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/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
#pragma once
#include "dfa/DFAState.h"
namespace antlr4 {
namespace dfa {
class ANTLR4CPP_PUBLIC DFA final {
private:
struct DFAStateHasher final {
size_t operator()(const DFAState *dfaState) const {
return dfaState->hashCode();
}
};
struct DFAStateComparer final {
bool operator()(const DFAState *lhs, const DFAState *rhs) const {
return lhs == rhs || *lhs == *rhs;
}
};
public:
/// A set of all DFA states. Use a map so we can get old state back.
/// Set only allows you to see if it's there.
/// From which ATN state did we create this DFA?
atn::DecisionState *atnStartState;
std::unordered_set<DFAState*, DFAStateHasher, DFAStateComparer> states; // States are owned by this class.
DFAState *s0;
size_t decision;
explicit DFA(atn::DecisionState *atnStartState);
DFA(atn::DecisionState *atnStartState, size_t decision);
DFA(const DFA &other) = delete;
DFA(DFA &&other);
~DFA();
/**
* Gets whether this DFA is a precedence DFA. Precedence DFAs use a special
* start state {@link #s0} which is not stored in {@link #states}. The
* {@link DFAState#edges} array for this start state contains outgoing edges
* supplying individual start states corresponding to specific precedence
* values.
*
* @return {@code true} if this is a precedence DFA; otherwise,
* {@code false}.
* @see Parser#getPrecedence()
*/
bool isPrecedenceDfa() const;
/**
* Get the start state for a specific precedence value.
*
* @param precedence The current precedence.
* @return The start state corresponding to the specified precedence, or
* {@code null} if no start state exists for the specified precedence.
*
* @throws IllegalStateException if this is not a precedence DFA.
* @see #isPrecedenceDfa()
*/
DFAState* getPrecedenceStartState(int precedence) const;
/**
* Set the start state for a specific precedence value.
*
* @param precedence The current precedence.
* @param startState The start state corresponding to the specified
* precedence.
*
* @throws IllegalStateException if this is not a precedence DFA.
* @see #isPrecedenceDfa()
*/
void setPrecedenceStartState(int precedence, DFAState *startState);
/// Return a list of all states in this DFA, ordered by state number.
std::vector<DFAState *> getStates() const;
std::string toString(const Vocabulary &vocabulary) const;
std::string toLexerString() const;
private:
/**
* {@code true} if this DFA is for a precedence decision; otherwise,
* {@code false}. This is the backing field for {@link #isPrecedenceDfa}.
*/
bool _precedenceDfa;
};
} // namespace atn
} // namespace antlr4
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