feat(highlight): allow complex keyword patterns (#185)

Match only the (KEYWORDS) portion of patterns for looking up highlight
information. Allows highlighting more complicated patterns, like
`NOTE(LunarLambda):` or `TODO 2:`.

Author: LunarLambda

lua/todo-comments/config.lua

@@ -123,11 +123,12 @@ function M._setup()
     return M.options.search.pattern:gsub("KEYWORDS", tags(keywords))
   end
 
+  M.kw_regex = tags()
   M.hl_regex = {}
   local patterns = M.options.highlight.pattern
   patterns = type(patterns) == "table" and patterns or { patterns }
   for _, p in pairs(patterns) do
-    p = p:gsub("KEYWORDS", tags())
+    p = p:gsub("KEYWORDS", M.kw_regex)
     table.insert(M.hl_regex, p)
   end
   M.colors()

lua/todo-comments/highlight.lua

@@ -47,7 +47,7 @@ function M.match(str, patterns)
     local m = vim.fn.matchlist(str, [[\v\C]] .. pattern)
     if #m > 1 and m[2] then
       local kw = m[2]
-      local start = str:find(kw)
+      local start = str:find(kw, 0, true)
       return start, start + #kw, kw
     end
   end
@@ -192,6 +192,12 @@ function M.highlight(buf, first, last, _event)
       end
     end
 
+    local sub_kw = vim.fn.matchstr(kw, [[\v\C]] .. Config.kw_regex)
+
+    if sub_kw ~= "" then
+      kw = sub_kw
+    end
+
     if kw then
       kw = Config.keywords[kw] or kw
     end