DisplayBuffer: check_invariant method to assert atoms consistency

src/display_buffer.cc

@@ -1,6 +1,6 @@
 #include "display_buffer.hh"
 
-#include "assert.h"
+#include "assert.hh"
 
 namespace Kakoune
 {
@@ -22,4 +22,14 @@ DisplayBuffer::iterator DisplayBuffer::split(iterator atom, size_t pos_in_atom)
     return insert(atom, std::move(new_atom));
 }
 
+void DisplayBuffer::check_invariant() const
+{
+    for (size_t i = 0; i < m_atoms.size(); ++i)
+    {
+        assert(m_atoms[i].end > m_atoms[i].begin);
+        if (i > 0)
+            assert(m_atoms[i-1].end == m_atoms[i].begin);
+    }
+}
+
 }

src/display_buffer.hh

@@ -75,6 +75,8 @@ public:
 
     const_iterator begin() const { return m_atoms.begin(); }
     const_iterator end()   const { return m_atoms.end(); }
+
+    void check_invariant() const;
 private:
     AtomList m_atoms;
 };

src/window.cc

@@ -309,7 +309,10 @@ void Window::update_display_buffer()
     m_display_buffer.append(DisplayAtom(begin, end, m_buffer.string(begin, end)));
 
     for (auto& filter : m_filters)
+    {
         filter(m_display_buffer);
+        m_display_buffer.check_invariant();
+    }
 }
 
 void Window::set_dimensions(const WindowCoord& dimensions)