private bool ParseLiteralValue(ref ASTNode retn)
{
tokenStream.Save();
// todo if we support bitwise not, add it here
if (tokenStream.Current == ExpressionTokenType.Not && tokenStream.Next == ExpressionTokenType.Boolean)
{
bool value = bool.Parse(tokenStream.Next.value);
retn = ASTNode.BooleanLiteralNode((!value).ToString()).WithLocation(tokenStream.Current);
tokenStream.Advance(2);
return(true);
}
if (tokenStream.Current == ExpressionTokenType.Minus && tokenStream.Next == ExpressionTokenType.Number && (tokenStream.Previous.IsOperator || !tokenStream.HasPrevious))
{
retn = ASTNode.NumericLiteralNode("-" + tokenStream.Next.value).WithLocation(tokenStream.Current);
tokenStream.Advance(2);
return(true);
}
if (tokenStream.Current == ExpressionTokenType.Plus && tokenStream.Next == ExpressionTokenType.Number && (tokenStream.Previous.IsOperator || !tokenStream.HasPrevious))
{
retn = ASTNode.NumericLiteralNode(tokenStream.Next.value).WithLocation(tokenStream.Current);
tokenStream.Advance(2);
return(true);
}
switch (tokenStream.Current.expressionTokenType)
{
case ExpressionTokenType.Null:
retn = ASTNode.NullLiteralNode(tokenStream.Current.value).WithLocation(tokenStream.Current);
break;
case ExpressionTokenType.String:
retn = ASTNode.StringLiteralNode(tokenStream.Current.value).WithLocation(tokenStream.Current);
break;
case ExpressionTokenType.Boolean:
retn = ASTNode.BooleanLiteralNode(tokenStream.Current.value).WithLocation(tokenStream.Current);
break;
case ExpressionTokenType.Number:
retn = ASTNode.NumericLiteralNode(tokenStream.Current.value).WithLocation(tokenStream.Current);
break;
case ExpressionTokenType.Default:
// todo -- allow a type expression a-la default(List<float>);
retn = ASTNode.DefaultLiteralNode(tokenStream.Current.value).WithLocation(tokenStream.Current);
break;
default:
return(false);
}
tokenStream.Advance();
return(true);
}