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// bsn GoldParser .NET Engine
// --------------------------
//
// Copyright 2009, 2010 by Ars�ne von Wyss - avw@gmx.ch
//
// Development has been supported by Sirius Technologies AG, Basel
//
// Source:
//
// https://bsn-goldparser.googlecode.com/hg/
//
// License:
//
// The library is distributed under the GNU Lesser General Public License:
// http://www.gnu.org/licenses/lgpl.html
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
using System;
using System.Collections.Generic;
using System.Diagnostics;
namespace bsn.GoldParser.Grammar {
/// <summary>
/// State in the Deterministic Finite Automata
/// which is used by the tokenizer.
/// </summary>
public sealed class DfaState: GrammarObject<DfaState> {
private readonly Dictionary<char, DfaState> transitionVector = new Dictionary<char, DfaState>();
private Symbol acceptSymbol;
private char sequenceEnd = char.MinValue;
private char sequenceStart = char.MaxValue;
private DfaState sequenceState;
/// <summary>
/// Creates a new instance of the <c>DfaState</c> class.
/// </summary>
internal DfaState(CompiledGrammar owner, int index): base(owner, index) {
if (owner == null) {
throw new ArgumentNullException("owner");
}
}
/// <summary>
/// Gets the symbol which can be accepted in this DFA state.
/// </summary>
public Symbol AcceptSymbol {
get {
return acceptSymbol;
}
}
/// <summary>
/// Gets the transition origin states.
/// </summary>
/// <returns></returns>
public ICollection<DfaState> GetOriginStates() {
return Owner.GetStateOrigins(this);
}
/// <summary>
/// Gets the transition for the given character.
/// </summary>
/// <param name="ch">The ch.</param>
/// <returns>The transition or null if there is not transition defined.</returns>
public DfaState GetTransition(char ch) {
DfaState result;
if ((ch >= sequenceStart) && (ch <= sequenceEnd)) {
return sequenceState;
}
if (transitionVector.TryGetValue(ch, out result)) {
return result;
}
return null;
}
/// <summary>
/// Gets the transition destination states.
/// </summary>
/// <returns></returns>
public IEnumerable<DfaState> GetTransitionStates() {
Dictionary<DfaState, IntPtr> result = new Dictionary<DfaState, IntPtr>();
if (sequenceState != null) {
result.Add(sequenceState, IntPtr.Zero);
}
foreach (DfaState state in transitionVector.Values) {
result[state] = IntPtr.Zero;
}
return result.Keys;
}
internal void Initialize(Symbol acceptSymbol, ICollection<CompiledGrammar.DfaEdge> edges) {
if (edges == null) {
throw new ArgumentNullException("edges");
}
if ((this.acceptSymbol != null) || (sequenceState != null) || (transitionVector.Count > 0)) {
throw new InvalidOperationException("The DfaState has already been initialized!");
}
this.acceptSymbol = acceptSymbol;
if (edges.Count == 0) {
Debug.Assert(acceptSymbol != null);
sequenceStart = char.MinValue;
sequenceEnd = char.MaxValue;
sequenceState = null;
} else {
DfaCharset sequence = null;
int sequenceLength = 0;
foreach (CompiledGrammar.DfaEdge edge in edges) {
DfaCharset charset = Owner.GetDfaCharset(edge.CharSetIndex);
if (charset.SequenceLength > sequenceLength) {
sequence = charset;
sequenceLength = charset.SequenceLength;
}
}
Debug.Assert(sequence != null);
foreach (CompiledGrammar.DfaEdge edge in edges) {
DfaState targetDfaState = Owner.GetDfaState(edge.TargetIndex);
DfaCharset charset = Owner.GetDfaCharset(edge.CharSetIndex);
ICollection<char> characters;
if (ReferenceEquals(charset, sequence)) {
Debug.Assert(sequenceState == null);
characters = charset.CharactersExcludingSequence;
sequenceStart = charset.SequenceStart;
sequenceEnd = charset.SequenceEnd;
sequenceState = targetDfaState;
} else {
characters = charset.CharactersIncludingSequence;
}
foreach (char ch in characters) {
transitionVector.Add(ch, targetDfaState);
}
}
}
}
}
}
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