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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 "Token.h"
namespace antlr4 {
/// <summary>
/// The interface for defining strategies to deal with syntax errors encountered
/// during a parse by ANTLR-generated parsers. We distinguish between three
/// different kinds of errors:
///
/// <ul>
/// <li>The parser could not figure out which path to take in the ATN (none of
/// the available alternatives could possibly match)</li>
/// <li>The current input does not match what we were looking for</li>
/// <li>A predicate evaluated to false</li>
/// </ul>
///
/// Implementations of this interface report syntax errors by calling
/// <seealso cref="Parser#notifyErrorListeners"/>.
/// <p/>
/// TODO: what to do about lexers
/// </summary>
class ANTLR4CPP_PUBLIC ANTLRErrorStrategy {
public:
/// <summary>
/// Reset the error handler state for the specified {@code recognizer}. </summary>
/// <param name="recognizer"> the parser instance </param>
virtual ~ANTLRErrorStrategy();
virtual void reset(Parser *recognizer) = 0;
/**
* This method is called when an unexpected symbol is encountered during an
* inline match operation, such as {@link Parser#match}. If the error
* strategy successfully recovers from the match failure, this method
* returns the {@link Token} instance which should be treated as the
* successful result of the match.
*
* <p>This method handles the consumption of any tokens - the caller should
* <b>not</b> call {@link Parser#consume} after a successful recovery.</p>
*
* <p>Note that the calling code will not report an error if this method
* returns successfully. The error strategy implementation is responsible
* for calling {@link Parser#notifyErrorListeners} as appropriate.</p>
*
* @param recognizer the parser instance
* @throws RecognitionException if the error strategy was not able to
* recover from the unexpected input symbol
*/
virtual Token* recoverInline(Parser *recognizer) = 0;
/// <summary>
/// This method is called to recover from exception {@code e}. This method is
/// called after <seealso cref="#reportError"/> by the default exception handler
/// generated for a rule method.
/// </summary>
/// <seealso cref= #reportError
/// </seealso>
/// <param name="recognizer"> the parser instance </param>
/// <param name="e"> the recognition exception to recover from </param>
/// <exception cref="RecognitionException"> if the error strategy could not recover from
/// the recognition exception </exception>
virtual void recover(Parser *recognizer, std::exception_ptr e) = 0;
/// <summary>
/// This method provides the error handler with an opportunity to handle
/// syntactic or semantic errors in the input stream before they result in a
/// <seealso cref="RecognitionException"/>.
/// <p/>
/// The generated code currently contains calls to <seealso cref="#sync"/> after
/// entering the decision state of a closure block ({@code (...)*} or
/// {@code (...)+}).
/// <p/>
/// For an implementation based on Jim Idle's "magic sync" mechanism, see
/// <seealso cref="DefaultErrorStrategy#sync"/>.
/// </summary>
/// <seealso cref= DefaultErrorStrategy#sync
/// </seealso>
/// <param name="recognizer"> the parser instance </param>
/// <exception cref="RecognitionException"> if an error is detected by the error
/// strategy but cannot be automatically recovered at the current state in
/// the parsing process </exception>
virtual void sync(Parser *recognizer) = 0;
/// <summary>
/// Tests whether or not {@code recognizer} is in the process of recovering
/// from an error. In error recovery mode, <seealso cref="Parser#consume"/> adds
/// symbols to the parse tree by calling
/// {@link Parser#createErrorNode(ParserRuleContext, Token)} then
/// {@link ParserRuleContext#addErrorNode(ErrorNode)} instead of
/// {@link Parser#createTerminalNode(ParserRuleContext, Token)}.
/// </summary>
/// <param name="recognizer"> the parser instance </param>
/// <returns> {@code true} if the parser is currently recovering from a parse
/// error, otherwise {@code false} </returns>
virtual bool inErrorRecoveryMode(Parser *recognizer) = 0;
/// <summary>
/// This method is called by when the parser successfully matches an input
/// symbol.
/// </summary>
/// <param name="recognizer"> the parser instance </param>
virtual void reportMatch(Parser *recognizer) = 0;
/// <summary>
/// Report any kind of <seealso cref="RecognitionException"/>. This method is called by
/// the default exception handler generated for a rule method.
/// </summary>
/// <param name="recognizer"> the parser instance </param>
/// <param name="e"> the recognition exception to report </param>
virtual void reportError(Parser *recognizer, const RecognitionException &e) = 0;
};
} // namespace antlr4
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