Merge pull request #5286 from ethereum/refactor-token-as-enum-class

refactor `libsolidity::Token` into a strongly typed enum

7 files changed, 203 insertions, 210 deletions

diff --git a/libsolidity/parsing/Parser.cpp b/libsolidity/parsing/Parser.cpp
index ca9a9b57..f99b9ea4 100644
--- a/libsolidity/parsing/Parser.cpp
+++ b/libsolidity/parsing/Parser.cpp
@@ -112,17 +112,17 @@ ASTPointer<PragmaDirective> Parser::parsePragmaDirective()
 	ASTNodeFactory nodeFactory(*this);
 	expectToken(Token::Pragma);
 	vector<string> literals;
-	vector<Token::Value> tokens;
+	vector<Token> tokens;
 	do
 	{
-		Token::Value token = m_scanner->currentToken();
+		Token token = m_scanner->currentToken();
 		if (token == Token::Illegal)
 			parserError("Token incompatible with Solidity parser as part of pragma directive.");
 		else
 		{
 			string literal = m_scanner->currentLiteral();
-			if (literal.empty() && Token::toString(token))
-				literal = Token::toString(token);
+			if (literal.empty() && TokenTraits::toString(token))
+				literal = TokenTraits::toString(token);
 			literals.push_back(literal);
 			tokens.push_back(token);
 		}
@@ -240,7 +240,7 @@ ASTPointer<ContractDefinition> Parser::parseContractDefinition()
 	expectToken(Token::LBrace);
 	while (true)
 	{
-		Token::Value currentTokenValue = m_scanner->currentToken();
+		Token currentTokenValue = m_scanner->currentToken();
 		if (currentTokenValue == Token::RBrace)
 			break;
 		else if (currentTokenValue == Token::Function || currentTokenValue == Token::Constructor)
@@ -254,7 +254,7 @@ ASTPointer<ContractDefinition> Parser::parseContractDefinition()
 		else if (
 			currentTokenValue == Token::Identifier ||
 			currentTokenValue == Token::Mapping ||
-			Token::isElementaryTypeName(currentTokenValue)
+			TokenTraits::isElementaryTypeName(currentTokenValue)
 		)
 		{
 			VarDeclParserOptions options;
@@ -304,7 +304,7 @@ ASTPointer<InheritanceSpecifier> Parser::parseInheritanceSpecifier()
 Declaration::Visibility Parser::parseVisibilitySpecifier()
 {
 	Declaration::Visibility visibility(Declaration::Visibility::Default);
-	Token::Value token = m_scanner->currentToken();
+	Token token = m_scanner->currentToken();
 	switch (token)
 	{
 		case Token::Public:
@@ -329,7 +329,7 @@ Declaration::Visibility Parser::parseVisibilitySpecifier()
 StateMutability Parser::parseStateMutability()
 {
 	StateMutability stateMutability(StateMutability::NonPayable);
-	Token::Value token = m_scanner->currentToken();
+	Token token = m_scanner->currentToken();
 	switch(token)
 	{
 		case Token::Payable:
@@ -386,7 +386,7 @@ Parser::FunctionHeaderParserResult Parser::parseFunctionHeader(bool _forceEmptyN
 	result.parameters = parseParameterList(options);
 	while (true)
 	{
-		Token::Value token = m_scanner->currentToken();
+		Token token = m_scanner->currentToken();
 		if (_allowModifiers && token == Token::Identifier)
 		{
 			// If the name is empty (and this is not a constructor),
@@ -401,7 +401,7 @@ Parser::FunctionHeaderParserResult Parser::parseFunctionHeader(bool _forceEmptyN
 			else
 				result.modifiers.push_back(parseModifierInvocation());
 		}
-		else if (Token::isVisibilitySpecifier(token))
+		else if (TokenTraits::isVisibilitySpecifier(token))
 		{
 			if (result.visibility != Declaration::Visibility::Default)
 			{
@@ -423,7 +423,7 @@ Parser::FunctionHeaderParserResult Parser::parseFunctionHeader(bool _forceEmptyN
 			else
 				result.visibility = parseVisibilitySpecifier();
 		}
-		else if (Token::isStateMutabilitySpecifier(token))
+		else if (TokenTraits::isStateMutabilitySpecifier(token))
 		{
 			if (result.stateMutability != StateMutability::NonPayable)
 			{
@@ -587,8 +587,8 @@ ASTPointer<VariableDeclaration> Parser::parseVariableDeclaration(
 
