Refactor column highlighter to make it more robust

Support arbitrary orders for column highlighters (it was previously
failing when column highlighters were not applied in column order).

Fix show_matching tab handling at the same time (horizontal scrolling,
tab characters and show_matching were behaving badly).

Window highlighting now runs user highlighters, then built-ins for each
phases, instead of running all phases for user highlighters, then all
phases for built-ins.

We now consider unprintable character to be 1-column width as we know
we will display them as "�".

Fixes #1615
Fixes #1023

1 files changed, 14 insertions, 7 deletions

diff --git a/src/display_buffer.cc b/src/display_buffer.cc
index e6ae2a34..3a1449d7 100644
--- a/src/display_buffer.cc
+++ b/src/display_buffer.cc
@@ -92,15 +92,22 @@ DisplayLine::iterator DisplayLine::split(iterator it, BufferCoord pos)
     return m_atoms.insert(it, std::move(atom));
 }
 
-DisplayLine::iterator DisplayLine::split(iterator it, ColumnCount pos)
+DisplayLine::iterator DisplayLine::split(iterator it, ColumnCount count)
 {
-    kak_assert(it->type() == DisplayAtom::Text);
-    kak_assert(pos > 0);
-    kak_assert(pos < it->length());
+    kak_assert(count > 0);
+    kak_assert(count < it->length());
 
-    DisplayAtom atom(it->m_text.substr(0, pos).str());
-    it->m_text = it->m_text.substr(pos).str();
-    return m_atoms.insert(it, std::move(atom));
+    if (it->type() == DisplayAtom::Text or it->type() == DisplayAtom::ReplacedRange)
+    {
+        DisplayAtom atom = *it;
+        atom.m_text = atom.m_text.substr(0, count).str();
+        it->m_text = it->m_text.substr(count).str();
+        return m_atoms.insert(it, std::move(atom));
+    }
+    auto pos = utf8::advance(get_iterator(it->buffer(), it->begin()),
+                             get_iterator(it->buffer(), it->end()), 
+                             count).coord();
+    return split(it, pos);
 }
 
 DisplayLine::iterator DisplayLine::insert(iterator it, DisplayAtom atom)