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240 lines
10 KiB
C#
240 lines
10 KiB
C#
/*
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* Copyright (C) 2007-2008, Jeff Thompson
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the copyright holder nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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using System;
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using System.Collections;
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using System.Collections.Generic;
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namespace OpenSim.Region.ScriptEngine.DotNetEngine.Compiler.YieldProlog
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{
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/// <summary>
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/// A BagofAnswers holds answers for bagof and setof.
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/// </summary>
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public class BagofAnswers
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{
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private object _template;
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private Variable[] _freeVariables;
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private Dictionary<object[], List<object>> _bagForFreeVariables;
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private List<object> _findallBagArray;
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private static TermArrayEqualityComparer _termArrayEqualityComparer =
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new TermArrayEqualityComparer();
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/// <summary>
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/// To get the free variables, split off any existential qualifiers from Goal such as the X in
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/// "X ^ f(Y)", get the set of unbound variables in Goal that are not qualifiers, then remove
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/// the unbound variables that are qualifiers as well as the unbound variables in Template.
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/// </summary>
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/// <param name="Template"></param>
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/// <param name="Goal"></param>
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public BagofAnswers(object Template, object Goal)
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{
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_template = Template;
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// First get the set of variables that are not free variables.
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List<Variable> variableSet = new List<Variable>();
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YP.addUniqueVariables(Template, variableSet);
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object UnqualifiedGoal = YP.getValue(Goal);
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while (UnqualifiedGoal is Functor2 && ((Functor2)UnqualifiedGoal)._name == Atom.HAT)
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{
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YP.addUniqueVariables(((Functor2)UnqualifiedGoal)._arg1, variableSet);
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UnqualifiedGoal = YP.getValue(((Functor2)UnqualifiedGoal)._arg2);
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}
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// Remember how many non-free variables there are so we can find the unique free variables
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// that are added.
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int nNonFreeVariables = variableSet.Count;
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YP.addUniqueVariables(UnqualifiedGoal, variableSet);
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int nFreeVariables = variableSet.Count - nNonFreeVariables;
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if (nFreeVariables == 0)
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{
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// There were no free variables added, so we won't waste time with _bagForFreeVariables.
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_freeVariables = null;
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_findallBagArray = new List<object>();
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}
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else
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{
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// Copy the free variables.
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_freeVariables = new Variable[nFreeVariables];
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for (int i = 0; i < nFreeVariables; ++i)
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_freeVariables[i] = variableSet[i + nNonFreeVariables];
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_bagForFreeVariables = new Dictionary<object[], List<object>>(_termArrayEqualityComparer);
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}
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}
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public void add()
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{
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if (_freeVariables == null)
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// The goal has bound the values in _template but we don't bother with _freeVariables.
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_findallBagArray.Add(YP.makeCopy(_template, new Variable.CopyStore()));
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else
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{
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// The goal has bound the values in _template and _freeVariables.
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// Find the entry for this set of _freeVariables values.
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object[] freeVariableValues = new object[_freeVariables.Length];
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for (int i = 0; i < _freeVariables.Length; ++i)
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freeVariableValues[i] = YP.getValue(_freeVariables[i]);
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List<object> bagArray;
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if (!_bagForFreeVariables.TryGetValue(freeVariableValues, out bagArray))
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{
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bagArray = new List<object>();
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_bagForFreeVariables[freeVariableValues] = bagArray;
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}
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// Now copy the template and add to the bag for the freeVariables values.
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bagArray.Add(YP.makeCopy(_template, new Variable.CopyStore()));
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}
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}
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// disable warning on l1, don't see how we can
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// code this differently
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#pragma warning disable 0168
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/// <summary>
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/// For each result, unify the _freeVariables and unify bagArrayVariable with the associated bag.