 	while (true)
 	{
-		Token::Value token = m_scanner->currentToken();
-		if (_options.isStateVariable && Token::isVariableVisibilitySpecifier(token))
+		Token token = m_scanner->currentToken();
+		if (_options.isStateVariable && TokenTraits::isVariableVisibilitySpecifier(token))
 		{
 			nodeFactory.markEndPosition();
 			if (visibility != Declaration::Visibility::Default)
@@ -609,7 +609,7 @@ ASTPointer<VariableDeclaration> Parser::parseVariableDeclaration(
 				isIndexed = true;
 			else if (token == Token::Constant)
 				isDeclaredConst = true;
-			else if (_options.allowLocationSpecifier && Token::isLocationSpecifier(token))
+			else if (_options.allowLocationSpecifier && TokenTraits::isLocationSpecifier(token))
 			{
 				if (location != VariableDeclaration::Location::Unspecified)
 					parserError(string("Location already specified."));
@@ -806,8 +806,8 @@ ASTPointer<TypeName> Parser::parseTypeName(bool _allowVar)
 	RecursionGuard recursionGuard(*this);
 	ASTNodeFactory nodeFactory(*this);
 	ASTPointer<TypeName> type;
-	Token::Value token = m_scanner->currentToken();
-	if (Token::isElementaryTypeName(token))
+	Token token = m_scanner->currentToken();
+	if (TokenTraits::isElementaryTypeName(token))
 	{
 		unsigned firstSize;
 		unsigned secondSize;
@@ -817,7 +817,7 @@ ASTPointer<TypeName> Parser::parseTypeName(bool _allowVar)
 		nodeFactory.markEndPosition();
 		m_scanner->next();
 		auto stateMutability = boost::make_optional(elemTypeName.token() == Token::Address, StateMutability::NonPayable);
-		if (Token::isStateMutabilitySpecifier(m_scanner->currentToken(), false))
+		if (TokenTraits::isStateMutabilitySpecifier(m_scanner->currentToken(), false))
 		{
 			if (elemTypeName.token() == Token::Address)
 			{
@@ -874,8 +874,8 @@ ASTPointer<Mapping> Parser::parseMapping()
 	expectToken(Token::Mapping);
 	expectToken(Token::LParen);
 	ASTPointer<ElementaryTypeName> keyType;
-	Token::Value token = m_scanner->currentToken();
-	if (!Token::isElementaryTypeName(token))
+	Token token = m_scanner->currentToken();
+	if (!TokenTraits::isElementaryTypeName(token))
 		fatalParserError(string("Expected elementary type name for mapping key type"));
 	unsigned firstSize;
 	unsigned secondSize;
@@ -1252,7 +1252,7 @@ pair<Parser::LookAheadInfo, Parser::IndexAccessedPath> Parser::tryParseIndexAcce
 	// VariableDeclarationStatement out of it.
 	IndexAccessedPath iap = parseIndexAccessedPath();
 
-	if (m_scanner->currentToken() == Token::Identifier || Token::isLocationSpecifier(m_scanner->currentToken()))
+	if (m_scanner->currentToken() == Token::Identifier || TokenTraits::isLocationSpecifier(m_scanner->currentToken()))
 		return make_pair(LookAheadInfo::VariableDeclaration, move(iap));
 	else
 		return make_pair(LookAheadInfo::Expression, move(iap));
@@ -1342,16 +1342,16 @@ ASTPointer<Expression> Parser::parseExpression(
 {
 	RecursionGuard recursionGuard(*this);
 	ASTPointer<Expression> expression = parseBinaryExpression(4, _partiallyParsedExpression);
-	if (Token::isAssignmentOp(m_scanner->currentToken()))
+	if (TokenTraits::isAssignmentOp(m_scanner->currentToken()))
 	{
-		Token::Value assignmentOperator = m_scanner->currentToken();
+		Token assignmentOperator = m_scanner->currentToken();
 		m_scanner->next();
 		ASTPointer<Expression> rightHandSide = parseExpression();
 		ASTNodeFactory nodeFactory(*this, expression);
 		nodeFactory.setEndPositionFromNode(rightHandSide);
 		return nodeFactory.createNode<Assignment>(expression, assignmentOperator, rightHandSide);
 	}
-	else if (m_scanner->currentToken() == Token::Value::Conditional)
+	else if (m_scanner->currentToken() == Token::Conditional)
 	{
 		m_scanner->next();
 		ASTPointer<Expression> trueExpression = parseExpression();
@@ -1373,11 +1373,11 @@ ASTPointer<Expression> Parser::parseBinaryExpression(
 	RecursionGuard recursionGuard(*this);
 	ASTPointer<Expression> expression = parseUnaryExpression(_partiallyParsedExpression);
 	ASTNodeFactory nodeFactory(*this, expression);
-	int precedence = Token::precedence(m_scanner->currentToken());
+	int precedence = TokenTraits::precedence(m_scanner->currentToken());
 	for (; precedence >= _minPrecedence; --precedence)
-		while (Token::precedence(m_scanner->currentToken()) == precedence)
+		while (TokenTraits::precedence(m_scanner->currentToken()) == precedence)
 		{
-			Token::Value op = m_scanner->currentToken();
+			Token op = m_scanner->currentToken();
 			m_scanner->next();
 			ASTPointer<Expression> right = parseBinaryExpression(precedence + 1);
 			nodeFactory.setEndPositionFromNode(right);
@@ -1393,8 +1393,8 @@ ASTPointer<Expression> Parser::parseUnaryExpression(
 	RecursionGuard recursionGuard(*this);
 	ASTNodeFactory nodeFactory = _partiallyParsedExpression ?
 		ASTNodeFactory(*this, _partiallyParsedExpression) : ASTNodeFactory(*this);
-	Token::Value token = m_scanner->currentToken();
-	if (!_partiallyParsedExpression && (Token::isUnaryOp(token) || Token::isCountOp(token)))
+	Token token = m_scanner->currentToken();
+	if (!_partiallyParsedExpression && (TokenTraits::isUnaryOp(token) || TokenTraits::isCountOp(token)))
 	{
 		// prefix expression
 		m_scanner->next();
@@ -1407,7 +1407,7 @@ ASTPointer<Expression> Parser::parseUnaryExpression(
 		// potential postfix expression
 		ASTPointer<Expression> subExpression = parseLeftHandSideExpression(_partiallyParsedExpression);
 		token = m_scanner->currentToken();
-		if (!Token::isCountOp(token))
+		if (!TokenTraits::isCountOp(token))
 			return subExpression;
 		nodeFactory.markEndPosition();
 		m_scanner->next();
@@ -1482,7 +1482,7 @@ ASTPointer<Expression> Parser::parsePrimaryExpression()
 {
 	RecursionGuard recursionGuard(*this);
 	ASTNodeFactory nodeFactory(*this);
-	Token::Value token = m_scanner->currentToken();
+	Token token = m_scanner->currentToken();
 	ASTPointer<Expression> expression;
 
