clockwerk-opensim-stable – Blame information for rev 1
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1 | vero | 1 | /* |
2 | * Copyright (C) 2007-2008, Jeff Thompson |
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3 | * |
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4 | * All rights reserved. |
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5 | * |
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6 | * Redistribution and use in source and binary forms, with or without |
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7 | * modification, are permitted provided that the following conditions are met: |
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8 | * |
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9 | * * Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * * Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * * Neither the name of the copyright holder nor the names of its contributors |
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15 | * may be used to endorse or promote products derived from this software |
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16 | * without specific prior written permission. |
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17 | * |
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18 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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19 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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20 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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21 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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22 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
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23 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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24 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
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25 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
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26 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
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27 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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28 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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29 | */ |
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30 | |||
31 | using System; |
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32 | using System.Collections; |
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33 | using System.Collections.Generic; |
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34 | |||
35 | namespace OpenSim.Region.ScriptEngine.Shared.YieldProlog |
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36 | { |
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37 | /// <summary> |
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38 | /// An IndexedAnswers holds answers to a query based on the values of index arguments. |
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39 | /// </summary> |
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40 | public class IndexedAnswers : YP.IClause |
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41 | { |
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42 | private int _arity; |
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43 | // addAnswer adds the answer here and indexes it later. |
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44 | private List<object[]> _allAnswers = new List<object[]>(); |
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45 | // The key has the arity of answers with non-null values for each indexed arg. The value |
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46 | // is a list of the matching answers. The signature is implicit in the pattern on non-null index args. |
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47 | private Dictionary<HashedList, List<object[]>> _indexedAnswers = |
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48 | new Dictionary<HashedList, List<object[]>>(); |
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49 | // Keeps track of whether we have started adding entries to _indexedAnswers for the signature. |
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50 | private Dictionary<int, object> _gotAnswersForSignature = new Dictionary<int, object>(); |
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51 | private const int MAX_INDEX_ARGS = 31; |
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52 | |||
53 | public IndexedAnswers(int arity) |
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54 | { |
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55 | _arity = arity; |
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56 | } |
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57 | |||
58 | /// <summary> |
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59 | /// Append the answer to the list and update the indexes, if any. |
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60 | /// Elements of answer must be ground, since arguments with unbound variables make this |
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61 | /// into a dynamic rule which we don't index. |
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62 | /// </summary> |
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63 | /// <param name="answer"></param> |
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64 | public void addAnswer(object[] answer) |
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65 | { |
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66 | addOrPrependAnswer(answer, false); |
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67 | } |
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68 | |||
69 | /// <summary> |
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70 | /// Prepend the answer to the list and clear the indexes so that they must be re-computed |
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71 | /// on the next call to match. (Only addAnswer will maintain the indexes while adding answers.) |
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72 | /// Elements of answer must be ground, since arguments with unbound variables make this |
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73 | /// into a dynamic rule which we don't index. |
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74 | /// </summary> |
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75 | /// <param name="answer"></param> |
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76 | public void prependAnswer(object[] answer) |
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77 | { |
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78 | addOrPrependAnswer(answer, true); |
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79 | } |
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80 | |||
81 | /// <summary> |
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82 | /// Do the work of addAnswer or prependAnswer. |
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83 | /// </summary> |
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84 | /// <param name="answer"></param> |
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85 | private void addOrPrependAnswer(object[] answer, bool prepend) |
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86 | { |
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87 | if (answer.Length != _arity) |
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88 | return; |
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89 | |||
90 | // Store a copy of the answer array. |
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91 | object[] answerCopy = new object[answer.Length]; |
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92 | Variable.CopyStore copyStore = new Variable.CopyStore(); |
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93 | for (int i = 0; i < answer.Length; ++i) |
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94 | answerCopy[i] = YP.makeCopy(answer[i], copyStore); |
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95 | if (copyStore.getNUniqueVariables() > 0) |
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96 | throw new InvalidOperationException |
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97 | ("Elements of answer must be ground, but found " + copyStore.getNUniqueVariables() + |
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98 | " unbound variables"); |
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99 | |||
100 | if (prepend) |
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101 | { |
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102 | _allAnswers.Insert(0, answerCopy); |
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103 | clearIndexes(); |
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104 | } |
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105 | else |
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106 | { |
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107 | _allAnswers.Add(answerCopy); |
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108 | // If match has already indexed answers for a signature, we need to add |
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109 | // this to the existing indexed answers. |
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110 | foreach (int signature in _gotAnswersForSignature.Keys) |
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111 | indexAnswerForSignature(answerCopy, signature); |
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112 | } |
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113 | } |
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114 | |||
115 | private void indexAnswerForSignature(object[] answer, int signature) |
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116 | { |
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117 | // First find out which of the answer values can be used as an index. |
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118 | object[] indexValues = new object[answer.Length]; |
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119 | for (int i = 0; i < answer.Length; ++i) |
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120 | { |
