--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hedgewars/uAIThinkStack.pas	Sun Oct 08 18:17:52 2006 +0000
@@ -0,0 +1,90 @@
+(*
+ * Hedgewars, a worms-like game
+ * Copyright (c) 2006 Andrey Korotaev <unC0Rr@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ *)
+
+unit uAIThinkStack;
+interface
+uses uAIActions, uGears;
+{$INCLUDE options.inc}
+const cBranchStackSize = 12;
+type TStackEntry = record
+                   WastedTicks: Longword;
+                   MadeActions: TActions;
+                   Hedgehog: TGear;
+                   end;
+
+var ThinkStack: record
+                Count: Longword;
+                States: array[0..Pred(cBranchStackSize)] of TStackEntry;
+                end;
+
+function  Push(Ticks: Longword; const Actions: TActions; const Me: TGear; Dir: integer): boolean;
+function  Pop(out Ticks: Longword; out Actions: TActions; out Me: TGear): boolean;
+function  PosInThinkStack(Me: PGear): boolean;
+procedure ClearThinkStack;
+
+implementation
+
+function Push(Ticks: Longword; const Actions: TActions; const Me: TGear; Dir: integer): boolean;
+begin
+Result:= (ThinkStack.Count < cBranchStackSize) and (Actions.Count < MAXACTIONS - 5);
+if Result then
+   with ThinkStack.States[ThinkStack.Count] do
+        begin
+        WastedTicks:= Ticks;
+        MadeActions:= Actions;
+        Hedgehog:= Me;
+        Hedgehog.Message:= Dir;
+        inc(ThinkStack.Count)
+        end
+end;
+
+function Pop(out Ticks: Longword; out Actions: TActions; out Me: TGear): boolean;
+begin
+Result:= ThinkStack.Count > 0;
+if Result then
+   begin
+   dec(ThinkStack.Count);
+   with ThinkStack.States[ThinkStack.Count] do
+        begin
+        Ticks:= WastedTicks;
+        Actions:= MadeActions;
+        Me:= Hedgehog
+        end
+   end
+end;
+
+function PosInThinkStack(Me: PGear): boolean;
+var i: Longword;
+begin
+i:= 0;
+Result:= false;
+while (i < ThinkStack.Count) and not Result do
+      begin
+      Result:= (abs(ThinkStack.States[i].Hedgehog.X - Me.X) +
+                abs(ThinkStack.States[i].Hedgehog.Y - Me.Y) <= 2)
+                and (ThinkStack.States[i].Hedgehog.Message = Me.Message);
+      inc(i)
+      end
+end;
+
+procedure ClearThinkStack;
+begin
+ThinkStack.Count:= 0
+end;
+
+end.