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using Implab;
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace Implab.Parsing {
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public abstract class DFAutomaton<T> {
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protected struct ContextFrame {
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public DFAStateDescriptior[] states;
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public int current;
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public T info;
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}
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public const int INITIAL_STATE = DFADefinitionBase.INITIAL_STATE;
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public const int UNREACHEBLE_STATE = DFADefinitionBase.UNREACHEBLE_STATE;
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protected ContextFrame m_context;
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Stack<ContextFrame> m_contextStack = new Stack<ContextFrame>();
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protected int Level {
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get { return m_contextStack.Count; }
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}
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protected DFAutomaton(DFAStateDescriptior[] states, int startState, T info) {
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Safe.ArgumentNotNull(states, "states");
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Safe.ArgumentInRange(startState, 0, states.Length - 1, "startState");
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m_context.states = states;
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m_context.current = startState;
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m_context.info = info;
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}
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protected void Switch(DFAStateDescriptior[] states, int current, T info) {
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Debug.Assert(states != null);
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Debug.Assert(current >= 0 && current < states.Length);
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m_contextStack.Push(m_context);
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m_context.states = states;
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m_context.current = current;
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m_context.info = info;
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}
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protected void Restore() {
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Debug.Assert(m_contextStack.Count > 0);
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m_context = m_contextStack.Pop();
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}
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protected void Move(int input) {
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Debug.Assert(input > 0 && input < m_context.states[m_context.current].transitions.Length);
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m_context.current = m_context.states[m_context.current].transitions[input];
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}
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protected bool CanMove(int input) {
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Debug.Assert(input > 0 && input < m_context.states[m_context.current].transitions.Length);
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return m_context.states[m_context.current].transitions[input] != UNREACHEBLE_STATE;
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}
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}
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}
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