Add c-s to pick word under doc cursor to prompt line & search completion (#831)

* Add prompt shourtcut to book
Add completions to search
Add c-s to pick word under doc cursor to prompt line

* limit 20 last items of search completion, update book

* Update book/src/keymap.md

Co-authored-by: Ivan Tham <pickfire@riseup.net>

* limit search completions 200

Co-authored-by: Ivan Tham <pickfire@riseup.net>

2 files changed, 35 insertions, 3 deletions

diff --git a/helix-term/src/ui/mod.rs b/helix-term/src/ui/mod.rs
index 30a9ec6b..24eb7acd 100644
--- a/helix-term/src/ui/mod.rs
+++ b/helix-term/src/ui/mod.rs
@@ -29,6 +29,7 @@ pub fn regex_prompt(
     cx: &mut crate::commands::Context,
     prompt: std::borrow::Cow<'static, str>,
     history_register: Option<char>,
+    completion_fn: impl FnMut(&str) -> Vec<prompt::Completion> + 'static,
     fun: impl Fn(&mut View, &mut Document, Regex, PromptEvent) + 'static,
 ) -> Prompt {
     let (view, doc) = current!(cx.editor);
@@ -38,7 +39,7 @@ pub fn regex_prompt(
     Prompt::new(
         prompt,
         history_register,
-        |_input: &str| Vec::new(), // this is fine because Vec::new() doesn't allocate
+        completion_fn,
         move |cx: &mut crate::compositor::Context, input: &str, event: PromptEvent| {
             match event {
                 PromptEvent::Abort => {
diff --git a/helix-term/src/ui/prompt.rs b/helix-term/src/ui/prompt.rs
index 853adfc2..c999ba14 100644
--- a/helix-term/src/ui/prompt.rs
+++ b/helix-term/src/ui/prompt.rs
@@ -185,6 +185,11 @@ impl Prompt {
         self.exit_selection();
     }
 
+    pub fn insert_str(&mut self, s: &str) {
+        self.line.insert_str(self.cursor, s);
+        self.cursor += s.len();
+    }
+
     pub fn move_cursor(&mut self, movement: Movement) {
         let pos = self.eval_movement(movement);
         self.cursor = pos
@@ -474,6 +479,26 @@ impl Component for Prompt {
                 (self.callback_fn)(cx, &self.line, PromptEvent::Update);
             }
             KeyEvent {
+                code: KeyCode::Char('s'),
+                modifiers: KeyModifiers::CONTROL,
+            } => {
+                let (view, doc) = current!(cx.editor);
+                let text = doc.text().slice(..);
+
+                use helix_core::textobject;
+                let range = textobject::textobject_word(
+                    text,
+                    doc.selection(view.id).primary(),
+                    textobject::TextObject::Inside,
+                    1,
+                );
+                let line = text.slice(range.from()..range.to()).to_string();
+                if !line.is_empty() {
+                    self.insert_str(line.as_str());
+                    (self.callback_fn)(cx, &self.line, PromptEvent::Update);
+                }
+            }
+            KeyEvent {
                 code: KeyCode::Enter,
                 ..
             } => {
@@ -520,11 +545,17 @@ impl Component for Prompt {
             }
             KeyEvent {
                 code: KeyCode::Tab, ..
-            } => self.change_completion_selection(CompletionDirection::Forward),
+            } => {
+                self.change_completion_selection(CompletionDirection::Forward);
+                (self.callback_fn)(cx, &self.line, PromptEvent::Update)
+            }
             KeyEvent {
                 code: KeyCode::BackTab,
                 ..
-            } => self.change_completion_selection(CompletionDirection::Backward),
+            } => {
+                self.change_completion_selection(CompletionDirection::Backward);
+                (self.callback_fn)(cx, &self.line, PromptEvent::Update)
+            }
             KeyEvent {
                 code: KeyCode::Char('q'),
                 modifiers: KeyModifiers::CONTROL,