progress

gpx-rs/engine/src/engine/derived/file_structure_cache.rs

@@ -0,0 +1,82 @@
+use std::collections::HashMap;
+
+use crate::{Diff, FileId, FileStructure, StackEntry as Files};
+
+/// The structure of each file, only recomputed for the files that changed according to the
+/// [`Diff`] of the stack.
+#[derive(Debug, Default)]
+pub struct FileStructureCache {
+    map: HashMap<FileId, FileStructure>,
+}
+
+impl FileStructureCache {
+    /// Brings the cache in line with `files`, given what changed since the last update.
+    pub fn update(&mut self, files: Option<&Files>, diff: &Option<Diff>) {
+        if let Some(diff) = diff {
+            for id in diff.removed.iter() {
+                self.map.remove(id);
+            }
+            for id in diff.added.iter().chain(&diff.modified) {
+                if let Some(file) = files.and_then(|files| files.get(id)) {
+                    self.map.insert(*id, FileStructure::new(file));
+                }
+            }
+        }
+    }
+
+    pub fn get(&self, id: &FileId) -> Option<&FileStructure> {
+        self.map.get(id)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::rc::Rc;
+
+    use crate::{Apply, Load, engine::command::fixture::Fixture};
+
+    use super::*;
+
+    #[test]
+    fn test_only_files_of_the_diff_are_recomputed() {
+        let mut fx = Fixture::default();
+        let data = std::fs::read("data/with_tracks_and_segments.gpx").unwrap();
+        Load { data: &data }.apply(&mut fx.state()).unwrap();
+        Load { data: &data }.apply(&mut fx.state()).unwrap();
+        let (a, b) = (fx.order.0[0], fx.order.0[1]);
+
+        let mut cache = FileStructureCache::default();
+        cache.update(
+            Some(&fx.files),
+            &Some(Diff {
+                added: vec![a, b],
+                ..Default::default()
+            }),
+        );
+        let before = cache.get(&b).unwrap() as *const FileStructure;
+
+        let mut file = (*fx.files[&a]).clone();
+        file.info.name = "renamed".into();
+        fx.files.insert(a, Rc::new(file));
+        cache.update(
+            Some(&fx.files),
+            &Some(Diff {
+                modified: vec![a],
+                ..Default::default()
+            }),
+        );
+        assert_eq!(cache.get(&a).unwrap().name, "renamed");
+        assert!(std::ptr::eq(cache.get(&b).unwrap(), before));
+
+        fx.files.remove(&b);
+        cache.update(
+            Some(&fx.files),
+            &Some(Diff {
+                removed: vec![b],
+                ..Default::default()
+            }),
+        );
+        assert!(cache.get(&b).is_none());
+        assert!(cache.get(&a).is_some());
+    }
+}