From 5b57d24afd4e3dec029bc32528d2d6e4dc8a3e64 Mon Sep 17 00:00:00 2001
From: Tim Culverhouse <tim@timculverhouse.com>
Date: Wed, 23 Oct 2024 08:51:01 -0500
Subject: textinput: make completions run async with cancellation

Make the Completer interface accept a context.Context. Provide a
cancellation feature on text input tab completion to cancel an inflight
completion command. This is particularly useful for address book
completion if the user has specified a network-accessing command, eg
carddav-query. The command is started according to the completion delay,
but is cancellable if another request comes in. We also check for
cancellation after the request is complete to ensure we only show valid
completion results.

Changelog-changed: Tab completions for text fields are run
 asynchronously. In-flight requests are cancelled when new input
 arrives.
Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Robin Jarry <robin@jarry.cc>
---
 lib/ui/textinput.go | 54 ++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 17 deletions(-)

(limited to 'lib')

diff --git a/lib/ui/textinput.go b/lib/ui/textinput.go
index d52859b7..08fc2c92 100644
--- a/lib/ui/textinput.go
+++ b/lib/ui/textinput.go
@@ -1,6 +1,7 @@
 package ui
 
 import (
+	"context"
 	"math"
 	"strings"
 	"sync"
@@ -28,7 +29,8 @@ type TextInput struct {
 	text              []vaxis.Character
 	change            []func(ti *TextInput)
 	focusLost         []func(ti *TextInput)
-	tabcomplete       func(s string) ([]opt.Completion, string)
+	tabcomplete       func(ctx context.Context, s string) ([]opt.Completion, string)
+	tabcompleteCancel context.CancelFunc
 	completions       []opt.Completion
 	prefix            string
 	completeIndex     int
@@ -45,10 +47,11 @@ type TextInput struct {
 func NewTextInput(text string, ui *config.UIConfig) *TextInput {
 	chars := vaxis.Characters(text)
 	return &TextInput{
-		cells:    -1,
-		text:     chars,
-		index:    len(chars),
-		uiConfig: ui,
+		cells:             -1,
+		text:              chars,
+		index:             len(chars),
+		uiConfig:          ui,
+		tabcompleteCancel: func() {},
 	}
 }
 
@@ -63,7 +66,7 @@ func (ti *TextInput) Prompt(prompt string) *TextInput {
 }
 
 func (ti *TextInput) TabComplete(
-	tabcomplete func(s string) ([]opt.Completion, string),
+	tabcomplete func(ctx context.Context, s string) ([]opt.Completion, string),
 	d time.Duration, minChars int, key *config.KeyStroke,
 ) *TextInput {
 	ti.tabcomplete = tabcomplete
@@ -342,17 +345,34 @@ func (ti *TextInput) showCompletions(explicit bool) {
 		// no completer
 		return
 	}
-	ti.completions, ti.prefix = ti.tabcomplete(ti.StringLeft())
-
-	if explicit && len(ti.completions) == 1 {
-		// automatically accept if there is only one choice
-		ti.completeIndex = 0
-		ti.executeCompletion()
-		ti.invalidateCompletions()
-	} else {
-		ti.completeIndex = -1
-	}
-	Invalidate()
+	if ti.tabcompleteCancel != nil {
+		// Cancel any inflight completions we currently have
+		ti.tabcompleteCancel()
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	ti.tabcompleteCancel = cancel
+	go func() {
+		defer log.PanicHandler()
+		matches, prefix := ti.tabcomplete(ctx, ti.StringLeft())
+		select {
+		case <-ctx.Done():
+			return
+		default:
+			ti.Lock()
+			defer ti.Unlock()
+			ti.completions = matches
+			ti.prefix = prefix
+			if explicit && len(ti.completions) == 1 {
+				// automatically accept if there is only one choice
+				ti.completeIndex = 0
+				ti.executeCompletion()
+				ti.invalidateCompletions()
+			} else {
+				ti.completeIndex = -1
+			}
+			Invalidate()
+		}
+	}()
 }
 
 func (ti *TextInput) OnChange(onChange func(ti *TextInput)) {
-- 
cgit