path: root/impl/antlr/libantlr3c-3.4/src/antlr3baserecognizer.c

/** \file
 * Contains the base functions that all recognizers require.
 * Any function can be overridden by a lexer/parser/tree parser or by the
 * ANTLR3 programmer.
 * 
 * \addtogroup pANTLR3_BASE_RECOGNIZER
 * @{
 */
#include    <antlr3baserecognizer.h>

// [The "BSD licence"]
// Copyright (c) 2005-2009 Jim Idle, Temporal Wave LLC
// http://www.temporal-wave.com
// http://www.linkedin.com/in/jimidle
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. The name of the author may not be used to endorse or promote products
//    derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
// IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifdef	ANTLR3_WINDOWS
#pragma warning( disable : 4100 )
#endif

/* Interface functions -standard implementations cover parser and treeparser
 * almost completely but are overridden by the parser or tree parser as needed. Lexer overrides
 * most of these functions.
 */
static void					beginResync					(pANTLR3_BASE_RECOGNIZER recognizer);
static pANTLR3_BITSET		computeErrorRecoverySet	    (pANTLR3_BASE_RECOGNIZER recognizer);
static void					endResync					(pANTLR3_BASE_RECOGNIZER recognizer);
static void					beginBacktrack				(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 level);
static void					endBacktrack				(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 level, ANTLR3_BOOLEAN successful);

static void *				match						(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 ttype, pANTLR3_BITSET_LIST follow);
static void					matchAny					(pANTLR3_BASE_RECOGNIZER recognizer);
static void					mismatch					(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 ttype, pANTLR3_BITSET_LIST follow);
static ANTLR3_BOOLEAN		mismatchIsUnwantedToken		(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM is, ANTLR3_UINT32 ttype);
static ANTLR3_BOOLEAN		mismatchIsMissingToken		(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM is, pANTLR3_BITSET_LIST follow);
static void					reportError					(pANTLR3_BASE_RECOGNIZER recognizer);
static pANTLR3_BITSET		computeCSRuleFollow			(pANTLR3_BASE_RECOGNIZER recognizer);
static pANTLR3_BITSET		combineFollows				(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_BOOLEAN exact);
static void					displayRecognitionError	    (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_UINT8 * tokenNames);
static void					recover						(pANTLR3_BASE_RECOGNIZER recognizer);
static void	*				recoverFromMismatchedToken  (pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 ttype, pANTLR3_BITSET_LIST follow);
static void	*				recoverFromMismatchedSet    (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_BITSET_LIST follow);
static ANTLR3_BOOLEAN		recoverFromMismatchedElement(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_BITSET_LIST follow);
static void					consumeUntil				(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 tokenType);
static void					consumeUntilSet				(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_BITSET set);
static pANTLR3_STACK		getRuleInvocationStack	    (pANTLR3_BASE_RECOGNIZER recognizer);
static pANTLR3_STACK		getRuleInvocationStackNamed (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_UINT8 name);
static pANTLR3_HASH_TABLE	toStrings					(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_HASH_TABLE);
static ANTLR3_MARKER		getRuleMemoization			(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_INTKEY ruleIndex, ANTLR3_MARKER ruleParseStart);
static ANTLR3_BOOLEAN		alreadyParsedRule			(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_MARKER ruleIndex);
static void					memoize						(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_MARKER ruleIndex, ANTLR3_MARKER ruleParseStart);
static ANTLR3_BOOLEAN		synpred						(pANTLR3_BASE_RECOGNIZER recognizer, void * ctx, void (*predicate)(void * ctx));
static void					reset						(pANTLR3_BASE_RECOGNIZER recognizer);
static void					freeBR						(pANTLR3_BASE_RECOGNIZER recognizer);
static void *				getCurrentInputSymbol		(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM istream);
static void *				getMissingSymbol			(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM	istream, pANTLR3_EXCEPTION	e,
															ANTLR3_UINT32 expectedTokenType, pANTLR3_BITSET_LIST follow);
static ANTLR3_UINT32		getNumberOfSyntaxErrors		(pANTLR3_BASE_RECOGNIZER recognizer);

ANTLR3_API pANTLR3_BASE_RECOGNIZER
antlr3BaseRecognizerNew(ANTLR3_UINT32 type, ANTLR3_UINT32 sizeHint, pANTLR3_RECOGNIZER_SHARED_STATE state)
{
    pANTLR3_BASE_RECOGNIZER recognizer;

    // Allocate memory for the structure
    //
    recognizer	    = (pANTLR3_BASE_RECOGNIZER) ANTLR3_MALLOC((size_t)sizeof(ANTLR3_BASE_RECOGNIZER));

    if	(recognizer == NULL)
    {
		// Allocation failed
		//
		return	NULL;
    }

	
	// If we have been supplied with a pre-existing recognizer state
	// then we just install it, otherwise we must create one from scratch
	//
	if	(state == NULL)
	{
		recognizer->state = (pANTLR3_RECOGNIZER_SHARED_STATE) ANTLR3_CALLOC(1, (size_t)sizeof(ANTLR3_RECOGNIZER_SHARED_STATE));

		if	(recognizer->state == NULL)
		{
			ANTLR3_FREE(recognizer);
			return	NULL;
		}

		// Initialize any new recognizer state
		//
		recognizer->state->errorRecovery	= ANTLR3_FALSE;
		recognizer->state->lastErrorIndex	= -1;
		recognizer->state->failed		= ANTLR3_FALSE;
		recognizer->state->errorCount		= 0;
		recognizer->state->backtracking		= 0;
		recognizer->state->following		= NULL;
		recognizer->state->ruleMemo		= NULL;
		recognizer->state->tokenNames		= NULL;
		recognizer->state->sizeHint             = sizeHint;
		recognizer->state->tokSource		= NULL;
                recognizer->state->tokFactory           = NULL;

		// Rather than check to see if we must initialize
		// the stack every time we are asked for an new rewrite stream
		// we just always create an empty stack and then just
		// free it when the base recognizer is freed.
		//
		recognizer->state->rStreams		= antlr3VectorNew(0);  // We don't know the size.

		if	(recognizer->state->rStreams == NULL)
		{
			// Out of memory
			//
			ANTLR3_FREE(recognizer->state);
			ANTLR3_FREE(recognizer);
			return	NULL;
		}
	}
	else
	{
		// Install the one we were given, and do not reset it here
		// as it will either already have been initialized or will
		// be in a state that needs to be preserved.
		//
		recognizer->state = state;
	}
		
    // Install the BR API
    //
    recognizer->alreadyParsedRule           = alreadyParsedRule;
    recognizer->beginResync                 = beginResync;
    recognizer->combineFollows              = combineFollows;
    recognizer->beginBacktrack              = beginBacktrack;
    recognizer->endBacktrack                = endBacktrack;
    recognizer->computeCSRuleFollow         = computeCSRuleFollow;
    recognizer->computeErrorRecoverySet     = computeErrorRecoverySet;
    recognizer->consumeUntil                = consumeUntil;
    recognizer->consumeUntilSet             = consumeUntilSet;
    recognizer->displayRecognitionError     = displayRecognitionError;
    recognizer->endResync                   = endResync;
    recognizer->exConstruct                 = antlr3MTExceptionNew;
    recognizer->getRuleInvocationStack      = getRuleInvocationStack;
    recognizer->getRuleInvocationStackNamed = getRuleInvocationStackNamed;
    recognizer->getRuleMemoization          = getRuleMemoization;
    recognizer->match                       = match;
    recognizer->matchAny                    = matchAny;
    recognizer->memoize                     = memoize;
    recognizer->mismatch                    = mismatch;
    recognizer->mismatchIsUnwantedToken     = mismatchIsUnwantedToken;
    recognizer->mismatchIsMissingToken      = mismatchIsMissingToken;
    recognizer->recover                     = recover;
    recognizer->recoverFromMismatchedElement= recoverFromMismatchedElement;
    recognizer->recoverFromMismatchedSet    = recoverFromMismatchedSet;
    recognizer->recoverFromMismatchedToken  = recoverFromMismatchedToken;
    recognizer->getNumberOfSyntaxErrors     = getNumberOfSyntaxErrors;
    recognizer->reportError                 = reportError;
    recognizer->reset                       = reset;
    recognizer->synpred                     = synpred;
    recognizer->toStrings                   = toStrings;
    recognizer->getCurrentInputSymbol       = getCurrentInputSymbol;
    recognizer->getMissingSymbol            = getMissingSymbol;
    recognizer->debugger                    = NULL;

    recognizer->free = freeBR;

    /* Initialize variables
     */
    recognizer->type			= type;


    return  recognizer;
}
static void	
freeBR	    (pANTLR3_BASE_RECOGNIZER recognizer)
{
    pANTLR3_EXCEPTION thisE;

