/** Implementation of matchc for the lexer, overrides any
 *  base implementation in the base recognizer. 
 *
 *  \remark
 *  Note that the generated code lays down arrays of ints for constant
 *  strings so that they are int UTF32 form!
 */
static ANTLR3_BOOLEAN
matchc(pANTLR3_LEXER lexer, ANTLR3_UCHAR c)
{
	if	(lexer->input->istream->_LA(lexer->input->istream, 1) == c)
	{
		/* Matched correctly, do consume it
		 */
		lexer->input->istream->consume(lexer->input->istream);

		/* Reset any failed indicator
		 */
		lexer->rec->state->failed = ANTLR3_FALSE;

		return	ANTLR3_TRUE;
	}

	/* Failed to match, exception and recovery time.
	 */
	if	(lexer->rec->state->backtracking > 0)
	{
		lexer->rec->state->failed  = ANTLR3_TRUE;
		return	ANTLR3_FALSE;
	}

	lexer->rec->exConstruct(lexer->rec);

	/* TODO: Implement exception creation more fully perhaps
	 */
	lexer->recover(lexer);

	return  ANTLR3_FALSE;
}

/** Implementation of matchs for the lexer, overrides any
 *  base implementation in the base recognizer. 
 *
 *  \remark
 *  Note that the generated code lays down arrays of ints for constant
 *  strings so that they are int UTF32 form!
 */
static ANTLR3_BOOLEAN
matchs(pANTLR3_LEXER lexer, ANTLR3_UCHAR * string)
{
	while   (*string != ANTLR3_STRING_TERMINATOR)
	{
		if  (lexer->input->istream->_LA(lexer->input->istream, 1) != (*string))
		{
			if	(lexer->rec->state->backtracking > 0)
			{
				lexer->rec->state->failed = ANTLR3_TRUE;
				return ANTLR3_FALSE;
			}

			lexer->rec->exConstruct(lexer->rec);
			lexer->rec->state->failed	 = ANTLR3_TRUE;

			/* TODO: Implement exception creation more fully perhaps
			 */
			lexer->recover(lexer);
			return  ANTLR3_FALSE;
		}

		/* Matched correctly, do consume it
		 */
		lexer->input->istream->consume(lexer->input->istream);
		string++;

		/* Reset any failed indicator
		 */
		lexer->rec->state->failed = ANTLR3_FALSE;
	}


	return  ANTLR3_TRUE;
}

/*!
 * \brief
 * Stops using the current input stream and reverts to any prior
 * input stream on the stack.
 * 
 * \param lexer
 * Description of parameter lexer.
 * 
 * Pointer to a function that abandons the current input stream, whether it
 * is empty or not and reverts to the previous stacked input stream.
 *
 * \remark
 * The function fails silently if there are no prior input streams.
 */
static void
popCharStream   (pANTLR3_LEXER lexer)
{
    pANTLR3_INPUT_STREAM input;

    // If we do not have a stream stack or we are already at the
    // stack bottom, then do nothing.
    //
    if	(lexer->rec->state->streams != NULL && lexer->rec->state->streams->size(lexer->rec->state->streams) > 0)
    {
	// We just leave the current stream to its fate, we do not close
	// it or anything as we do not know what the programmer intended
	// for it. This method can always be overridden of course.
	// So just find out what was currently saved on the stack and use
	// that now, then pop it from the stack.
	//
	input	= (pANTLR3_INPUT_STREAM)(lexer->rec->state->streams->top);
	lexer->rec->state->streams->pop(lexer->rec->state->streams);

	// Now install the stream as the current one.
	//
	lexer->setCharStream(lexer, input);
	lexer->input->istream->rewindLast(lexer->input->istream);
    }
    return;
}

/*!
 * \brief
 * Change to a new input stream, remembering the old one.
 * 
 * \param lexer
 * Pointer to the lexer instance to switch input streams for.
 * 
 * \param input
 * New input stream to install as the current one.
 * 
 * Switches the current character input stream to 
 * a new one, saving the old one, which we will revert to at the end of this 
 * new one.
 */
static void
pushCharStream  (pANTLR3_LEXER lexer,  pANTLR3_INPUT_STREAM input)
{
	// Do we need a new input stream stack?
	//
	if	(lexer->rec->state->streams == NULL)
	{
		// This is the first call to stack a new
		// stream and so we must create the stack first.
		//
		lexer->rec->state->streams = antlr3StackNew(0);

		if  (lexer->rec->state->streams == NULL)
		{
			// Could not do this, we just fail to push it.
			// TODO: Consider if this is what we want to do, but then
			//       any programmer can override this method to do something else.
			return;
		}
	}

	// We have a stack, so we can save the current input stream
	// into it.
	//
	lexer->input->istream->mark(lexer->input->istream);
	lexer->rec->state->streams->push(lexer->rec->state->streams, lexer->input, NULL);

