Most object types get their own file now

This is hopefully going to make navigating the source tree easier.
Hopefully.

The only types that don't get their own files are:

* function types (UserFunction, BuiltinFunction, Method), which all live
  in obj/function.rs
* Nil, which lives in obj.rs
* Obj, which lives in obj.rs

Type definitions and init_types now live in obj/ty.rs.

New obj::prelude module for common imports.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/obj/macros.rs

@@ -38,13 +38,54 @@ macro_rules! impl_base_obj {
 
 macro_rules! impl_create {
     ($($arg:ident : $ty:ty),* $(,)?) => {
+        // TODO - obj::macros::impl_create - remove this #[allow(dead_code)] designator
+        #[allow(dead_code)]
         pub fn create($($arg : $ty ),*) -> $crate::obj::ObjP {
-            let ptr = make_ptr(Self::new($($arg),*));
+            let ptr = $crate::obj::make_ptr(Self::new($($arg),*));
             ptr.borrow_mut().instantiate();
             ptr
         }
     }
 }
 
+macro_rules! impl_do_call {
+    ($name:ident) => {
+        pub(crate) fn do_call(
+            vm: &mut $crate::vm::Vm,
+            state: $crate::obj::function::FunctionState,
+        ) -> $crate::obj::function::FunctionResult {
+            match state {
+                $crate::obj::function::FunctionState::Begin => {
+                    // get the top item off the stack and call to_float on it
+                    let arg = vm.peek();
+                    let method = if let Some(method) =
+                        arg.borrow().get_vtable_attr(arg.clone(), stringify!($name))
+                    {
+                        method
+                    } else {
+                        // TODO builtins::do_call - throw exception when target doesn't have a
+                        // to_$name method
+                        // BLOCKED-ON: exceptions
+                        todo!(
+                            concat!("{} does not have a ", stringify!($name), " method"),
+                            arg.borrow().ty_name()
+                        );
+                    };
+                    vm.push(method.clone());
+                    method.borrow().call(vm, 0);
+
+                    // resume execution
+                    $crate::obj::function::FunctionResult::Yield(0)
+                }
+                $crate::obj::function::FunctionState::Resume(0) => {
+                    $crate::obj::function::FunctionResult::Return
+                }
+                _ => unreachable!(),
+            }
+        }
+    };
+}
+
 pub(crate) use impl_base_obj;
 pub(crate) use impl_create;
+pub(crate) use impl_do_call;