feat: allow multiple hlgroups inside one column (#240)

* feat: allow multiple hlgroups inside one column

* types: refactor formatting of highlight types

* types: LuaLS can't infer type information from unpack

---------

Co-authored-by: Steven Arcangeli <506791+stevearc@users.noreply.github.com>

lua/oil/init.lua

@@ -7,7 +7,10 @@ local M = {}
 ---@field parsed_name nil|string
 
 ---@alias oil.EntryType "file"|"directory"|"socket"|"link"|"fifo"
----@alias oil.TextChunk string|string[]
+---@alias oil.HlRange { [1]: string, [2]: integer, [3]: integer } A tuple of highlight group name, col_start, col_end
+---@alias oil.HlTuple { [1]: string, [2]: string } A tuple of text, highlight group
+---@alias oil.HlRangeTuple { [1]: string, [2]: oil.HlRange[] } A tuple of text, internal highlights
+---@alias oil.TextChunk string|oil.HlTuple|oil.HlRangeTuple
 ---@alias oil.CrossAdapterAction "copy"|"move"
 
 ---@class (exact) oil.Adapter

lua/oil/util.lua

@@ -294,7 +294,8 @@ M.render_table = function(lines, col_width)
     for i, chunk in ipairs(cols) do
       local text, hl
       if type(chunk) == "table" then
-        text, hl = unpack(chunk)
+        text = chunk[1]
+        hl = chunk[2]
       else
         text = chunk
       end
@@ -302,7 +303,21 @@ M.render_table = function(lines, col_width)
       table.insert(pieces, text)
       local col_end = col + text:len() + 1
       if hl then
-        table.insert(highlights, { hl, #str_lines, col, col_end })
+        if type(hl) == "table" then
+          -- hl has the form { [1]: hl_name, [2]: col_start, [3]: col_end }[]
+          -- Notice that col_start and col_end are relative position inside
+          -- that col, so we need to add the offset to them
+          for _, sub_hl in ipairs(hl) do
+            table.insert(highlights, {
+              sub_hl[1],
+              #str_lines,
+              col + sub_hl[2],
+              col + sub_hl[3],
+            })
+          end
+        else
+          table.insert(highlights, { hl, #str_lines, col, col_end })
+        end
       end
       col = col_end
     end