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#ifndef INC_TokenStreamHiddenTokenFilter_h__
#define INC_TokenStreamHiddenTokenFilter_h__
/* ANTLR Translator Generator
* Project led by Terence Parr at http://www.jGuru.com
* Software rights: http://www.antlr.org/license.html
*
* $Id$
*/
#include <antlr/config.h>
#include <antlr/TokenStreamBasicFilter.h>
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
namespace antlr {
#endif
/**This object filters a token stream coming from a lexer
* or another TokenStream so that only certain token channels
* get transmitted to the parser.
*
* Any of the channels can be filtered off as "hidden" channels whose
* tokens can be accessed from the parser.
*/
class ANTLR_API TokenStreamHiddenTokenFilter : public TokenStreamBasicFilter {
// protected BitSet discardMask;
protected:
BitSet hideMask;
private:
RefToken nextMonitoredToken;
protected:
/** track tail of hidden list emanating from previous
* monitored token
*/
RefToken lastHiddenToken;
RefToken firstHidden; // = null;
public:
TokenStreamHiddenTokenFilter(TokenStream& input);
protected:
void consume();
private:
void consumeFirst();
public:
BitSet getDiscardMask() const;
/** Return a ptr to the hidden token appearing immediately after
* token t in the input stream.
*/
RefToken getHiddenAfter(RefToken t);
/** Return a ptr to the hidden token appearing immediately before
* token t in the input stream.
*/
RefToken getHiddenBefore(RefToken t);
BitSet getHideMask() const;
/** Return the first hidden token if one appears
* before any monitored token.
*/
RefToken getInitialHiddenToken();
void hide(int m);
void hide(const BitSet& mask);
protected:
RefToken LA(int i);
public:
/** Return the next monitored token.
* Test the token following the monitored token.
* If following is another monitored token, save it
* for the next invocation of nextToken (like a single
* lookahead token) and return it then.
* If following is unmonitored, nondiscarded (hidden)
* channel token, add it to the monitored token.
*
* Note: EOF must be a monitored Token.
*/
RefToken nextToken();
};
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
}
#endif
#endif //INC_TokenStreamHiddenTokenFilter_h__
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