support prefilling prompt (helix-editor#2459)

* support prefilling prompt

* introduce with_line builder method in Prompt

* extract show_prompt

* use textobject_word as fallback input

helix-term/src/commands/lsp.rs

@@ -885,9 +885,21 @@ pub fn hover(cx: &mut Context) {
 }
 
 pub fn rename_symbol(cx: &mut Context) {
-    ui::prompt(
+    let (view, doc) = current_ref!(cx.editor);
+    let text = doc.text().slice(..);
+    let primary_selection = doc.selection(view.id).primary();
+    let prefill = if primary_selection.len() > 1 {
+        primary_selection
+    } else {
+        use helix_core::textobject::{textobject_word, TextObject};
+        textobject_word(text, primary_selection, TextObject::Inside, 1, false)
+    }
+    .fragment(text)
+    .into();
+    ui::prompt_with_input(
         cx,
         "rename-to:".into(),
+        prefill,
         None,
         ui::completers::none,
         move |cx: &mut compositor::Context, input: &str, event: PromptEvent| {

helix-term/src/ui/mod.rs

@@ -34,7 +34,27 @@ pub fn prompt(
     completion_fn: impl FnMut(&Editor, &str) -> Vec<prompt::Completion> + 'static,
     callback_fn: impl FnMut(&mut crate::compositor::Context, &str, PromptEvent) + 'static,
 ) {
-    let mut prompt = Prompt::new(prompt, history_register, completion_fn, callback_fn);
+    show_prompt(
+        cx,
+        Prompt::new(prompt, history_register, completion_fn, callback_fn),
+    );
+}
+
+pub fn prompt_with_input(
+    cx: &mut crate::commands::Context,
+    prompt: std::borrow::Cow<'static, str>,
+    input: String,
+    history_register: Option<char>,
+    completion_fn: impl FnMut(&Editor, &str) -> Vec<prompt::Completion> + 'static,
+    callback_fn: impl FnMut(&mut crate::compositor::Context, &str, PromptEvent) + 'static,
+) {
+    show_prompt(
+        cx,
+        Prompt::new(prompt, history_register, completion_fn, callback_fn).with_line(input),
+    );
+}
+
+fn show_prompt(cx: &mut crate::commands::Context, mut prompt: Prompt) {
     // Calculate initial completion
     prompt.recalculate_completion(cx.editor);
     cx.push_layer(Box::new(prompt));

helix-term/src/ui/prompt.rs

@@ -84,6 +84,13 @@ impl Prompt {
         }
     }
 
+    pub fn with_line(mut self, line: String) -> Self {
+        let cursor = line.len();
+        self.line = line;
+        self.cursor = cursor;
+        self
+    }
+
     pub fn line(&self) -> &String {
         &self.line
     }