data: TrackSection thing objects

Sorry this commit is kind of monolithic! It's difficult to
separate out any of the changes since they're all related to
track sections' basic functionality.

2 files changed, 23 insertions, 0 deletions

diff --git a/src/data/composite/things/track-section/index.js b/src/data/composite/things/track-section/index.js
new file mode 100644
index 00000000..3202ed49
--- /dev/null
+++ b/src/data/composite/things/track-section/index.js
@@ -0,0 +1 @@
+export {default as withAlbum} from './withAlbum.js';
diff --git a/src/data/composite/things/track-section/withAlbum.js b/src/data/composite/things/track-section/withAlbum.js
new file mode 100644
index 00000000..608cc0cd
--- /dev/null
+++ b/src/data/composite/things/track-section/withAlbum.js
@@ -0,0 +1,22 @@
+// Gets the track section's album. This will early exit if ownAlbumData is
+// missing. If there's no album whose list of track sections includes this one,
+// the output dependency will be null.
+
+import {input, templateCompositeFrom} from '#composite';
+
+import {withUniqueReferencingThing} from '#composite/wiki-data';
+
+export default templateCompositeFrom({
+  annotation: `withAlbum`,
+
+  outputs: ['#album'],
+
+  steps: () => [
+    withUniqueReferencingThing({
+      data: 'ownAlbumData',
+      list: input.value('trackSections'),
+    }).outputs({
+      ['#uniqueReferencingThing']: '#album',
+    }),
+  ],
+});