1 files changed, 156 insertions, 0 deletions

diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/YieldProlog/ListPair.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/YieldProlog/ListPair.cs
new file mode 100644
index 0000000..83ace2d
--- /dev/null
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/YieldProlog/ListPair.cs
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2007-2008, Jeff Thompson
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the copyright holder nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+using System;
+using System.Collections.Generic;
+
+namespace OpenSim.Region.ScriptEngine.Shared.YieldProlog
+{
+    public class ListPair : Functor2
+    {
+        public ListPair(object head, object tail) : base(Atom.DOT, head, tail)
+        {
+        }
+
+        public static object make(List<object> list)
+        {
+            if (list.Count <= 0)
+                return Atom.NIL;
+
+            object result = Atom.NIL;
+            // Start from the end.
+            for (int i = list.Count - 1; i >= 0; --i)
+                result = new ListPair(list[i], result);
+            return result;
+        }
+
+        public static object make(object[] array)
+        {
+            if (array.Length <= 0)
+                return Atom.NIL;
+
+            object result = Atom.NIL;
+            // Start from the end.
+            for (int i = array.Length - 1; i >= 0; --i)
+                result = new ListPair(array[i], result);
+            return result;
+        }
+
+        /// <summary>
+        /// Return a ListPair version of array, where repeated elements
+        /// (according to YP.termEqual) are removed.
+        /// </summary>
+        /// <param name="array"></param>
+        /// <returns></returns>
+        public static object makeWithoutRepeatedTerms(object[] array)
+        {
+            if (array.Length <= 0)
+                return Atom.NIL;
+
+            // Start from the end.
+            object previousTerm = array[array.Length - 1];
+            object result = new ListPair(previousTerm, Atom.NIL);
+            for (int i = array.Length - 2; i >= 0; --i)
+            {
+                object term = array[i];
+                if (YP.termEqual(term, previousTerm))
+                    continue;
+                result = new ListPair(term, result);
+                previousTerm = term;
+            }
+            return result;
+        }
+
+        /// <summary>
+        /// Return a ListPair version of array, where repeated elements
+        /// (according to YP.termEqual) are removed.
+        /// </summary>
+        /// <param name="array"></param>
+        /// <returns></returns>
+        public static object makeWithoutRepeatedTerms(List<object> array)
+        {
+            if (array.Count <= 0)
+                return Atom.NIL;
+
+            // Start from the end.
+            object previousTerm = array[array.Count - 1];
+            object result = new ListPair(previousTerm, Atom.NIL);
+            for (int i = array.Count - 2; i >= 0; --i)
+            {
+                object term = array[i];
+                if (YP.termEqual(term, previousTerm))
+                    continue;
+                result = new ListPair(term, result);
+                previousTerm = term;
+            }
+            return result;
+        }
+
+        public static object make(object element1)
+        {
+            return new ListPair(element1, Atom.NIL);
+        }
+
+        public static object make(object element1, object element2)
+        {
+            return new ListPair(element1, new ListPair(element2, Atom.NIL));
+        }
+
+        public static object make(object element1, object element2, object element3)
+        {
+            return new ListPair(element1,
+                new ListPair(element2, new ListPair(element3, Atom.NIL)));
+        }
+
+        /// <summary>
+        /// Return an array of the elements in list or null if it is not
+        /// a proper list.  If list is Atom.NIL, return an array of zero elements.
+        /// This does not call YP.getValue on each element.
+        /// </summary>
+        /// <param name="list"></param>
+        /// <returns></returns>
+        public static object[] toArray(object list)
+        {
+            list = YP.getValue(list);
+            if (list.Equals(Atom.NIL))
+                return new object[0];
+
+            List<object> result = new List<object>();
+            for (object element = list;
+                 element is Functor2 && ((Functor2)element)._name == Atom.DOT;
+                 element = YP.getValue(((Functor2)element)._arg2))
+                result.Add(((Functor2)element)._arg1);
+
+            if (result.Count <= 0)
+                return null;
+            return result.ToArray();
+        }
+    }
+}