Implement step back

src/tui/app/app.rs

@@ -109,7 +109,7 @@ pub trait IAppInteractReload {
 pub trait IAppInteractSearch {
     fn append_character(&mut self, ch: char);
     fn search_next(&mut self);
-    fn remove_character(&mut self);
+    fn step_back(&mut self);
     fn finish_search(&mut self);
 }
 
@@ -142,7 +142,8 @@ pub struct App<MH: IMusicHoard> {
     state: AppState<(), (), (), String, String, String>,
     // FIXME: is it possible to use a wrapper struct? - when state() is called return a wrapper
     // around App<MH> which will contain App.
-    memo: Vec<Option<usize>>,
+    orig: Option<usize>,
+    memo: Vec<(Option<usize>, bool)>,
 }
 
 impl<MH: IMusicHoard> App<MH> {
@@ -157,6 +158,7 @@ impl<MH: IMusicHoard> App<MH> {
             music_hoard,
             selection,
             state,
+            orig: None,
             memo: vec![],
         }
     }
@@ -248,7 +250,8 @@ impl<MH: IMusicHoard> IAppInteractBrowse for App<MH> {
         assert!(self.state.is_browse());
         self.state = AppState::Search(String::new());
         // FIXME: this should be the entire selection - not just the artist.
-        self.memo = vec![self.selection.selected_artist()];
+        self.orig = self.selection.selected_artist();
+        self.memo = vec![];
         self.selection
             .reset_artist(self.music_hoard.get_collection());
     }
@@ -298,31 +301,36 @@ impl<MH: IMusicHoard> IAppInteractReloadPrivate for App<MH> {
     }
 }
 
-// FIXME: once `search_next` is added, backspace should step back. If the previous action was
-//        `search_next` then no character should be removed. If the previous action was to append
-//        a character, a character should be removed. When in doubt see how Emacs's isearch works.
 // FIXME: Also add a `cancel_search` which returns to the previous selection.
 impl<MH: IMusicHoard> IAppInteractSearch for App<MH> {
     fn append_character(&mut self, ch: char) {
         let collection = self.music_hoard.get_collection();
         let search = self.state.as_mut().unwrap_search();
         search.push(ch);
-        let prev = self.selection.incremental_artist_search(collection, search, false);
-        self.memo.push(prev);
+        let prev = self
+            .selection
+            .incremental_artist_search(collection, search, false);
+        self.memo.push((prev, true));
     }
 
     fn search_next(&mut self) {
         let collection = self.music_hoard.get_collection();
         let search = self.state.as_mut().unwrap_search();
-        let prev = self.selection.incremental_artist_search(collection, search, true);
-        self.memo.push(prev);
+        if !search.is_empty() {
+            let prev = self
+                .selection
+                .incremental_artist_search(collection, search, true);
+            self.memo.push((prev, false));
+        }
     }
 
-    fn remove_character(&mut self) {
+    fn step_back(&mut self) {
         let collection = self.music_hoard.get_collection();
+        if let Some((prev, pop_char)) = self.memo.pop() {
+            if pop_char {
                 let search = self.state.as_mut().unwrap_search();
-        if search.pop().is_some() {
-            let prev = self.memo.pop().unwrap();
+                search.pop();
+            }
             self.selection.select_artist(collection, prev);
         }
     }

src/tui/app/selection.rs

@@ -110,7 +110,8 @@ impl Selection {
         artist_name: &str,
         next: bool,
     ) -> Option<usize> {
-        self.artist.incremental_search(collection, artist_name, next)
+        self.artist
+            .incremental_search(collection, artist_name, next)
     }
 
     pub fn increment_selection(&mut self, collection: &Collection, delta: Delta) {
@@ -196,9 +197,11 @@ impl ArtistSelection {
         }
     }
 
-    fn select(&mut self, artists: &[Artist], mut to: Option<usize>) {
-        to = to.map(|i| cmp::min(i, artists.len() - 1));
-        self.state.list.select(to);
+    fn select(&mut self, artists: &[Artist], to: Option<usize>) {
+        match to {
+            Some(to) => self.select_to(artists, to),
+            None => self.state.list.select(None),
+        }
     }
 
     fn select_to(&mut self, artists: &[Artist], mut to: usize) {

src/tui/handler.rs

@@ -159,7 +159,7 @@ impl<APP: IAppInteract> IEventHandlerPrivate<APP> for EventHandler {
         match key_event.code {
             // Add/remove character to search.
             KeyCode::Char(ch) => app.append_character(ch),
-            KeyCode::Backspace => app.remove_character(),
+            KeyCode::Backspace => app.step_back(),
             // Return.
             KeyCode::Esc | KeyCode::Enter => app.finish_search(),
             // Othey keys.