Handle prompt completions with AsyncHook.

This change allows prompt completions to be calculated in the
background, to avoid blocking the UI on slow file IO such as over a
networked FS.

Author: Rose Hogenson

helix-term/src/commands.rs

@@ -59,7 +59,10 @@ use crate::{
     compositor::{self, Component, Compositor},
     filter_picker_entry,
     job::Callback,
-    ui::{self, overlay::overlaid, Picker, PickerColumn, Popup, Prompt, PromptEvent},
+    ui::{
+        self, completers::CompletionResult, overlay::overlaid, Picker, PickerColumn, Popup, Prompt,
+        PromptEvent,
+    },
 };
 
 use crate::job::{self, Jobs};
@@ -2183,11 +2186,13 @@ fn searcher(cx: &mut Context, direction: Direction) {
         "search:".into(),
         Some(reg),
         move |_editor: &Editor, input: &str| {
-            completions
-                .iter()
-                .filter(|comp| comp.starts_with(input))
-                .map(|comp| (0.., std::borrow::Cow::Owned(comp.clone())))
-                .collect()
+            CompletionResult::Immediate(
+                completions
+                    .iter()
+                    .filter(|comp| comp.starts_with(input))
+                    .map(|comp| (0.., std::borrow::Cow::Owned(comp.clone())))
+                    .collect(),
+            )
         },
         move |cx, regex, event| {
             if event == PromptEvent::Validate {

helix-term/src/commands/typed.rs

@@ -12,7 +12,7 @@ use helix_core::{line_ending, shellwords::Shellwords};
 use helix_view::document::{read_to_string, DEFAULT_LANGUAGE_NAME};
 use helix_view::editor::{CloseError, ConfigEvent};
 use serde_json::Value;
-use ui::completers::{self, Completer};
+use ui::completers::{self, Completer, CompletionResult};
 
 #[derive(Clone)]
 pub struct TypableCommand {
@@ -3164,14 +3164,16 @@ pub(super) fn command_mode(cx: &mut Context) {
             let words = shellwords.words();
 
             if words.is_empty() || (words.len() == 1 && !shellwords.ends_with_whitespace()) {
-                fuzzy_match(
-                    input,
-                    TYPABLE_COMMAND_LIST.iter().map(|command| command.name),
-                    false,
+                CompletionResult::Immediate(
+                    fuzzy_match(
+                        input,
+                        TYPABLE_COMMAND_LIST.iter().map(|command| command.name),
+                        false,
+                    )
+                    .into_iter()
+                    .map(|(name, _)| (0.., name.into()))
+                    .collect(),
                 )
-                .into_iter()
-                .map(|(name, _)| (0.., name.into()))
-                .collect()
             } else {
                 // Otherwise, use the command's completer and the last shellword
                 // as completion input.
@@ -3187,19 +3189,22 @@ pub(super) fn command_mode(cx: &mut Context) {
                     .get(&words[0] as &str)
                     .map(|tc| tc.completer_for_argument_number(argument_number))
                 {
-                    completer(editor, word)
-                        .into_iter()
-                        .map(|(range, file)| {
-                            let file = shellwords::escape(file);
-
-                            // offset ranges to input
-                            let offset = input.len() - word_len;
-                            let range = (range.start + offset)..;
-                            (range, file)
-                        })
-                        .collect()
+                    let input = String::from(input);
+                    completer(editor, word).map(move |completion| {
+                        completion
+                            .into_iter()
+                            .map(|(range, file)| {
+                                let file = shellwords::escape(file);
+
+                                // offset ranges to input
+                                let offset = input.len() - word_len;
+                                let range = (range.start + offset)..;
+                                (range, file)
+                            })
+                            .collect()
+                    })
                 } else {
-                    Vec::new()
+                    CompletionResult::Immediate(Vec::new())
                 }
             }
         }, // completion