	// Did we have a state allocated?
	//
	if	(recognizer->state != NULL)
	{
		// Free any rule memoization we set up
		//
		if	(recognizer->state->ruleMemo != NULL)
		{
			recognizer->state->ruleMemo->free(recognizer->state->ruleMemo);
			recognizer->state->ruleMemo = NULL;
		}

		// Free any exception space we have left around
		//
		thisE = recognizer->state->exception;
		if	(thisE != NULL)
		{
			thisE->freeEx(thisE);
		}

		// Free any rewrite streams we have allocated
		//
		if	(recognizer->state->rStreams != NULL)
		{
			recognizer->state->rStreams->free(recognizer->state->rStreams);
		}

		// Free up any token factory we created (error recovery for instance)
		//
		if	(recognizer->state->tokFactory != NULL)
		{
			recognizer->state->tokFactory->close(recognizer->state->tokFactory);
		}
		// Free the shared state memory
		//
		ANTLR3_FREE(recognizer->state);
	}

	// Free the actual recognizer space
	//
    ANTLR3_FREE(recognizer);
}

/**
 * Creates a new Mismatched Token Exception and inserts in the recognizer
 * exception stack.
 * 
 * \param recognizer
 * Context pointer for this recognizer
 * 
 */
ANTLR3_API	void
antlr3MTExceptionNew(pANTLR3_BASE_RECOGNIZER recognizer)
{
    /* Create a basic recognition exception structure
     */
    antlr3RecognitionExceptionNew(recognizer);

    /* Now update it to indicate this is a Mismatched token exception
     */
    recognizer->state->exception->name		= ANTLR3_MISMATCHED_EX_NAME;
    recognizer->state->exception->type		= ANTLR3_MISMATCHED_TOKEN_EXCEPTION;

    return;
}

ANTLR3_API	void
antlr3RecognitionExceptionNew(pANTLR3_BASE_RECOGNIZER recognizer)
{
	pANTLR3_EXCEPTION				ex;
	pANTLR3_LEXER					lexer;
	pANTLR3_PARSER					parser;
	pANTLR3_TREE_PARSER				tparser;

	pANTLR3_INPUT_STREAM			ins;
	pANTLR3_INT_STREAM				is;
	pANTLR3_COMMON_TOKEN_STREAM	    cts;
	pANTLR3_TREE_NODE_STREAM	    tns;

	ins	    = NULL;
	cts	    = NULL;
	tns	    = NULL;
	is	    = NULL;
	lexer   = NULL;
	parser  = NULL;
	tparser = NULL;

	switch	(recognizer->type)
	{
	case	ANTLR3_TYPE_LEXER:

		lexer	= (pANTLR3_LEXER) (recognizer->super);
		ins	= lexer->input;
		is	= ins->istream;

		break;

	case	ANTLR3_TYPE_PARSER:

		parser  = (pANTLR3_PARSER) (recognizer->super);
		cts	= (pANTLR3_COMMON_TOKEN_STREAM)(parser->tstream->super);
		is	= parser->tstream->istream;

		break;

	case	ANTLR3_TYPE_TREE_PARSER:

		tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
		tns	= tparser->ctnstream->tnstream;
		is	= tns->istream;

		break;

	default:

		ANTLR3_FPRINTF(stderr, "Base recognizer function antlr3RecognitionExceptionNew called by unknown parser type - provide override for this function\n");
		return;

		break;
	}

	/* Create a basic exception structure
	 */
	ex = antlr3ExceptionNew(ANTLR3_RECOGNITION_EXCEPTION,
		(void *)ANTLR3_RECOGNITION_EX_NAME,
		NULL,
		ANTLR3_FALSE);

	/* Rest of information depends on the base type of the 
	 * input stream.
	 */
	switch  (is->type & ANTLR3_INPUT_MASK)
	{
	case    ANTLR3_CHARSTREAM:

		ex->c			= is->_LA		    	(is, 1);					/* Current input character			*/
		ex->line		= ins->getLine			(ins);						/* Line number comes from stream		*/
		ex->charPositionInLine	= ins->getCharPositionInLine	(ins);	    /* Line offset also comes from the stream   */
		ex->index		= is->index			(is);
		ex->streamName		= ins->fileName;
		ex->message		= "Unexpected character";
		break;

	case    ANTLR3_TOKENSTREAM:

		ex->token		= cts->tstream->_LT						(cts->tstream, 1);	    /* Current input token			    */
		ex->line		= ((pANTLR3_COMMON_TOKEN)(ex->token))->getLine			(ex->token);
		ex->charPositionInLine	= ((pANTLR3_COMMON_TOKEN)(ex->token))->getCharPositionInLine	(ex->token);
		ex->index		= cts->tstream->istream->index					(cts->tstream->istream);
		if	(((pANTLR3_COMMON_TOKEN)(ex->token))->type == ANTLR3_TOKEN_EOF)
		{
			ex->streamName		= NULL;
		}
		else
		{
			ex->streamName		= ((pANTLR3_COMMON_TOKEN)(ex->token))->input->fileName;
		}
		ex->message		= "Unexpected token";
		break;

	case    ANTLR3_COMMONTREENODE:

		ex->token		= tns->_LT						    (tns, 1);	    /* Current input tree node			    */
		ex->line		= ((pANTLR3_BASE_TREE)(ex->token))->getLine		    (ex->token);
		ex->charPositionInLine	= ((pANTLR3_BASE_TREE)(ex->token))->getCharPositionInLine   (ex->token);
		ex->index		= tns->istream->index					    (tns->istream);

		// Are you ready for this? Deep breath now...
		//
		{
			pANTLR3_COMMON_TREE tnode;

			tnode		= ((pANTLR3_COMMON_TREE)(((pANTLR3_BASE_TREE)(ex->token))->super));

			if	(tnode->token    == NULL)
			{
				ex->streamName = ((pANTLR3_BASE_TREE)(ex->token))->strFactory->newStr(((pANTLR3_BASE_TREE)(ex->token))->strFactory, (pANTLR3_UINT8)"-unknown source-");
			}
			else
			{
				if	(tnode->token->input == NULL)
				{
					ex->streamName		= NULL;
				}
				else
				{
					ex->streamName		= tnode->token->input->fileName;
				}
			}
			ex->message		= "Unexpected node";
		}
		break;
	}

	ex->input						= is;
	ex->nextException				= recognizer->state->exception;	/* So we don't leak the memory */
	recognizer->state->exception	= ex;
	recognizer->state->error	    = ANTLR3_TRUE;	    /* Exception is outstanding	*/

	return;
}


/// Match current input symbol against ttype.  Upon error, do one token
/// insertion or deletion if possible.  
/// To turn off single token insertion or deletion error
/// recovery, override mismatchRecover() and have it call
/// plain mismatch(), which does not recover.  Then any error
/// in a rule will cause an exception and immediate exit from
/// rule.  Rule would recover by resynchronizing to the set of
/// symbols that can follow rule ref.
///
static void *
match(	pANTLR3_BASE_RECOGNIZER recognizer,
		ANTLR3_UINT32 ttype, pANTLR3_BITSET_LIST follow)
{
    pANTLR3_PARSER			parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;
	void					* matchedSymbol;

    switch	(recognizer->type)
    {
		case	ANTLR3_TYPE_PARSER:

			parser  = (pANTLR3_PARSER) (recognizer->super);
			tparser	= NULL;
			is	= parser->tstream->istream;

			break;

		case	ANTLR3_TYPE_TREE_PARSER:

			tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
			parser	= NULL;
			is	= tparser->ctnstream->tnstream->istream;

			break;

		default:
		    
			ANTLR3_FPRINTF(stderr, "Base recognizer function 'match' called by unknown parser type - provide override for this function\n");
			return ANTLR3_FALSE;

			break;
    }

	// Pick up the current input token/node for assignment to labels
	//
	matchedSymbol = recognizer->getCurrentInputSymbol(recognizer, is);

    if	(is->_LA(is, 1) == ttype)
    {
		// The token was the one we were told to expect
		//
		is->consume(is);									// Consume that token from the stream
		recognizer->state->errorRecovery	= ANTLR3_FALSE;	// Not in error recovery now (if we were)
		recognizer->state->failed			= ANTLR3_FALSE;	// The match was a success
		return matchedSymbol;								// We are done
    }

    // We did not find the expected token type, if we are backtracking then
    // we just set the failed flag and return.
    //
    if	(recognizer->state->backtracking > 0)
    {
		// Backtracking is going on
		//
		recognizer->state->failed  = ANTLR3_TRUE;
		return matchedSymbol;
	}

    // We did not find the expected token and there is no backtracking
    // going on, so we mismatch, which creates an exception in the recognizer exception
    // stack.
    //
	matchedSymbol = recognizer->recoverFromMismatchedToken(recognizer, ttype, follow);
    return matchedSymbol;
}

