Mercurial > pub > ImplabNet
annotate Implab/Parsing/DFABuilder.cs @ 158:130781364799 v2
refactoring, code cleanup
| author | cin |
|---|---|
| date | Thu, 18 Feb 2016 14:34:02 +0300 |
| parents | 97fbbf816844 |
| children |
| rev | line source |
|---|---|
| 55 | 1 using Implab; |
| 2 using System; | |
| 3 using System.Collections.Generic; | |
| 4 using System.Diagnostics; | |
| 5 using System.Linq; | |
| 6 | |
| 7 namespace Implab.Parsing { | |
| 8 /// <summary> | |
| 9 /// Используется для построения ДКА по регулярному выражению, сначала обходит | |
| 10 /// регулярное выражение и вычисляет followpos, затем используется метод | |
| 11 /// <see cref="BuildDFA(IDFADefinition)"/> для построения автомата. | |
| 12 /// </summary> | |
| 13 public class DFABuilder : IVisitor { | |
| 14 int m_idx = 0; | |
| 15 Token m_root; | |
| 16 HashSet<int> m_firstpos; | |
| 17 HashSet<int> m_lastpos; | |
| 18 | |
| 19 Dictionary<int, HashSet<int>> m_followpos = new Dictionary<int, HashSet<int>>(); | |
| 20 Dictionary<int, int> m_indexes = new Dictionary<int, int>(); | |
| 21 Dictionary<int, int> m_ends = new Dictionary<int, int>(); | |
| 22 | |
| 23 public Dictionary<int, HashSet<int>> FollowposMap { | |
| 24 get { return m_followpos; } | |
| 25 } | |
| 26 | |
| 27 public HashSet<int> Followpos(int pos) { | |
| 28 HashSet<int> set; | |
| 29 if (m_followpos.TryGetValue(pos, out set)) | |
| 30 return set; | |
| 31 return m_followpos[pos] = new HashSet<int>(); | |
| 32 } | |
| 33 | |
| 34 bool Nullable(object n) { | |
| 35 if (n is EmptyToken || n is StarToken) | |
| 36 return true; | |
| 37 if (n is AltToken) | |
| 38 return Nullable(((AltToken)n).Left) || Nullable(((AltToken)n).Right); | |
| 39 if (n is CatToken) | |
| 40 return Nullable(((CatToken)n).Left) && Nullable(((CatToken)n).Right); | |
| 41 return false; | |
| 42 } | |
| 43 | |
| 44 | |
| 45 public void Visit(AltToken token) { | |
| 46 if (m_root == null) | |
| 47 m_root = token; | |
| 48 var firtspos = new HashSet<int>(); | |
| 49 var lastpos = new HashSet<int>(); | |
| 50 | |
| 51 token.Left.Accept(this); | |
| 52 firtspos.UnionWith(m_firstpos); | |
| 53 lastpos.UnionWith(m_lastpos); | |
| 54 | |
| 55 token.Right.Accept(this); | |
| 56 firtspos.UnionWith(m_firstpos); | |
| 57 lastpos.UnionWith(m_lastpos); | |
| 58 | |
| 59 m_firstpos = firtspos; | |
| 60 m_lastpos = lastpos; | |
| 61 } | |
| 62 | |
| 63 public void Visit(StarToken token) { | |
| 64 if (m_root == null) | |
| 65 m_root = token; | |
| 66 token.Token.Accept(this); | |
| 67 | |
| 68 foreach (var i in m_lastpos) | |
| 69 Followpos(i).UnionWith(m_firstpos); | |
| 70 } | |
| 71 | |
| 72 public void Visit(CatToken token) { | |
| 73 if (m_root == null) | |
| 74 m_root = token; | |
| 75 | |
| 76 var firtspos = new HashSet<int>(); | |
| 77 var lastpos = new HashSet<int>(); | |
| 78 token.Left.Accept(this); | |
| 79 firtspos.UnionWith(m_firstpos); | |
| 80 var leftLastpos = m_lastpos; | |
| 81 | |
| 82 token.Right.Accept(this); | |
| 83 lastpos.UnionWith(m_lastpos); | |
| 84 var rightFirstpos = m_firstpos; | |
| 85 | |
| 86 if (Nullable(token.Left)) | |
