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IndexedAlphabetBase.cs
103 lines | 3.6 KiB | text/x-csharp | CSharpLexer
using Implab;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
namespace Implab.Automaton {
/// <summary>
/// Indexed alphabet is the finite set of symbols where each symbol has a zero-based unique index.
/// </summary>
public abstract class IndexedAlphabetBase<T> : IAlphabetBuilder<T> {
int m_nextId = 1;
readonly int[] m_map;
public int Count {
get { return m_nextId; }
}
protected IndexedAlphabetBase(int mapSize) {
m_map = new int[mapSize];
}
protected IndexedAlphabetBase(int[] map) {
Debug.Assert(map != null);
m_map = map;
m_nextId = map.Max() + 1;
}
public int DefineSymbol(T symbol) {
var index = GetSymbolIndex(symbol);
if (m_map[index] == DFAConst.UNCLASSIFIED_INPUT)
m_map[index] = m_nextId++;
return m_map[index];
}
public int DefineClass(IEnumerable<T> symbols) {
Safe.ArgumentNotNull(symbols, "symbols");
symbols = symbols.Distinct();
foreach (var symbol in symbols) {
var index = GetSymbolIndex(symbol);
if (m_map[index] == DFAConst.UNCLASSIFIED_INPUT)
m_map[GetSymbolIndex(symbol)] = m_nextId;
else
throw new InvalidOperationException(String.Format("Symbol '{0}' already in use", symbol));
}
return m_nextId++;
}
public List<T>[] CreateReverseMap() {
return
Enumerable.Range(0, Count)
.Select(
i => InputSymbols
.Where(x => i != DFAConst.UNCLASSIFIED_INPUT && m_map[GetSymbolIndex(x)] == i)
.ToList()
)
.ToArray();
}
public int[] Reclassify(IAlphabetBuilder<T> newAlphabet, IEnumerable<IEnumerable<int>> classes) {
Safe.ArgumentNotNull(newAlphabet, "newAlphabet");
Safe.ArgumentNotNull(classes, "classes");
var reverseMap = CreateReverseMap();
var translationMap = new int[Count];
foreach (var scl in classes) {
// skip if the supper class contains the unclassified element
if (scl.Contains(DFAConst.UNCLASSIFIED_INPUT))
continue;
var range = new List<T>();
foreach (var cl in scl) {
if (cl < 0 || cl >= reverseMap.Length)
throw new ArgumentOutOfRangeException(String.Format("Class {0} is not valid for the current alphabet", cl));
range.AddRange(reverseMap[cl]);
}
var newClass = newAlphabet.DefineClass(range);
foreach (var cl in scl)
translationMap[cl] = newClass;
}
return translationMap;
}
public virtual int Translate(T symbol) {
return m_map[GetSymbolIndex(symbol)];
}
public abstract int GetSymbolIndex(T symbol);
public abstract IEnumerable<T> InputSymbols { get; }
/// <summary>
/// Gets the translation map from the index of the symbol to it's class this is usefull for the optimized input symbols transtaion.
/// </summary>
/// <returns>The translation map.</returns>
public int[] GetTranslationMap() {
return m_map;
}
}
}