/// Consumes the next token, whatever it is, and resets the recognizer state
/// so that it is not in error.
///
/// \param recognizer
/// Recognizer context pointer
///
static void
matchAny(pANTLR3_BASE_RECOGNIZER recognizer)
{
    pANTLR3_PARSER	    parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;

    switch	(recognizer->type)
    {
		case	ANTLR3_TYPE_PARSER:

			parser  = (pANTLR3_PARSER) (recognizer->super);
			tparser	= NULL;
			is	= parser->tstream->istream;

			break;

		case	ANTLR3_TYPE_TREE_PARSER:

			tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
			parser	= NULL;
			is	= tparser->ctnstream->tnstream->istream;

			break;

		default:
		    
			ANTLR3_FPRINTF(stderr, "Base recognizer function 'matchAny' called by unknown parser type - provide override for this function\n");
			return;

		break;
    }
    recognizer->state->errorRecovery	= ANTLR3_FALSE;
    recognizer->state->failed		    = ANTLR3_FALSE;
    is->consume(is);

    return;
}
///
///
static ANTLR3_BOOLEAN
mismatchIsUnwantedToken(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM is, ANTLR3_UINT32 ttype)
{
	ANTLR3_UINT32 nextt;

	nextt = is->_LA(is, 2);

	if	(nextt == ttype)
	{
		if	(recognizer->state->exception != NULL)
		{
			recognizer->state->exception->expecting = nextt;
		}
		return ANTLR3_TRUE;		// This token is unknown, but the next one is the one we wanted
	}
	else
	{
		return ANTLR3_FALSE;	// Neither this token, nor the one following is the one we wanted
	}
}

///
///
static ANTLR3_BOOLEAN
mismatchIsMissingToken(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM is, pANTLR3_BITSET_LIST follow)
{
	ANTLR3_BOOLEAN	retcode;
	pANTLR3_BITSET	followClone;
	pANTLR3_BITSET	viableTokensFollowingThisRule;

	if	(follow == NULL)
	{
		// There is no information about the tokens that can follow the last one
		// hence we must say that the current one we found is not a member of the 
		// follow set and does not indicate a missing token. We will just consume this
		// single token and see if the parser works it out from there.
		//
		return	ANTLR3_FALSE;
	}

	followClone						= NULL;
	viableTokensFollowingThisRule	= NULL;

	// The C bitset maps are laid down at compile time by the
	// C code generation. Hence we cannot remove things from them
	// and so on. So, in order to remove EOR (if we need to) then
	// we clone the static bitset.
	//
	followClone = antlr3BitsetLoad(follow);
	if	(followClone == NULL)
	{
		return ANTLR3_FALSE;
	}

	// Compute what can follow this grammar reference
	//
	if	(followClone->isMember(followClone, ANTLR3_EOR_TOKEN_TYPE))
	{
		// EOR can follow, but if we are not the start symbol, we
		// need to remove it.
		//
		if	(recognizer->state->following->vector->count >= 0)
		{
			followClone->remove(followClone, ANTLR3_EOR_TOKEN_TYPE);
		}

		// Now compute the visiable tokens that can follow this rule, according to context
		// and make them part of the follow set.
		//
		viableTokensFollowingThisRule = recognizer->computeCSRuleFollow(recognizer);
		followClone->borInPlace(followClone, viableTokensFollowingThisRule);
	}

	/// if current token is consistent with what could come after set
	/// then we know we're missing a token; error recovery is free to
	/// "insert" the missing token
	///
	/// BitSet cannot handle negative numbers like -1 (EOF) so I leave EOR
	/// in follow set to indicate that the fall of the start symbol is
	/// in the set (EOF can follow).
	///
	if	(		followClone->isMember(followClone, is->_LA(is, 1))
			||	followClone->isMember(followClone, ANTLR3_EOR_TOKEN_TYPE)
		)
	{
		retcode = ANTLR3_TRUE;
	}
	else
	{
		retcode	= ANTLR3_FALSE;
	}

	if	(viableTokensFollowingThisRule != NULL)
	{
		viableTokensFollowingThisRule->free(viableTokensFollowingThisRule);
	}
	if	(followClone != NULL)
	{
		followClone->free(followClone);
	}

	return retcode;

}

/// Factor out what to do upon token mismatch so tree parsers can behave
/// differently.  Override and call mismatchRecover(input, ttype, follow)
/// to get single token insertion and deletion.  Use this to turn off
/// single token insertion and deletion. Override mismatchRecover
/// to call this instead.
///
/// \remark mismatch only works for parsers and must be overridden for anything else.
///
static	void
mismatch(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 ttype, pANTLR3_BITSET_LIST follow)
{
    pANTLR3_PARSER	    parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;

    // Install a mismatched token exception in the exception stack
    //
    antlr3MTExceptionNew(recognizer);
    recognizer->state->exception->expecting    = ttype;

    switch	(recognizer->type)
    {
		case	ANTLR3_TYPE_PARSER:

			parser  = (pANTLR3_PARSER) (recognizer->super);
			tparser	= NULL;
			is	= parser->tstream->istream;

			break;

		default:
		    
			ANTLR3_FPRINTF(stderr, "Base recognizer function 'mismatch' called by unknown parser type - provide override for this function\n");
			return;

			break;
    }

	if	(mismatchIsUnwantedToken(recognizer, is, ttype))
	{
		// Create a basic recognition exception structure
		//
	    antlr3RecognitionExceptionNew(recognizer);
		
		// Now update it to indicate this is an unwanted token exception
		//
		recognizer->state->exception->name		= ANTLR3_UNWANTED_TOKEN_EXCEPTION_NAME;
		recognizer->state->exception->type		= ANTLR3_UNWANTED_TOKEN_EXCEPTION;

		return;
	}
	
	if	(mismatchIsMissingToken(recognizer, is, follow))
	{
		// Create a basic recognition exception structure
		//
	    antlr3RecognitionExceptionNew(recognizer);
		
		// Now update it to indicate this is an unwanted token exception
		//
		recognizer->state->exception->name		= ANTLR3_MISSING_TOKEN_EXCEPTION_NAME;
		recognizer->state->exception->type		= ANTLR3_MISSING_TOKEN_EXCEPTION;

		return;
	}

	// Just a mismatched token is all we can dtermine
	//
	antlr3MTExceptionNew(recognizer);

	return;
}
/// Report a recognition problem.
///
/// This method sets errorRecovery to indicate the parser is recovering
/// not parsing.  Once in recovery mode, no errors are generated.
/// To get out of recovery mode, the parser must successfully match
/// a token (after a resync).  So it will go:
///
///		1. error occurs
///		2. enter recovery mode, report error
///		3. consume until token found in resynch set
///		4. try to resume parsing
///		5. next match() will reset errorRecovery mode
///
/// If you override, make sure to update errorCount if you care about that.
///
static void			
reportError		    (pANTLR3_BASE_RECOGNIZER recognizer)
{
    	// Invoke the debugger event if there is a debugger listening to us
	//
	if	(recognizer->debugger != NULL)
	{
		recognizer->debugger->recognitionException(recognizer->debugger, recognizer->state->exception);
	}

    if	(recognizer->state->errorRecovery == ANTLR3_TRUE)
    {
		// Already in error recovery so don't display another error while doing so
		//
		return;
    }

    // Signal we are in error recovery now
    //
    recognizer->state->errorRecovery = ANTLR3_TRUE;
	
	// Indicate this recognizer had an error while processing.
	//
	recognizer->state->errorCount++;

	// Call the error display routine
	//
    recognizer->displayRecognitionError(recognizer, recognizer->state->tokenNames);
}

static void
beginBacktrack		(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 level)
{
	if	(recognizer->debugger != NULL)
	{
		recognizer->debugger->beginBacktrack(recognizer->debugger, level);
	}
}

static void
endBacktrack		(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 level, ANTLR3_BOOLEAN successful)
{
	if	(recognizer->debugger != NULL)
	{
		recognizer->debugger->endBacktrack(recognizer->debugger, level, successful);
	}
}
static void			
beginResync		    (pANTLR3_BASE_RECOGNIZER recognizer)
{
	if	(recognizer->debugger != NULL)
	{
		recognizer->debugger->beginResync(recognizer->debugger);
	}
}

static void			
endResync		    (pANTLR3_BASE_RECOGNIZER recognizer)
{
	if	(recognizer->debugger != NULL)
	{
		recognizer->debugger->endResync(recognizer->debugger);
	}
}

