solidity/Scanner.h

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#pragma once

#include <boost/assert.hpp>

#include <libdevcore/Common.h>
#include <libdevcore/Log.h>
#include <libdevcore/CommonData.h>
#include <libsolidity/BaseTypes.h>
#include <libsolidity/Token.h>

namespace dev
{
namespace solidity
{


class AstRawString;
class AstValueFactory;
class ParserRecorder;

class CharStream
{
public:
	CharStream()
		: m_pos(0)
	{}

	explicit CharStream(const std::string& _source) : m_source(_source), m_pos(0) {}
	int getPos() const { return m_pos; }
	bool isPastEndOfInput() const { return m_pos >= m_source.size(); }
	char get() const { return m_source[m_pos]; }
	char advanceAndGet()
	{
		if (isPastEndOfInput()) return 0;
		++m_pos;
		if (isPastEndOfInput()) return 0;
		return get();
	}
	char rollback(size_t _amount)
	{
		BOOST_ASSERT(m_pos >= _amount);
		m_pos -= _amount;
		return get();
	}

	/// Functions that help pretty-printing parse errors
	/// Do only use in error cases, they are quite expensive.
	/// @{
	std::string getLineAtPosition(int _position) const;
	std::tuple<int, int> translatePositionToLineColumn(int _position) const;
	/// @}
private:
	std::string m_source;
	size_t m_pos;
};

// ----------------------------------------------------------------------------
// JavaScript Scanner.

class Scanner
{
public:
	// Scoped helper for literal recording. Automatically drops the literal
	// if aborting the scanning before it's complete.
	class LiteralScope
	{
	public:
		explicit LiteralScope(Scanner* self) : scanner_(self), complete_(false) { scanner_->startNewLiteral(); }
		~LiteralScope() { if (!complete_) scanner_->dropLiteral(); }
		void Complete() { complete_ = true; }

	private:
		Scanner* scanner_;
		bool complete_;
	};

	explicit Scanner(const CharStream& _source);

	// Resets the scanner as if newly constructed with _input as input.
	void reset(const CharStream& _source);

	// Returns the next token and advances input.
	Token::Value next();
	// Returns the current token again.
	Token::Value getCurrentToken() { return m_current_token.token; }
	// Returns the location information for the current token
	// (the token last returned by Next()).
	Location getCurrentLocation() const { return m_current_token.location; }
	const std::string& getCurrentLiteral() const { return m_current_token.literal; }

	// Similar functions for the upcoming token.

	// One token look-ahead (past the token returned by Next()).
	Token::Value peek() const { return m_next_token.token; }

	Location peekLocation() const { return m_next_token.location; }
	const std::string& peekLiteral() const { return m_next_token.literal; }

	/// Functions that help pretty-printing parse errors.
	/// Do only use in error cases, they are quite expensive.
	/// @{
	std::string getLineAtPosition(int _position) const
	{
		return m_source.getLineAtPosition(_position);
	}
	std::tuple<int, int> translatePositionToLineColumn(int _position) const
	{
		return m_source.translatePositionToLineColumn(_position);
	}
	/// @}

	// Returns true if there was a line terminator before the peek'ed token,
	// possibly inside a multi-line comment.
	bool hasAnyLineTerminatorBeforeNext() const
	{
		return m_hasLineTerminatorBeforeNext ||
			   m_hasMultilineCommentBeforeNext;
	}

private:
	// Used for the current and look-ahead token.
	struct TokenDesc
	{
		Token::Value token;
		Location location;
		std::string literal;
	};

	// Literal buffer support
	inline void startNewLiteral() { m_next_token.literal.clear(); }

	inline void addLiteralChar(char c) { m_next_token.literal.push_back(c); }

	inline void dropLiteral() { m_next_token.literal.clear(); }

	inline void addLiteralCharAndAdvance() { addLiteralChar(m_char); advance(); }

	// Low-level scanning support.
	bool advance() { m_char = m_source.advanceAndGet(); return !m_source.isPastEndOfInput(); }
	void rollback(int amount) { m_char = m_source.rollback(amount); }

	inline Token::Value selectToken(Token::Value tok) { advance(); return tok; }

	inline Token::Value selectToken(char next, Token::Value then, Token::Value else_)
	{
		advance();
		if (m_char == next)
		{
			advance();
			return then;
		}
		else
			return else_;
	}

	bool scanHexNumber(char& scanned_number, int expected_length);

	// Scans a single JavaScript token.
	void scanToken();

	bool skipWhitespace();
	Token::Value skipSingleLineComment();
	Token::Value skipMultiLineComment();

	void scanDecimalDigits();
	Token::Value scanNumber(bool _periodSeen);
	Token::Value scanIdentifierOrKeyword();

	Token::Value scanString();

	// Scans an escape-sequence which is part of a string and adds the
	// decoded character to the current literal. Returns true if a pattern
	// is scanned.
	bool scanEscape();

	// Return the current source position.
	int getSourcePos() { return m_source.getPos(); }
	bool isSourcePastEndOfInput() { return m_source.isPastEndOfInput(); }

	TokenDesc m_current_token;  // desc for current token (as returned by Next())
	TokenDesc m_next_token;     // desc for next token (one token look-ahead)

	CharStream m_source;

	// one character look-ahead, equals 0 at end of input
	char m_char;

	// Whether there is a line terminator whitespace character after
	// the current token, and  before the next. Does not count newlines
	// inside multiline comments.
	bool m_hasLineTerminatorBeforeNext;
	// Whether there is a multi-line comment that contains a
	// line-terminator after the current token, and before the next.
	bool m_hasMultilineCommentBeforeNext;
};

}
}