Make file preview callback optional

When Picker and FilePicker are merged, not all Pickers will be able to
show a preview.

Co-authored-by: Gokul Soumya <gokulps15@gmail.com>

helix-term/src/commands.rs

@@ -2184,11 +2184,9 @@ fn global_search(cx: &mut Context) {
 
                         doc.set_selection(view.id, Selection::single(start, end));
                         align_view(doc, view, Align::Center);
-                    },
-                    |_editor, FileResult { path, line_num }| {
+                    }).with_preview(|_editor, FileResult { path, line_num }| {
                         Some((path.clone().into(), Some((*line_num, *line_num))))
-                    },
-                );
+                    });
                 compositor.push(Box::new(overlaid(picker)));
             },
         ));
@@ -2579,13 +2577,10 @@ fn buffer_picker(cx: &mut Context) {
     // mru
     items.sort_unstable_by_key(|item| std::cmp::Reverse(item.focused_at));
 
-    let picker = FilePicker::new(
-        items,
-        (),
-        |cx, meta, action| {
+    let picker = FilePicker::new(items, (), |cx, meta, action| {
         cx.editor.switch(meta.id, action);
-        },
-        |editor, meta| {
+    })
+    .with_preview(|editor, meta| {
         let doc = &editor.documents.get(&meta.id)?;
         let &view_id = doc.selections().keys().next()?;
         let line = doc
@@ -2593,8 +2588,7 @@ fn buffer_picker(cx: &mut Context) {
             .primary()
             .cursor_line(doc.text().slice(..));
         Some((meta.id.into(), Some((line, line))))
-        },
-    );
+    });
     cx.push_layer(Box::new(overlaid(picker)));
 }
 
@@ -2678,12 +2672,12 @@ fn jumplist_picker(cx: &mut Context) {
             doc.set_selection(view.id, meta.selection.clone());
             view.ensure_cursor_in_view_center(doc, config.scrolloff);
         },
-        |editor, meta| {
+    )
+    .with_preview(|editor, meta| {
         let doc = &editor.documents.get(&meta.id)?;
         let line = meta.selection.primary().cursor_line(doc.text().slice(..));
         Some((meta.id.into(), Some((line, line))))
-        },
-    );
+    });
     cx.push_layer(Box::new(overlaid(picker)));
 }
 

helix-term/src/commands/dap.rs

@@ -73,11 +73,10 @@ fn thread_picker(
             let debugger = debugger!(editor);
 
             let thread_states = debugger.thread_states.clone();
-            let picker = FilePicker::new(
-                threads,
-                thread_states,
-                move |cx, thread, _action| callback_fn(cx.editor, thread),
-                move |editor, thread| {
+            let picker = FilePicker::new(threads, thread_states, move |cx, thread, _action| {
+                callback_fn(cx.editor, thread)
+            })
+            .with_preview(move |editor, thread| {
                 let frames = editor.debugger.as_ref()?.stack_frames.get(&thread.id)?;
                 let frame = frames.get(0)?;
                 let path = frame.source.as_ref()?.path.clone()?;
@@ -86,8 +85,7 @@ fn thread_picker(
                     frame.end_line.unwrap_or(frame.line).saturating_sub(1),
                 ));
                 Some((path.into(), pos))
-                },
-            );
+            });
             compositor.push(Box::new(picker));
         },
     );
@@ -728,10 +726,7 @@ pub fn dap_switch_stack_frame(cx: &mut Context) {
 
     let frames = debugger.stack_frames[&thread_id].clone();
 
-    let picker = FilePicker::new(
-        frames,
-        (),
-        move |cx, frame, _action| {
+    let picker = FilePicker::new(frames, (), move |cx, frame, _action| {
         let debugger = debugger!(cx.editor);
         // TODO: this should be simpler to find
         let pos = debugger.stack_frames[&thread_id]
@@ -745,8 +740,8 @@ pub fn dap_switch_stack_frame(cx: &mut Context) {
         if let Some(frame) = &frame {
             jump_to_stack_frame(cx.editor, frame);
         }
-        },
-        move |_editor, frame| {
+    })
+    .with_preview(move |_editor, frame| {
         frame
             .source
             .as_ref()
@@ -760,7 +755,6 @@ pub fn dap_switch_stack_frame(cx: &mut Context) {
                     )),
                 )
             })
-        },
-    );
+    });
     cx.push_layer(Box::new(picker))
 }

helix-term/src/commands/lsp.rs

@@ -240,10 +240,7 @@ type SymbolPicker = FilePicker<SymbolInformationItem>;
 
 fn sym_picker(symbols: Vec<SymbolInformationItem>, current_path: Option<lsp::Url>) -> SymbolPicker {
     // TODO: drop current_path comparison and instead use workspace: bool flag?
-    FilePicker::new(
-        symbols,
-        current_path.clone(),
-        move |cx, item, action| {
+    FilePicker::new(symbols, current_path.clone(), move |cx, item, action| {
         let (view, doc) = current!(cx.editor);
         push_jump(view, doc);
 