/// Compute the error recovery set for the current rule.
/// Documentation below is from the Java implementation.
///
/// During rule invocation, the parser pushes the set of tokens that can
/// follow that rule reference on the stack; this amounts to
/// computing FIRST of what follows the rule reference in the
/// enclosing rule. This local follow set only includes tokens
/// from within the rule; i.e., the FIRST computation done by
/// ANTLR stops at the end of a rule.
//
/// EXAMPLE
//
/// When you find a "no viable alt exception", the input is not
/// consistent with any of the alternatives for rule r.  The best
/// thing to do is to consume tokens until you see something that
/// can legally follow a call to r *or* any rule that called r.
/// You don't want the exact set of viable next tokens because the
/// input might just be missing a token--you might consume the
/// rest of the input looking for one of the missing tokens.
///
/// Consider grammar:
///
/// a : '[' b ']'
///   | '(' b ')'
///   ;
/// b : c '^' INT ;
/// c : ID
///   | INT
///   ;
///
/// At each rule invocation, the set of tokens that could follow
/// that rule is pushed on a stack.  Here are the various "local"
/// follow sets:
///
/// FOLLOW(b1_in_a) = FIRST(']') = ']'
/// FOLLOW(b2_in_a) = FIRST(')') = ')'
/// FOLLOW(c_in_b) = FIRST('^') = '^'
///
/// Upon erroneous input "[]", the call chain is
///
/// a -> b -> c
///
/// and, hence, the follow context stack is:
///
/// depth  local follow set     after call to rule
///   0         <EOF>                    a (from main())
///   1          ']'                     b
///   3          '^'                     c
///
/// Notice that ')' is not included, because b would have to have
/// been called from a different context in rule a for ')' to be
/// included.
///
/// For error recovery, we cannot consider FOLLOW(c)
/// (context-sensitive or otherwise).  We need the combined set of
/// all context-sensitive FOLLOW sets--the set of all tokens that
/// could follow any reference in the call chain.  We need to
/// resync to one of those tokens.  Note that FOLLOW(c)='^' and if
/// we resync'd to that token, we'd consume until EOF.  We need to
/// sync to context-sensitive FOLLOWs for a, b, and c: {']','^'}.
/// In this case, for input "[]", LA(1) is in this set so we would
/// not consume anything and after printing an error rule c would
/// return normally.  It would not find the required '^' though.
/// At this point, it gets a mismatched token error and throws an
/// exception (since LA(1) is not in the viable following token
/// set).  The rule exception handler tries to recover, but finds
/// the same recovery set and doesn't consume anything.  Rule b
/// exits normally returning to rule a.  Now it finds the ']' (and
/// with the successful match exits errorRecovery mode).
///
/// So, you can see that the parser walks up call chain looking
/// for the token that was a member of the recovery set.
///
/// Errors are not generated in errorRecovery mode.
///
/// ANTLR's error recovery mechanism is based upon original ideas:
///
/// "Algorithms + Data Structures = Programs" by Niklaus Wirth
///
/// and
///
/// "A note on error recovery in recursive descent parsers":
/// http://portal.acm.org/citation.cfm?id=947902.947905
///
/// Later, Josef Grosch had some good ideas:
///
/// "Efficient and Comfortable Error Recovery in Recursive Descent
/// Parsers":
/// ftp://www.cocolab.com/products/cocktail/doca4.ps/ell.ps.zip
///
/// Like Grosch I implemented local FOLLOW sets that are combined
/// at run-time upon error to avoid overhead during parsing.
///
static pANTLR3_BITSET		
computeErrorRecoverySet	    (pANTLR3_BASE_RECOGNIZER recognizer)
{
    return   recognizer->combineFollows(recognizer, ANTLR3_FALSE);
}

/// Compute the context-sensitive FOLLOW set for current rule.
/// Documentation below is from the Java runtime.
///
/// This is the set of token types that can follow a specific rule
/// reference given a specific call chain.  You get the set of
/// viable tokens that can possibly come next (look ahead depth 1)
/// given the current call chain.  Contrast this with the
/// definition of plain FOLLOW for rule r:
///
///  FOLLOW(r)={x | S=>*alpha r beta in G and x in FIRST(beta)}
///
/// where x in T* and alpha, beta in V*; T is set of terminals and
/// V is the set of terminals and non terminals.  In other words,
/// FOLLOW(r) is the set of all tokens that can possibly follow
/// references to r in///any* sentential form (context).  At
/// runtime, however, we know precisely which context applies as
/// we have the call chain.  We may compute the exact (rather
/// than covering superset) set of following tokens.
///
/// For example, consider grammar:
///
/// stat : ID '=' expr ';'      // FOLLOW(stat)=={EOF}
///      | "return" expr '.'
///      ;
/// expr : atom ('+' atom)* ;   // FOLLOW(expr)=={';','.',')'}
/// atom : INT                  // FOLLOW(atom)=={'+',')',';','.'}
///      | '(' expr ')'
///      ;
///
/// The FOLLOW sets are all inclusive whereas context-sensitive
/// FOLLOW sets are precisely what could follow a rule reference.
/// For input input "i=(3);", here is the derivation:
///
/// stat => ID '=' expr ';'
///      => ID '=' atom ('+' atom)* ';'
///      => ID '=' '(' expr ')' ('+' atom)* ';'
///      => ID '=' '(' atom ')' ('+' atom)* ';'
///      => ID '=' '(' INT ')' ('+' atom)* ';'
///      => ID '=' '(' INT ')' ';'
///
/// At the "3" token, you'd have a call chain of
///
///   stat -> expr -> atom -> expr -> atom
///
/// What can follow that specific nested ref to atom?  Exactly ')'
/// as you can see by looking at the derivation of this specific
/// input.  Contrast this with the FOLLOW(atom)={'+',')',';','.'}.
///
/// You want the exact viable token set when recovering from a
/// token mismatch.  Upon token mismatch, if LA(1) is member of
/// the viable next token set, then you know there is most likely
/// a missing token in the input stream.  "Insert" one by just not
/// throwing an exception.
///
static pANTLR3_BITSET		
computeCSRuleFollow	    (pANTLR3_BASE_RECOGNIZER recognizer)
{
    return   recognizer->combineFollows(recognizer, ANTLR3_FALSE);
}

/// Compute the current followset for the input stream.
///
static pANTLR3_BITSET		
combineFollows		    (pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_BOOLEAN exact)
{
    pANTLR3_BITSET	followSet;
    pANTLR3_BITSET	localFollowSet;
    ANTLR3_UINT32	top;
    ANTLR3_UINT32	i;

    top	= recognizer->state->following->size(recognizer->state->following);

    followSet	    = antlr3BitsetNew(0);
	localFollowSet	= NULL;

    for (i = top; i>0; i--)
    {
		localFollowSet = antlr3BitsetLoad((pANTLR3_BITSET_LIST) recognizer->state->following->get(recognizer->state->following, i-1));

		if  (localFollowSet != NULL)
		{
			followSet->borInPlace(followSet, localFollowSet);

			if	(exact == ANTLR3_TRUE)
			{
				if	(localFollowSet->isMember(localFollowSet, ANTLR3_EOR_TOKEN_TYPE) == ANTLR3_FALSE)
				{
					// Only leave EOR in the set if at top (start rule); this lets us know
					// if we have to include the follow(start rule); I.E., EOF
					//
					if	(i>1)
					{
						followSet->remove(followSet, ANTLR3_EOR_TOKEN_TYPE);
					}
				}
				else
				{
					break;	// Cannot see End Of Rule from here, just drop out
				}
			}
			localFollowSet->free(localFollowSet);
			localFollowSet = NULL;
		}
    }

	if	(localFollowSet != NULL)
	{
		localFollowSet->free(localFollowSet);
	}
    return  followSet;
}

/// Standard/Example error display method.
/// No generic error message display funciton coudl possibly do everything correctly
/// for all possible parsers. Hence you are provided with this example routine, which
/// you should override in your parser/tree parser to do as you will.
///
/// Here we depart somewhat from the Java runtime as that has now split up a lot
/// of the error display routines into spearate units. However, ther is little advantage
/// to this in the C version as you will probably implement all such routines as a 
/// separate translation unit, rather than install them all as pointers to functions
/// in the base recognizer.
///
static void			
displayRecognitionError	    (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_UINT8 * tokenNames)
{
	pANTLR3_PARSER			parser;
	pANTLR3_TREE_PARSER	    tparser;
	pANTLR3_INT_STREAM	    is;
	pANTLR3_STRING			ttext;
	pANTLR3_STRING			ftext;
	pANTLR3_EXCEPTION	    ex;
	pANTLR3_COMMON_TOKEN    theToken;
	pANTLR3_BASE_TREE	    theBaseTree;
	pANTLR3_COMMON_TREE	    theCommonTree;

	// Retrieve some info for easy reading.
	//
	ex	    =		recognizer->state->exception;
	ttext   =		NULL;

	// See if there is a 'filename' we can use
	//
	if	(ex->streamName == NULL)
	{
		if	(((pANTLR3_COMMON_TOKEN)(ex->token))->type == ANTLR3_TOKEN_EOF)
		{
			ANTLR3_FPRINTF(stderr, "-end of input-(");
		}
		else
		{
			ANTLR3_FPRINTF(stderr, "-unknown source-(");
		}
	}
	else
	{
		ftext = ex->streamName->to8(ex->streamName);
		ANTLR3_FPRINTF(stderr, "%s(", ftext->chars);
	}