 	switch (token)
@@ -1493,7 +1493,7 @@ ASTPointer<Expression> Parser::parsePrimaryExpression()
 		expression = nodeFactory.createNode<Literal>(token, getLiteralAndAdvance());
 		break;
 	case Token::Number:
-		if (Token::isEtherSubdenomination(m_scanner->peekNextToken()))
+		if (TokenTraits::isEtherSubdenomination(m_scanner->peekNextToken()))
 		{
 			ASTPointer<ASTString> literal = getLiteralAndAdvance();
 			nodeFactory.markEndPosition();
@@ -1501,7 +1501,7 @@ ASTPointer<Expression> Parser::parsePrimaryExpression()
 			m_scanner->next();
 			expression = nodeFactory.createNode<Literal>(token, literal, subdenomination);
 		}
-		else if (Token::isTimeSubdenomination(m_scanner->peekNextToken()))
+		else if (TokenTraits::isTimeSubdenomination(m_scanner->peekNextToken()))
 		{
 			ASTPointer<ASTString> literal = getLiteralAndAdvance();
 			nodeFactory.markEndPosition();
@@ -1531,7 +1531,7 @@ ASTPointer<Expression> Parser::parsePrimaryExpression()
 		// (x,) is one-dimensional tuple, elements in arrays cannot be left out, only in tuples.
 		m_scanner->next();
 		vector<ASTPointer<Expression>> components;
-		Token::Value oppositeToken = (token == Token::LParen ? Token::RParen : Token::RBrack);
+		Token oppositeToken = (token == Token::LParen ? Token::RParen : Token::RBrack);
 		bool isArray = (token == Token::LBrack);
 
 		if (m_scanner->currentToken() != oppositeToken)
@@ -1558,7 +1558,7 @@ ASTPointer<Expression> Parser::parsePrimaryExpression()
 		fatalParserError("Expected even number of hex-nibbles within double-quotes.");
 		break;		
 	default:
-		if (Token::isElementaryTypeName(token))
+		if (TokenTraits::isElementaryTypeName(token))
 		{
 			//used for casts
 			unsigned firstSize;
@@ -1595,7 +1595,7 @@ pair<vector<ASTPointer<Expression>>, vector<ASTPointer<ASTString>>> Parser::pars
 {
 	RecursionGuard recursionGuard(*this);
 	pair<vector<ASTPointer<Expression>>, vector<ASTPointer<ASTString>>> ret;
-	Token::Value token = m_scanner->currentToken();
+	Token token = m_scanner->currentToken();
 	if (token == Token::LBrace)
 	{
 		// call({arg1 : 1, arg2 : 2 })
@@ -1638,21 +1638,21 @@ Parser::LookAheadInfo Parser::peekStatementType() const
 	// or a mutability specifier, we also have a variable declaration.
 	// If we get an identifier followed by a "[" or ".", it can be both ("lib.type[9] a;" or "variable.el[9] = 7;").
 	// In all other cases, we have an expression statement.
-	Token::Value token(m_scanner->currentToken());
-	bool mightBeTypeName = (Token::isElementaryTypeName(token) || token == Token::Identifier);
+	Token token(m_scanner->currentToken());
+	bool mightBeTypeName = (TokenTraits::isElementaryTypeName(token) || token == Token::Identifier);
 
 	if (token == Token::Mapping || token == Token::Function || token == Token::Var)
 		return LookAheadInfo::VariableDeclaration;
 	if (mightBeTypeName)
 	{
-		Token::Value next = m_scanner->peekNextToken();
+		Token next = m_scanner->peekNextToken();
 		// So far we only allow ``address payable`` in variable declaration statements and in no other
 		// kind of statement. This means, for example, that we do not allow type expressions of the form
 		// ``address payable;``.
 		// If we want to change this in the future, we need to consider another scanner token here.
-		if (Token::isElementaryTypeName(token) && Token::isStateMutabilitySpecifier(next, false))
+		if (TokenTraits::isElementaryTypeName(token) && TokenTraits::isStateMutabilitySpecifier(next, false))
 			return LookAheadInfo::VariableDeclaration;
-		if (next == Token::Identifier || Token::isLocationSpecifier(next))
+		if (next == Token::Identifier || TokenTraits::isLocationSpecifier(next))
 			return LookAheadInfo::VariableDeclaration;
 		if (next == Token::LBrack || next == Token::Period)
 			return LookAheadInfo::IndexAccessStructure;
diff --git a/libsolidity/parsing/ParserBase.cpp b/libsolidity/parsing/ParserBase.cpp
index 71133746..1d4cb1e2 100644
--- a/libsolidity/parsing/ParserBase.cpp
+++ b/libsolidity/parsing/ParserBase.cpp
@@ -43,12 +43,12 @@ int ParserBase::endPosition() const
 	return m_scanner->currentLocation().end;
 }
 
-Token::Value ParserBase::currentToken() const
+Token ParserBase::currentToken() const
 {
 	return m_scanner->currentToken();
 }
 
-Token::Value ParserBase::peekNextToken() const
+Token ParserBase::peekNextToken() const
 {
 	return m_scanner->peekNextToken();
 }
@@ -58,31 +58,31 @@ std::string ParserBase::currentLiteral() const
 	return m_scanner->currentLiteral();
 }
 
-Token::Value ParserBase::advance()
+Token ParserBase::advance()
 {
 	return m_scanner->next();
 }
 
