private AstItem ReadEnumDecl(TokenIterator tokens)
{
//Skip "enum"
tokens.Pop();
var enumName = tokens.PopExpected(TokenKind.Word).Value;
tokens.PopExpected(TokenKind.CurlyBracketOpen);
var currentIndex = 0;
var elements = new List <AstItem>();
var current = tokens.Current();
while (current.Kind != TokenKind.CurlyBracketClose)
{
var elementName = tokens.PopExpected(TokenKind.Word).Value;
var next = tokens.Pop();
switch (next.Kind)
{
case TokenKind.AssigmnentOperator:
var indexStr = tokens.PopExpected(TokenKind.Number).Value;
var index = int.Parse(indexStr);
if (index < currentIndex)
{
throw new Exception("Invalid enum element index for " + enumName + "." + elementName + "! Must be >= " + currentIndex);
}
currentIndex = index;
next = tokens.PopExpected(TokenKind.Comma, TokenKind.CurlyBracketClose);
break;
case TokenKind.Comma:
case TokenKind.CurlyBracketClose:
//Nothing to do here, but also no error
break;
default:
throw new Exception("Unexpected token in enum declaration: " + next);
}
elements.Add(AstItem.EnumElement(elementName, currentIndex));
currentIndex += 1;
current = next;
}
return(AstItem.EnumDecl(enumName, elements));
}