	// Next comes the line number
	//

	ANTLR3_FPRINTF(stderr, "%d) ", recognizer->state->exception->line);
	ANTLR3_FPRINTF(stderr, " : error %d : %s", 
										recognizer->state->exception->type,
					(pANTLR3_UINT8)	   (recognizer->state->exception->message));


	// How we determine the next piece is dependent on which thing raised the
	// error.
	//
	switch	(recognizer->type)
	{
	case	ANTLR3_TYPE_PARSER:

		// Prepare the knowledge we know we have
		//
		parser	    = (pANTLR3_PARSER) (recognizer->super);
		tparser	    = NULL;
		is			= parser->tstream->istream;
		theToken    = (pANTLR3_COMMON_TOKEN)(recognizer->state->exception->token);
		ttext	    = theToken->toString(theToken);

		ANTLR3_FPRINTF(stderr, ", at offset %d", recognizer->state->exception->charPositionInLine);
		if  (theToken != NULL)
		{
			if (theToken->type == ANTLR3_TOKEN_EOF)
			{
				ANTLR3_FPRINTF(stderr, ", at <EOF>");
			}
			else
			{
				// Guard against null text in a token
				//
				ANTLR3_FPRINTF(stderr, "\n    near %s\n    ", ttext == NULL ? (pANTLR3_UINT8)"<no text for the token>" : ttext->chars);
			}
		}
		break;

	case	ANTLR3_TYPE_TREE_PARSER:

		tparser		= (pANTLR3_TREE_PARSER) (recognizer->super);
		parser		= NULL;
		is			= tparser->ctnstream->tnstream->istream;
		theBaseTree	= (pANTLR3_BASE_TREE)(recognizer->state->exception->token);
		ttext		= theBaseTree->toStringTree(theBaseTree);

		if  (theBaseTree != NULL)
		{
			theCommonTree	= (pANTLR3_COMMON_TREE)	    theBaseTree->super;

			if	(theCommonTree != NULL)
			{
				theToken	= (pANTLR3_COMMON_TOKEN)    theBaseTree->getToken(theBaseTree);
			}
			ANTLR3_FPRINTF(stderr, ", at offset %d", theBaseTree->getCharPositionInLine(theBaseTree));
			ANTLR3_FPRINTF(stderr, ", near %s", ttext->chars);
		}
		break;

	default:

		ANTLR3_FPRINTF(stderr, "Base recognizer function displayRecognitionError called by unknown parser type - provide override for this function\n");
		return;
		break;
	}

	// Although this function should generally be provided by the implementation, this one
	// should be as helpful as possible for grammar developers and serve as an example
	// of what you can do with each exception type. In general, when you make up your
	// 'real' handler, you should debug the routine with all possible errors you expect
	// which will then let you be as specific as possible about all circumstances.
	//
	// Note that in the general case, errors thrown by tree parsers indicate a problem
	// with the output of the parser or with the tree grammar itself. The job of the parser
	// is to produce a perfect (in traversal terms) syntactically correct tree, so errors
	// at that stage should really be semantic errors that your own code determines and handles
	// in whatever way is appropriate.
	//
	switch  (ex->type)
	{
	case	ANTLR3_UNWANTED_TOKEN_EXCEPTION:

		// Indicates that the recognizer was fed a token which seesm to be
		// spurious input. We can detect this when the token that follows
		// this unwanted token would normally be part of the syntactically
		// correct stream. Then we can see that the token we are looking at
		// is just something that should not be there and throw this exception.
		//
		if	(tokenNames == NULL)
		{
			ANTLR3_FPRINTF(stderr, " : Extraneous input...");
		}
		else
		{
			if	(ex->expecting == ANTLR3_TOKEN_EOF)
			{
				ANTLR3_FPRINTF(stderr, " : Extraneous input - expected <EOF>\n");
			}
			else
			{
				ANTLR3_FPRINTF(stderr, " : Extraneous input - expected %s ...\n", tokenNames[ex->expecting]);
			}
		}
		break;

	case	ANTLR3_MISSING_TOKEN_EXCEPTION:

		// Indicates that the recognizer detected that the token we just
		// hit would be valid syntactically if preceeded by a particular 
		// token. Perhaps a missing ';' at line end or a missing ',' in an
		// expression list, and such like.
		//
		if	(tokenNames == NULL)
		{
			ANTLR3_FPRINTF(stderr, " : Missing token (%d)...\n", ex->expecting);
		}
		else
		{
			if	(ex->expecting == ANTLR3_TOKEN_EOF)
			{
				ANTLR3_FPRINTF(stderr, " : Missing <EOF>\n");
			}
			else
			{
				ANTLR3_FPRINTF(stderr, " : Missing %s \n", tokenNames[ex->expecting]);
			}
		}
		break;

	case	ANTLR3_RECOGNITION_EXCEPTION:

		// Indicates that the recognizer received a token
		// in the input that was not predicted. This is the basic exception type 
		// from which all others are derived. So we assume it was a syntax error.
		// You may get this if there are not more tokens and more are needed
		// to complete a parse for instance.
		//
		ANTLR3_FPRINTF(stderr, " : syntax error...\n");    
		break;

	case    ANTLR3_MISMATCHED_TOKEN_EXCEPTION:

		// We were expecting to see one thing and got another. This is the
		// most common error if we coudl not detect a missing or unwanted token.
		// Here you can spend your efforts to
		// derive more useful error messages based on the expected
		// token set and the last token and so on. The error following
		// bitmaps do a good job of reducing the set that we were looking
		// for down to something small. Knowing what you are parsing may be
		// able to allow you to be even more specific about an error.
		//
		if	(tokenNames == NULL)
		{
			ANTLR3_FPRINTF(stderr, " : syntax error...\n");
		}
		else
		{
			if	(ex->expecting == ANTLR3_TOKEN_EOF)
			{
				ANTLR3_FPRINTF(stderr, " : expected <EOF>\n");
			}
			else
			{
				ANTLR3_FPRINTF(stderr, " : expected %s ...\n", tokenNames[ex->expecting]);
			}
		}
		break;

	case	ANTLR3_NO_VIABLE_ALT_EXCEPTION:

		// We could not pick any alt decision from the input given
		// so god knows what happened - however when you examine your grammar,
		// you should. It means that at the point where the current token occurred
		// that the DFA indicates nowhere to go from here.
		//
		ANTLR3_FPRINTF(stderr, " : cannot match to any predicted input...\n");

		break;

	case	ANTLR3_MISMATCHED_SET_EXCEPTION:

		{
			ANTLR3_UINT32	  count;
			ANTLR3_UINT32	  bit;
			ANTLR3_UINT32	  size;
			ANTLR3_UINT32	  numbits;
			pANTLR3_BITSET	  errBits;

			// This means we were able to deal with one of a set of
			// possible tokens at this point, but we did not see any
			// member of that set.
			//
			ANTLR3_FPRINTF(stderr, " : unexpected input...\n  expected one of : ");

			// What tokens could we have accepted at this point in the
			// parse?
			//
			count   = 0;
			errBits = antlr3BitsetLoad		(ex->expectingSet);
			numbits = errBits->numBits		(errBits);
			size    = errBits->size			(errBits);

			if  (size > 0)
			{
				// However many tokens we could have dealt with here, it is usually
				// not useful to print ALL of the set here. I arbitrarily chose 8
				// here, but you should do whatever makes sense for you of course.
				// No token number 0, so look for bit 1 and on.
				//
				for	(bit = 1; bit < numbits && count < 8 && count < size; bit++)
				{
					// TODO: This doesn;t look right - should be asking if the bit is set!!
					//
					if  (tokenNames[bit])
					{
						ANTLR3_FPRINTF(stderr, "%s%s", count > 0 ? ", " : "", tokenNames[bit]); 
						count++;
					}
				}
				ANTLR3_FPRINTF(stderr, "\n");
			}
			else
			{
				ANTLR3_FPRINTF(stderr, "Actually dude, we didn't seem to be expecting anything here, or at least\n");
				ANTLR3_FPRINTF(stderr, "I could not work out what I was expecting, like so many of us these days!\n");
			}
		}
		break;

	case	ANTLR3_EARLY_EXIT_EXCEPTION:

		// We entered a loop requiring a number of token sequences
		// but found a token that ended that sequence earlier than
		// we should have done.
		//
		ANTLR3_FPRINTF(stderr, " : missing elements...\n");
		break;

	default:

		// We don't handle any other exceptions here, but you can
		// if you wish. If we get an exception that hits this point
		// then we are just going to report what we know about the
		// token.
		//
		ANTLR3_FPRINTF(stderr, " : syntax not recognized...\n");
		break;
	}

	// Here you have the token that was in error which if this is
	// the standard implementation will tell you the line and offset
	// and also record the address of the start of the line in the
	// input stream. You could therefore print the source line and so on.
	// Generally though, I would expect that your lexer/parser will keep
	// its own map of lines and source pointers or whatever as there
	// are a lot of specific things you need to know about the input
	// to do something like that.
	// Here is where you do it though :-).
	//
}

