80 lines
2.6 KiB
C++
80 lines
2.6 KiB
C++
/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
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* Use of this file is governed by the BSD 3-clause license that
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* can be found in the LICENSE.txt file in the project root.
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*/
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#pragma once
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#include "BufferedTokenStream.h"
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namespace antlr4 {
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/**
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* This class extends {@link BufferedTokenStream} with functionality to filter
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* token streams to tokens on a particular channel (tokens where
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* {@link Token#getChannel} returns a particular value).
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*
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* <p>
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* This token stream provides access to all tokens by index or when calling
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* methods like {@link #getText}. The channel filtering is only used for code
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* accessing tokens via the lookahead methods {@link #LA}, {@link #LT}, and
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* {@link #LB}.</p>
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*
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* <p>
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* By default, tokens are placed on the default channel
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* ({@link Token#DEFAULT_CHANNEL}), but may be reassigned by using the
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* {@code ->channel(HIDDEN)} lexer command, or by using an embedded action to
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* call {@link Lexer#setChannel}.
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* </p>
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*
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* <p>
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* Note: lexer rules which use the {@code ->skip} lexer command or call
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* {@link Lexer#skip} do not produce tokens at all, so input text matched by
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* such a rule will not be available as part of the token stream, regardless of
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* channel.</p>
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*/
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class ANTLR4CPP_PUBLIC CommonTokenStream : public BufferedTokenStream {
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public:
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/**
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* Constructs a new {@link CommonTokenStream} using the specified token
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* source and the default token channel ({@link Token#DEFAULT_CHANNEL}).
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*
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* @param tokenSource The token source.
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*/
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CommonTokenStream(TokenSource *tokenSource);
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/**
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* Constructs a new {@link CommonTokenStream} using the specified token
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* source and filtering tokens to the specified channel. Only tokens whose
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* {@link Token#getChannel} matches {@code channel} or have the
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* {@link Token#getType} equal to {@link Token#EOF} will be returned by the
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* token stream lookahead methods.
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*
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* @param tokenSource The token source.
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* @param channel The channel to use for filtering tokens.
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*/
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CommonTokenStream(TokenSource *tokenSource, size_t channel);
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virtual Token* LT(ssize_t k) override;
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/// Count EOF just once.
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virtual int getNumberOfOnChannelTokens();
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protected:
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/**
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* Specifies the channel to use for filtering tokens.
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*
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* <p>
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* The default value is {@link Token#DEFAULT_CHANNEL}, which matches the
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* default channel assigned to tokens created by the lexer.</p>
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*/
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size_t channel;
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virtual ssize_t adjustSeekIndex(size_t i) override;
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virtual Token* LB(size_t k) override;
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};
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} // namespace antlr4
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