| 87 firtspos.UnionWith(rightFirstpos); | |
| 88 | |
| 89 if (Nullable(token.Right)) | |
| 90 lastpos.UnionWith(leftLastpos); | |
| 91 | |
| 92 m_firstpos = firtspos; | |
| 93 m_lastpos = lastpos; | |
| 94 | |
| 95 foreach (var i in leftLastpos) | |
| 96 Followpos(i).UnionWith(rightFirstpos); | |
| 97 | |
| 98 } | |
| 99 | |
| 100 public void Visit(EmptyToken token) { | |
| 101 if (m_root == null) | |
| 102 m_root = token; | |
| 103 ; | |
| 104 } | |
| 105 | |
| 106 public void Visit(SymbolToken token) { | |
| 107 if (m_root == null) | |
| 108 m_root = token; | |
| 109 m_idx++; | |
| 110 m_indexes[m_idx] = token.Value; | |
| 111 m_firstpos = new HashSet<int>(new[] { m_idx }); | |
| 112 m_lastpos = new HashSet<int>(new[] { m_idx }); | |
| 113 } | |
| 114 | |
| 115 public void Visit(EndToken token) { | |
| 116 if (m_root == null) | |
| 117 m_root = token; | |
| 118 m_idx++; | |
| 158 | 119 m_indexes[m_idx] = IndexedAlphabetBase<char>.UNCLASSIFIED; |
| 55 | 120 m_firstpos = new HashSet<int>(new[] { m_idx }); |
| 121 m_lastpos = new HashSet<int>(new[] { m_idx }); | |
| 122 Followpos(m_idx); | |
| 123 m_ends.Add(m_idx, token.Tag); | |
| 124 } | |
| 125 | |
| 126 public void BuildDFA(IDFADefinition dfa) { | |
| 127 Safe.ArgumentNotNull(dfa,"dfa"); | |
| 128 | |
| 129 var stateMap = new Dictionary<HashSet<int>, int>(new CustomEqualityComparer<HashSet<int>>( | |
| 130 (x, y) => x.SetEquals(y), | |
| 131 (x) => x.Sum(n => n.GetHashCode()) | |
| 132 )); | |
| 133 | |
| 134 stateMap[m_firstpos] = DefineState( dfa, m_firstpos); | |
| 158 | 135 Debug.Assert(stateMap[m_firstpos] == DFADefinition.INITIAL_STATE); |
| 55 | 136 |
| 137 var queue = new Queue<HashSet<int>>(); | |
| 138 | |
| 139 queue.Enqueue(m_firstpos); | |
| 140 | |
| 141 while (queue.Count > 0) { | |
| 142 var state = queue.Dequeue(); | |
| 143 var s1 = stateMap[state]; | |
| 144 | |
| 145 for (int a = 0; a < dfa.AlphabetSize; a++) { | |
| 146 var next = new HashSet<int>(); | |
| 147 foreach (var p in state) { | |
| 148 if (m_indexes[p] == a) { | |
| 149 next.UnionWith(Followpos(p)); | |
| 150 } | |
| 151 } | |
| 152 if (next.Count > 0) { | |
| 153 int s2; | |
| 154 if (!stateMap.TryGetValue(next, out s2)) { | |
| 155 stateMap[next] = s2 = DefineState(dfa, next); | |
| 156 queue.Enqueue(next); | |
| 157 } | |
| 158 dfa.DefineTransition(s1, s2, a); | |
| 159 } | |
| 160 } | |
| 161 | |
| 162 } | |
| 163 } | |
| 164 | |
| 165 int[] GetStateTags(HashSet<int> state) { | |
| 166 Debug.Assert(state != null); | |
|
156
97fbbf816844
Promises: SignalXXX methods merged into SignalHandler method.
cin
parents:
55
diff
changeset
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167 return state.Where(m_ends.ContainsKey).Select(pos => m_ends[pos]).ToArray(); |
| 55 | 168 } |
| 169 | |
| 170 int DefineState(IDFADefinition automa, HashSet<int> state) { | |
| 171 Debug.Assert(automa != null); | |
| 172 Debug.Assert(state != null); | |
| 173 | |
| 174 var tags = GetStateTags(state); | |
| 175 | |
| 176 return tags.Length > 0 ? automa.AddState(tags) : automa.AddState(); | |
| 177 } | |
| 178 | |
| 179 } | |
| 180 } |