/*
	This file is part of cpp-ethereum.

	cpp-ethereum is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	cpp-ethereum is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	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.
	Redistribution and use in source and binary forms, with or without
	modification, are permitted provided that the following conditions are
	met:

	* Redistributions of source code must retain the above copyright
	  notice, this list of conditions and the following disclaimer.
	* Redistributions in binary form must reproduce the above
	  copyright notice, this list of conditions and the following
	  disclaimer in the documentation and/or other materials provided
	  with the distribution.
	* Neither the name of Google Inc. nor the names of its
	  contributors may be used to endorse or promote products derived
	  from this software without specific prior written permission.

	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
 * @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() const { return m_pos >= m_source.size(); }
	char get() const { return m_source[m_pos]; }
	char advanceAndGet();
	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:
	// 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_;
	};

	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_current_token.token; }
	Location getCurrentLocation() const { return m_current_token.location; }
	std::string const& getCurrentLiteral() const { return m_current_token.literal; }
	///@}

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

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

	///@{
	///@name 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(); }
	///@}

	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 scanHexNumber(char& o_scannedNumber, int _expectedLength);

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

	/// Skips all whitespace and @returns true if something was skipped.
	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;
};

}
}