Allow conversion to dynamic arrays and update grammar.

AST.cpp

@@ -614,6 +614,8 @@ void IndexAccess::checkTypeRequirements()
 	case Type::Category::Array:
 	{
 		ArrayType const& type = dynamic_cast<ArrayType const&>(*m_base->getType());
+		if (!m_index)
+			BOOST_THROW_EXCEPTION(createTypeError("Index expression cannot be omitted."));
 		m_index->expectType(IntegerType(256));
 		m_type = type.getBaseType();
 		m_isLValue = true;
@@ -622,14 +624,32 @@ void IndexAccess::checkTypeRequirements()
 	case Type::Category::Mapping:
 	{
 		MappingType const& type = dynamic_cast<MappingType const&>(*m_base->getType());
+		if (!m_index)
+			BOOST_THROW_EXCEPTION(createTypeError("Index expression cannot be omitted."));
 		m_index->expectType(*type.getKeyType());
 		m_type = type.getValueType();
 		m_isLValue = true;
 		break;
 	}
+	case Type::Category::TypeType:
+	{
+		TypeType const& type = dynamic_cast<TypeType const&>(*m_base->getType());
+		if (!m_index)
+			m_type = make_shared<TypeType>(make_shared<ArrayType>(ArrayType::Location::Memory, type.getActualType()));
+		else
+		{
+			m_index->checkTypeRequirements();
+			auto length = dynamic_cast<IntegerConstantType const*>(m_index->getType().get());
+			if (!length)
+				BOOST_THROW_EXCEPTION(m_index->createTypeError("Integer constant expected."));
+			m_type = make_shared<TypeType>(make_shared<ArrayType>(
+				ArrayType::Location::Memory, type.getActualType(), length->literalValue(nullptr)));
+		}
+		break;
+	}
 	default:
 		BOOST_THROW_EXCEPTION(m_base->createTypeError(
-			"Indexed expression has to be a mapping or array (is " + m_base->getType()->toString() + ")"));
+			"Indexed expression has to be a type, mapping or array (is " + m_base->getType()->toString() + ")"));
 	}
 }
 

AST.h

@@ -1102,7 +1102,7 @@ public:
 	virtual void checkTypeRequirements() override;
 
 	Expression const& getBaseExpression() const { return *m_base; }
-	Expression const& getIndexExpression() const { return *m_index; }
+	Expression const* getIndexExpression() const { return m_index.get(); }
 
 private:
 	ASTPointer<Expression> m_base;

AST_accept.h

@@ -626,7 +626,8 @@ void IndexAccess::accept(ASTVisitor& _visitor)
 	if (_visitor.visit(*this))
 	{
 		m_base->accept(_visitor);
-		m_index->accept(_visitor);
+		if (m_index)
+			m_index->accept(_visitor);
 	}
 	_visitor.endVisit(*this);
 }
@@ -636,7 +637,8 @@ void IndexAccess::accept(ASTConstVisitor& _visitor) const
 	if (_visitor.visit(*this))
 	{
 		m_base->accept(_visitor);
-		m_index->accept(_visitor);
+		if (m_index)
+			m_index->accept(_visitor);
 	}
 	_visitor.endVisit(*this);
 }

ExpressionCompiler.cpp

@@ -562,7 +562,8 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 	solAssert(baseType.getCategory() == Type::Category::Mapping, "");
 	Type const& keyType = *dynamic_cast<MappingType const&>(baseType).getKeyType();
 	m_context << u256(0);
-	appendExpressionCopyToMemory(keyType, _indexAccess.getIndexExpression());
+	solAssert(_indexAccess.getIndexExpression(), "Index expression expected.");
+	appendExpressionCopyToMemory(keyType, *_indexAccess.getIndexExpression());
 	solAssert(baseType.getSizeOnStack() == 1,
 			  "Unexpected: Not exactly one stack slot taken by subscriptable expression.");
 	m_context << eth::Instruction::SWAP1;

Parser.cpp

@@ -645,14 +645,11 @@ ASTPointer<Statement> Parser::parseSimpleStatement()
 	vector<pair<ASTPointer<Expression>, Location>> indices;
 	solAssert(m_scanner->getCurrentToken() == Token::LBrack, "");
 	Location indexLocation = primary->getLocation();
-	bool encounteredEmptyBrackets = false;
 	do
 	{
 		expectToken(Token::LBrack);
 		ASTPointer<Expression> index;
-		if (m_scanner->getCurrentToken() == Token::RBrack)
+		if (m_scanner->getCurrentToken() != Token::RBrack)
-			encounteredEmptyBrackets = true;
-		else
 			index = parseExpression();
 		indexLocation.end = getEndPosition();
 		indices.push_back(make_pair(index, indexLocation));
@@ -660,7 +657,7 @@ ASTPointer<Statement> Parser::parseSimpleStatement()
 	}
 	while (m_scanner->getCurrentToken() == Token::LBrack);
 
-	if (m_scanner->getCurrentToken() == Token::Identifier || encounteredEmptyBrackets)
+	if (m_scanner->getCurrentToken() == Token::Identifier)
 		return parseVariableDeclarationStatement(typeNameFromArrayIndexStructure(primary, indices));
 	else
 		return parseExpressionStatement(expressionFromArrayIndexStructure(primary, indices));
@@ -768,7 +765,9 @@ ASTPointer<Expression> Parser::parseLeftHandSideExpression(
 		case Token::LBrack:
 		{
 			m_scanner->next();
-			ASTPointer<Expression> index = parseExpression();
+			ASTPointer<Expression> index;
+			if (m_scanner->getCurrentToken() != Token::RBrack)
+				index = parseExpression();
 			nodeFactory.markEndPosition();
 			expectToken(Token::RBrack);
 			expression = nodeFactory.createNode<IndexAccess>(expression, index);

grammar.txt

@@ -18,8 +18,9 @@ ParameterList = '(' ( VariableDeclaration (',' VariableDeclaration)* )? ')'
 // semantic restriction: mappings and structs (recursively) containing mappings
 // are not allowed in argument lists
 VariableDeclaration = TypeName Identifier
-TypeName = ElementaryTypeName | Identifier | Mapping
+TypeName = ElementaryTypeName | Identifier | Mapping | ArrayTypeName
 Mapping = 'mapping' '(' ElementaryTypeName '=>' TypeName ')'
+ArrayTypeName = TypeName '[' (Expression)? ']'
 
 Block = '{' Statement* '}'
 Statement = IfStatement | WhileStatement | Block |
@@ -42,5 +43,5 @@ Assignment = Expression (AssignmentOp Expression)
 FunctionCall = Expression '(' Expression ( ',' Expression )* ')'
 NewExpression = 'new' Identifier
 MemberAccess = Expression '.' Identifier
-IndexAccess = Expression '[' Expresison ']'
+IndexAccess = Expression '[' (Expresison)? ']'
 PrimaryExpression = Identifier | NumberLiteral | StringLiteral | ElementaryTypeName | '(' Expression ')'