/// Return how many syntax errors were detected by this recognizer
///
static ANTLR3_UINT32
getNumberOfSyntaxErrors(pANTLR3_BASE_RECOGNIZER recognizer)
{
	return	recognizer->state->errorCount;
}

/// Recover from an error found on the input stream.  Mostly this is
/// NoViableAlt exceptions, but could be a mismatched token that
/// the match() routine could not recover from.
///
static void			
recover			    (pANTLR3_BASE_RECOGNIZER recognizer)
{
    // Used to compute the follow set of tokens
    //
    pANTLR3_BITSET			followSet;
    pANTLR3_PARSER			parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;

    switch	(recognizer->type)
    {
		case	ANTLR3_TYPE_PARSER:

		parser  = (pANTLR3_PARSER) (recognizer->super);
		tparser	= NULL;
		is		= parser->tstream->istream;

	break;

    case	ANTLR3_TYPE_TREE_PARSER:

		tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
		parser	= NULL;
		is		= tparser->ctnstream->tnstream->istream;

	break;

    default:
	    
		ANTLR3_FPRINTF(stderr, "Base recognizer function recover called by unknown parser type - provide override for this function\n");
		return;

	break;
    }

	// Are we about to repeat the same error?
	//
    if	(recognizer->state->lastErrorIndex == is->index(is))
    {
		// The last error was at the same token index point. This must be a case
		// where LT(1) is in the recovery token set so nothing is
		// consumed. Consume a single token so at least to prevent
		// an infinite loop; this is a failsafe.
		//
		is->consume(is);
    }

    // Record error index position
    //
    recognizer->state->lastErrorIndex	 = is->index(is);
    
    // Work out the follows set for error recovery
    //
    followSet	= recognizer->computeErrorRecoverySet(recognizer);

    // Call resync hook (for debuggers and so on)
    //
    recognizer->beginResync(recognizer);

    // Consume tokens until we have resynced to something in the follows set
    //
    recognizer->consumeUntilSet(recognizer, followSet);

    // End resync hook 
    //
    recognizer->endResync(recognizer);

    // Destroy the temporary bitset we produced.
    //
    followSet->free(followSet);

    // Reset the inError flag so we don't re-report the exception
    //
    recognizer->state->error	= ANTLR3_FALSE;
    recognizer->state->failed	= ANTLR3_FALSE;
}


/// Attempt to recover from a single missing or extra token.
///
/// 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 ')'.
///
/// The exception that was passed in, in the java implementation is
/// sorted in the recognizer exception stack in the C version. To 'throw' it we set the
/// error flag and rules cascade back when this is set.
///
static void *	
recoverFromMismatchedToken  (pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 ttype, pANTLR3_BITSET_LIST follow)
{
	pANTLR3_PARSER			  parser;
	pANTLR3_TREE_PARSER	      tparser;
	pANTLR3_INT_STREAM	      is;
	void					* matchedSymbol;



	switch	(recognizer->type)
	{
	case	ANTLR3_TYPE_PARSER:

		parser  = (pANTLR3_PARSER) (recognizer->super);
		tparser	= NULL;
		is	= parser->tstream->istream;

		break;

	case	ANTLR3_TYPE_TREE_PARSER:

		tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
		parser	= NULL;
		is	= tparser->ctnstream->tnstream->istream;

		break;

	default:

		ANTLR3_FPRINTF(stderr, "Base recognizer function recoverFromMismatchedToken called by unknown parser type - provide override for this function\n");
		return NULL;

		break;
	}

	// Create an exception if we need one
	//
	if	(recognizer->state->exception == NULL)
	{
		antlr3RecognitionExceptionNew(recognizer);
	}

	// If the next token after the one we are looking at in the input stream
	// is what we are looking for then we remove the one we have discovered
	// from the stream by consuming it, then consume this next one along too as
	// if nothing had happened.
	//
	if	( recognizer->mismatchIsUnwantedToken(recognizer, is, ttype) == ANTLR3_TRUE)
	{
		recognizer->state->exception->type		= ANTLR3_UNWANTED_TOKEN_EXCEPTION;
		recognizer->state->exception->message	= ANTLR3_UNWANTED_TOKEN_EXCEPTION_NAME;

		// Call resync hook (for debuggers and so on)
		//
		if	(recognizer->debugger != NULL)
		{
			recognizer->debugger->beginResync(recognizer->debugger);
		}

		// "delete" the extra token
		//
		recognizer->beginResync(recognizer);
		is->consume(is);
		recognizer->endResync(recognizer);
		// End resync hook 
		//
		if	(recognizer->debugger != NULL)
		{
			recognizer->debugger->endResync(recognizer->debugger);
		}

		// Print out the error after we consume so that ANTLRWorks sees the
		// token in the exception.
		//
		recognizer->reportError(recognizer);

		// Return the token we are actually matching
		//
		matchedSymbol = recognizer->getCurrentInputSymbol(recognizer, is);

		// Consume the token that the rule actually expected to get as if everything
		// was hunky dory.
		//
		is->consume(is);

		recognizer->state->error  = ANTLR3_FALSE;	// Exception is not outstanding any more

		return	matchedSymbol;
	}

	// Single token deletion (Unwanted above) did not work
	// so we see if we can insert a token instead by calculating which
	// token would be missing
	//
	if	(mismatchIsMissingToken(recognizer, is, follow))
	{
		// We can fake the missing token and proceed
		//
		matchedSymbol = recognizer->getMissingSymbol(recognizer, is, recognizer->state->exception, ttype, follow);
		recognizer->state->exception->type		= ANTLR3_MISSING_TOKEN_EXCEPTION;
		recognizer->state->exception->message	= ANTLR3_MISSING_TOKEN_EXCEPTION_NAME;
		recognizer->state->exception->token		= matchedSymbol;
		recognizer->state->exception->expecting	= ttype;

		// Print out the error after we insert so that ANTLRWorks sees the
		// token in the exception.
		//
		recognizer->reportError(recognizer);

		recognizer->state->error  = ANTLR3_FALSE;	// Exception is not outstanding any more

		return	matchedSymbol;
	}


	// Neither deleting nor inserting tokens allows recovery
	// must just report the exception.
	//
	recognizer->state->error	    = ANTLR3_TRUE;
	return NULL;
}

static void *
recoverFromMismatchedSet	    (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_BITSET_LIST follow)
{
    pANTLR3_PARSER			parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;
	pANTLR3_COMMON_TOKEN	matchedSymbol;

    switch	(recognizer->type)
    {
    case	ANTLR3_TYPE_PARSER:

		parser  = (pANTLR3_PARSER) (recognizer->super);
		tparser	= NULL;
		is	= parser->tstream->istream;

	break;

    case	ANTLR3_TYPE_TREE_PARSER:

		tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
		parser	= NULL;
		is	= tparser->ctnstream->tnstream->istream;

	break;

    default:
	    
		ANTLR3_FPRINTF(stderr, "Base recognizer function recoverFromMismatchedSet called by unknown parser type - provide override for this function\n");
		return NULL;

	break;
    }

	if	(recognizer->mismatchIsMissingToken(recognizer, is, follow) == ANTLR3_TRUE)
	{
		// We can fake the missing token and proceed
		//
		matchedSymbol = recognizer->getMissingSymbol(recognizer, is, recognizer->state->exception, ANTLR3_TOKEN_INVALID, follow);
		recognizer->state->exception->type	= ANTLR3_MISSING_TOKEN_EXCEPTION;
		recognizer->state->exception->token	= matchedSymbol;

		// Print out the error after we insert so that ANTLRWorks sees the
		// token in the exception.
		//
		recognizer->reportError(recognizer);

		recognizer->state->error  = ANTLR3_FALSE;	// Exception is not outstanding any more

		return	matchedSymbol;
	}

    // TODO - Single token deletion like in recoverFromMismatchedToken()
    //
    recognizer->state->error	= ANTLR3_TRUE;
	recognizer->state->failed	= ANTLR3_TRUE;
	return NULL;
}

/// This code is factored out from mismatched token and mismatched set
///  recovery.  It handles "single token insertion" error recovery for
/// both.  No tokens are consumed to recover from insertions.  Return
/// true if recovery was possible else return false.
///
static ANTLR3_BOOLEAN	
recoverFromMismatchedElement	    (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_BITSET_LIST followBits)
{
    pANTLR3_BITSET	    viableToksFollowingRule;
    pANTLR3_BITSET	    follow;
    pANTLR3_PARSER	    parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;

    switch	(recognizer->type)
    {
    case	ANTLR3_TYPE_PARSER:

		parser  = (pANTLR3_PARSER) (recognizer->super);
		tparser	= NULL;
		is	= parser->tstream->istream;

	break;

    case	ANTLR3_TYPE_TREE_PARSER:

		tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
		parser	= NULL;
		is	= tparser->ctnstream->tnstream->istream;

	break;

    default:
	    
