Merge remote-tracking branch 'krobelus/selection-undo-fix-standstill-after-buffer-change'

1 files changed, 34 insertions, 51 deletions

diff --git a/src/context.cc b/src/context.cc
index fe9bd346..0c1b8aad 100644
--- a/src/context.cc
+++ b/src/context.cc
@@ -204,9 +204,11 @@ void Context::SelectionHistory::end_edition()
 
     if (m_history_id != HistoryId::Invalid and current_history_node().selections == m_staging->selections)
     {
-        auto& sels = m_history[(size_t)m_history_id].selections;
-        sels.force_timestamp(m_staging->selections.timestamp());
-        sels.set_main_index(m_staging->selections.main_index());
+        // No change, except maybe the index of the main selection.
+        // Update timestamp to potentially improve interaction with content undo.
+        auto& node = current_history_node();
+        node.selections.force_timestamp(m_staging->selections.timestamp());
+        node.selections.set_main_index(m_staging->selections.main_index());
     }
     else
     {
@@ -216,53 +218,36 @@ void Context::SelectionHistory::end_edition()
     m_staging.reset();
 }
 
+template<Direction direction>
 void Context::SelectionHistory::undo()
 {
+    static constexpr bool backward = direction == Backward;
     if (in_edition())
         throw runtime_error("selection undo is only supported at top-level");
     kak_assert(not empty());
-    begin_edition();
-    auto end = on_scope_end([&] {
-        kak_assert(current_history_node().selections == m_staging->selections);
-        end_edition();
-    });
-    HistoryId parent = current_history_node().parent;
-    if (parent == HistoryId::Invalid)
-        throw runtime_error("no selection change to undo");
-    auto select_parent = [&, parent] {
-        HistoryId before_undo = m_history_id;
-        m_history_id = parent;
-        current_history_node().redo_child = before_undo;
-        m_staging = current_history_node();
-    };
-    if (&history_node(parent).selections.buffer() == &m_context.buffer())
-        select_parent();
-    else
-        m_context.change_buffer(history_node(parent).selections.buffer(), { std::move(select_parent) });
-                                                                           // });
-}
-
-void Context::SelectionHistory::redo()
-{
-    if (in_edition())
-        throw runtime_error("selection redo is only supported at top-level");
-    kak_assert(not empty());
-    begin_edition();
-    auto end = on_scope_end([&] {
-        kak_assert(current_history_node().selections == m_staging->selections);
-        end_edition();
-    });
-    HistoryId child = current_history_node().redo_child;
-    if (child == HistoryId::Invalid)
-        throw runtime_error("no selection change to redo");
-    auto select_child = [&, child] {
-        m_history_id = child;
-        m_staging = current_history_node();
-    };
-    if (&history_node(child).selections.buffer() == &m_context.buffer())
-        select_child();
-    else
-        m_context.change_buffer(history_node(child).selections.buffer(), { std::move(select_child) });
+    SelectionList old_selections = selections();
+    HistoryId next;
+    do
+    {
+        if constexpr (backward)
+            next = current_history_node().parent;
+        else
+            next = current_history_node().redo_child;
+        if (next == HistoryId::Invalid)
+            throw runtime_error(backward ? "no selection change to undo" : "no selection change to redo");
+        auto select_next = [&, next] {
+            HistoryId previous_id = m_history_id;
+            m_history_id = next;
+            if constexpr (backward)
+                current_history_node().redo_child = previous_id;
+        };
+        Buffer& destination_buffer = history_node(next).selections.buffer();
+        if (&destination_buffer == &m_context.buffer())
+            select_next();
+        else
+            m_context.change_buffer(destination_buffer, { std::move(select_next) });
+    }
+    while (selections() == old_selections);
 }
 
 void Context::SelectionHistory::forget_buffer(Buffer& buffer)
@@ -376,15 +361,13 @@ SelectionList& Context::selections(bool update)
     return m_selection_history.selections(update);
 }
 
+template<Direction direction>
 void Context::undo_selection_change()
 {
-    m_selection_history.undo();
-}
-
-void Context::redo_selection_change()
-{
-    m_selection_history.redo();
+    m_selection_history.undo<direction>();
 }
+template void Context::undo_selection_change<Backward>();
+template void Context::undo_selection_change<Forward>();
 
 SelectionList& Context::selections_write_only()
 {