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/// </summary>
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/// <param name="bagArrayVariable">this is unified with the List<object> of matches for template that
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/// corresponds to the bindings for freeVariables. Be very careful: this does not unify with a Prolog
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/// list.</param>
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/// <returns></returns>
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public IEnumerable<bool> resultArray(Variable bagArrayVariable)
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{
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if (_freeVariables == null)
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{
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// No unbound free variables, so we only filled one bag. If empty, bagof fails.
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if (_findallBagArray.Count > 0)
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{
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foreach (bool l1 in bagArrayVariable.unify(_findallBagArray))
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yield return false;
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}
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}
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else
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{
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foreach (KeyValuePair<object[], List<object>> valuesAndBag in _bagForFreeVariables)
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{
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foreach (bool l1 in YP.unifyArrays(_freeVariables, valuesAndBag.Key))
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{
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foreach (bool l2 in bagArrayVariable.unify(valuesAndBag.Value))
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yield return false;
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}
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// Debug: Should we free memory of the answers already returned?
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}
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}
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}
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/// <summary>
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/// For each result, unify the _freeVariables and unify Bag with the associated bag.
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/// </summary>
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/// <param name="Bag"></param>
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/// <returns></returns>
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public IEnumerable<bool> result(object Bag)
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{
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Variable bagArrayVariable = new Variable();
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foreach (bool l1 in resultArray(bagArrayVariable))
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{
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foreach (bool l2 in YP.unify(Bag, ListPair.make((List<object>)bagArrayVariable.getValue())))
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yield return false;
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}
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}
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/// <summary>
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/// For each result, unify the _freeVariables and unify Bag with the associated bag which is sorted
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/// with duplicates removed, as in setof.
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/// </summary>
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/// <param name="Bag"></param>
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/// <returns></returns>
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public IEnumerable<bool> resultSet(object Bag)
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{
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Variable bagArrayVariable = new Variable();
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foreach (bool l1 in resultArray(bagArrayVariable))
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{
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List<object> bagArray = (List<object>)bagArrayVariable.getValue();
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YP.sortArray(bagArray);
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foreach (bool l2 in YP.unify(Bag, ListPair.makeWithoutRepeatedTerms(bagArray)))
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yield return false;
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}
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}
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public static IEnumerable<bool> bagofArray
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(object Template, object Goal, IEnumerable<bool> goalIterator, Variable bagArrayVariable)
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{
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BagofAnswers bagOfAnswers = new BagofAnswers(Template, Goal);
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foreach (bool l1 in goalIterator)
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bagOfAnswers.add();
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return bagOfAnswers.resultArray(bagArrayVariable);
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}
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public static IEnumerable<bool> bagof
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(object Template, object Goal, IEnumerable<bool> goalIterator, object Bag)
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{
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BagofAnswers bagOfAnswers = new BagofAnswers(Template, Goal);
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foreach (bool l1 in goalIterator)
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bagOfAnswers.add();
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return bagOfAnswers.result(Bag);
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}
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public static IEnumerable<bool> setof
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(object Template, object Goal, IEnumerable<bool> goalIterator, object Bag)
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{
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BagofAnswers bagOfAnswers = new BagofAnswers(Template, Goal);
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foreach (bool l1 in goalIterator)
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bagOfAnswers.add();
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return bagOfAnswers.resultSet(Bag);
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}
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#pragma warning restore 0168
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/// <summary>
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/// A TermArrayEqualityComparer implements IEqualityComparer to compare two object arrays using YP.termEqual.
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/// </summary>
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private class TermArrayEqualityComparer : IEqualityComparer<object[]>
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{
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public bool Equals(object[] array1, object[] array2)
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{
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if (array1.Length != array2.Length)
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return false;
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for (int i = 0; i < array1.Length; ++i)
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{
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if (!YP.termEqual(array1[i], array2[i]))
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return false;
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}
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return true;
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}
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public int GetHashCode(object[] array)
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{
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int hashCode = 0;
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for (int i = 0; i < array.Length; ++i)
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hashCode ^= array[i].GetHashCode();
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return hashCode;
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}
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}
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}
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}
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