@@ -275,9 +272,8 @@ fn sym_picker(symbols: Vec<SymbolInformationItem>, current_path: Option<lsp::Url
             doc.set_selection(view.id, Selection::single(range.head, range.anchor));
             align_view(doc, view, Align::Center);
         }
-        },
-        move |_editor, item| Some(location_to_file_location(&item.symbol.location)),
-    )
+    })
+    .with_preview(move |_editor, item| Some(location_to_file_location(&item.symbol.location)))
     .truncate_start(false)
 }
 
@@ -345,11 +341,11 @@ fn diag_picker(
                 align_view(doc, view, Align::Center);
             }
         },
-        move |_editor, PickerDiagnostic { url, diag, .. }| {
+    )
+    .with_preview(move |_editor, PickerDiagnostic { url, diag, .. }| {
         let location = lsp::Location::new(url.clone(), diag.range);
         Some(location_to_file_location(&location))
-        },
-    )
+    })
     .truncate_start(false)
 }
 
@@ -1047,14 +1043,10 @@ fn goto_impl(
             editor.set_error("No definition found.");
         }
         _locations => {
-            let picker = FilePicker::new(
-                locations,
-                cwdir,
-                move |cx, location, action| {
+            let picker = FilePicker::new(locations, cwdir, move |cx, location, action| {
                 jump_to_location(cx.editor, location, offset_encoding, action)
-                },
-                move |_editor, location| Some(location_to_file_location(location)),
-            );
+            })
+            .with_preview(move |_editor, location| Some(location_to_file_location(location)));
             compositor.push(Box::new(overlaid(picker)));
         }
     }

helix-term/src/ui/mod.rs

@@ -217,10 +217,7 @@ pub fn file_picker(root: PathBuf, config: &helix_view::editor::Config) -> FilePi
 
     log::debug!("file_picker init {:?}", Instant::now().duration_since(now));
 
-    FilePicker::new(
-        files,
-        root,
-        move |cx, path: &PathBuf, action| {
+    FilePicker::new(files, root, move |cx, path: &PathBuf, action| {
         if let Err(e) = cx.editor.open(path, action) {
             let err = if let Some(err) = e.source() {
                 format!("{}", err)
@@ -229,9 +226,8 @@ pub fn file_picker(root: PathBuf, config: &helix_view::editor::Config) -> FilePi
             };
             cx.editor.set_error(err);
         }
-        },
-        |_editor, path| Some((path.clone().into(), None)),
-    )
+    })
+    .with_preview(|_editor, path| Some((path.clone().into(), None)))
 }
 
 pub mod completers {

helix-term/src/ui/picker.rs

@@ -141,7 +141,7 @@ pub struct FilePicker<T: Item> {
     preview_cache: HashMap<PathBuf, CachedPreview>,
     read_buffer: Vec<u8>,
     /// Given an item in the picker, return the file path and line number to display.
-    file_fn: FileCallback<T>,
+    file_fn: Option<FileCallback<T>>,
 }
 
 impl<T: Item + 'static> FilePicker<T> {
@@ -149,7 +149,6 @@ impl<T: Item + 'static> FilePicker<T> {
         options: Vec<T>,
         editor_data: T::Data,
         callback_fn: impl Fn(&mut Context, &T, Action) + 'static,
-        preview_fn: impl Fn(&Editor, &T) -> Option<FileLocation> + 'static,
     ) -> Self {
         let prompt = Prompt::new(
             "".into(),
@@ -173,7 +172,7 @@ impl<T: Item + 'static> FilePicker<T> {
             widths: Vec::new(),
             preview_cache: HashMap::new(),
             read_buffer: Vec::with_capacity(1024),
-            file_fn: Box::new(preview_fn),
+            file_fn: None,
 
             picker: unimplemented!(),
         };
@@ -202,6 +201,14 @@ impl<T: Item + 'static> FilePicker<T> {
         self
     }
 
+    pub fn with_preview(
+        mut self,
+        preview_fn: impl Fn(&Editor, &T) -> Option<FileLocation> + 'static,
+    ) -> Self {
+        self.file_fn = Some(Box::new(preview_fn));
+        self
+    }
+
     pub fn set_options(&mut self, new_options: Vec<T>) {
         self.options = new_options;
         self.cursor = 0;
@@ -372,7 +379,7 @@ impl<T: Item + 'static> FilePicker<T> {
     fn current_file(&self, editor: &Editor) -> Option<FileLocation> {
         self.picker
             .selection()
-            .and_then(|current| (self.file_fn)(editor, current))
+            .and_then(|current| (self.file_fn.as_ref()?)(editor, current))
             .and_then(|(path_or_id, line)| path_or_id.get_canonicalized().ok().zip(Some(line)))
     }