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121 | // We limit the number of indexed args in a 32-bit signature. |
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122 | if (i >= MAX_INDEX_ARGS) |
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123 | indexValues[i] = null; |
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124 | else |
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125 | indexValues[i] = getIndexValue(YP.getValue(answer[i])); |
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126 | } |
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127 | |||
128 | // We need an entry in indexArgs from indexValues for each 1 bit in signature. |
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129 | HashedList indexArgs = new HashedList(indexValues.Length); |
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130 | for (int i = 0; i < indexValues.Length; ++i) |
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131 | { |
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132 | if ((signature & (1 << i)) == 0) |
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133 | indexArgs.Add(null); |
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134 | else |
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135 | { |
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136 | if (indexValues[i] == null) |
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137 | // The signature wants an index value here, but we don't have one so |
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138 | // we can't add it as an answer for this signature. |
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139 | return; |
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140 | else |
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141 | indexArgs.Add(indexValues[i]); |
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142 | } |
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143 | } |
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144 | |||
145 | // Add the answer to the answers list for indexArgs, creating the entry if needed. |
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146 | List<object[]> answers; |
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147 | if (!_indexedAnswers.TryGetValue(indexArgs, out answers)) |
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148 | { |
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149 | answers = new List<object[]>(); |
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150 | _indexedAnswers[indexArgs] = answers; |
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151 | } |
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152 | answers.Add(answer); |
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153 | } |
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154 | |||
155 | public IEnumerable<bool> match(object[] arguments) |
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156 | { |
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157 | if (arguments.Length != _arity) |
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158 | yield break; |
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159 | |||
160 | // Set up indexArgs, up to arg position MAX_INDEX_ARGS. The signature has a 1 bit for |
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161 | // each non-null index arg. |
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162 | HashedList indexArgs = new HashedList(arguments.Length); |
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163 | bool gotAllIndexArgs = true; |
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164 | int signature = 0; |
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165 | for (int i = 0; i < arguments.Length; ++i) |
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166 | { |
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167 | object indexValue = null; |
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168 | if (i < MAX_INDEX_ARGS) |
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169 | { |
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170 | // We limit the number of args in a 32-bit signature. |
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171 | indexValue = getIndexValue(YP.getValue(arguments[i])); |
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172 | if (indexValue != null) |
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173 | signature += (1 << i); |
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174 | } |
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175 | if (indexValue == null) |
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176 | gotAllIndexArgs = false; |
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177 | indexArgs.Add(indexValue); |
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178 | } |
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179 | |||
180 | List<object[]> answers; |
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181 | if (signature == 0) |
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182 | // No index args, so we have to match from _allAnswers. |
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183 | answers = _allAnswers; |
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184 | else |
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185 | { |
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186 | if (!_gotAnswersForSignature.ContainsKey(signature)) |
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187 | { |
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188 | // We need to create the entry in _indexedAnswers. |
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189 | foreach (object[] answer in _allAnswers) |
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190 | indexAnswerForSignature(answer, signature); |
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191 | // Mark that we did this signature. |
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192 | _gotAnswersForSignature[signature] = null; |
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193 | } |
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194 | if (!_indexedAnswers.TryGetValue(indexArgs, out answers)) |
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195 | yield break; |
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196 | } |
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197 | |||
198 | if (gotAllIndexArgs) |
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199 | { |
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200 | // All the arguments were already bound, so we don't need to do bindings. |
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201 | yield return false; |
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202 | yield break; |
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203 | } |
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204 | |||
205 | // Find matches in answers. |
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206 | IEnumerator<bool>[] iterators = new IEnumerator<bool>[arguments.Length]; |
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207 | // Debug: If the caller asserts another answer into this same predicate during yield, the iterator |
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208 | // over clauses will be corrupted. Should we take the time to copy answers? |
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209 | foreach (object[] answer in answers) |
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210 | { |
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211 | bool gotMatch = true; |
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212 | int nIterators = 0; |
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213 | // Try to bind all the arguments. |
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214 | for (int i = 0; i < arguments.Length; ++i) |
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215 | { |
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216 | if (indexArgs[i] != null) |
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217 | // We already matched this argument by looking up _indexedAnswers. |
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218 | continue; |
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219 | |||
220 | IEnumerator<bool> iterator = YP.unify(arguments[i], answer[i]).GetEnumerator(); |
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221 | iterators[nIterators++] = iterator; |
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222 | // MoveNext() is true if YP.unify succeeds. |
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223 | if (!iterator.MoveNext()) |
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224 | { |
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225 | gotMatch = false; |
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226 | break; |
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227 | } |
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228 | } |
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229 | int z = 0; |
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230 | try |
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231 | { |
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232 | if (gotMatch) |
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233 | yield return false; |
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234 | } |
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235 | finally |
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236 | { |
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237 | // Manually finalize all the iterators. |
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238 | for (z = 0; z < nIterators; ++z) |
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239 | iterators[z].Dispose(); |
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240 | } |
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241 | } |
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242 | } |
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243 | |||
244 | public IEnumerable<bool> clause(object Head, object Body) |
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245 | { |
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246 | Head = YP.getValue(Head); |
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247 | if (Head is Variable) |
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248 | throw new PrologException("instantiation_error", "Head is an unbound variable"); |