	// And now we can install this new one
	//
	lexer->setCharStream(lexer, input);
}

static bool newInputStream(const std::string& filename, pANTLR3_LEXER lexer) {
  Debug("parser") << "Including " << filename << std::endl;
  // Create a new input stream and take advantage of built in stream stacking
  // in C target runtime.
  //
  pANTLR3_INPUT_STREAM    in;
#ifdef CVC4_ANTLR3_OLD_INPUT_STREAM
  in = antlr3AsciiFileStreamNew((pANTLR3_UINT8) filename.c_str());
#else /* CVC4_ANTLR3_OLD_INPUT_STREAM */
  in = antlr3FileStreamNew((pANTLR3_UINT8) filename.c_str(), ANTLR3_ENC_8BIT);
#endif /* CVC4_ANTLR3_OLD_INPUT_STREAM */
  if( in == NULL ) {
    Debug("parser") << "Can't open " << filename << std::endl;
    return false;
  }
  // Same thing as the predefined PUSHSTREAM(in);
  lexer->pushCharStream(lexer, in);
  // restart it
  //lexer->rec->state->tokenStartCharIndex      = -10;
  //lexer->emit(lexer);

  // Note that the input stream is not closed when it EOFs, I don't bother
  // to do it here, but it is up to you to track streams created like this
  // and destroy them when the whole parse session is complete. Remember that you
  // don't want to do this until all tokens have been manipulated all the way through
  // your tree parsers etc as the token does not store the text it just refers
  // back to the input stream and trying to get the text for it will abort if you
  // close the input stream too early.

  //TODO what said before
  return true;
}

static pANTLR3_STRING
getText	    (pANTLR3_LEXER lexer)
{
	if (lexer->rec->state->text)
	{
		return	lexer->rec->state->text;

	}
	return  lexer->input->substr(
									lexer->input, 
									lexer->rec->state->tokenStartCharIndex,
									lexer->getCharIndex(lexer) - lexer->input->charByteSize
							);

}

static pANTLR3_COMMON_TOKEN
emit	    (pANTLR3_LEXER lexer)
{
    pANTLR3_COMMON_TOKEN	token;

    /* We could check pointers to token factories and so on, but
    * we are in code that we want to run as fast as possible
    * so we are not checking any errors. So make sure you have installed an input stream before
    * trying to emit a new token.
    */
    token   = lexer->rec->state->tokFactory->newToken(lexer->rec->state->tokFactory);
	if (token == NULL) { return NULL; }

    /* Install the supplied information, and some other bits we already know
    * get added automatically, such as the input stream it is associated with
    * (though it can all be overridden of course)
    */
    token->type		    = lexer->rec->state->type;
    token->channel	    = lexer->rec->state->channel;
    token->start	    = lexer->rec->state->tokenStartCharIndex;
    token->stop		    = lexer->getCharIndex(lexer) - 1;
    token->line		    = lexer->rec->state->tokenStartLine;
    token->charPosition	= lexer->rec->state->tokenStartCharPositionInLine;

    if	(lexer->rec->state->text != NULL)
    {
        token->textState	    = ANTLR3_TEXT_STRING;
        token->tokText.text	    = lexer->rec->state->text;
    }
    else
    {
        token->textState	= ANTLR3_TEXT_NONE;
    }
    token->lineStart	= lexer->input->currentLine;
    token->user1	= lexer->rec->state->user1;
    token->user2	= lexer->rec->state->user2;
    token->user3	= lexer->rec->state->user3;
    token->custom	= lexer->rec->state->custom;

    lexer->rec->state->token	    = token;

    return  token;
}

/** Implementation of match range for the lexer, overrides any
 *  base implementation in the base recognizer. 
 *
 *  \remark
 *  Note that the generated code lays down arrays of ints for constant
 *  strings so that they are int UTF32 form!
 */
static ANTLR3_BOOLEAN
matchRange(pANTLR3_LEXER lexer, ANTLR3_UCHAR low, ANTLR3_UCHAR high)
{
    ANTLR3_UCHAR    c;

    /* What is in the stream at the moment?
     */
    c	= lexer->input->istream->_LA(lexer->input->istream, 1);
    if	( c >= low && c <= high)
    {
	/* Matched correctly, consume it
	 */
	lexer->input->istream->consume(lexer->input->istream);

	/* Reset any failed indicator
	 */
	lexer->rec->state->failed = ANTLR3_FALSE;

	return	ANTLR3_TRUE;
    }
    
    /* Failed to match, execption and recovery time.
     */

    if	(lexer->rec->state->backtracking > 0)
    {
	lexer->rec->state->failed  = ANTLR3_TRUE;
	return	ANTLR3_FALSE;
    }

    lexer->rec->exConstruct(lexer->rec);

    /* TODO: Implement exception creation more fully
     */
    lexer->recover(lexer);

    return  ANTLR3_FALSE;
}