Functions now store their base clip (the code that contains the
executing bytecode). This is because `GotoFrame` and other actions
will execute on the clip the bytecode exists on, not on `this`.
(Note that `this.gotoAndStop` uses `GetMember` actions, which
worked correctly).
`Activation` now stores `target_clip`, and `Avm1::target_clip` and
`target_clip_or_root` grab this from the current stack frame.
Renamed `start_clip` to `base_clip` to match Flash conventions.
Removed `active_clip` as this was superfluous. Now you can use
`Avm1::target_clip_or_root`.
`UpdateContext` no longer contains `target_clip` etc.
Note that host objects that do so will *not* have access to their standard representation from within member functions - you will need to extend the interface to accomodate for them. This is due to long-standing limitations with type IDs and downcasting with types that bear lifetimes - it's entirely an unsafe operation and exposing such a facility to safe Rust is unsound. However, this will at least let us separate out several things from ScriptObject that don't need to be there for the time being.
This type explicitly signals if an immediate value is to be returned, if a value is to be returned on the stack, or if no return value is to be generated. Holders of a `ReturnValue` can also use `and_then` to schedule a `StackContinuation` to be executed when and if that value is ready.
`StackContinuations` now yield `ReturnValues` as well, so they have a moderate level of composability. For example, if you need to get a property from an object and push it on the stack, you can return the result of calling `get` directly and the machinery ensures it eventually gets there.
This involved yet another macro, `and_then!`, to avoid a ridiculous amount of duplicate code. It calls a continuation whenever it's value is ready, even if the value resolved on the Rust stack.
`locals_into_form_values` does not currently support this. It skips any property that does not resolve on the Rust stack. Future work is required to resolve this.
This involves the use of a "stack continuation" system. Due to previous lifetime issues with using closures directly (see `8ea6c6234dba925ec5fbc61502627fb62b05916c`), we instead use a macro that constructs a `Collect`able type holding the things the continuation needs to continue working with. The syntax is largely similar to Rust closures but with the addition of an explicit list of bound variables, all of which must be `Collect`.
This has the side effect of letting us remove the `Option` on register_count since setting this to `0` is equivalent now. Furthermore, we can skip an allocation if a function requests no registers.
On SWF5, the SWF version of the callee depends on it's this parameter. Calling it as a function rather than a method downgrades the callee. SWF6+ use the callee's inherent SWF version and do not allow changing the SWF version like this.
* Remove clone calls from Copy objects
* Used Iterator::cloned() instead of manually cloning
* Pass swf::Function into AvmFunction2::new()
* Use action_clone_sprite
1. We no longer implicitly return Undefined unless we're specifically returning from a function (this also keeps actions from filling the stack with Undefined)
2. With scopes are now always inserted behind the current set of locals rather than overriding them
3. `ActionSubtract` now subtracts (instead of adds)
Mike Welsh