//class-dec ::= 'class' <class-name> '{' <class-var-dec>* <sub-dec>* '}'
private void ParseClass()
{
Match(new Token(TokenType.Keyword, "class"));
Token className = NextToken();
if (className == null)
{
Expected("class name");
}
if (className.Type != TokenType.Ident)
{
Expected("identifier");
}
_currentClassName = className.Value;
_codeGenerator.BeginClass(className.Value);
Match(new Token(TokenType.Symbol, "{"));
ParseClassVarDecls();
ParseSubDecls();
Match(new Token(TokenType.Symbol, "}"));
_codeGenerator.EndClass();
_currentClassName = String.Empty;
_classSymTable.Clear();
}
private void ParseSubDecl()
{
Contract.Requires(IsNextTokenSubDecl());
Token subKind = NextToken();
Token returnType = NextToken();
Token subName = NextToken();
if (subKind.Type != TokenType.Keyword ||
!new[] { "constructor", "method", "function" }.Contains(subKind.Value))
{
ThrowCompilationException("Expected: 'constructor', 'method', or 'function', but got: " + subKind.Value);
}
if (returnType.Type != TokenType.Keyword &&
returnType.Type != TokenType.Ident)
{
ThrowCompilationException("Invalid return type '" + returnType.Value + "'");
}
if (subName.Type != TokenType.Ident)
{
ThrowCompilationException("Invalid subroutine name '" + subName.Value + "'");
}
_currentSub = new Subroutine(
(SubroutineKind)Enum.Parse(typeof(SubroutineKind), subKind.Value, ignoreCase: true),
_currentClassName, subName.Value, returnType.Value);
if (_currentSub.Kind == SubroutineKind.Constructor &&
_currentSub.ReturnType != _currentClassName)
{
ThrowCompilationException("Constructor must return '" + _currentClassName + "'");
}
Match(new Token(TokenType.Symbol, "("));
ParseFormalParamList();
Match(new Token(TokenType.Symbol, ")"));
//NOTE: We notify the code generator of the new subroutine only
//after we have its local variable declarations.
ParseSubBody();
_currentSub = null;
_methodSymTable.Clear();
}