tabs: optimize switching by offsets

I imagine no sane user requires aerc to correctly handle commands like
`:next-tab 1000000000`, but I tried anyway and it froze aerc while
also eating up many GBs of system memory. This behavior is not ideal,
so I improved it.

This commit adds functions for selecting a tab at an offset from the
currently-selected tab and changes the next-tab, prev-tab, and
change-tab commands to use these functions instead of looping.

Signed-off-by: delitako <delitako@delitako.xyz>
Tested-by: Thomas Böhler <witcher@wiredspace.de>
Reviewed-by: Thomas Böhler <witcher@wiredspace.de>
Acked-by: Robin Jarry <robin@jarry.cc>

2 files changed, 13 insertions, 18 deletions

diff --git a/commands/ct.go b/commands/ct.go
index 1f99c6a5..4f908fcf 100644
--- a/commands/ct.go
+++ b/commands/ct.go
@@ -37,20 +37,12 @@ func (c ChangeTab) Execute(args []string) error {
 	} else {
 		n, err := strconv.Atoi(c.Tab)
 		if err == nil {
-			switch {
-			case strings.HasPrefix(c.Tab, "+"):
-				for ; n > 0; n-- {
-					app.NextTab()
-				}
-			case strings.HasPrefix(c.Tab, "-"):
-				for ; n < 0; n++ {
-					app.PrevTab()
-				}
-			default:
+			if strings.HasPrefix(c.Tab, "+") || strings.HasPrefix(c.Tab, "-") {
+				app.SelectTabAtOffset(n)
+			} else {
 				ok := app.SelectTabIndex(n)
 				if !ok {
-					return errors.New(
-						"No tab with that index")
+					return errors.New("No tab with that index")
 				}
 			}
 		} else {
diff --git a/commands/next-tab.go b/commands/next-tab.go
index adab95ae..12f659c9 100644
--- a/commands/next-tab.go
+++ b/commands/next-tab.go
@@ -21,13 +21,16 @@ func (NextPrevTab) Aliases() []string {
 }
 
 func (np NextPrevTab) Execute(args []string) error {
-	for n := 0; n < np.Offset; n++ {
-		if args[0] == "prev-tab" {
-			app.PrevTab()
-		} else {
-			app.NextTab()
-		}
+	if np.Offset <= 0 {
+		return nil
 	}
+
+	offset := np.Offset
+	if args[0] == "prev-tab" {
+		offset *= -1
+	}
+
+	app.SelectTabAtOffset(offset)
 	app.UpdateStatus()
 	return nil
 }