-void ParserBase::expectToken(Token::Value _value, bool _advance)
+void ParserBase::expectToken(Token _value, bool _advance)
 {
-	Token::Value tok = m_scanner->currentToken();
+	Token tok = m_scanner->currentToken();
 	if (tok != _value)
 	{
-		auto tokenName = [this](Token::Value _token)
+		auto tokenName = [this](Token _token)
 		{
 			if (_token == Token::Identifier)
 				return string("identifier");
 			else if (_token == Token::EOS)
 				return string("end of source");
-			else if (Token::isReservedKeyword(_token))
-				return string("reserved keyword '") + Token::friendlyName(_token) + "'";
-			else if (Token::isElementaryTypeName(_token)) //for the sake of accuracy in reporting
+			else if (TokenTraits::isReservedKeyword(_token))
+				return string("reserved keyword '") + TokenTraits::friendlyName(_token) + "'";
+			else if (TokenTraits::isElementaryTypeName(_token)) //for the sake of accuracy in reporting
 			{
 				ElementaryTypeNameToken elemTypeName = m_scanner->currentElementaryTypeNameToken();
 				return string("'") + elemTypeName.toString() + "'";
 			}
 			else
-				return string("'") + Token::friendlyName(_token) + "'";
+				return string("'") + TokenTraits::friendlyName(_token) + "'";
 		};
 
 		fatalParserError(string("Expected ") + tokenName(_value) + string(" but got ") + tokenName(tok));
diff --git a/libsolidity/parsing/ParserBase.h b/libsolidity/parsing/ParserBase.h
index b28e1b1b..e01f37d8 100644
--- a/libsolidity/parsing/ParserBase.h
+++ b/libsolidity/parsing/ParserBase.h
@@ -63,11 +63,11 @@ protected:
 	///@{
 	///@name Helper functions
 	/// If current token value is not _value, throw exception otherwise advance token.
-	void expectToken(Token::Value _value, bool _advance = true);
-	Token::Value currentToken() const;
-	Token::Value peekNextToken() const;
+	void expectToken(Token _value, bool _advance = true);
+	Token currentToken() const;
+	Token peekNextToken() const;
 	std::string currentLiteral() const;
-	Token::Value advance();
+	Token advance();
 	///@}
 
 	/// Increases the recursion depth and throws an exception if it is too deep.
diff --git a/libsolidity/parsing/Scanner.cpp b/libsolidity/parsing/Scanner.cpp
index 87d7c535..e9dad2ad 100644
--- a/libsolidity/parsing/Scanner.cpp
+++ b/libsolidity/parsing/Scanner.cpp
@@ -214,9 +214,9 @@ void Scanner::addUnicodeAsUTF8(unsigned codepoint)
 }
 
 // Ensure that tokens can be stored in a byte.
-BOOST_STATIC_ASSERT(Token::NUM_TOKENS <= 0x100);
+BOOST_STATIC_ASSERT(TokenTraits::count() <= 0x100);
 
-Token::Value Scanner::next()
+Token Scanner::next()
 {
 	m_currentToken = m_nextToken;
 	m_skippedComment = m_nextSkippedComment;
@@ -225,7 +225,7 @@ Token::Value Scanner::next()
 	return m_currentToken.token;
 }
 
-Token::Value Scanner::selectToken(char _next, Token::Value _then, Token::Value _else)
+Token Scanner::selectToken(char _next, Token _then, Token _else)
 {
 	advance();
 	if (m_char == _next)
@@ -249,7 +249,7 @@ void Scanner::skipWhitespaceExceptUnicodeLinebreak()
 		advance();
 }
 
-Token::Value Scanner::skipSingleLineComment()
+Token Scanner::skipSingleLineComment()
 {
 	// Line terminator is not part of the comment. If it is a
 	// non-ascii line terminator, it will result in a parser error.
@@ -259,7 +259,7 @@ Token::Value Scanner::skipSingleLineComment()
 	return Token::Whitespace;
 }
 
-Token::Value Scanner::scanSingleLineDocComment()
+Token Scanner::scanSingleLineDocComment()
 {
 	LiteralScope literal(this, LITERAL_TYPE_COMMENT);
 	advance(); //consume the last '/' at ///
@@ -295,7 +295,7 @@ Token::Value Scanner::scanSingleLineDocComment()
 	return Token::CommentLiteral;
 }
 
-Token::Value Scanner::skipMultiLineComment()
+Token Scanner::skipMultiLineComment()
 {
 	advance();
 	while (!isSourcePastEndOfInput())
@@ -316,7 +316,7 @@ Token::Value Scanner::skipMultiLineComment()
 	return Token::Illegal;
 }
 
-Token::Value Scanner::scanMultiLineDocComment()
+Token Scanner::scanMultiLineDocComment()
 {
 	LiteralScope literal(this, LITERAL_TYPE_COMMENT);
 	bool endFound = false;
@@ -369,7 +369,7 @@ Token::Value Scanner::scanMultiLineDocComment()
 		return Token::CommentLiteral;
 }
 
-Token::Value Scanner::scanSlash()
+Token Scanner::scanSlash()
 {
 	int firstSlashPosition = sourcePos();
 	advance();
@@ -380,7 +380,7 @@ Token::Value Scanner::scanSlash()
 		else if (m_char == '/')
 		{
 			// doxygen style /// comment
-			Token::Value comment;
+			Token comment;
 			m_nextSkippedComment.location.start = firstSlashPosition;
 			comment = scanSingleLineDocComment();
 			m_nextSkippedComment.location.end = sourcePos();
@@ -406,7 +406,7 @@ Token::Value Scanner::scanSlash()
 				return Token::Whitespace;
 			}
 			// we actually have a multiline documentation comment
-			Token::Value comment;
+			Token comment;
 			m_nextSkippedComment.location.start = firstSlashPosition;
 			comment = scanMultiLineDocComment();
 			m_nextSkippedComment.location.end = sourcePos();
@@ -432,7 +432,7 @@ void Scanner::scanToken()
 	m_nextSkippedComment.literal.clear();
 	m_nextSkippedComment.extendedTokenInfo = make_tuple(0, 0);
 
