3 files changed, 78 insertions, 2 deletions
diff --git a/helix-term/src/ui/mod.rs b/helix-term/src/ui/mod.rs
index 107e48dd..5b5924bf 100644
--- a/helix-term/src/ui/mod.rs
+++ b/helix-term/src/ui/mod.rs
@@ -19,7 +19,7 @@ pub use completion::Completion;
 pub use editor::EditorView;
 pub use markdown::Markdown;
 pub use menu::Menu;
-pub use picker::{FileLocation, FilePicker, Picker};
+pub use picker::{DynamicPicker, FileLocation, FilePicker, Picker};
 pub use popup::Popup;
 pub use prompt::{Prompt, PromptEvent};
 pub use spinner::{ProgressSpinners, Spinner};
diff --git a/helix-term/src/ui/overlay.rs b/helix-term/src/ui/overlay.rs
index 0b8a93ae..5b2bc806 100644
--- a/helix-term/src/ui/overlay.rs
+++ b/helix-term/src/ui/overlay.rs
@@ -69,4 +69,8 @@ impl<T: Component + 'static> Component for Overlay<T> {
         let dimensions = (self.calc_child_size)(area);
         self.content.cursor(dimensions, ctx)
     }
+
+    fn id(&self) -> Option<&'static str> {
+        self.content.id()
+    }
 }
diff --git a/helix-term/src/ui/picker.rs b/helix-term/src/ui/picker.rs
index 8b5d20ec..821a282c 100644
--- a/helix-term/src/ui/picker.rs
+++ b/helix-term/src/ui/picker.rs
@@ -3,6 +3,7 @@ use crate::{
     ctrl, key, shift,
     ui::{self, fuzzy_match::FuzzyQuery, EditorView},
 };
+use futures_util::future::BoxFuture;
 use tui::{
     buffer::Buffer as Surface,
     widgets::{Block, BorderType, Borders},
@@ -22,7 +23,7 @@ use helix_view::{
     Document, DocumentId, Editor,
 };
 
-use super::menu::Item;
+use super::{menu::Item, overlay::Overlay};
 
 pub const MIN_AREA_WIDTH_FOR_PREVIEW: u16 = 72;
 /// Biggest file size to preview in bytes
@@ -751,3 +752,74 @@ impl<T: Item + 'static> Component for Picker<T> {
         self.prompt.cursor(area, editor)
     }
 }
+
+/// Returns a new list of options to replace the contents of the picker
+/// when called with the current picker query,
+pub type DynQueryCallback<T> =
+    Box<dyn Fn(String, &mut Editor) -> BoxFuture<'static, anyhow::Result<Vec<T>>>>;
+
+/// A picker that updates its contents via a callback whenever the
+/// query string changes. Useful for live grep, workspace symbols, etc.
+pub struct DynamicPicker<T: ui::menu::Item + Send> {
+    file_picker: FilePicker<T>,
+    query_callback: DynQueryCallback<T>,
+}
+
+impl<T: ui::menu::Item + Send> DynamicPicker<T> {
+    pub const ID: &'static str = "dynamic-picker";
+
+    pub fn new(file_picker: FilePicker<T>, query_callback: DynQueryCallback<T>) -> Self {
+        Self {
+            file_picker,
+            query_callback,
+        }
+    }
+}
+
+impl<T: Item + Send + 'static> Component for DynamicPicker<T> {
+    fn render(&mut self, area: Rect, surface: &mut Surface, cx: &mut Context) {
+        self.file_picker.render(area, surface, cx);
+    }
+
+    fn handle_event(&mut self, event: &Event, cx: &mut Context) -> EventResult {
+        let prev_query = self.file_picker.picker.prompt.line().to_owned();
+        let event_result = self.file_picker.handle_event(event, cx);
+        let current_query = self.file_picker.picker.prompt.line();
+
+        if *current_query == prev_query || matches!(event_result, EventResult::Ignored(_)) {
+            return event_result;
+        }
+
+        let new_options = (self.query_callback)(current_query.to_owned(), cx.editor);
+
+        cx.jobs.callback(async move {
+            let new_options = new_options.await?;
+            let callback =
+                crate::job::Callback::EditorCompositor(Box::new(move |_editor, compositor| {
+                    // Wrapping of pickers in overlay is done outside the picker code,
+                    // so this is fragile and will break if wrapped in some other widget.
+                    let picker = match compositor.find_id::<Overlay<DynamicPicker<T>>>(Self::ID) {
+                        Some(overlay) => &mut overlay.content.file_picker.picker,
+                        None => return,
+                    };
+                    picker.options = new_options;
+                    picker.cursor = 0;
+                    picker.force_score();
+                }));
+            anyhow::Ok(callback)
+        });
+        EventResult::Consumed(None)
+    }
+
+    fn cursor(&self, area: Rect, ctx: &Editor) -> (Option<Position>, CursorKind) {
+        self.file_picker.cursor(area, ctx)
+    }
+
+    fn required_size(&mut self, viewport: (u16, u16)) -> Option<(u16, u16)> {
+        self.file_picker.required_size(viewport)
+    }
+
+    fn id(&self) -> Option<&'static str> {
+        Some(Self::ID)
+    }
+}