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