-	Token::Value token;
+	Token token;
 	// M and N are for the purposes of grabbing different type sizes
 	unsigned m;
 	unsigned n;
@@ -703,7 +703,7 @@ bool Scanner::isUnicodeLinebreak()
 		return false;
 }
 
-Token::Value Scanner::scanString()
+Token Scanner::scanString()
 {
 	char const quote = m_char;
 	advance();  // consume quote
@@ -727,7 +727,7 @@ Token::Value Scanner::scanString()
 	return Token::StringLiteral;
 }
 
-Token::Value Scanner::scanHexString()
+Token Scanner::scanHexString()
 {
 	char const quote = m_char;
 	advance();  // consume quote
@@ -760,7 +760,7 @@ void Scanner::scanDecimalDigits()
 	// Defer further validation of underscore to SyntaxChecker.
 }
 
-Token::Value Scanner::scanNumber(char _charSeen)
+Token Scanner::scanNumber(char _charSeen)
 {
 	enum { DECIMAL, HEX, BINARY } kind = DECIMAL;
 	LiteralScope literal(this, LITERAL_TYPE_NUMBER);
@@ -854,7 +854,7 @@ Token::Value Scanner::scanNumber(char _charSeen)
 	return Token::Number;
 }
 
-tuple<Token::Value, unsigned, unsigned> Scanner::scanIdentifierOrKeyword()
+tuple<Token, unsigned, unsigned> Scanner::scanIdentifierOrKeyword()
 {
 	solAssert(isIdentifierStart(m_char), "");
 	LiteralScope literal(this, LITERAL_TYPE_STRING);
@@ -863,7 +863,7 @@ tuple<Token::Value, unsigned, unsigned> Scanner::scanIdentifierOrKeyword()
 	while (isIdentifierPart(m_char)) //get full literal
 		addLiteralCharAndAdvance();
 	literal.complete();
-	return Token::fromIdentifierOrKeyword(m_nextToken.literal);
+	return TokenTraits::fromIdentifierOrKeyword(m_nextToken.literal);
 }
 
 char CharStream::advanceAndGet(size_t _chars)
diff --git a/libsolidity/parsing/Scanner.h b/libsolidity/parsing/Scanner.h
index 7564c788..02e0553f 100644
--- a/libsolidity/parsing/Scanner.h
+++ b/libsolidity/parsing/Scanner.h
@@ -112,13 +112,13 @@ public:
 	void reset();
 
 	/// @returns the next token and advances input
-	Token::Value next();
+	Token next();
 
 	///@{
 	///@name Information about the current token
 
 	/// @returns the current token
-	Token::Value currentToken() const
+	Token currentToken() const
 	{
 		return m_currentToken.token;
 	}
@@ -149,7 +149,7 @@ public:
 	///@name Information about the next token
 
 	/// @returns the next token without advancing input.
-	Token::Value peekNextToken() const { return m_nextToken.token; }
+	Token peekNextToken() const { return m_nextToken.token; }
 	SourceLocation peekLocation() const { return m_nextToken.location; }
 	std::string const& peekLiteral() const { return m_nextToken.literal; }
 	///@}
@@ -168,7 +168,7 @@ private:
 	/// Used for the current and look-ahead token and comments
 	struct TokenDesc
 	{
-		Token::Value token;
+		Token token;
 		SourceLocation location;
 		std::string literal;
 		std::tuple<unsigned, unsigned> extendedTokenInfo;
@@ -185,9 +185,9 @@ private:
 	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 selectToken(Token _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);
+	inline Token selectToken(char _next, Token _then, Token _else);
 
 	bool scanHexByte(char& o_scannedByte);
 	bool scanUnicode(unsigned& o_codepoint);
@@ -199,19 +199,19 @@ private:
 	bool skipWhitespace();
 	/// Skips all whitespace that are neither '\r' nor '\n'.
 	void skipWhitespaceExceptUnicodeLinebreak();
-	Token::Value skipSingleLineComment();
-	Token::Value skipMultiLineComment();
+	Token skipSingleLineComment();
+	Token skipMultiLineComment();
 
 	void scanDecimalDigits();
-	Token::Value scanNumber(char _charSeen = 0);
-	std::tuple<Token::Value, unsigned, unsigned> scanIdentifierOrKeyword();
+	Token scanNumber(char _charSeen = 0);
+	std::tuple<Token, unsigned, unsigned> scanIdentifierOrKeyword();
 
-	Token::Value scanString();
-	Token::Value scanHexString();
-	Token::Value scanSingleLineDocComment();
-	Token::Value scanMultiLineDocComment();
+	Token scanString();
+	Token scanHexString();
+	Token scanSingleLineDocComment();
+	Token scanMultiLineDocComment();
 	/// Scans a slash '/' and depending on the characters returns the appropriate token
-	Token::Value scanSlash();
+	Token scanSlash();
 
 	/// Scans an escape-sequence which is part of a string and adds the
 	/// decoded character to the current literal. Returns true if a pattern
diff --git a/libsolidity/parsing/Token.cpp b/libsolidity/parsing/Token.cpp
index 27acb7d4..dccd9037 100644
--- a/libsolidity/parsing/Token.cpp
+++ b/libsolidity/parsing/Token.cpp
@@ -51,9 +51,9 @@ namespace dev
 namespace solidity
 {
 
