Show file preview in split pane in fuzzy finder (#534)

* Add preview pane for fuzzy finder

* Fix picker preview lag by caching

* Add picker preview for document symbols

* Cache picker preview per document instead of view

* Use line instead of range for preview doc

* Add picker preview for buffer picker

* Fix render bug and refactor picker

* Refactor picker preview rendering

* Split picker and preview and compose

The current selected item is cloned on every event, which is
undesirable

* Refactor out clones in previewed picker

* Retrieve doc from editor if possible in filepicker

* Disable syntax highlight for picker preview

Files already loaded in memory have syntax highlighting enabled

* Ignore directory symlinks in file picker

* Cleanup unnecessary pubs and derives

* Remove unnecessary highlight from file picker

* Reorganize buffer rendering

* Use normal picker for code actions

* Remove unnecessary generics and trait impls

* Remove prepare_for_render and make render mutable

* Skip picker preview if screen small, less padding

1 files changed, 26 insertions, 7 deletions

diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index 2b1b859b..0d118dbc 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -27,7 +27,7 @@ use movement::Movement;
 
 use crate::{
     compositor::{self, Component, Compositor},
-    ui::{self, Picker, Popup, Prompt, PromptEvent},
+    ui::{self, FilePicker, Picker, Popup, Prompt, PromptEvent},
 };
 
 use crate::job::{self, Job, Jobs};
@@ -2212,7 +2212,7 @@ fn file_picker(cx: &mut Context) {
 fn buffer_picker(cx: &mut Context) {
     let current = view!(cx.editor).doc;
 
-    let picker = Picker::new(
+    let picker = FilePicker::new(
         cx.editor
             .documents
             .iter()
@@ -2234,6 +2234,15 @@ fn buffer_picker(cx: &mut Context) {
         |editor: &mut Editor, (id, _path): &(DocumentId, Option<PathBuf>), _action| {
             editor.switch(*id, Action::Replace);
         },
+        |editor, (id, path)| {
+            let doc = &editor.documents.get(*id)?;
+            let &view_id = doc.selections().keys().next()?;
+            let line = doc
+                .selection(view_id)
+                .primary()
+                .cursor_line(doc.text().slice(..));
+            Some((path.clone()?, Some(line)))
+        },
     );
     cx.push_layer(Box::new(picker));
 }
@@ -2287,7 +2296,7 @@ fn symbol_picker(cx: &mut Context) {
                     }
                 };
 
-                let picker = Picker::new(
+                let picker = FilePicker::new(
                     symbols,
                     |symbol| (&symbol.name).into(),
                     move |editor: &mut Editor, symbol, _action| {
@@ -2297,10 +2306,15 @@ fn symbol_picker(cx: &mut Context) {
                         if let Some(range) =
                             lsp_range_to_range(doc.text(), symbol.location.range, offset_encoding)
                         {
-                            doc.set_selection(view.id, Selection::single(range.to(), range.from()));
+                            doc.set_selection(view.id, Selection::single(range.anchor, range.head));
                             align_view(doc, view, Align::Center);
                         }
                     },
+                    move |_editor, symbol| {
+                        let path = symbol.location.uri.to_file_path().unwrap();
+                        let line = Some(symbol.location.range.start.line as usize);
+                        Some((path, line))
+                    },
                 );
                 compositor.push(Box::new(picker))
             }
@@ -2332,6 +2346,7 @@ pub fn code_action(cx: &mut Context) {
               response: Option<lsp::CodeActionResponse>| {
             if let Some(actions) = response {
                 let picker = Picker::new(
+                    true,
                     actions,
                     |action| match action {
                         lsp::CodeActionOrCommand::CodeAction(action) => {
@@ -2703,7 +2718,7 @@ fn goto_impl(
             editor.set_error("No definition found.".to_string());
         }
         _locations => {
-            let picker = ui::Picker::new(
+            let picker = FilePicker::new(
                 locations,
                 move |location| {
                     let file: Cow<'_, str> = (location.uri.scheme() == "file")
@@ -2728,6 +2743,11 @@ fn goto_impl(
                 move |editor: &mut Editor, location, action| {
                     jump_to(editor, location, offset_encoding, action)
                 },
+                |_editor, location| {
+                    let path = location.uri.to_file_path().unwrap();
+                    let line = Some(location.range.start.line as usize);
+                    Some((path, line))
+                },
             );
             compositor.push(Box::new(picker));
         }
@@ -3729,8 +3749,7 @@ fn keep_primary_selection(cx: &mut Context) {
     let (view, doc) = current!(cx.editor);
 
     let range = doc.selection(view.id).primary();
-    let selection = Selection::single(range.anchor, range.head);
-    doc.set_selection(view.id, selection);
+    doc.set_selection(view.id, Selection::single(range.anchor, range.head));
 }
 
 fn completion(cx: &mut Context) {