/// <summary>
/// Reads an S-expression from the input source
/// </summary>
public static object Read(InPort port)
{
Func <object, object> readAhead = null;
readAhead = token =>
{
Symbol quote;
if (object.Equals(token, Symbol.EOF))
{
throw new SyntaxError("unexpected EOF");
}
else if (token is string)
{
string tokenStr = (string)token;
if (tokenStr == "(")
{
var L = new List <object>();
while (true)
{
token = port.NextToken();
if (token is string && (string)token == ")")
{
return(L);
}
else
{
L.Add(readAhead(token));
}
}
}
else if (tokenStr == ")")
{
throw new SyntaxError("unexpected )");
}
else if (Symbol.QuotesMap.TryGetValue(tokenStr, out quote))
{
object quoted = Read(port);
return(new List <object> {
quote, quoted
});
}
else
{
return(ParseAtom(tokenStr));
}
}
else
{
throw new SyntaxError("unexpected token: " + token);
}
};
var token1 = port.NextToken();
return(Symbol.EOF.Equals(token1) ? Symbol.EOF : readAhead(token1));
}
