script: Create structures for TextTrack API

Fill out the basics for the WebIDLs for the following:

  - TextTrack
  - TextTrackCue
  - TextTrackCueList
  - TextTrackList

components/script/dom/texttrack.rs

@@ -0,0 +1,145 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use crate::dom::bindings::codegen::Bindings::TextTrackBinding::{
+    self, TextTrackKind, TextTrackMethods, TextTrackMode,
+};
+use crate::dom::bindings::error::{Error, ErrorResult};
+use crate::dom::bindings::reflector::{reflect_dom_object, DomObject};
+use crate::dom::bindings::root::{DomRoot, MutNullableDom};
+use crate::dom::bindings::str::DOMString;
+use crate::dom::eventtarget::EventTarget;
+use crate::dom::texttrackcue::TextTrackCue;
+use crate::dom::texttrackcuelist::TextTrackCueList;
+use crate::dom::window::Window;
+use dom_struct::dom_struct;
+use std::cell::Cell;
+
+#[dom_struct]
+pub struct TextTrack {
+    eventtarget: EventTarget,
+    kind: TextTrackKind,
+    label: String,
+    language: String,
+    id: String,
+    mode: Cell<TextTrackMode>,
+    cue_list: MutNullableDom<TextTrackCueList>,
+}
+
+impl TextTrack {
+    pub fn new_inherited(
+        id: DOMString,
+        kind: TextTrackKind,
+        label: DOMString,
+        language: DOMString,
+        mode: TextTrackMode,
+    ) -> TextTrack {
+        TextTrack {
+            eventtarget: EventTarget::new_inherited(),
+            kind: kind,
+            label: label.into(),
+            language: language.into(),
+            id: id.into(),
+            mode: Cell::new(mode),
+            cue_list: Default::default(),
+        }
+    }
+
+    pub fn new(
+        window: &Window,
+        id: DOMString,
+        kind: TextTrackKind,
+        label: DOMString,
+        language: DOMString,
+        mode: TextTrackMode,
+    ) -> DomRoot<TextTrack> {
+        reflect_dom_object(
+            Box::new(TextTrack::new_inherited(id, kind, label, language, mode)),
+            window,
+            TextTrackBinding::Wrap,
+        )
+    }
+
+    pub fn get_cues(&self) -> DomRoot<TextTrackCueList> {
+        self.cue_list
+            .or_init(|| TextTrackCueList::new(&self.global().as_window(), &[]))
+    }
+
+    pub fn id(&self) -> &str {
+        &self.id
+    }
+}
+
+impl TextTrackMethods for TextTrack {
+    // https://html.spec.whatwg.org/multipage/#dom-texttrack-kind
+    fn Kind(&self) -> TextTrackKind {
+        self.kind
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-texttrack-label
+    fn Label(&self) -> DOMString {
+        DOMString::from(self.label.clone())
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-texttrack-language
+    fn Language(&self) -> DOMString {
+        DOMString::from(self.language.clone())
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-texttrack-id
+    fn Id(&self) -> DOMString {
+        DOMString::from(self.id.clone())
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-texttrack-mode
+    fn Mode(&self) -> TextTrackMode {
+        self.mode.get()
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-texttrack-mode
+    fn SetMode(&self, value: TextTrackMode) {
+        self.mode.set(value)
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-texttrack-cues
+    fn GetCues(&self) -> Option<DomRoot<TextTrackCueList>> {
+        match self.Mode() {
+            TextTrackMode::Disabled => None,
+            _ => Some(self.get_cues()),
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-texttrack-addcue
+    fn AddCue(&self, cue: &TextTrackCue) -> ErrorResult {
+        // FIXME(#22314, dlrobertson) add Step 1 & 2
+        // Step 3
+        if let Some(old_track) = cue.get_track() {
+            // gecko calls RemoveCue when the given cue
+            // has an associated track, but doesn't return
+            // the error from it, so we wont either.
+            if let Err(_) = old_track.RemoveCue(cue) {
+                warn!("Failed to remove cues for the added cue's text track");
+            }
+        }
+        // Step 4
+        self.get_cues().add(cue);
+        Ok(())
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-texttrack-removecue
+    fn RemoveCue(&self, cue: &TextTrackCue) -> ErrorResult {
+        // Step 1
+        let cues = self.get_cues();
+        let index = match cues.find(cue) {
+            Some(i) => Ok(i),
+            None => Err(Error::NotFound),
+        }?;
+        // Step 2
+        cues.remove(index);
+        Ok(())
+    }
+
+    // https://html.spec.whatwg.org/multipage/#handler-texttrack-oncuechange
+    event_handler!(oncuechange, GetOncuechange, SetOncuechange);
+}