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1 using Implab;
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2 using System;
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3 using System.Collections.Generic;
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4 using System.Diagnostics;
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5 using System.Linq;
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6
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7 namespace Implab.Automaton {
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8 /// <summary>
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9 /// Indexed alphabet is the finite set of symbols where each symbol has a zero-based unique index.
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10 /// </summary>
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11 public abstract class IndexedAlphabetBase<T> : IAlphabetBuilder<T> {
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12 public const int UNCLASSIFIED = 0;
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13
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14 int m_nextId = 1;
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15 readonly int[] m_map;
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16
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17 public int Count {
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18 get { return m_nextId; }
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19 }
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20
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21 protected IndexedAlphabetBase(int mapSize) {
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22 m_map = new int[mapSize];
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23 }
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24
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25 protected IndexedAlphabetBase(int[] map) {
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26 Debug.Assert(map != null);
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27
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28 m_map = map;
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29 m_nextId = map.Max() + 1;
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30 }
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31
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32 public int DefineSymbol(T symbol) {
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33 var index = GetSymbolIndex(symbol);
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34 if (m_map[index] == UNCLASSIFIED)
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35 m_map[index] = m_nextId++;
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36 return m_map[index];
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37 }
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38
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39 public int DefineClass(IEnumerable<T> symbols) {
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40 Safe.ArgumentNotNull(symbols, "symbols");
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41 symbols = symbols.Distinct();
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42
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43 foreach (var symbol in symbols) {
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44 var index = GetSymbolIndex(symbol);
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45 if (m_map[index] == UNCLASSIFIED)
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46 m_map[GetSymbolIndex(symbol)] = m_nextId;
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47 else
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48 throw new InvalidOperationException(String.Format("Symbol '{0}' already in use", symbol));
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49 }
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50 return m_nextId++;
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51 }
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52
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53 public List<T>[] CreateReverseMap() {
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54 return
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55 Enumerable.Range(UNCLASSIFIED, Count)
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56 .Select(
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57 i => InputSymbols
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58 .Where(x => i != UNCLASSIFIED && m_map[GetSymbolIndex(x)] == i)
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59 .ToList()
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60 )
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61 .ToArray();
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62 }
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63
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64 public int[] Reclassify(IAlphabetBuilder<T> newAlphabet, IEnumerable<IEnumerable<int>> classes) {
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65 Safe.ArgumentNotNull(newAlphabet, "newAlphabet");
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66 Safe.ArgumentNotNull(classes, "classes");
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67 var reverseMap = CreateReverseMap();
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68
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69 var translationMap = new int[Count];
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70
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71 foreach (var scl in classes) {
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72 // skip if the supper class contains the unclassified element
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73 if (scl.Contains(UNCLASSIFIED))
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74 continue;
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75 var range = new List<T>();
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76 foreach (var cl in scl) {
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77 if (cl < 0 || cl >= reverseMap.Length)
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78 throw new ArgumentOutOfRangeException(String.Format("Class {0} is not valid for the current alphabet", cl));
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79 range.AddRange(reverseMap[cl]);
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80 }
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81 var newClass = newAlphabet.DefineClass(range);
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82 foreach (var cl in scl)
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83 translationMap[cl] = newClass;
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84 }
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85
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86 return translationMap;
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87 }
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88
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89 public virtual int Translate(T symbol) {
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90 return m_map[GetSymbolIndex(symbol)];
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91 }
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92
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93 public abstract int GetSymbolIndex(T symbol);
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94
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95 public abstract IEnumerable<T> InputSymbols { get; }
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96
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97 /// <summary>
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98 /// Gets the translation map from the index of the symbol to it's class this is usefull for the optimized input symbols transtaion.
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99 /// </summary>
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100 /// <returns>The translation map.</returns>
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101 public int[] GetTranslationMap() {
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102 return m_map;
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103 }
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104 }
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105 }
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