/// <summary>
/// <inheritDoc/>
/// <p>The default implementation resynchronizes the parser by consuming tokens
/// until we find one in the resynchronization set--loosely the set of tokens
/// that can follow the current rule.</p>
/// </summary>
public virtual void Recover(Parser recognizer, RecognitionException e)
{
// System.out.println("recover in "+recognizer.getRuleInvocationStack()+
// " index="+recognizer.getInputStream().index()+
// ", lastErrorIndex="+
// lastErrorIndex+
// ", states="+lastErrorStates);
if (lastErrorIndex == ((ITokenStream)recognizer.InputStream).Index && lastErrorStates != null && lastErrorStates.Contains(recognizer.State))
{
// uh oh, another error at same token index and previously-visited
// state in ATN; must be a case where LT(1) is in the recovery
// token set so nothing got consumed. Consume a single token
// at least to prevent an infinite loop; this is a failsafe.
// System.err.println("seen error condition before index="+
// lastErrorIndex+", states="+lastErrorStates);
// System.err.println("FAILSAFE consumes "+recognizer.getTokenNames()[recognizer.getInputStream().LA(1)]);
recognizer.Consume();
}
lastErrorIndex = ((ITokenStream)recognizer.InputStream).Index;
if (lastErrorStates == null)
{
lastErrorStates = new IntervalSet();
}
lastErrorStates.Add(recognizer.State);
IntervalSet followSet = GetErrorRecoverySet(recognizer);
ConsumeUntil(recognizer, followSet);
}
protected internal virtual IToken SingleTokenDeletion([NotNull] Parser recognizer)
{
int nextTokenType = ((ITokenStream)recognizer.InputStream).La(2);
IntervalSet expecting = GetExpectedTokens(recognizer);
if (expecting.Contains(nextTokenType))
{
ReportUnwantedToken(recognizer);
/*
* System.err.println("recoverFromMismatchedToken deleting "+
* ((TokenStream)recognizer.getInputStream()).LT(1)+
* " since "+((TokenStream)recognizer.getInputStream()).LT(2)+
* " is what we want");
*/
recognizer.Consume();
// simply delete extra token
// we want to return the token we're actually matching
IToken matchedSymbol = recognizer.CurrentToken;
ReportMatch(recognizer);
// we know current token is correct
return(matchedSymbol);
}
return(null);
}
/// <summary>
/// <inheritDoc/>
/// <p>The default implementation attempts to recover from the mismatched input
/// by using single token insertion and deletion as described below. If the
/// recovery attempt fails, this method throws an
/// <see cref="InputMismatchException"/>
/// .</p>
/// <p><strong>EXTRA TOKEN</strong> (single token deletion)</p>
/// <p>
/// <c>LA(1)</c>
/// is not what we are looking for. If
/// <c>LA(2)</c>
/// has the
/// right token, however, then assume
/// <c>LA(1)</c>
/// is some extra spurious
/// token and delete it. Then consume and return the next token (which was
/// the
/// <c>LA(2)</c>
/// token) as the successful result of the match operation.</p>
/// <p>This recovery strategy is implemented by
/// <see cref="SingleTokenDeletion(Parser)"/>
/// .</p>
/// <p><strong>MISSING TOKEN</strong> (single token insertion)</p>
/// <p>If current token (at
/// <c>LA(1)</c>
/// ) is consistent with what could come
/// after the expected
/// <c>LA(1)</c>
/// token, then assume the token is missing
/// and use the parser's
/// <see cref="ITokenFactory"/>
/// to create it on the fly. The
/// "insertion" is performed by returning the created token as the successful
/// result of the match operation.</p>
/// <p>This recovery strategy is implemented by
/// <see cref="SingleTokenInsertion(Parser)"/>
/// .</p>
/// <p><strong>EXAMPLE</strong></p>
/// <p>For example, Input
/// <c>i=(3;</c>
/// is clearly missing the
/// <c>')'</c>
/// . When
/// the parser returns from the nested call to
/// <c>expr</c>
/// , it will have
/// call chain:</p>
/// <pre>
/// stat → expr → atom
/// </pre>
/// and it will be trying to match the
/// <c>')'</c>
/// at this point in the
/// derivation:
/// <pre>
/// => ID '=' '(' INT ')' ('+' atom)* ';'
/// ^
/// </pre>
/// The attempt to match
/// <c>')'</c>
/// will fail when it sees
/// <c>';'</c>
/// and
/// call
/// <see cref="RecoverInline(Parser)"/>
/// . To recover, it sees that
/// <c>LA(1)==';'</c>
/// is in the set of tokens that can follow the
/// <c>')'</c>
/// token reference
/// in rule
/// <c>atom</c>
/// . It can assume that you forgot the
/// <c>')'</c>
/// .