		ANTLR3_FPRINTF(stderr, "Base recognizer function recover called by unknown parser type - provide override for this function\n");
		return ANTLR3_FALSE;

	break;
    }

    follow	= antlr3BitsetLoad(followBits);

    if	(follow == NULL)
    {
		/* The follow set is NULL, which means we don't know what can come 
		 * next, so we "hit and hope" by just signifying that we cannot
		 * recover, which will just cause the next token to be consumed,
		 * which might dig us out.
		 */
		return	ANTLR3_FALSE;
    }

    /* We have a bitmap for the follow set, hence we can compute 
     * what can follow this grammar element reference.
     */
    if	(follow->isMember(follow, ANTLR3_EOR_TOKEN_TYPE) == ANTLR3_TRUE)
    {
		/* First we need to know which of the available tokens are viable
		 * to follow this reference.
		 */
		viableToksFollowingRule	= recognizer->computeCSRuleFollow(recognizer);

		/* Remove the EOR token, which we do not wish to compute with
		 */
		follow->remove(follow, ANTLR3_EOR_TOKEN_TYPE);
		viableToksFollowingRule->free(viableToksFollowingRule);
		/* We now have the computed set of what can follow the current token
		 */
    }

    /* We can now see if the current token works with the set of tokens
     * that could follow the current grammar reference. If it looks like it
     * is consistent, then we can "insert" that token by not throwing
     * an exception and assuming that we saw it. 
     */
    if	( follow->isMember(follow, is->_LA(is, 1)) == ANTLR3_TRUE)
    {
		/* report the error, but don't cause any rules to abort and stuff
		 */
		recognizer->reportError(recognizer);
		if	(follow != NULL)
		{
			follow->free(follow);
		}
		recognizer->state->error			= ANTLR3_FALSE;
		recognizer->state->failed			= ANTLR3_FALSE;
		return ANTLR3_TRUE;	/* Success in recovery	*/
    }

    if	(follow != NULL)
    {
		follow->free(follow);
    }

    /* We could not find anything viable to do, so this is going to 
     * cause an exception.
     */
    return  ANTLR3_FALSE;
}

/// Eat tokens from the input stream until we get one of JUST the right type
///
static void		
consumeUntil	(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_UINT32 tokenType)
{
    ANTLR3_UINT32			ttype;
    pANTLR3_PARSER			parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;

    switch	(recognizer->type)
    {
		case	ANTLR3_TYPE_PARSER:

			parser  = (pANTLR3_PARSER) (recognizer->super);
			tparser	= NULL;
			is	= parser->tstream->istream;

			break;

		case	ANTLR3_TYPE_TREE_PARSER:

			tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
			parser	= NULL;
			is	= tparser->ctnstream->tnstream->istream;

			break;

		default:
		    
			ANTLR3_FPRINTF(stderr, "Base recognizer function 'consumeUntil' called by unknown parser type - provide override for this function\n");
			return;

			break;
    }

    // What do have at the moment?
    //
    ttype	= is->_LA(is, 1);

    // Start eating tokens until we get to the one we want.
    //
    while   (ttype != ANTLR3_TOKEN_EOF && ttype != tokenType)
    {
		is->consume(is);
		ttype	= is->_LA(is, 1);
    }
}

/// Eat tokens from the input stream until we find one that
/// belongs to the supplied set.
///
static void		
consumeUntilSet			    (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_BITSET set)
{
    ANTLR3_UINT32	    ttype;
    pANTLR3_PARSER	    parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;

    switch	(recognizer->type)
    {
		case	ANTLR3_TYPE_PARSER:

			parser  = (pANTLR3_PARSER) (recognizer->super);
			tparser	= NULL;
			is	= parser->tstream->istream;

			break;

		case	ANTLR3_TYPE_TREE_PARSER:

			tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
			parser	= NULL;
			is	= tparser->ctnstream->tnstream->istream;

			break;

		default:
		    
			ANTLR3_FPRINTF(stderr, "Base recognizer function 'consumeUntilSet' called by unknown parser type - provide override for this function\n");
			return;

			break;
    }

    // What do have at the moment?
    //
    ttype	= is->_LA(is, 1);

    // Start eating tokens until we get to one we want.
    //
    while   (ttype != ANTLR3_TOKEN_EOF && set->isMember(set, ttype) == ANTLR3_FALSE)
    {
		is->consume(is);
		ttype	= is->_LA(is, 1);
    }
}

/** Return the rule invocation stack (how we got here in the parse.
 *  In the java version Ter just asks the JVM for all the information
 *  but in C we don't get this information, so I am going to do nothing 
 *  right now.
 */
static pANTLR3_STACK	
getRuleInvocationStack		    (pANTLR3_BASE_RECOGNIZER recognizer)
{
    return NULL;
}

static pANTLR3_STACK	
getRuleInvocationStackNamed	    (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_UINT8 name)
{
    return NULL;
}

/** Convenience method for template rewrites - NYI.
 */
static pANTLR3_HASH_TABLE	
toStrings			    (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_HASH_TABLE tokens)
{
    return NULL;
}

static	void ANTLR3_CDECL
freeIntTrie    (void * trie)
{
    ((pANTLR3_INT_TRIE)trie)->free((pANTLR3_INT_TRIE)trie);
}


/** Pointer to a function to return whether the rule has parsed input starting at the supplied 
 *  start index before. If the rule has not parsed input starting from the supplied start index,
 *  then it will return ANTLR3_MEMO_RULE_UNKNOWN. If it has parsed from the suppled start point
 *  then it will return the point where it last stopped parsing after that start point.
 *
 * \remark
 * The rule memos are an ANTLR3_LIST of ANTLR3_LISTS, however if this becomes any kind of performance
 * issue (it probably won't, the hash tables are pretty quick) then we could make a special int only
 * version of the table.
 */
static ANTLR3_MARKER	
getRuleMemoization		    (pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_INTKEY ruleIndex, ANTLR3_MARKER ruleParseStart)
{
    /* The rule memos are an ANTLR3_LIST of ANTLR3_LIST.
     */
    pANTLR3_INT_TRIE	ruleList;
    ANTLR3_MARKER	stopIndex;
    pANTLR3_TRIE_ENTRY	entry;

    /* See if we have a list in the ruleMemos for this rule, and if not, then create one
     * as we will need it eventually if we are being asked for the memo here.
     */
    entry	= recognizer->state->ruleMemo->get(recognizer->state->ruleMemo, (ANTLR3_INTKEY)ruleIndex);

    if	(entry == NULL)
    {
		/* Did not find it, so create a new one for it, with a bit depth based on the 
		 * size of the input stream. We need the bit depth to incorporate the number if
		 * bits required to represent the largest possible stop index in the input, which is the
		 * last character. An int stream is free to return the largest 64 bit offset if it has
		 * no idea of the size, but you should remember that this will cause the leftmost
		 * bit match algorithm to run to 63 bits, which will be the whole time spent in the trie ;-)
		 */
		ruleList    = antlr3IntTrieNew(63);	/* Depth is theoretically 64 bits, but probably not ;-)	*/

		if (ruleList != NULL)
		{
			recognizer->state->ruleMemo->add(recognizer->state->ruleMemo, (ANTLR3_INTKEY)ruleIndex, ANTLR3_HASH_TYPE_STR, 0, ANTLR3_FUNC_PTR(ruleList), freeIntTrie);
		}

		/* We cannot have a stopIndex in a trie we have just created of course
		 */
		return	MEMO_RULE_UNKNOWN;
    }

    ruleList	= (pANTLR3_INT_TRIE) (entry->data.ptr);

    /* See if there is a stop index associated with the supplied start index.
     */
    stopIndex	= 0;

    entry = ruleList->get(ruleList, ruleParseStart);
    if (entry != NULL)
    {
		stopIndex = (ANTLR3_MARKER)(entry->data.intVal);
    }

    if	(stopIndex == 0)
    {
		return MEMO_RULE_UNKNOWN;
    }

    return  stopIndex;
}

/** Has this rule already parsed input at the current index in the
 *  input stream?  Return ANTLR3_TRUE if we have and ANTLR3_FALSE
 *  if we have not.
 *
 *  This method has a side-effect: if we have seen this input for
 *  this rule and successfully parsed before, then seek ahead to
 *  1 past the stop token matched for this rule last time.
 */
static ANTLR3_BOOLEAN	
alreadyParsedRule		    (pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_MARKER ruleIndex)
{
    ANTLR3_MARKER			stopIndex;
    pANTLR3_LEXER			lexer;
    pANTLR3_PARSER			parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;

    switch	(recognizer->type)
    {
		case	ANTLR3_TYPE_PARSER:

			parser  = (pANTLR3_PARSER) (recognizer->super);
			tparser	= NULL;
			lexer	= NULL;
			is	= parser->tstream->istream;

			break;

		case	ANTLR3_TYPE_TREE_PARSER:

			tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
			parser	= NULL;
			lexer	= NULL;
			is	= tparser->ctnstream->tnstream->istream;

			break;

		case	ANTLR3_TYPE_LEXER:

			lexer	= (pANTLR3_LEXER)   (recognizer->super);
			parser	= NULL;
			tparser	= NULL;
			is	= lexer->input->istream;
			break;

		default:
		    
