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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 "atn/LexerActionType.h"
#include "antlr4-common.h"
namespace antlr4 {
namespace atn {
/// <summary>
/// Represents a single action which can be executed following the successful
/// match of a lexer rule. Lexer actions are used for both embedded action syntax
/// and ANTLR 4's new lexer command syntax.
///
/// @author Sam Harwell
/// @since 4.2
/// </summary>
class ANTLR4CPP_PUBLIC LexerAction {
public:
virtual ~LexerAction() = default;
/// <summary>
/// Gets the serialization type of the lexer action.
/// </summary>
/// <returns> The serialization type of the lexer action. </returns>
///
/// IMPORTANT: Unlike Java, this returns LexerActionType::INDEXED_CUSTOM for instances of
/// LexerIndexedCustomAction. If you need the wrapped action type, use
/// LexerIndexedCustomAction::getAction()->getActionType().
LexerActionType getActionType() const { return _actionType; }
/// <summary>
/// Gets whether the lexer action is position-dependent. Position-dependent
/// actions may have different semantics depending on the <seealso cref="CharStream"/>
/// index at the time the action is executed.
///
/// <para>Many lexer commands, including {@code type}, {@code skip}, and
/// {@code more}, do not check the input index during their execution.
/// Actions like this are position-independent, and may be stored more
/// efficiently as part of the <seealso cref="LexerATNConfig#lexerActionExecutor"/>.</para>
/// </summary>
/// <returns> {@code true} if the lexer action semantics can be affected by the
/// position of the input <seealso cref="CharStream"/> at the time it is executed;
/// otherwise, {@code false}. </returns>
bool isPositionDependent() const { return _positionDependent; }
/// <summary>
/// Execute the lexer action in the context of the specified <seealso cref="Lexer"/>.
///
/// <para>For position-dependent actions, the input stream must already be
/// positioned correctly prior to calling this method.</para>
/// </summary>
/// <param name="lexer"> The lexer instance. </param>
virtual void execute(Lexer *lexer) const = 0;
size_t hashCode() const;
virtual bool equals(const LexerAction &other) const = 0;
virtual std::string toString() const = 0;
protected:
LexerAction(LexerActionType actionType, bool positionDependent)
: _actionType(actionType), _hashCode(0), _positionDependent(positionDependent) {}
virtual size_t hashCodeImpl() const = 0;
size_t cachedHashCode() const { return _hashCode.load(std::memory_order_relaxed); }
private:
const LexerActionType _actionType;
mutable std::atomic<size_t> _hashCode;
const bool _positionDependent;
};
inline bool operator==(const LexerAction &lhs, const LexerAction &rhs) {
return lhs.equals(rhs);
}
inline bool operator!=(const LexerAction &lhs, const LexerAction &rhs) {
return !operator==(lhs, rhs);
}
} // namespace atn
} // namespace antlr4
namespace std {
template <>
struct hash<::antlr4::atn::LexerAction> {
size_t operator()(const ::antlr4::atn::LexerAction &lexerAction) const {
return lexerAction.hashCode();
}
};
} // namespace std
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