-void ElementaryTypeNameToken::assertDetails(Token::Value _baseType, unsigned const& _first, unsigned const& _second)
+void ElementaryTypeNameToken::assertDetails(Token _baseType, unsigned const& _first, unsigned const& _second)
 {
-	solAssert(Token::isElementaryTypeName(_baseType), "Expected elementary type name: " + string(Token::toString(_baseType)));
+	solAssert(TokenTraits::isElementaryTypeName(_baseType), "Expected elementary type name: " + string(TokenTraits::toString(_baseType)));
 	if (_baseType == Token::BytesM)
 	{
 		solAssert(_second == 0, "There should not be a second size argument to type bytesM.");
@@ -61,17 +61,17 @@ void ElementaryTypeNameToken::assertDetails(Token::Value _baseType, unsigned con
 	}
 	else if (_baseType == Token::UIntM || _baseType == Token::IntM)
 	{
-		solAssert(_second == 0, "There should not be a second size argument to type " + string(Token::toString(_baseType)) + ".");
+		solAssert(_second == 0, "There should not be a second size argument to type " + string(TokenTraits::toString(_baseType)) + ".");
 		solAssert(
 			_first <= 256 && _first % 8 == 0,
-			"No elementary type " + string(Token::toString(_baseType)) + to_string(_first) + "."
+			"No elementary type " + string(TokenTraits::toString(_baseType)) + to_string(_first) + "."
 		);
 	}
 	else if (_baseType == Token::UFixedMxN || _baseType == Token::FixedMxN)
 	{
 		solAssert(
 			_first >= 8 && _first <= 256 && _first % 8 == 0 && _second <= 80,
-			"No elementary type " + string(Token::toString(_baseType)) + to_string(_first) + "x" + to_string(_second) + "."
+			"No elementary type " + string(TokenTraits::toString(_baseType)) + to_string(_first) + "x" + to_string(_second) + "."
 		);
 	}
 	m_token = _baseType;
@@ -79,38 +79,54 @@ void ElementaryTypeNameToken::assertDetails(Token::Value _baseType, unsigned con
 	m_secondNumber = _second;
 }
 
-#define T(name, string, precedence) #name,
-char const* const Token::m_name[NUM_TOKENS] =
+namespace TokenTraits
 {
-	TOKEN_LIST(T, T)
-};
-#undef T
 
+char const* toString(Token tok)
+{
+	switch (tok)
+	{
+#define T(name, string, precedence) case Token::name: return string;
+		TOKEN_LIST(T, T)
+#undef T
+		default: // Token::NUM_TOKENS:
+			return "";
+	}
+}
 
-#define T(name, string, precedence) string,
-char const* const Token::m_string[NUM_TOKENS] =
+char const* name(Token tok)
 {
-	TOKEN_LIST(T, T)
-};
+#define T(name, string, precedence) #name,
+	static char const* const names[TokenTraits::count()] = { TOKEN_LIST(T, T) };
 #undef T
 
+	solAssert(static_cast<size_t>(tok) < TokenTraits::count(), "");
+	return names[static_cast<size_t>(tok)];
+}
 
-#define T(name, string, precedence) precedence,
-int8_t const Token::m_precedence[NUM_TOKENS] =
+std::string friendlyName(Token tok)
 {
-	TOKEN_LIST(T, T)
-};
-#undef T
+	char const* ret = toString(tok);
+	if (ret)
+		return std::string(ret);
 
+	ret = name(tok);
+	solAssert(ret != nullptr, "");
+	return std::string(ret);
+}
 
-#define KT(a, b, c) 'T',
-#define KK(a, b, c) 'K',
-char const Token::m_tokenType[] =
+#define T(name, string, precedence) precedence,
+int precedence(Token tok)
 {
-	TOKEN_LIST(KT, KK)
-};
+	int8_t const static precs[TokenTraits::count()] =
+	{
+		TOKEN_LIST(T, T)
+	};
+	return precs[static_cast<size_t>(tok)];
+}
+#undef T
 
-int Token::parseSize(string::const_iterator _begin, string::const_iterator _end)
+int parseSize(string::const_iterator _begin, string::const_iterator _end)
 {
 	try
 	{
@@ -123,7 +139,20 @@ int Token::parseSize(string::const_iterator _begin, string::const_iterator _end)
 	}
 }
 
-tuple<Token::Value, unsigned int, unsigned int> Token::fromIdentifierOrKeyword(string const& _literal)
+static Token keywordByName(string const& _name)
+{
+	// The following macros are used inside TOKEN_LIST and cause non-keyword tokens to be ignored
+	// and keywords to be put inside the keywords variable.
+#define KEYWORD(name, string, precedence) {string, Token::name},
+#define TOKEN(name, string, precedence)
+	static const map<string, Token> keywords({TOKEN_LIST(TOKEN, KEYWORD)});
+#undef KEYWORD
+#undef TOKEN
+	auto it = keywords.find(_name);
+	return it == keywords.end() ? Token::Identifier : it->second;
+}
+
+tuple<Token, unsigned int, unsigned int> fromIdentifierOrKeyword(string const& _literal)
 {
 	auto positionM = find_if(_literal.begin(), _literal.end(), ::isdigit);
 	if (positionM != _literal.end())
@@ -131,7 +160,7 @@ tuple<Token::Value, unsigned int, unsigned int> Token::fromIdentifierOrKeyword(s
 		string baseType(_literal.begin(), positionM);
 		auto positionX = find_if_not(positionM, _literal.end(), ::isdigit);
 		int m = parseSize(positionM, positionX);
-		Token::Value keyword = keywordByName(baseType);
+		Token keyword = keywordByName(baseType);
 		if (keyword == Token::Bytes)
 		{
 			if (0 < m && m <= 32 && positionX == _literal.end())
@@ -172,20 +201,7 @@ tuple<Token::Value, unsigned int, unsigned int> Token::fromIdentifierOrKeyword(s
 
 	return make_tuple(keywordByName(_literal), 0, 0);
 }
-Token::Value Token::keywordByName(string const& _name)
-{
-	// The following macros are used inside TOKEN_LIST and cause non-keyword tokens to be ignored
-	// and keywords to be put inside the keywords variable.
-#define KEYWORD(name, string, precedence) {string, Token::name},
-#define TOKEN(name, string, precedence)
-	static const map<string, Token::Value> keywords({TOKEN_LIST(TOKEN, KEYWORD)});
-#undef KEYWORD
-#undef TOKEN
-	auto it = keywords.find(_name);
-	return it == keywords.end() ? Token::Identifier : it->second;
-}
 
