public virtual void Match( string s )
{
int i = 0;
while ( i < s.Length )
{
if ( input.LA( 1 ) != s[i] )
{
if ( state.backtracking > 0 )
{
state.failed = true;
return;
}
MismatchedTokenException mte = new MismatchedTokenException(s[i], input, TokenNames);
Recover( mte );
throw mte;
}
i++;
input.Consume();
state.failed = false;
}
}
public virtual void Match( int c )
{
if ( input.LA( 1 ) != c )
{
if ( state.backtracking > 0 )
{
state.failed = true;
return;
}
MismatchedTokenException mte = new MismatchedTokenException(c, input, TokenNames);
Recover( mte ); // don't really recover; just consume in lexer
throw mte;
}
input.Consume();
state.failed = false;
}
/** <summary>Attempt to recover from a single missing or extra token.</summary>
*
* EXTRA TOKEN
*
* LA(1) is not what we are looking for. If LA(2) has the right token,
* however, then assume LA(1) is some extra spurious token. Delete it
* and LA(2) as if we were doing a normal match(), which advances the
* input.
*
* MISSING TOKEN
*
* If current token is consistent with what could come after
* ttype then it is ok to "insert" the missing token, else throw
* exception For example, Input "i=(3;" is clearly missing the
* ')'. When the parser returns from the nested call to expr, it
* will have call chain:
*
* stat -> expr -> atom
*
* and it will be trying to match the ')' at this point in the
* derivation:
*
* => ID '=' '(' INT ')' ('+' atom)* ';'
* ^
* match() will see that ';' doesn't match ')' and report a
* mismatched token error. To recover, it sees that LA(1)==';'
* is in the set of tokens that can follow the ')' token
* reference in rule atom. It can assume that you forgot the ')'.
*/
protected virtual object RecoverFromMismatchedToken( IIntStream input, int ttype, BitSet follow )
{
RecognitionException e = null;
// if next token is what we are looking for then "delete" this token
if ( MismatchIsUnwantedToken( input, ttype ) )
{
e = new UnwantedTokenException( ttype, input, TokenNames );
/*
System.err.println("recoverFromMismatchedToken deleting "+
((TokenStream)input).LT(1)+
" since "+((TokenStream)input).LT(2)+" is what we want");
*/
BeginResync();
input.Consume(); // simply delete extra token
EndResync();
ReportError( e ); // report after consuming so AW sees the token in the exception
// we want to return the token we're actually matching
object matchedSymbol = GetCurrentInputSymbol( input );
input.Consume(); // move past ttype token as if all were ok
return matchedSymbol;
}
// can't recover with single token deletion, try insertion
if ( MismatchIsMissingToken( input, follow ) )
{
object inserted = GetMissingSymbol( input, e, ttype, follow );
e = new MissingTokenException( ttype, input, inserted );
ReportError( e ); // report after inserting so AW sees the token in the exception
return inserted;
}
// even that didn't work; must throw the exception
e = new MismatchedTokenException(ttype, input, TokenNames);
throw e;
}
