1 files changed, 218 insertions, 0 deletions

diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/YieldProlog/Atom.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/YieldProlog/Atom.cs
new file mode 100644
index 0000000..27ab04e
--- /dev/null
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/YieldProlog/Atom.cs
@@ -0,0 +1,218 @@
+/*
+ * 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;
+using System.Text;
+
+namespace OpenSim.Region.ScriptEngine.Shared.YieldProlog
+{
+    public class Atom : IUnifiable
+    {
+        private static Dictionary<string, Atom> _atomStore = new Dictionary<string, Atom>();
+        public readonly string _name;
+        public readonly Atom _module;
+
+        /// <summary>
+        /// You should not call this constructor, but use Atom.a instead.
+        /// </summary>
+        /// <param name="name"></param>
+        /// <param name="module"></param>
+        private Atom(string name, Atom module)
+        {
+            _name = name;
+            _module = module;
+        }
+
+        /// <summary>
+        /// Return the unique Atom object for name where module is null. You should use this to create
+        /// an Atom instead of calling the Atom constructor.
+        /// </summary>
+        /// <param name="name"></param>
+        /// <returns></returns>
+        public static Atom a(string name)
+        {
+            Atom atom;
+            if (!_atomStore.TryGetValue(name, out atom))
+            {
+                atom = new Atom(name, null);
+                _atomStore[name] = atom;
+            }
+            return atom;
+        }
+
+        /// <summary>
+        /// Return an Atom object with the name and module.  If module is null or Atom.NIL,
+        /// this behaves like Atom.a(name) and returns the unique object where the module is null.
+        /// If module is not null or Atom.NIL, this may or may not be the same object as another Atom
+        /// with the same name and module.
+        /// </summary>
+        /// <param name="name"></param>
+        /// <param name="module"></param>
+        /// <returns></returns>
+        public static Atom a(string name, Atom module)
+        {
+            if (module == null || module == Atom.NIL)
+                return a(name);
+            return new Atom(name, module);
+        }
+
+        /// <summary>
+        /// If Obj is an Atom unify its _module with Module.  If the Atom's _module is null, use Atom.NIL.
+        /// </summary>
+        /// <param name="Atom"></param>
+        /// <param name="Module"></param>
+        /// <returns></returns>
+        public static IEnumerable<bool> module(object Obj, object Module)
+        {
+            Obj = YP.getValue(Obj);
+            if (Obj is Atom)
+            {
+                if (((Atom)Obj)._module == null)
+                    return YP.unify(Module, Atom.NIL);
+                else
+                    return YP.unify(Module, ((Atom)Obj)._module);
+            }
+            return YP.fail();
+        }
+
+        public static readonly Atom NIL = Atom.a("[]");
+        public static readonly Atom DOT = Atom.a(".");
+        public static readonly Atom F = Atom.a("f");
+        public static readonly Atom SLASH = Atom.a("/");
+        public static readonly Atom HAT = Atom.a("^");
+        public static readonly Atom RULE = Atom.a(":-");
+
+        public IEnumerable<bool> unify(object arg)
+        {
+            arg = YP.getValue(arg);
+            if (arg is Atom)
+                return Equals(arg) ? YP.succeed() : YP.fail();
+            else if (arg is Variable)
+                return ((Variable)arg).unify(this);
+            else
+                return YP.fail();
+        }
+
+        public void addUniqueVariables(List<Variable> variableSet)
+        {
+            // Atom does not contain variables.
+        }
+
+        public object makeCopy(Variable.CopyStore copyStore)
+        {
+            // Atom does not contain variables that need to be copied.
+            return this;
+        }
+
+        public bool termEqual(object term)
+        {
+            return Equals(YP.getValue(term));
+        }
+
+        public bool ground()
+        {
+            // Atom is always ground.
+            return true;
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (obj is Atom)
+            {
+                if (_module == null && ((Atom)obj)._module == null)
+                    // When _declaringClass is null, we always use an identical object from _atomStore.
+                    return this == obj;
+                // Otherwise, ignore _declaringClass and do a normal string compare on the _name.
+                return _name == ((Atom)obj)._name;
+            }
+            return false;
+        }
+
+        public override string ToString()
+        {
+            return _name;
+        }
+
+        public override int GetHashCode()
+        {
+            // Debug: need to check _declaringClass.
+            return _name.GetHashCode();
+        }
+
+        public string toQuotedString()
+        {
+            if (_name.Length == 0)
+                return "''";
+            else if (this == Atom.NIL)
+                return "[]";
+
+            StringBuilder result = new StringBuilder(_name.Length);
+            bool useQuotes = false;
+            foreach (char c in _name)
+            {
+                int cInt = (int)c;
+                if (c == '\'')
+                {
+                    result.Append("''");
+                    useQuotes = true;
+                }
+                else if (c == '_' || cInt >= (int)'a' && cInt <= (int)'z' ||
+                         cInt >= (int)'A' && cInt <= (int)'Z' || cInt >= (int)'0' && cInt <= (int)'9')
+                    result.Append(c);
+                else
+                {
+                    // Debug: Need to handle non-printable chars.
+                    result.Append(c);
+                    useQuotes = true;
+                }
+            }
+
+            if (!useQuotes && (int)_name[0] >= (int)'a' && (int)_name[0] <= (int)'z')
+                return result.ToString();
+            else
+            {
+                // Surround in single quotes.
+                result.Append('\'');
+                return "'" + result;
+            }
+        }
+
+        /// <summary>
+        /// Return true if _name is lexicographically less than atom._name.
+        /// </summary>
+        /// <param name="atom"></param>
+        /// <returns></returns>
+        public bool lessThan(Atom atom)
+        {
+            return _name.CompareTo(atom._name) < 0;
+        }
+    }
+}