-#undef KT
-#undef KK
+}
 }
 }
diff --git a/libsolidity/parsing/Token.h b/libsolidity/parsing/Token.h
index 8ecc850a..81e8dd98 100644
--- a/libsolidity/parsing/Token.h
+++ b/libsolidity/parsing/Token.h
@@ -45,6 +45,7 @@
 #include <libdevcore/Common.h>
 #include <libsolidity/interface/Exceptions.h>
 #include <libsolidity/parsing/UndefMacros.h>
+#include <iosfwd>
 
 namespace dev
 {
@@ -267,119 +268,95 @@ namespace solidity
 	/* Scanner-internal use only. */                                   \
 	T(Whitespace, NULL, 0)
 
-
-class Token
-{
-public:
-	// All token values.
-	// attention! msvc issue:
-	// http://stackoverflow.com/questions/9567868/compile-errors-after-adding-v8-to-my-project-c2143-c2059
-	// @todo: avoid TOKEN_LIST macro
+// All token values.
+// attention! msvc issue:
+// http://stackoverflow.com/questions/9567868/compile-errors-after-adding-v8-to-my-project-c2143-c2059
+// @todo: avoid TOKEN_LIST macro
+enum class Token : unsigned int {
 #define T(name, string, precedence) name,
-	enum Value
-	{
-		TOKEN_LIST(T, T)
-		NUM_TOKENS
-	};
+	TOKEN_LIST(T, T)
+	NUM_TOKENS
 #undef T
+};
 
-	// @returns a string corresponding to the C++ token name
-	// (e.g. "LT" for the token LT).
-	static char const* name(Value tok)
-	{
-		solAssert(tok < NUM_TOKENS, "");
-		return m_name[tok];
-	}
+namespace TokenTraits
+{
+	constexpr size_t count() { return static_cast<size_t>(Token::NUM_TOKENS); }
 
 	// Predicates
-	static bool isElementaryTypeName(Value tok) { return Int <= tok && tok < TypesEnd; }
-	static bool isAssignmentOp(Value tok) { return Assign <= tok && tok <= AssignMod; }
-	static bool isBinaryOp(Value op) { return Comma <= op && op <= Exp; }
-	static bool isCommutativeOp(Value op) { return op == BitOr || op == BitXor || op == BitAnd ||
-				op == Add || op == Mul || op == Equal || op == NotEqual; }
-	static bool isArithmeticOp(Value op) { return Add <= op && op <= Exp; }
-	static bool isCompareOp(Value op) { return Equal <= op && op <= GreaterThanOrEqual; }
+	constexpr bool isElementaryTypeName(Token tok) { return Token::Int <= tok && tok < Token::TypesEnd; }
+	constexpr bool isAssignmentOp(Token tok) { return Token::Assign <= tok && tok <= Token::AssignMod; }
+	constexpr bool isBinaryOp(Token op) { return Token::Comma <= op && op <= Token::Exp; }
+	constexpr bool isCommutativeOp(Token op) { return op == Token::BitOr || op == Token::BitXor || op == Token::BitAnd ||
+		 op == Token::Add || op == Token::Mul || op == Token::Equal || op == Token::NotEqual; }
+	constexpr bool isArithmeticOp(Token op) { return Token::Add <= op && op <= Token::Exp; }
+	constexpr bool isCompareOp(Token op) { return Token::Equal <= op && op <= Token::GreaterThanOrEqual; }
 
-	static Value AssignmentToBinaryOp(Value op)
-	{
-		solAssert(isAssignmentOp(op) && op != Assign, "");
-		return Value(op + (BitOr - AssignBitOr));
-	}
+	constexpr bool isBitOp(Token op) { return (Token::BitOr <= op && op <= Token::BitAnd) || op == Token::BitNot; }
+	constexpr bool isBooleanOp(Token op) { return (Token::Or <= op && op <= Token::And) || op == Token::Not; }
+	constexpr bool isUnaryOp(Token op) { return (Token::Not <= op && op <= Token::Delete) || op == Token::Add || op == Token::Sub; }
+	constexpr bool isCountOp(Token op) { return op == Token::Inc || op == Token::Dec; }
+	constexpr bool isShiftOp(Token op) { return (Token::SHL <= op) && (op <= Token::SHR); }
+	constexpr bool isVariableVisibilitySpecifier(Token op) { return op == Token::Public || op == Token::Private || op == Token::Internal; }
+	constexpr bool isVisibilitySpecifier(Token op) { return isVariableVisibilitySpecifier(op) || op == Token::External; }
+	constexpr bool isLocationSpecifier(Token op) { return op == Token::Memory || op == Token::Storage || op == Token::CallData; }
 
