Update ranges highlighter options according to buffer changes

1 files changed, 97 insertions, 0 deletions

diff --git a/src/changes.cc b/src/changes.cc
new file mode 100644
index 00000000..7feb82ec
--- /dev/null
+++ b/src/changes.cc
@@ -0,0 +1,97 @@
+#include "changes.hh"
+
+namespace Kakoune
+{
+void ForwardChangesTracker::update(const Buffer::Change& change)
+{
+    kak_assert(change.begin >= cur_pos);
+
+    if (change.type == Buffer::Change::Insert)
+    {
+        old_pos = get_old_coord(change.begin);
+        cur_pos = change.end;
+    }
+    else if (change.type == Buffer::Change::Erase)
+    {
+        old_pos = get_old_coord(change.end);
+        cur_pos = change.begin;
+    }
+}
+
+void ForwardChangesTracker::update(const Buffer& buffer, size_t& timestamp)
+{
+    for (auto& change : buffer.changes_since(timestamp))
+        update(change);
+    timestamp = buffer.timestamp();
+}
+
+BufferCoord ForwardChangesTracker::get_old_coord(BufferCoord coord) const
+{
+    kak_assert(cur_pos <= coord);
+    auto pos_change = cur_pos - old_pos;
+    if (cur_pos.line == coord.line)
+    {
+        kak_assert(pos_change.column <= coord.column);
+        coord.column -= pos_change.column;
+    }
+    coord.line -= pos_change.line;
+    kak_assert(old_pos <= coord);
+    return coord;
+}
+
+BufferCoord ForwardChangesTracker::get_new_coord(BufferCoord coord) const
+{
+    kak_assert(old_pos <= coord);
+    auto pos_change = cur_pos - old_pos;
+    if (old_pos.line == coord.line)
+    {
+        kak_assert(-pos_change.column <= coord.column);
+        coord.column += pos_change.column;
+    }
+    coord.line += pos_change.line;
+    kak_assert(cur_pos <= coord);
+    return coord;
+}
+
+BufferCoord ForwardChangesTracker::get_new_coord_tolerant(BufferCoord coord) const
+{
+    if (coord < old_pos)
+        return cur_pos;
+    return get_new_coord(coord);
+}
+
+bool ForwardChangesTracker::relevant(const Buffer::Change& change, BufferCoord old_coord) const
+{
+    auto new_coord = get_new_coord_tolerant(old_coord);
+    return change.type == Buffer::Change::Insert ? change.begin <= new_coord
+                                                 : change.begin < new_coord;
+}
+
+const Buffer::Change* forward_sorted_until(const Buffer::Change* first, const Buffer::Change* last)
+{
+    if (first != last) {
+        const Buffer::Change* next = first;
+        while (++next != last) {
+            const auto& ref = first->type == Buffer::Change::Insert ? first->end : first->begin;
+            if (next->begin <= ref)
+                return next;
+            first = next;
+        }
+    }
+    return last;
+}
+
+const Buffer::Change* backward_sorted_until(const Buffer::Change* first, const Buffer::Change* last)
+{
+    if (first != last) {
+        const Buffer::Change* next = first;
+        while (++next != last) {
+            if (first->begin <= next->end)
+                return next;
+            first = next;
+        }
+    }
+    return last;
+}
+
+}