1 files changed, 46 insertions, 63 deletions

diff --git a/src/line_modification.cc b/src/line_modification.cc
index 96249856..1943350f 100644
--- a/src/line_modification.cc
+++ b/src/line_modification.cc
@@ -5,41 +5,33 @@
 namespace Kakoune
 {
 
-namespace
+static LineModification make_line_modif(const Buffer::Change& change)
 {
-
-struct LineChange
-{
-    LineChange(const Buffer::Change& change)
+    LineModification res = {};
+    res.old_line = change.begin.line;
+    res.new_line = change.begin.line;
+    if (change.type == Buffer::Change::Insert)
     {
-        ByteCoord begin = change.begin;
-        ByteCoord end = change.end;
-        if (change.type == Buffer::Change::Insert)
-        {
-            if (change.at_end and begin != ByteCoord{0,0})
-            {
-                kak_assert(begin.column == 0);
-                --begin.line;
-            }
-            pos = begin.line;
-            num = end.line - begin.line;
-        }
-        else
-        {
-            if (change.at_end and begin != ByteCoord{0,0})
-            {
-                kak_assert(begin.column == 0);
-                --begin.line;
-            }
-            pos = begin.line;
-            num = begin.line - end.line;
-        }
+        res.num_added = change.end.line - change.begin.line;
+         // inserted a new line at buffer end but end coord is on same line
+        if (change.at_end and change.end.column != 0)
+            ++res.num_added;
     }
-
-    LineCount pos;
-    LineCount num;
-};
-
+    else
+    {
+        res.num_removed = change.end.line - change.begin.line;
+        // removed last line, but end coord is on same line
+        if (change.at_end and change.end.column != 0)
+            ++res.num_removed;
+    }
+    // modified a line
+    if (not change.at_end and
+        (change.begin.column != 0 or change.end.column != 0))
+    {
+        ++res.num_removed;
+        ++res.num_added;
+    }
+    return res;
 }
 
 Vector<LineModification> compute_line_modifications(const Buffer& buffer, size_t timestamp)
@@ -47,60 +39,51 @@ Vector<LineModification> compute_line_modifications(const Buffer& buffer, size_t
     Vector<LineModification> res;
     for (auto& buf_change : buffer.changes_since(timestamp))
     {
-        const LineChange change(buf_change);
+        auto change = make_line_modif(buf_change);
 
-        auto pos = std::upper_bound(res.begin(), res.end(), change.pos,
+        auto pos = std::upper_bound(res.begin(), res.end(), change.new_line,
                                     [](const LineCount& l, const LineModification& c)
                                     { return l < c.new_line; });
 
         if (pos != res.begin())
         {
             auto& prev = *(pos-1);
-            if (change.pos <= prev.new_line + prev.num_added)
+            if (change.new_line <= prev.new_line + prev.num_added)
+            {
                 --pos;
+                LineCount removed_from_previously_added_by_pos = clamp(pos->new_line + pos->num_added - change.new_line, 0_line, std::min(pos->num_added, change.num_removed));
+                pos->num_removed += change.num_removed - removed_from_previously_added_by_pos;
+                pos->num_added += change.num_added - removed_from_previously_added_by_pos;
+            }
             else
-                pos = res.insert(pos, {change.pos - prev.diff(), change.pos, 0, 0});
+            {
+                change.old_line -= prev.diff();
+                pos = res.insert(pos, change);
+            }
         }
         else
-            pos = res.insert(pos, {change.pos, change.pos, 0, 0});
+            pos = res.insert(pos, change);
 
         auto& modif = *pos;
         auto next = pos + 1;
-        if (change.num > 0)
+        if (buf_change.type == Buffer::Change::Erase)
         {
-            modif.num_added += change.num;
-            for (auto it = next; it != res.end(); ++it)
-                it->new_line += change.num;
-        }
-        if (change.num < 0)
-        {
-            const LineCount num_removed = -change.num;
-
-            auto delend = std::upper_bound(next, res.end(), change.pos + num_removed,
+            auto delend = std::upper_bound(next, res.end(), change.new_line + change.num_removed,
                                            [](const LineCount& l, const LineModification& c)
                                            { return l < c.new_line; });
 
             for (auto it = next; it != delend; ++it)
             {
-                LineCount removed_from_it = (change.pos + num_removed - it->new_line);
-                modif.num_removed += it->num_removed - std::min(removed_from_it, it->num_added);
-                modif.num_added += std::max(0_line, it->num_added - removed_from_it);
+                LineCount removed_from_previously_added_by_it = std::min(it->num_added, change.new_line + change.num_removed - it->new_line);
+                modif.num_removed += it->num_removed - removed_from_previously_added_by_it;
+                modif.num_added += it->num_added - removed_from_previously_added_by_it;
             }
             next = res.erase(next, delend);
-
-            const LineCount num_added_after_pos =
-                modif.new_line + modif.num_added - change.pos;
-            const LineCount num_removed_from_added =
-                std::min(num_removed, num_added_after_pos);
-
-            kak_assert(modif.num_added >= num_removed_from_added);
-
-            modif.num_added -= num_removed_from_added;
-            modif.num_removed += num_removed - num_removed_from_added;
-
-            for (auto it = next; it != res.end(); ++it)
-                it->new_line -= num_removed;
         }
+
+        auto diff = buf_change.end.line - buf_change.begin.line;
+        for (auto it = next; it != res.end(); ++it)
+            it->new_line += diff;
     }
     return res;
 }