			ANTLR3_FPRINTF(stderr, "Base recognizer function 'alreadyParsedRule' called by unknown parser type - provide override for this function\n");
			return ANTLR3_FALSE;

			break;
    }

    /* See if we have a memo marker for this.
     */
    stopIndex	    = recognizer->getRuleMemoization(recognizer, ruleIndex, is->index(is));

    if	(stopIndex  == MEMO_RULE_UNKNOWN)
    {
		return ANTLR3_FALSE;
    }

    if	(stopIndex == MEMO_RULE_FAILED)
    {
		recognizer->state->failed = ANTLR3_TRUE;
    }
    else
    {
		is->seek(is, stopIndex+1);
    }

    /* If here then the rule was executed for this input already
     */
    return  ANTLR3_TRUE;
}

/** Record whether or not this rule parsed the input at this position
 *  successfully.
 */
static void		
memoize	(pANTLR3_BASE_RECOGNIZER recognizer, ANTLR3_MARKER ruleIndex, ANTLR3_MARKER ruleParseStart)
{
    /* The rule memos are an ANTLR3_LIST of ANTLR3_LIST.
     */
    pANTLR3_INT_TRIE	    ruleList;
    pANTLR3_TRIE_ENTRY	    entry;
    ANTLR3_MARKER	    stopIndex;
    pANTLR3_LEXER	    lexer;
    pANTLR3_PARSER	    parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;

    switch	(recognizer->type)
    {
		case	ANTLR3_TYPE_PARSER:

			parser  = (pANTLR3_PARSER) (recognizer->super);
			tparser	= NULL;
			is	= parser->tstream->istream;

			break;

		case	ANTLR3_TYPE_TREE_PARSER:

			tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
			parser	= NULL;
			is	= tparser->ctnstream->tnstream->istream;

			break;

		case	ANTLR3_TYPE_LEXER:

			lexer	= (pANTLR3_LEXER)   (recognizer->super);
			parser	= NULL;
			tparser	= NULL;
			is		= lexer->input->istream;
			break;

		default:
		    
			ANTLR3_FPRINTF(stderr, "Base recognizer function consumeUntilSet called by unknown parser type - provide override for this function\n");
			return;

			break;
    }
    
    stopIndex	= recognizer->state->failed == ANTLR3_TRUE ? MEMO_RULE_FAILED : is->index(is) - 1;

    entry	= recognizer->state->ruleMemo->get(recognizer->state->ruleMemo, (ANTLR3_INTKEY)ruleIndex);

    if	(entry != NULL)
    {
		ruleList = (pANTLR3_INT_TRIE)(entry->data.ptr);

		/* If we don't already have this entry, append it. The memoize trie does not
		 * accept duplicates so it won't add it if already there and we just ignore the
		 * return code as we don't care if it is there already.
		 */
		ruleList->add(ruleList, ruleParseStart, ANTLR3_HASH_TYPE_INT, stopIndex, NULL, NULL);
    }
}
/** A syntactic predicate.  Returns true/false depending on whether
 *  the specified grammar fragment matches the current input stream.
 *  This resets the failed instance var afterwards.
 */
static ANTLR3_BOOLEAN	
synpred	(pANTLR3_BASE_RECOGNIZER recognizer, void * ctx, void (*predicate)(void * ctx))
{
    ANTLR3_MARKER   start;
    pANTLR3_PARSER	    parser;
    pANTLR3_TREE_PARSER	    tparser;
    pANTLR3_INT_STREAM	    is;

    switch	(recognizer->type)
    {
		case	ANTLR3_TYPE_PARSER:

			parser  = (pANTLR3_PARSER) (recognizer->super);
			tparser	= NULL;
			is	= parser->tstream->istream;

			break;

		case	ANTLR3_TYPE_TREE_PARSER:

			tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
			parser	= NULL;
			is	= tparser->ctnstream->tnstream->istream;

			break;

		default:
		    
			ANTLR3_FPRINTF(stderr, "Base recognizer function 'synPred' called by unknown parser type - provide override for this function\n");
			return ANTLR3_FALSE;

			break;
    }

    /* Begin backtracking so we can get back to where we started after trying out
     * the syntactic predicate.
     */
    start   = is->mark(is);
    recognizer->state->backtracking++;

    /* Try the syntactical predicate
     */
    predicate(ctx);

    /* Reset
     */
    is->rewind(is, start);
    recognizer->state->backtracking--;

    if	(recognizer->state->failed == ANTLR3_TRUE)
    {
		/* Predicate failed
		 */
		recognizer->state->failed = ANTLR3_FALSE;
		return	ANTLR3_FALSE;
    }
    else
    {
		/* Predicate was successful
		 */
		recognizer->state->failed	= ANTLR3_FALSE;
		return	ANTLR3_TRUE;
    }
}

static void
reset(pANTLR3_BASE_RECOGNIZER recognizer)
{
    if	(recognizer->state->following != NULL)
    {
		recognizer->state->following->free(recognizer->state->following);
    }

	// Reset the state flags
	//
	recognizer->state->errorRecovery	= ANTLR3_FALSE;
	recognizer->state->lastErrorIndex	= -1;
	recognizer->state->failed			= ANTLR3_FALSE;
	recognizer->state->errorCount		= 0;
	recognizer->state->backtracking		= 0;
	recognizer->state->following		= NULL;

	if	(recognizer->state != NULL)
	{
		if	(recognizer->state->ruleMemo != NULL)
		{
			recognizer->state->ruleMemo->free(recognizer->state->ruleMemo);
			recognizer->state->ruleMemo = antlr3IntTrieNew(15);	/* 16 bit depth is enough for 32768 rules! */
		}
	}
	

    // Install a new following set
    //
    recognizer->state->following   = antlr3StackNew(8);

}

// Default implementation is for parser and assumes a token stream as supplied by the runtime.
// You MAY need override this function if the standard TOKEN_STREAM is not what you are using.
//
static void *				
getCurrentInputSymbol		(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM istream)
{
	return ((pANTLR3_TOKEN_STREAM)istream->super)->_LT((pANTLR3_TOKEN_STREAM)istream->super, 1);
}

// Default implementation is for parser and assumes a token stream as supplied by the runtime.
// You MAY need override this function if the standard COMMON_TOKEN_STREAM is not what you are using.
//
static void *				
getMissingSymbol			(pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM	istream, pANTLR3_EXCEPTION	e,
									ANTLR3_UINT32 expectedTokenType, pANTLR3_BITSET_LIST follow)
{
	pANTLR3_TOKEN_STREAM			ts;
	pANTLR3_COMMON_TOKEN_STREAM		cts;
	pANTLR3_COMMON_TOKEN			token;
	pANTLR3_COMMON_TOKEN			current;
	pANTLR3_STRING					text;

	// Dereference the standard pointers
	//
	ts		= (pANTLR3_TOKEN_STREAM)istream->super;
	cts		= (pANTLR3_COMMON_TOKEN_STREAM)ts->super;
	
	// Work out what to use as the current symbol to make a line and offset etc
	// If we are at EOF, we use the token before EOF
	//
	current	= ts->_LT(ts, 1);
	if	(current->getType(current) == ANTLR3_TOKEN_EOF)
	{
		current = ts->_LT(ts, -1);
	}

	// Create a new empty token
	//
	if	(recognizer->state->tokFactory == NULL)
	{
		// We don't yet have a token factory for making tokens
		// we just need a fake one using the input stream of the current
		// token.
		//
		recognizer->state->tokFactory = antlr3TokenFactoryNew(current->input);
	}
	token	= recognizer->state->tokFactory->newToken(recognizer->state->tokFactory);

	// Set some of the token properties based on the current token
	//
	token->setLine					(token, current->getLine(current));
	token->setCharPositionInLine	(token, current->getCharPositionInLine(current));
	token->setChannel				(token, ANTLR3_TOKEN_DEFAULT_CHANNEL);
	token->setType					(token, expectedTokenType);
    token->user1                    = current->user1;
    token->user2                    = current->user2;
    token->user3                    = current->user3;
    token->custom                   = current->custom;
    token->lineStart                = current->lineStart;
    
	// Create the token text that shows it has been inserted
	//
	token->setText8(token, (pANTLR3_UINT8)"<missing ");
	text = token->getText(token);

	if	(text != NULL)
	{
		text->append8(text, (const char *)recognizer->state->tokenNames[expectedTokenType]);
		text->append8(text, (const char *)">");
	}
	
	// Finally return the pointer to our new token
	//
	return	token;
}


#ifdef	ANTLR3_WINDOWS
#pragma warning( default : 4100 )
#endif

/// @}
///