Simplify column highlighter and make it more robust

Fixes #1382

src/highlighters.cc

@@ -647,54 +647,20 @@ HighlighterAndId create_column_highlighter(HighlighterParameters params)
             }
             if (not found)
             {
-                ColumnCount first_buffer_col = -1;
+                ColumnCount last_buffer_col = context.window().position().column;
-                ColumnCount first_display_col = 0;
                 for (auto& atom : line)
                 {
-                    if (atom.has_buffer_range())
+                    if (atom.has_buffer_range() and atom.begin() != atom.end())
-                    {
+                        last_buffer_col = get_column(buffer, tabstop, atom.end());
-                        first_buffer_col = get_column(buffer, tabstop, atom.begin());
-                        break;
-                    }
-                    first_display_col += atom.length();
                 }
 
-                if (first_buffer_col == -1)
+                ColumnCount count = column - last_buffer_col;
-                    continue;
-
-                ColumnCount eol_col = line.length();
-                ColumnCount count = column + first_display_col - first_buffer_col - eol_col;
                 if (count >= 0)
                 {
                     if (count > 0)
                         line.push_back({String{' ',  count}});
                     line.push_back({String{" "}, face});
                 }
-                else
-                {
-                    for (auto atom_it = line.end(); atom_it != line.begin() and count < 0; --atom_it)
-                    {
-                        DisplayAtom& atom = *(atom_it-1);
-
-                        const ColumnCount len = atom.length();
-                        if (atom.type() == DisplayAtom::Text and -count <= len)
-                        {
-                            auto it = atom_it - 1;
-                            ColumnCount pos = len + count;
-                            if (pos > 0)
-                            {
-                                it = ++line.split(it, pos);
-                                pos = 0;
-                            }
-                            if (pos+1 != it->length())
-                                it = line.split(it, pos+1);
-
-                            apply_face(face)(*it);
-                            break;
-                        }
-                        count += len;
-                    }
-                }
             }
         }
     };

test/regression/1382-column-highlighter-broken-on-horizontal-scroll/.in.kak.jk5AyT

@@ -0,0 +1,4 @@
+xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+xxxxxxxx
+xxxx	xxxx
+

test/regression/1382-column-highlighter-broken-on-horizontal-scroll/cmd

@@ -0,0 +1 @@
+gl

test/regression/1382-column-highlighter-broken-on-horizontal-scroll/display

@@ -0,0 +1,6 @@
+{ "jsonrpc": "2.0", "method": "draw", "params": [[[{ "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": "xxxxxxxxxx" }, { "face": { "fg": "default", "bg": "blue", "attributes": [] }, "contents": "x" }, { "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" }, { "face": { "fg": "black", "bg": "white", "attributes": [] }, "contents": "x" }], [{ "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": "xxx\u000a" }, { "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": "      " }, { "face": { "fg": "default", "bg": "blue", "attributes": [] }, "contents": " " }], [{ "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": "" }, { "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": "          " }, { "face": { "fg": "default", "bg": "blue", "attributes": [] }, "contents": " " }], [{ "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": "" }, { "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": "          " }, { "face": { "fg": "default", "bg": "blue", "attributes": [] }, "contents": " " }]], { "fg": "default", "bg": "default", "attributes": [] }, { "fg": "blue", "bg": "default", "attributes": [] }] }
+{ "jsonrpc": "2.0", "method": "menu_hide", "params": [] }
+{ "jsonrpc": "2.0", "method": "info_hide", "params": [] }
+{ "jsonrpc": "2.0", "method": "draw_status", "params": [[], [{ "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": "out 1:89 " }, { "face": { "fg": "black", "bg": "yellow", "attributes": [] }, "contents": "" }, { "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": " " }, { "face": { "fg": "blue", "bg": "default", "attributes": [] }, "contents": "1 sel" }, { "face": { "fg": "default", "bg": "default", "attributes": [] }, "contents": " - unnamed0@[kak-tests]" }], { "fg": "cyan", "bg": "default", "attributes": [] }] }
+{ "jsonrpc": "2.0", "method": "set_cursor", "params": ["buffer", { "line": 0, "column": 79 }] }
+{ "jsonrpc": "2.0", "method": "refresh", "params": [true] }

test/regression/1382-column-highlighter-broken-on-horizontal-scroll/in

@@ -0,0 +1,4 @@
+xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+xxxx	xxxx
+xxxxxxxx
+

test/regression/1382-column-highlighter-broken-on-horizontal-scroll/rc

@@ -0,0 +1 @@
+add-highlighter column 20 default,blue