/// <summary>
/// The symbol table for the Z# compiler.
/// </summary>
public class Tab
{
    public static readonly Struct
        noType = new Struct(Struct.Kind.None),
        intType = new Struct(Struct.Kind.Int),
        charType = new Struct(Struct.Kind.Char),
        nullType = new Struct(Struct.Kind.Class),
        objType = new Struct(Struct.Kind.Class);

    // Symbol to indicate that an error has occurred in the symbol table
    public static readonly Symbol noSym = new Symbol(Symbol.Kind.Const, "noSymbol", noType);

    public static Symbol chrSym, ordSym, lenSym;

    // current scope
    public static Scope topScope;
    private static Scope universe;

    public static void Init ()
    {
        objType.sysType = typeof(object);

        // TODO

        // set up "universe" (= predefined names)

    }

    public static void OpenScope ()
    {
        // TODO
    }

    public static void CloseScope ()
    {
        // TODO
    }

    public static Symbol Insert (Symbol.Kind kind, string name, Struct type)
    {
        // TODO
        return noSym;
    }

    // Retrieves the Symbol with name from the innermost scope.
    public static Symbol Find (string name)
    {

        // TODO

        // name not found
        Parser.Error("Name not found: '" + name + "'");
        return noSym;
    }

    //  Retrieves the field name from the fields of type.
    public static Symbol FindField (string name, Struct type)
    {

        // TODO

        // name not found
        Parser.Error("Field not found: '" + name + "'");
        return noSym;
    }

    public static void Dump()
    {
        if (universe != null) {
            universe.Dump();
        }
    }
}