1 files changed, 84 insertions, 0 deletions
diff --git a/poxml/antlr/antlr/TokenStreamHiddenTokenFilter.hpp b/poxml/antlr/antlr/TokenStreamHiddenTokenFilter.hpp
new file mode 100644
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+++ b/poxml/antlr/antlr/TokenStreamHiddenTokenFilter.hpp
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+#ifndef INC_TokenStreamHiddenTokenFilter_hpp__
+#define INC_TokenStreamHiddenTokenFilter_hpp__
+
+#include "antlr/config.hpp"
+#include "antlr/TokenStreamBasicFilter.hpp"
+
+ANTLR_BEGIN_NAMESPACE(antlr)
+
+/**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 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();
+};
+
+ANTLR_END_NAMESPACE
+
+#endif //INC_TokenStreamHiddenTokenFilter_hpp__