ContractDefinition = 'contract' Identifier '{' ContractPart* '}'
ContractPart = VariableDeclaration ';' | StructDefinition |
               FunctionDefinition | 'public:' | 'private:'

StructDefinition = 'struct' Identifier '{'
                     ( VariableDeclaration (';' VariableDeclaration)* )? '}

FunctionDefinition = 'function' Identifier ParameterList 'const'?
                     ( 'returns' ParameterList )? Block
ParameterList = '(' ( VariableDeclaration (',' VariableDeclaration)* )? ')'
// semantic restriction: mappings and structs (recursively) containing mappings
// are not allowed in argument lists
VariableDeclaration = TypeName Identifier
TypeName = ElementaryTypeName | Identifier | Mapping
Mapping = 'mapping' '(' ElementaryTypeName '=>' TypeName ')'

Block = '{' Statement* '}'
Statement = IfStatement | WhileStatement | Block |
			( Continue | Break | Return | VariableDefinition | Expression ) ';'

IfStatement = 'if' '(' Expression ')' Statement ( 'else' Statement )?
WhileStatement = 'while' '(' Expression ')' Statement
Continue = 'continue' ';'
Break = 'break' ';'
Return = 'return' Expression? ';'
VariableDefinition = VariableDeclaration ( = Expression )? ';'

Expression = Assignment | UnaryOperation | BinaryOperation | FunctionCall | NewExpression | IndexAccess |
			 MemberAccess | PrimaryExpression
// The expression syntax is actually much more complicated
Assignment = Expression (AssignmentOp Expression)
FunctionCall = Expression '(' Expression ( ',' Expression )* ')'
NewExpression = 'new' Identifier '(' ( Expression ( ',' Expression )* ) ')'
MemberAccess = Expression '.' Identifier
IndexAccess = Expression '[' Expresison ']'
PrimaryExpression = Identifier | NumberLiteral | StringLiteral | ElementaryTypeName | '(' Expression ')'