Children[0].GetParentMoveDesc());
}
}
UpdateTime();
if (report)
{
Factory.Instance.AnalysisStatsReporter?.Report(this);
}
}
private void AnalyzeChildren(AnalysisNode root, int depth_to_go)
{
// If this is not true, then we must continue recursively after
// we have statically evaluated a grandchild node
Debug.Assert(depth_to_go <= 2);
m_tree.GenerateAllChildren(root, 1);
for (int i = 0; i < root.Children.Count; ++i)
{
var child = root.Children[i];
var move = child.ParentMove;
// For some kind of moves we can't say if they are so
// good or not without seeing possible replies
if (move.IsCapture || move.IsPromotion
|| child.Position.IsInCheck)
{
m_tree.GenerateAllChildren(child, 1);
for (int j = 0; j < child.Children.Count; ++j)
{
var grandchild = child.Children[j];
MakeStaticEvaluation(grandchild);
// Continue recursively here if depth_to_go > 2
}
}
else
{
MakeStaticEvaluation(child);
if (depth_to_go > 1)
{
AnalyzeChildren(child, depth_to_go - 1);
}
}
}
}
// Returns best children
private AnalysisNode AnalyzeFourBestChildren(AnalysisNode root,
int depth_to_go)
{
AnalysisNode best_1 = null;
AnalysisNode best_2 = null;
AnalysisNode best_3 = null;
AnalysisNode best_4 = null;
bool is_white_to_move = root.IsWhiteToMove;
for (int i = 0; i < root.Children.Count; ++i)
{
var child = root.Children[i];
if (depth_to_go > 1)
{
var best_grandchild = AnalyzeFourBestChildren(child,
depth_to_go - 1);
if (best_grandchild != null)
child.MinmaxEvaluation = best_grandchild.MinmaxEvaluation;
}
else
{
AnalyzeChildren(child, 2);
MinMax.Evaluate(child);
}
bool is_release_grandchildren = true;
if (child.HasMinmaxEvaluation)
{
if (best_4 == null || MinMax.IsBetter(child.MinmaxEvaluation,
best_4.MinmaxEvaluation, is_white_to_move))
{
is_release_grandchildren = false;
if (best_4 != null)
m_tree.ReleaseChildren(best_4);
best_4 = child;
if (best_3 == null || MinMax.IsBetter(
child.MinmaxEvaluation, best_3.MinmaxEvaluation,
is_white_to_move))
{
best_4 = best_3;
best_3 = child;
if (best_2 == null || MinMax.IsBetter(
child.MinmaxEvaluation, best_2.MinmaxEvaluation,
is_white_to_move))
{
best_3 = best_2;
best_2 = child;
if (best_1 == null || MinMax.IsBetter(
child.MinmaxEvaluation, best_1.MinmaxEvaluation,
is_white_to_move))
{
best_2 = best_1;
best_1 = child;
}
}
}
}
}
if (is_release_grandchildren)
m_tree.ReleaseChildren(child);
} // loop over root's children
m_tree.ReleaseChildren(x => !(ReferenceEquals(x, best_1)
|| ReferenceEquals(x, best_2) || ReferenceEquals(x, best_3)
|| ReferenceEquals(x, best_4)), root);
return best_1;
}
/// <summary>
/// Generates all immediate children of the specified node
/// WARNING: this method is not thread-safe, run it in parallel only
/// for nodes in non-overlapping subtrees
/// </summary>
public void GenerateAllChildren(AnalysisNode parent, uint depth,
bool is_restore_missing_positions = true)
{
Debug.Assert(parent != null && parent.Position != null);
Debug.Assert(depth > 0);
// Check if all moves were generated for the parent node
// If not, clear the list of children and re-generate them all
if (parent.IsSomeChildrenErased)
{
parent.SetChildrenList(null);
}
if (parent.Children == null)
{
parent.InitChildrenList();
// TODO - conside memory pooling for the list of moves
var moves = new List<Move>(64);
MovesGenerator.GenerateMoves(parent.Position, moves);
var player_to_move = parent.Position.PlayerToMove;
bool is_parent_in_check = parent.Position.IsInCheck;
foreach (var m in moves)
{
var child_position = parent.Position.PlayMove(m);
// Last check if the move is a legal move
// Didn't do it earlier, as we need resulting position
// for this
if (!PositionValidator.IsMyMovePutsMyKingInCheck(
player_to_move, m, child_position, is_parent_in_check))
{
parent.Children.Add(new AnalysisNode(parent, child_position,
