From 667777521b654156722cfe0a307fbd381fa1f629 Mon Sep 17 00:00:00 2001
From: Maxime Coste <mawww@kakoune.org>
Date: Thu, 21 Jun 2018 08:07:17 +1000
Subject: [PATCH] Refactor the way main selection is determined after rotating
 contents

Fixes #2133
---
 src/normal.cc                                 | 19 ++++++++-----------
 .../2133-assert-on-rotate-contents/cmd        |  1 +
 .../2133-assert-on-rotate-contents/in         |  1 +
 .../2133-assert-on-rotate-contents/out        |  1 +
 4 files changed, 11 insertions(+), 11 deletions(-)
 create mode 100644 test/regression/2133-assert-on-rotate-contents/cmd
 create mode 100644 test/regression/2133-assert-on-rotate-contents/in
 create mode 100644 test/regression/2133-assert-on-rotate-contents/out

diff --git a/src/normal.cc b/src/normal.cc
index 37e25931..0fe60ef8 100644
--- a/src/normal.cc
+++ b/src/normal.cc
@@ -1435,23 +1435,20 @@ void rotate_selections_content(Context& context, NormalParams params)
     if (group == 0 or group > (int)strings.size())
         group = (int)strings.size();
     count = count % group;
+    auto& selections = context.selections();
+    auto main = strings.begin() + selections.main_index();
     for (auto it = strings.begin(); it != strings.end(); )
     {
         auto end = std::min(strings.end(), it + group);
-        if (direction == Direction::Forward)
-            std::rotate(it, end-count, end);
-        else
-            std::rotate(it, it+count, end);
+        auto new_beg = (direction == Direction::Forward) ? end - count : it + count;
+        std::rotate(it, new_beg, end);
+
+        if (it <= main and main < end)
+            main = main < new_beg ? end - (new_beg - main) : it + (main - new_beg);
         it = end;
     }
-    auto& selections = context.selections();
     selections.insert(strings, InsertMode::Replace);
-    const size_t index = selections.main_index();
-    const size_t index_in_group = index % group;
-    selections.set_main_index(index - index_in_group +
-                              ((direction == Forward) ?
-                                 (index_in_group + count) % group
-                               : (index_in_group + group - count % group) % group));
+    selections.set_main_index(main - strings.begin());
 }
 
 enum class SelectFlags
diff --git a/test/regression/2133-assert-on-rotate-contents/cmd b/test/regression/2133-assert-on-rotate-contents/cmd
new file mode 100644
index 00000000..1e43e08f
--- /dev/null
+++ b/test/regression/2133-assert-on-rotate-contents/cmd
@@ -0,0 +1 @@
+2<a-)>
diff --git a/test/regression/2133-assert-on-rotate-contents/in b/test/regression/2133-assert-on-rotate-contents/in
new file mode 100644
index 00000000..478a6fee
--- /dev/null
+++ b/test/regression/2133-assert-on-rotate-contents/in
@@ -0,0 +1 @@
+%(foo) %(bar) %(baz)
diff --git a/test/regression/2133-assert-on-rotate-contents/out b/test/regression/2133-assert-on-rotate-contents/out
new file mode 100644
index 00000000..1a5d2c33
--- /dev/null
+++ b/test/regression/2133-assert-on-rotate-contents/out
@@ -0,0 +1 @@
+bar foo baz