store: reverse message list order with iterators

Reverse the order of the messages in the message list. The complexity of
reversing the order is abstracted away by the iterators. To reverse the
message list, add the following to your aerc.conf:

[ui]
reverse-msglist-order=true

Thanks to |cos| for sharing his initial implementation of reversing the
order in the message list [0].

[0]: https://git.netizen.se/aerc/commit/?h=topic/asc_sort_imap

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 16 insertions, 10 deletions

diff --git a/lib/threadbuilder.go b/lib/threadbuilder.go
index 6cd98e87..75a80797 100644
--- a/lib/threadbuilder.go
+++ b/lib/threadbuilder.go
@@ -4,6 +4,7 @@ import (
 	"sync"
 	"time"
 
+	"git.sr.ht/~rjarry/aerc/lib/iterator"
 	"git.sr.ht/~rjarry/aerc/logging"
 	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/worker/types"
@@ -16,13 +17,15 @@ type ThreadBuilder struct {
 	messageidToUid map[string]uint32
 	seen           map[uint32]bool
 	threadedUids   []uint32
+	iterFactory    iterator.Factory
 }
 
-func NewThreadBuilder() *ThreadBuilder {
+func NewThreadBuilder(i iterator.Factory) *ThreadBuilder {
 	tb := &ThreadBuilder{
 		threadBlocks:   make(map[uint32]jwz.Threadable),
 		messageidToUid: make(map[string]uint32),
 		seen:           make(map[uint32]bool),
+		iterFactory:    i,
 	}
 	return tb
 }
@@ -154,17 +157,20 @@ func (builder *ThreadBuilder) sortThreads(threads []*types.Thread, orderedUids [
 // RebuildUids rebuilds the uids from the given slice of threads
 func (builder *ThreadBuilder) RebuildUids(threads []*types.Thread) {
 	uids := make([]uint32, 0, len(threads))
-	for i := len(threads) - 1; i >= 0; i-- {
-		_ = threads[i].Walk(func(t *types.Thread, level int, currentErr error) error {
-			uids = append(uids, t.Uid)
-			return nil
-		})
+	iterT := builder.iterFactory.NewIterator(threads)
+	for iterT.Next() {
+		_ = iterT.Value().(*types.Thread).Walk(
+			func(t *types.Thread, level int, currentErr error) error {
+				uids = append(uids, t.Uid)
+				return nil
+			})
 	}
-	// copy in reverse as msgList displays backwards
-	for i, j := 0, len(uids)-1; i < j; i, j = i+1, j-1 {
-		uids[i], uids[j] = uids[j], uids[i]
+	result := make([]uint32, 0, len(uids))
+	iterU := builder.iterFactory.NewIterator(uids)
+	for iterU.Next() {
+		result = append(result, iterU.Value().(uint32))
 	}
-	builder.threadedUids = uids
+	builder.threadedUids = result
 }
 
 // threadable implements the jwz.threadable interface which is required for the