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/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
#pragma once
#include "CharStream.h"
#include "Recognizer.h"
#include "Token.h"
#include "TokenSource.h"
namespace antlr4 {
/// A lexer is recognizer that draws input symbols from a character stream.
/// lexer grammars result in a subclass of this object. A Lexer object
/// uses simplified match() and error recovery mechanisms in the interest
/// of speed.
class ANTLR4CPP_PUBLIC Lexer : public Recognizer, public TokenSource {
public:
static const size_t DEFAULT_MODE = 0;
static const size_t MORE = static_cast<size_t>(-2);
static const size_t SKIP = static_cast<size_t>(-3);
static const size_t DEFAULT_TOKEN_CHANNEL = Token::DEFAULT_CHANNEL;
static const size_t HIDDEN = Token::HIDDEN_CHANNEL;
static const size_t MIN_CHAR_VALUE = 0;
static const size_t MAX_CHAR_VALUE = 0x10FFFF;
CharStream*
_input; // Pure reference, usually from statically allocated instance.
protected:
/// How to create token objects.
Ref<TokenFactory<CommonToken>> _factory;
public:
/// The goal of all lexer rules/methods is to create a token object.
/// This is an instance variable as multiple rules may collaborate to
/// create a single token. nextToken will return this object after
/// matching lexer rule(s). If you subclass to allow multiple token
/// emissions, then set this to the last token to be matched or
/// something nonnull so that the auto token emit mechanism will not
/// emit another token.
// Life cycle of a token is this:
// Created by emit() (via the token factory) or by action code, holding
// ownership of it. Ownership is handed over to the token stream when calling
// nextToken().
std::unique_ptr<Token> token;
/// <summary>
/// What character index in the stream did the current token start at?
/// Needed, for example, to get the text for current token. Set at
/// the start of nextToken.
/// </summary>
size_t tokenStartCharIndex;
/// <summary>
/// The line on which the first character of the token resides </summary>
size_t tokenStartLine;
/// The character position of first character within the line.
size_t tokenStartCharPositionInLine;
/// Once we see EOF on char stream, next token will be EOF.
/// If you have DONE : EOF ; then you see DONE EOF.
bool hitEOF;
/// The channel number for the current token.
size_t channel;
/// The token type for the current token.
size_t type;
// Use the vector as a stack.
std::vector<size_t> modeStack;
size_t mode;
Lexer();
Lexer(CharStream* input);
virtual ~Lexer() {}
virtual void reset();
/// Return a token from this source; i.e., match a token on the char stream.
virtual std::unique_ptr<Token> nextToken() override;
/// Instruct the lexer to skip creating a token for current lexer rule
/// and look for another token. nextToken() knows to keep looking when
/// a lexer rule finishes with token set to SKIP_TOKEN. Recall that
/// if token == null at end of any token rule, it creates one for you
/// and emits it.
virtual void skip();
virtual void more();
virtual void setMode(size_t m);
virtual void pushMode(size_t m);
virtual size_t popMode();
template <typename T1>
void setTokenFactory(TokenFactory<T1>* factory) {
this->_factory = factory;
}
virtual Ref<TokenFactory<CommonToken>> getTokenFactory() override;
/// Set the char stream and reset the lexer
virtual void setInputStream(IntStream* input) override;
virtual std::string getSourceName() override;
virtual CharStream* getInputStream() override;
/// By default does not support multiple emits per nextToken invocation
/// for efficiency reasons. Subclasses can override this method, nextToken,
/// and getToken (to push tokens into a list and pull from that list
/// rather than a single variable as this implementation does).
virtual void emit(std::unique_ptr<Token> newToken);
/// The standard method called to automatically emit a token at the
/// outermost lexical rule. The token object should point into the
/// char buffer start..stop. If there is a text override in 'text',
/// use that to set the token's text. Override this method to emit
/// custom Token objects or provide a new factory.
virtual Token* emit();
virtual Token* emitEOF();
virtual size_t getLine() const override;
virtual size_t getCharPositionInLine() override;
virtual void setLine(size_t line);
virtual void setCharPositionInLine(size_t charPositionInLine);
/// What is the index of the current character of lookahead?
virtual size_t getCharIndex();
/// Return the text matched so far for the current token or any
/// text override.
virtual std::string getText();
/// Set the complete text of this token; it wipes any previous
/// changes to the text.
virtual void setText(const std::string& text);
/// Override if emitting multiple tokens.
virtual std::unique_ptr<Token> getToken();
virtual void setToken(std::unique_ptr<Token> newToken);
virtual void setType(size_t ttype);
virtual size_t getType();
virtual void setChannel(size_t newChannel);
virtual size_t getChannel();
virtual const std::vector<std::string>& getChannelNames() const = 0;
virtual const std::vector<std::string>& getModeNames() const = 0;
/// Return a list of all Token objects in input char stream.
/// Forces load of all tokens. Does not include EOF token.
virtual std::vector<std::unique_ptr<Token>> getAllTokens();
virtual void recover(const LexerNoViableAltException& e);
virtual void notifyListeners(const LexerNoViableAltException& e);
virtual std::string getErrorDisplay(const std::string& s);
/// Lexers can normally match any char in it's vocabulary after matching
/// a token, so do the easy thing and just kill a character and hope
/// it all works out. You can instead use the rule invocation stack
/// to do sophisticated error recovery if you are in a fragment rule.
virtual void recover(RecognitionException* re);
/// <summary>
/// Gets the number of syntax errors reported during parsing. This value is
/// incremented each time <seealso cref="#notifyErrorListeners"/> is called.
/// </summary>
/// <seealso cref= #notifyListeners </seealso>
virtual size_t getNumberOfSyntaxErrors();
protected:
/// You can set the text for the current token to override what is in
/// the input char buffer (via setText()).
std::string _text;
private:
size_t _syntaxErrors;
void InitializeInstanceFields();
};
} // namespace antlr4
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