-	static bool isBitOp(Value op) { return (BitOr <= op && op <= BitAnd) || op == BitNot; }
-	static bool isBooleanOp(Value op) { return (Or <= op && op <= And) || op == Not; }
-	static bool isUnaryOp(Value op) { return (Not <= op && op <= Delete) || op == Add || op == Sub; }
-	static bool isCountOp(Value op) { return op == Inc || op == Dec; }
-	static bool isShiftOp(Value op) { return (SHL <= op) && (op <= SHR); }
-	static bool isVisibilitySpecifier(Value op) { return isVariableVisibilitySpecifier(op) || op == External; }
-	static bool isVariableVisibilitySpecifier(Value op) { return op == Public || op == Private || op == Internal; }
-	static bool isLocationSpecifier(Value op) { return op == Memory || op == Storage || op == CallData; }
-	static bool isStateMutabilitySpecifier(Value op, bool _allowConstant = true)
+	constexpr bool isStateMutabilitySpecifier(Token op, bool _allowConstant = true)
 	{
-		if (op == Constant && _allowConstant)
-			return true;
-		return op == Pure || op == View || op == Payable;
+		return (op == Token::Constant && _allowConstant)
+			|| op == Token::Pure || op == Token::View || op == Token::Payable;
 	}
-	static bool isEtherSubdenomination(Value op) { return op == SubWei || op == SubSzabo || op == SubFinney || op == SubEther; }
-	static bool isTimeSubdenomination(Value op) { return op == SubSecond || op == SubMinute || op == SubHour || op == SubDay || op == SubWeek || op == SubYear; }
-	static bool isReservedKeyword(Value op) { return (Abstract <= op && op <= Unchecked); }
 
-	// @returns a string corresponding to the JS token string
-	// (.e., "<" for the token LT) or NULL if the token doesn't
-	// have a (unique) string (e.g. an IDENTIFIER).
-	static char const* toString(Value tok)
-	{
-		solAssert(tok < NUM_TOKENS, "");
-		return m_string[tok];
-	}
+	constexpr bool isEtherSubdenomination(Token op) { return op == Token::SubWei || op == Token::SubSzabo || op == Token::SubFinney || op == Token::SubEther; }
+	constexpr bool isTimeSubdenomination(Token op) { return op == Token::SubSecond || op == Token::SubMinute || op == Token::SubHour || op == Token::SubDay || op == Token::SubWeek || op == Token::SubYear; }
+	constexpr bool isReservedKeyword(Token op) { return (Token::Abstract <= op && op <= Token::Unchecked); }
 
-	static std::string friendlyName(Value tok)
+	inline Token AssignmentToBinaryOp(Token op)
 	{
-		char const* ret = toString(tok);
-		if (ret == nullptr)
-		{
-			ret = name(tok);
-			solAssert(ret != nullptr, "");
-		}
-		return std::string(ret);
+		solAssert(isAssignmentOp(op) && op != Token::Assign, "");
+		return static_cast<Token>(static_cast<int>(op) + (static_cast<int>(Token::BitOr) - static_cast<int>(Token::AssignBitOr)));
 	}
 
 	// @returns the precedence > 0 for binary and compare
 	// operators; returns 0 otherwise.
-	static int precedence(Value tok)
-	{
-		solAssert(tok < NUM_TOKENS, "");
-		return m_precedence[tok];
-	}
+	int precedence(Token tok);
 
-	static std::tuple<Token::Value, unsigned int, unsigned int> fromIdentifierOrKeyword(std::string const& _literal);
+	std::tuple<Token, unsigned int, unsigned int> fromIdentifierOrKeyword(std::string const& _literal);
 
-private:
-	// @returns -1 on error (invalid digit or number too large)
-	static int parseSize(std::string::const_iterator _begin, std::string::const_iterator _end);
-	// @returns the keyword with name @a _name or Token::Identifier of no such keyword exists.
-	static Token::Value keywordByName(std::string const& _name);
-	static char const* const m_name[NUM_TOKENS];
-	static char const* const m_string[NUM_TOKENS];
-	static int8_t const m_precedence[NUM_TOKENS];
-	static char const m_tokenType[NUM_TOKENS];
-};
+	// @returns a string corresponding to the C++ token name
+	// (e.g. "LT" for the token LT).
+	char const* name(Token tok);
+
+	// @returns a string corresponding to the JS token string
+	// (.e., "<" for the token LT) or NULL if the token doesn't
+	// have a (unique) string (e.g. an IDENTIFIER).
+	char const* toString(Token tok);
+
+	std::string friendlyName(Token tok);
+}
+
+inline std::ostream& operator<<(std::ostream& os, Token token)
+{
+	os << TokenTraits::friendlyName(token);
+	return os;
+}
 
 class ElementaryTypeNameToken
 {
 public:
-	ElementaryTypeNameToken(Token::Value _token, unsigned const& _firstNumber, unsigned const& _secondNumber)
+	ElementaryTypeNameToken(Token _token, unsigned const& _firstNumber, unsigned const& _secondNumber)
 	{
 		assertDetails(_token, _firstNumber, _secondNumber);
 	}
 
 	unsigned int firstNumber() const { return m_firstNumber; }
 	unsigned int secondNumber() const { return m_secondNumber; }
-	Token::Value token() const { return m_token; }
+	Token token() const { return m_token; }
+
 	///if tokValue is set to true, then returns the actual token type name, otherwise, returns full type
 	std::string toString(bool const& tokenValue = false) const
 	{
-		std::string name = Token::toString(m_token);
+		std::string name = TokenTraits::toString(m_token);
 		if (tokenValue || (firstNumber() == 0 && secondNumber() == 0))
 			return name;
 		solAssert(name.size() >= 3, "Token name size should be greater than 3. Should not reach here.");
@@ -390,11 +367,11 @@ public:
 	}
 
 private:
-	Token::Value m_token;
+	Token m_token;
 	unsigned int m_firstNumber;
 	unsigned int m_secondNumber;
 	/// throws if type is not properly sized
-	void assertDetails(Token::Value _baseType, unsigned const& _first, unsigned const& _second);
+	void assertDetails(Token _baseType, unsigned const& _first, unsigned const& _second);
 };
 
 }