Highlight icons using highlight regions rather than matching rules

lua/symbols-outline/parser.lua

@@ -161,6 +161,7 @@ end
 
 function M.get_lines(flattened_outline_items)
     local lines = {}
+    local hl_info = {}
     for _, value in ipairs(flattened_outline_items) do
         local line = str_to_table(string.rep(" ", value.depth))
 
@@ -194,10 +195,15 @@ function M.get_lines(flattened_outline_items)
             table.insert(final_prefix, " ")
         end
 
-        table.insert(lines, table_to_str(final_prefix) .. value.icon .. " " ..
+        local string_prefix = table_to_str(final_prefix)
+        local hl_start = #string_prefix + 1
+        local hl_end = #string_prefix + #value.icon
+        table.insert(lines, string_prefix .. value.icon .. " " ..
                          value.name)
+        hl_type = config.options.symbols[symbols.kinds[value.kind]].hl
+        table.insert(hl_info, {hl_start, hl_end, hl_type})
     end
-    return lines
+    return lines, hl_info
 end
 
 function M.get_details(flattened_outline_items)

lua/symbols-outline/ui.lua

@@ -52,12 +52,6 @@ function M.setup_highlights()
     highlight_text("markers_horizontal", M.markers.horizontal,
                    "SymbolsOutlineConnector")
     highlight_text("markers_bottom", M.markers.bottom, "SymbolsOutlineConnector")
-
-    for _, value in ipairs(symbol_kinds) do
-        local symbol = symbols[value]
-        highlight_text(value, symbol.icon, symbol.hl)
-    end
-
 end
 
 return M

lua/symbols-outline/writer.lua

@@ -12,6 +12,8 @@ local function is_buffer_outline(bufnr)
     return string.match(name, "OUTLINE") ~= nil and ft == "Outline" and isValid
 end
 
+local hlns = vim.api.nvim_create_namespace("symbols-outline-icon-highlight")
+
 function M.write_outline(bufnr, lines)
     if not is_buffer_outline(bufnr) then return end
     vim.api.nvim_buf_set_option(bufnr, "modifiable", true)
@@ -19,6 +21,13 @@ function M.write_outline(bufnr, lines)
     vim.api.nvim_buf_set_option(bufnr, "modifiable", false)
 end
 
+function M.add_highlights(bufnr, hl_info)
+    for line, line_hl in ipairs(hl_info) do
+        hl_start, hl_end, hl_type = unpack(line_hl)
+        vim.api.nvim_buf_add_highlight(bufnr, hlns, hl_type, line - 1, hl_start - 1, hl_end)
+    end
+end
+
 local ns = vim.api.nvim_create_namespace("symbols-outline-virt-text")
 
 function M.write_details(bufnr, lines)
@@ -41,11 +50,12 @@ end
 -- runs the whole writing routine where the text is cleared, new data is parsed
 -- and then written
 function M.parse_and_write(bufnr, flattened_outline_items)
-    local lines = parser.get_lines(flattened_outline_items)
+    local lines, hl_info = parser.get_lines(flattened_outline_items)
     M.write_outline(bufnr, lines)
 
     clear_virt_text(bufnr)
     local details = parser.get_details(flattened_outline_items)
+    M.add_highlights(bufnr, hl_info)
     M.write_details(bufnr, details)
 end