1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
|
/*
* 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;
using System.Collections.Generic;
namespace OpenSim.Region.ScriptEngine.Shared.YieldProlog
{
/// <summary>
/// A BagofAnswers holds answers for bagof and setof.
/// </summary>
public class BagofAnswers
{
private object _template;
private Variable[] _freeVariables;
private Dictionary<object[], List<object>> _bagForFreeVariables;
private List<object> _findallBagArray;
private static TermArrayEqualityComparer _termArrayEqualityComparer =
new TermArrayEqualityComparer();
/// <summary>
/// To get the free variables, split off any existential qualifiers from Goal such as the X in
/// "X ^ f(Y)", get the set of unbound variables in Goal that are not qualifiers, then remove
/// the unbound variables that are qualifiers as well as the unbound variables in Template.
/// </summary>
/// <param name="Template"></param>
/// <param name="Goal"></param>
public BagofAnswers(object Template, object Goal)
{
_template = Template;
// First get the set of variables that are not free variables.
List<Variable> variableSet = new List<Variable>();
YP.addUniqueVariables(Template, variableSet);
object UnqualifiedGoal = YP.getValue(Goal);
while (UnqualifiedGoal is Functor2 && ((Functor2)UnqualifiedGoal)._name == Atom.HAT)
{
YP.addUniqueVariables(((Functor2)UnqualifiedGoal)._arg1, variableSet);
UnqualifiedGoal = YP.getValue(((Functor2)UnqualifiedGoal)._arg2);
}
// Remember how many non-free variables there are so we can find the unique free variables
// that are added.
int nNonFreeVariables = variableSet.Count;
YP.addUniqueVariables(UnqualifiedGoal, variableSet);
int nFreeVariables = variableSet.Count - nNonFreeVariables;
if (nFreeVariables == 0)
{
// There were no free variables added, so we won't waste time with _bagForFreeVariables.
_freeVariables = null;
_findallBagArray = new List<object>();
}
else
{
// Copy the free variables.
_freeVariables = new Variable[nFreeVariables];
for (int i = 0; i < nFreeVariables; ++i)
_freeVariables[i] = variableSet[i + nNonFreeVariables];
_bagForFreeVariables = new Dictionary<object[], List<object>>(_termArrayEqualityComparer);
}
}
public void add()
{
if (_freeVariables == null)
// The goal has bound the values in _template but we don't bother with _freeVariables.
_findallBagArray.Add(YP.makeCopy(_template, new Variable.CopyStore()));
else
{
// The goal has bound the values in _template and _freeVariables.
// Find the entry for this set of _freeVariables values.
object[] freeVariableValues = new object[_freeVariables.Length];
for (int i = 0; i < _freeVariables.Length; ++i)
freeVariableValues[i] = YP.getValue(_freeVariables[i]);
List<object> bagArray;
if (!_bagForFreeVariables.TryGetValue(freeVariableValues, out bagArray))
{
bagArray = new List<object>();
_bagForFreeVariables[freeVariableValues] = bagArray;
}
// Now copy the template and add to the bag for the freeVariables values.
bagArray.Add(YP.makeCopy(_template, new Variable.CopyStore()));
}
}
// disable warning on l1, don't see how we can
// code this differently
#pragma warning disable 0168, 0219
/// <summary>
/// For each result, unify the _freeVariables and unify bagArrayVariable with the associated bag.
/// </summary>
/// <param name="bagArrayVariable">this is unified with the List<object> of matches for template that
/// corresponds to the bindings for freeVariables. Be very careful: this does not unify with a Prolog
/// list.</param>
/// <returns></returns>
public IEnumerable<bool> resultArray(Variable bagArrayVariable)
{
if (_freeVariables == null)
{
// No unbound free variables, so we only filled one bag. If empty, bagof fails.
if (_findallBagArray.Count > 0)
{
foreach (bool l1 in bagArrayVariable.unify(_findallBagArray))
yield return false;
}
}
else
{
foreach (KeyValuePair<object[], List<object>> valuesAndBag in _bagForFreeVariables)
{
foreach (bool l1 in YP.unifyArrays(_freeVariables, valuesAndBag.Key))
{
foreach (bool l2 in bagArrayVariable.unify(valuesAndBag.Value))
yield return false;
}
// Debug: Should we free memory of the answers already returned?
}
}
}
/// <summary>
/// For each result, unify the _freeVariables and unify Bag with the associated bag.
/// </summary>
/// <param name="Bag"></param>
/// <returns></returns>
public IEnumerable<bool> result(object Bag)
{
Variable bagArrayVariable = new Variable();
foreach (bool l1 in resultArray(bagArrayVariable))
{
foreach (bool l2 in YP.unify(Bag, ListPair.make((List<object>)bagArrayVariable.getValue())))
yield return false;
}
}
/// <summary>
/// For each result, unify the _freeVariables and unify Bag with the associated bag which is sorted
/// with duplicates removed, as in setof.
/// </summary>
/// <param name="Bag"></param>
/// <returns></returns>
public IEnumerable<bool> resultSet(object Bag)
{
Variable bagArrayVariable = new Variable();
foreach (bool l1 in resultArray(bagArrayVariable))
{
List<object> bagArray = (List<object>)bagArrayVariable.getValue();
YP.sortArray(bagArray);
foreach (bool l2 in YP.unify(Bag, ListPair.makeWithoutRepeatedTerms(bagArray)))
yield return false;
}
}
public static IEnumerable<bool> bagofArray
(object Template, object Goal, IEnumerable<bool> goalIterator, Variable bagArrayVariable)
{
BagofAnswers bagOfAnswers = new BagofAnswers(Template, Goal);
foreach (bool l1 in goalIterator)
bagOfAnswers.add();
return bagOfAnswers.resultArray(bagArrayVariable);
}
public static IEnumerable<bool> bagof
(object Template, object Goal, IEnumerable<bool> goalIterator, object Bag)
{
BagofAnswers bagOfAnswers = new BagofAnswers(Template, Goal);
foreach (bool l1 in goalIterator)
bagOfAnswers.add();
return bagOfAnswers.result(Bag);
}
public static IEnumerable<bool> setof
(object Template, object Goal, IEnumerable<bool> goalIterator, object Bag)
{
BagofAnswers bagOfAnswers = new BagofAnswers(Template, Goal);
foreach (bool l1 in goalIterator)
bagOfAnswers.add();
return bagOfAnswers.resultSet(Bag);
}
#pragma warning restore 0168, 0219
/// <summary>
/// A TermArrayEqualityComparer implements IEqualityComparer to compare two object arrays using YP.termEqual.
/// </summary>
private class TermArrayEqualityComparer : IEqualityComparer<object[]>
{
public bool Equals(object[] array1, object[] array2)
{
if (array1.Length != array2.Length)
return false;
for (int i = 0; i < array1.Length; ++i)
{
if (!YP.termEqual(array1[i], array2[i]))
return false;
}
return true;
}
public int GetHashCode(object[] array)
{
int hashCode = 0;
for (int i = 0; i < array.Length; ++i)
hashCode ^= array[i].GetHashCode();
return hashCode;
}
}
}
}
|