m));
Interlocked.Increment(ref m_node_count);
}
}
// Let the position to know whether there are legal moves
parent.Position.HasLegalMoves = !parent.IsLeaf;
}
else if (is_restore_missing_positions)
{
foreach (var node in parent.Children)
{
if (node.Position == null)
{
// Position object was destroyed to free the memory
// Re-create it now
node.RecreatePosition();
}
}
}
// Indicate that all children are generated and present in the collection
// Unless we have generated the moves having some restrictions imposed
parent.IsSomeChildrenErased = false;
// Generate next levels of child nodes recursively
if (depth > 1)
{
foreach (var node in parent.Children)
{
GenerateAllChildren(node, depth - 1, is_restore_missing_positions);
}
}
if (ReferenceEquals(parent, Root))
{
m_listener.RootChildrenGenerated(Root.Children);
}
}
// Assumes the tree is locked
private void ReleaseNode(AnalysisNode subtree_root)
{
if (subtree_root.Children != null)
{
foreach (var child in subtree_root.Children)
{
ReleaseNode(child);
}
subtree_root.SetChildrenList(null);
}
Interlocked.Decrement(ref m_node_count);
}
// Assumes that the tree is locked
private void Clean()
{
if (Root != null)
{
ReleaseNode(Root);
Debug.Assert(NodeCount == 0);
Root = null;
m_listener.RootChildrenGenerated(null);
}
}
public void SetRoot(Position.Position p, Move parent_move)
{
Clean();
if (p != null)
{
Root = new AnalysisNode(null, p, parent_move);
m_node_count = 1;
// Probably this position was not analyzed yet, and IsInCheck
// is not initialized yet. Evaluate and set IsInCheck flag
p.IsInCheck = PositionHelper.IsCellAttacked(
new ChessboardCell(p.GetPieces(p.PlayerToMove).KingsCell),
Helper.GetOtherPlayer(p.PlayerToMove), p);
// For root we want to create children and grandchildren
// To detect stalemate or checkmate
GenerateAllChildren(Root, 2);
}
m_listener.RootPositionChanged(p);
}
/// <summary>
/// Erases all children nodes
/// WARNING: this method is not thread-safe, run it in parallel only
/// for nodes in non-overlapping subtrees
/// </summary>
public void ReleaseChildren(AnalysisNode subtree_root)
{
if (subtree_root.Children != null)
{
foreach (var child in subtree_root.Children)
{
ReleaseNode(child);
}
}
subtree_root.IsSomeChildrenErased = true;
subtree_root.SetChildrenList(null);
}
public bool MakeChildNewRoot(ChessboardCell from, ChessboardCell to,
Exports.Pieces promote_to = Exports.Pieces.NoPiece)
{
if (Root == null)
{
return false;
}
// Discard all root children and their subtrees, except the child
// specified by the method parameters
ReleaseChildren(child =>
{
return child.ParentMove.FromCell != from.Value
|| child.ParentMove.ToCell != to.Value
|| child.ParentMove.PromoteToPiece != promote_to;
}, Root);
if (Root.Children.Count != 1)
{
Clean();
m_listener.RootPositionChanged(null);
return false;
}
// Discard current root
Interlocked.Decrement(ref m_node_count);
// Set a new root
Root = Root.Children[0];
m_listener.RootPositionChanged(Root.Position);
GenerateAllChildren(Root, 2);
return true;
}
private void Run(AnalysisNode root, int depth_to_go, ulong max_node_count)
{
if (depth_to_go == 1)
{
AnalyzeFourBestChildren(root, 2);
// TODO - remove
Console.WriteLine("Node count: " + m_tree.NodeCount);
// Update stats for the whole tree
MinMax.Evaluate(m_tree.Root);
m_stats.UpdateBestLine(m_tree.Root, true);
}
else
{
root?.Children.ForEach(x =>
{
if (m_stats.NodesEvaluated < max_node_count)
Run(x, depth_to_go - 1, max_node_count);
});
}
}
private void MakeStaticEvaluation(AnalysisNode node)
{
if (node.Position == null)
{
node.RecreatePosition();
}
node.StaticEvaluation = m_data_buffer.Evaluate(node, m_stats.Personality);
//node.Fingerprint = data_buffer.MakeFingerprint();
m_stats.IncNodesEvaluatedCounter();
}