From c915e189500f6f6e986826e2e09a06009119ca9a Mon Sep 17 00:00:00 2001
From: Maxime Coste <frrrwww@gmail.com>
Date: Mon, 16 Jul 2012 21:53:00 +0200
Subject: [PATCH] Move selection to last modification position in
 editor::{undo,redo}

---
 src/editor.cc | 53 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 51 insertions(+), 2 deletions(-)

diff --git a/src/editor.cc b/src/editor.cc
index 1c300a61..f1b30cae 100644
--- a/src/editor.cc
+++ b/src/editor.cc
@@ -226,14 +226,63 @@ void Editor::multi_select(const MultiSelector& selector)
     }
 }
 
+class LastModifiedRangeListener : public BufferChangeListener
+{
+public:
+    LastModifiedRangeListener(Buffer& buffer)
+       : m_buffer(buffer)
+    { m_buffer.add_change_listener(*this); }
+
+    ~LastModifiedRangeListener()
+    { m_buffer.remove_change_listener(*this); }
+
+    void on_insert(const BufferIterator& begin, const BufferIterator& end)
+    {
+        m_first = begin;
+        m_last = end-1;
+    }
+
+    void on_erase(const BufferIterator& begin, const BufferIterator& end)
+    {
+        m_first = begin;
+        if (m_first >= m_buffer.end())
+            m_first = m_buffer.end() - 1;
+        m_last = m_first;
+    }
+
+    const BufferIterator& first() const { return m_first; }
+    const BufferIterator& last() const { return m_last; }
+
+private:
+    BufferIterator m_first;
+    BufferIterator m_last;
+    Buffer& m_buffer;
+};
+
 bool Editor::undo()
 {
-    return m_buffer.undo();
+    LastModifiedRangeListener listener(buffer());
+    bool res = m_buffer.undo();
+    if (res)
+    {
+        m_selections.back().clear();
+        m_selections.back().push_back(Selection(listener.first(),
+                                                listener.last()));
+    }
+    return res;
 }
 
 bool Editor::redo()
 {
-    return m_buffer.redo();
+    LastModifiedRangeListener listener(buffer());
+    bool res = m_buffer.redo();
+    if (res)
+    {
+        m_selections.back().clear();
+        m_selections.back().push_back(Selection(listener.first(),
+                                                listener.last()));
+    }
+    return res;
 }
 
 void Editor::check_invariant() const