core: Implement _target property

Add DisplayObject::slash_path to get the Flash 4-style slash path
to the clip. This fixes the tellTarget regression test and removes
the superfluous `target_path` from `UpdateContext`.

core/src/avm1.rs

@@ -1707,13 +1707,11 @@ impl<'gc> Avm1<'gc> {
         if target.is_empty() {
             context.active_clip = context.start_clip;
             context.target_clip = Some(context.start_clip);
-            context.target_path = target.into();
         } else if let Some(clip) =
             Avm1::resolve_slash_path(context.start_clip, context.root, target)
         {
             context.target_clip = Some(clip);
             context.active_clip = clip;
-            context.target_path = target.into();
         } else {
             log::warn!("SetTarget failed: {} not found", target);
             // TODO: Emulate AVM1 trace error message.
@@ -1724,7 +1722,6 @@ impl<'gc> Avm1<'gc> {
             // fail silenty.
             context.target_clip = None;
             context.active_clip = context.root;
-            context.target_path = Value::Undefined;
         }
 
         let scope = self.current_stack_frame().unwrap().read().scope_cell();

core/src/avm1/script_object.rs

@@ -436,7 +436,6 @@ mod tests {
                 start_clip: root,
                 active_clip: root,
                 target_clip: Some(root),
-                target_path: Value::Undefined,
                 rng: &mut SmallRng::from_seed([0u8; 16]),
                 action_queue: &mut crate::context::ActionQueue::new(),
                 audio: &mut NullAudioBackend::new(),

core/src/avm1/stage_object.rs

@@ -575,10 +575,9 @@ fn set_rotation<'gc>(
 fn target<'gc>(
     _avm: &mut Avm1<'gc>,
     _context: &mut UpdateContext<'_, 'gc, '_>,
-    _this: DisplayObject<'gc>,
+    this: DisplayObject<'gc>,
 ) -> Result<Value<'gc>, Error> {
-    log::warn!("Unimplemented property _target");
-    Ok("".into())
+    Ok(this.slash_path().into())
 }
 
 fn frames_loaded<'gc>(

core/src/avm1/test_utils.rs

@@ -1,5 +1,5 @@
 use crate::avm1::activation::Activation;
-use crate::avm1::{Avm1, Object, UpdateContext, Value};
+use crate::avm1::{Avm1, Object, UpdateContext};
 use crate::backend::audio::NullAudioBackend;
 use crate::backend::navigator::NullNavigatorBackend;
 use crate::backend::render::NullRenderer;
@@ -32,7 +32,6 @@ where
             start_clip: root,
             active_clip: root,
             target_clip: Some(root),
-            target_path: Value::Undefined,
             rng: &mut SmallRng::from_seed([0u8; 16]),
             audio: &mut NullAudioBackend::new(),
             action_queue: &mut ActionQueue::new(),

core/src/context.rs

@@ -77,13 +77,6 @@ pub struct UpdateContext<'a, 'gc, 'gc_context> {
     /// `target_clip` will reset to this value with `SetTarget ""` action.
     pub start_clip: DisplayObject<'gc>,
 
-    /// The last path string used by `tellTarget`.
-    /// Returned by `GetProperty`.
-    /// TODO: This should actually be built dynamically upon
-    /// request, but this requires us to implement auto-generated
-    /// _names ("instanceN" etc. for unnamed clips).
-    pub target_path: avm1::Value<'gc>,
-
     /// The current set of system-specified prototypes to use when constructing
     /// new built-in objects.
     pub system_prototypes: avm1::SystemPrototypes<'gc>,

core/src/display_object.rs

@@ -521,6 +521,7 @@ pub trait TDisplayObject<'gc>: 'gc + Collect + Debug {
     fn set_alpha(&self, gc_context: MutationContext<'gc, '_>, value: f64);
     fn name(&self) -> Ref<str>;
     fn set_name(&mut self, context: MutationContext<'gc, '_>, name: &str);
+
     /// Returns the dot-syntax path to this display object, e.g. `_level0.foo.clip`
     fn path(&self) -> String {
         if let Some(parent) = self.parent() {
@@ -532,6 +533,21 @@ pub trait TDisplayObject<'gc>: 'gc + Collect + Debug {
             self.name().to_string()
         }
     }
+
+    /// Returns the Flash 4 slash-syntax path to this display object, e.g. `/foo/clip`.
+    /// Returned by the `_target` property in AVM1.
+    fn slash_path(&self) -> String {
+        if let Some(parent) = self.parent() {
+            let mut path = parent.slash_path();
+            path.push_str("/");
+            path.push_str(&*self.name());
+            path
+        } else {
+            // The stage/root levels do not append their name in slash syntax.
+            "".to_string()
+        }
+    }
+
     fn clip_depth(&self) -> Depth;
     fn set_clip_depth(&mut self, context: MutationContext<'gc, '_>, depth: Depth);
     fn parent(&self) -> Option<DisplayObject<'gc>>;

core/src/player.rs

@@ -1,4 +1,4 @@
-use crate::avm1::{Avm1, Value};
+use crate::avm1::Avm1;
 use crate::backend::{
     audio::AudioBackend, navigator::NavigatorBackend, render::Letterbox, render::RenderBackend,
 };
@@ -594,7 +594,6 @@ impl<Audio: AudioBackend, Renderer: RenderBackend, Navigator: NavigatorBackend>
                 start_clip: root,
                 target_clip: Some(root),
                 root,
-                target_path: Value::Undefined,
                 system_prototypes: avm.prototypes().clone(),
                 mouse_hovered_object,
             };