solidity/Scanner.h

/*
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	You should have received a copy of the GNU General Public License
	along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.

	This file is derived from the file "scanner.h", which was part of the
	V8 project. The original copyright header follows:

	Copyright 2006-2012, the V8 project authors. All rights reserved.
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	modification, are permitted provided that the following conditions are
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	* Redistributions of source code must retain the above copyright
	  notice, this list of conditions and the following disclaimer.
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*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2014
 * Solidity scanner.
 */

#pragma once

#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(std::string const& _source): m_source(_source), m_pos(0) {}
	int getPos() const { return m_pos; }
	bool isPastEndOfInput(size_t _charsForward = 0) const { return (m_pos + _charsForward) >= m_source.size(); }
	char get(size_t _charsForward = 0) const { return m_source[m_pos + _charsForward]; }
	char advanceAndGet();
	void advanceBy(size_t _chars);
	char rollback(size_t _amount);

	///@{
	///@name Error printing helper functions
	/// 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;
};



class Scanner
{
public:

	enum LiteralType {
		LITERAL_TYPE_STRING,
		LITERAL_TYPE_NUMBER, // not really different from string type in behaviour
		LITERAL_TYPE_COMMENT
	};
	/// Scoped helper for literal recording. Automatically drops the literal
	/// if aborting the scanning before it's complete.
	class LiteralScope
	{
	public:
		explicit LiteralScope(Scanner* _self, enum LiteralType _type)
		: m_type(_type)
		, m_scanner(_self)
		, m_complete(false)
		{
			if (_type == LITERAL_TYPE_COMMENT)
				m_scanner->startNewCommentLiteral();
			else
				m_scanner->startNewLiteral();
		}
		~LiteralScope()
		{
			if (!m_complete)
			{
				if (m_type == LITERAL_TYPE_COMMENT)
					m_scanner->dropCommentLiteral();
				else
					m_scanner->dropLiteral();
			}
		}
		void complete() { m_complete = true; }

	private:
		enum LiteralType m_type;
		Scanner* m_scanner;
		bool m_complete;
	};

	Scanner() { reset(CharStream()); }
	explicit Scanner(CharStream const& _source) { reset(_source); }

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

	/// Returns the next token and advances input
	Token::Value next();

	///@{
	///@name Information about the current token

	/// Returns the current token
	Token::Value getCurrentToken()
	{
		return m_currentToken.token;
	}
	Location getCurrentLocation() const { return m_currentToken.location; }
	std::string const& getCurrentLiteral() const { return m_currentToken.literal; }
	///@}

	///@{
	///@name Information about the current comment token

	Location getCurrentCommentLocation() const { return m_skippedComment.location; }
	std::string const& getCurrentCommentLiteral() const { return m_skippedComment.literal; }
	/// Called by the parser during FunctionDefinition parsing to clear the current comment
	void clearCurrentCommentLiteral() { m_skippedComment.literal.clear(); }

	///@}

	///@{
	///@name Information about the next token

	/// Returns the next token without advancing input.
	Token::Value peekNextToken() const { return m_nextToken.token; }
	Location peekLocation() const { return m_nextToken.location; }
	std::string const& peekLiteral() const { return m_nextToken.literal; }
	///@}

	///@{
	///@name Error printing helper functions
	/// 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); }
	///@}

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

	///@{
	///@name Literal buffer support
	inline void startNewLiteral() { m_nextToken.literal.clear(); }
	inline void startNewCommentLiteral() { m_nextSkippedComment.literal.clear(); }
	inline void addLiteralChar(char c) { m_nextToken.literal.push_back(c); }
	inline void addCommentLiteralChar(char c) { m_nextSkippedComment.literal.push_back(c); }
	inline void dropLiteral() { m_nextToken.literal.clear(); }
	inline void dropCommentLiteral() { m_nextSkippedComment.literal.clear(); }
	inline void addLiteralCharAndAdvance() { addLiteralChar(m_char); advance(); }
	///@}

	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; }
	/// If the next character is _next, advance and return _then, otherwise return _else.
	inline Token::Value selectToken(char _next, Token::Value _then, Token::Value _else);

	bool scanHexByte(char& o_scannedByte);

	/// Scans a single Solidity token. Returns true if the scanned token was
	/// a skipped documentation comment. False in all other cases.
	bool scanToken();

	/// Skips all whitespace and @returns true if something was skipped.
	bool skipWhitespace();
	Token::Value skipSingleLineComment();
	Token::Value skipMultiLineComment();

	void scanDecimalDigits();
	Token::Value scanNumber(char _charSeen = 0);
	Token::Value scanIdentifierOrKeyword();

	Token::Value scanString();
	Token::Value scanDocumentationComment();

	/// 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_skippedComment;  // desc for current skipped comment
	TokenDesc m_nextSkippedComment; // desc for next skiped comment

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

	CharStream m_source;

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

}
}