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249 | object[] arguments = YP.getFunctorArgs(Head); |
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250 | |||
251 | // We always match Head from _allAnswers, and the Body is Atom.a("true"). |
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252 | #pragma warning disable 0168, 0219 |
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253 | foreach (bool l1 in YP.unify(Body, Atom.a("true"))) |
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254 | { |
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255 | // The caller can assert another answer into this same predicate during yield, so we have to |
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256 | // make a copy of the answers. |
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257 | foreach (object[] answer in _allAnswers.ToArray()) |
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258 | { |
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259 | foreach (bool l2 in YP.unifyArrays(arguments, answer)) |
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260 | yield return false; |
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261 | } |
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262 | } |
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263 | #pragma warning restore 0168, 0219 |
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264 | } |
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265 | |||
266 | public IEnumerable<bool> retract(object Head, object Body) |
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267 | { |
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268 | Head = YP.getValue(Head); |
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269 | if (Head is Variable) |
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270 | throw new PrologException("instantiation_error", "Head is an unbound variable"); |
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271 | object[] arguments = YP.getFunctorArgs(Head); |
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272 | |||
273 | // We always match Head from _allAnswers, and the Body is Atom.a("true"). |
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274 | #pragma warning disable 0168, 0219 |
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275 | foreach (bool l1 in YP.unify(Body, Atom.a("true"))) |
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276 | { |
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277 | // The caller can assert another answer into this same predicate during yield, so we have to |
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278 | // make a copy of the answers. |
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279 | foreach (object[] answer in _allAnswers.ToArray()) |
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280 | { |
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281 | foreach (bool l2 in YP.unifyArrays(arguments, answer)) |
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282 | { |
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283 | _allAnswers.Remove(answer); |
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284 | clearIndexes(); |
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285 | yield return false; |
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286 | } |
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287 | } |
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288 | } |
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289 | #pragma warning restore 0168, 0219 |
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290 | } |
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291 | |||
292 | /// <summary> |
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293 | /// After retracting or prepending an answer in _allAnswers, the indexes are invalid, so clear them. |
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294 | /// </summary> |
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295 | private void clearIndexes() |
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296 | { |
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297 | _indexedAnswers.Clear(); |
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298 | _gotAnswersForSignature.Clear(); |
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299 | } |
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300 | |||
301 | /// <summary> |
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302 | /// A HashedList extends an ArrayList with methods to get a hash and to check equality |
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303 | /// based on the elements of the list. |
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304 | /// </summary> |
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305 | public class HashedList : ArrayList |
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306 | { |
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307 | private bool _gotHashCode = false; |
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308 | private int _hashCode; |
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309 | |||
310 | public HashedList() |
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311 | : base() |
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312 | { |
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313 | } |
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314 | |||
315 | public HashedList(int capacity) |
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316 | : base(capacity) |
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317 | { |
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318 | } |
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319 | |||
320 | public HashedList(ICollection c) |
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321 | : base(c) |
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322 | { |
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323 | } |
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324 | |||
325 | // Debug: Should override all the other methods that change this. |
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326 | public override int Add(object value) |
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327 | { |
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328 | _gotHashCode = false; |
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329 | return base.Add(value); |
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330 | } |
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331 | |||
332 | public override int GetHashCode() |
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333 | { |
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334 | if (!_gotHashCode) |
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335 | { |
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336 | int hashCode = 1; |
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337 | foreach (object obj in this) |
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338 | hashCode = 31 * hashCode + (obj == null ? 0 : obj.GetHashCode()); |
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339 | _hashCode = hashCode; |
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340 | _gotHashCode = true; |
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341 | } |
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342 | return _hashCode; |
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343 | } |
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344 | |||
345 | public override bool Equals(object obj) |
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346 | { |
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347 | if (!(obj is ArrayList)) |
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348 | return false; |
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349 | |||
350 | ArrayList objList = (ArrayList)obj; |
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351 | if (objList.Count != Count) |
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352 | return false; |
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353 | |||
354 | for (int i = 0; i < Count; ++i) |
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355 | { |
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356 | object value = objList[i]; |
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357 | if (value == null) |
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358 | { |
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359 | if (this[i] != null) |
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360 | return false; |
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361 | } |
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362 | else |
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363 | { |
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364 | if (!value.Equals(this[i])) |
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365 | return false; |
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366 | } |
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367 | } |
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368 | return true; |
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369 | } |
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370 | } |
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371 | |||
372 | /// <summary> |
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373 | /// If we keep an index on value, return the value, or null if we don't index it. |
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374 | /// </summary> |
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375 | /// <param name="value">the term to examine. Assume you already called YP.getValue(value)</param> |
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376 | /// <returns></returns> |
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377 | public static object getIndexValue(object value) |
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378 | { |
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379 | if (value is Atom || value is string || value is Int32 || value is DateTime) |
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380 | return value; |
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381 | else |
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382 | return null; |
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383 | } |
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384 | } |
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385 | } |