/// </summary>
/// <exception cref="Antlr4.Runtime.RecognitionException"/>
public virtual IToken RecoverInline(Parser recognizer)
{
// SINGLE TOKEN DELETION
IToken matchedSymbol = SingleTokenDeletion(recognizer);
if (matchedSymbol != null)
{
// we have deleted the extra token.
// now, move past ttype token as if all were ok
recognizer.Consume();
return(matchedSymbol);
}
// SINGLE TOKEN INSERTION
if (SingleTokenInsertion(recognizer))
{
return(GetMissingSymbol(recognizer));
}
// even that didn't work; must throw the exception
//throw new InputMismatchException(recognizer);
InputMismatchException e;
if (nextTokensContext == null)
{
e = new InputMismatchException(recognizer);
}
else
{
e = new InputMismatchException(recognizer, nextTokensState, nextTokensContext);
}
throw e;
}
/// <summary>Consume tokens until one matches the given token set.</summary>
/// <remarks>Consume tokens until one matches the given token set.</remarks>
protected internal virtual void ConsumeUntil(Parser recognizer, IntervalSet set)
{
// System.err.println("consumeUntil("+set.toString(recognizer.getTokenNames())+")");
int ttype = ((ITokenStream)recognizer.InputStream).La(1);
while (ttype != TokenConstants.Eof && !set.Contains(ttype))
{
//System.out.println("consume during recover LA(1)="+getTokenNames()[input.LA(1)]);
// recognizer.getInputStream().consume();
recognizer.Consume();
ttype = ((ITokenStream)recognizer.InputStream).La(1);
}
}
/// <summary>
/// Multiple token deletion resynchronization strategy
/// </summary>
protected override void ConsumeUntil(Antlr4.Runtime.Parser recognizer, IntervalSet set)
{
Token lastConsumedToken = (Token)((ITokenStream)recognizer.InputStream).Lt(-1);
Token nextToken = (Token)((ITokenStream)recognizer.InputStream).Lt(1);
int ttype = nextToken.Type;
while (ttype != TokenConstants.Eof && !set.Contains(ttype) &&
!ErrorStrategyShouldNotConsumeThisToken(lastConsumedToken, nextToken))
{
recognizer.Consume();
lastConsumedToken = nextToken;
nextToken = (Token)((ITokenStream)recognizer.InputStream).Lt(1);
ttype = nextToken.Type;
}
}
protected internal virtual IToken SingleTokenDeletion(Parser recognizer)
{
int nextTokenType = ((ITokenStream)recognizer.InputStream).La(2);
IntervalSet expecting = GetExpectedTokens(recognizer);
if (expecting.Contains(nextTokenType))
{
ReportUnwantedToken(recognizer);
recognizer.Consume();
// simply delete extra token
// we want to return the token we're actually matching
IToken matchedSymbol = recognizer.CurrentToken;
ReportMatch(recognizer);
// we know current token is correct
return(matchedSymbol);
}
return(null);
}
protected override void ConsumeUntil(Antlr4.Runtime.Parser recognizer, IntervalSet set)
{
int tokenType = ((ITokenStream)recognizer.InputStream).La(1);
int indents = 1;
while (tokenType != TokenConstants.Eof && indents > 0)
{
recognizer.Consume();
tokenType = ((ITokenStream)recognizer.InputStream).La(1);
if (tokenType == MalinaLexer.INDENT)
{
indents++;
}
if (tokenType == MalinaLexer.DEDENT)
{
indents--;
}
}
}
public override void Recover(Antlr4.Runtime.Parser recognizer, RecognitionException e)
{
int tokenType = ((ITokenStream)recognizer.InputStream).La(1);
int indents = 1;
while (tokenType != TokenConstants.Eof && indents > 0)
{
recognizer.Consume();
tokenType = ((ITokenStream)recognizer.InputStream).La(1);
if (tokenType == MalinaLexer.INDENT)
{
indents++;
}
if (tokenType == MalinaLexer.DEDENT)
{
indents--;
}
}
}
