Add startswith and endswith function to gears.string, change awful.completion to use startswith over local function

lib/awful/completion.lua

@@ -21,6 +21,7 @@ local pairs = pairs
 local string = string
 
 local gears_debug = require("gears.debug")
+local gstring = require("gears.string")
 
 local completion = {}
 
@@ -79,10 +80,6 @@ function completion.shell(command, cur_pos, ncomp, shell)
     local i = 1
     local comptype = "file"
 
-    local function str_starts(str, start)
-        return string.sub(str, 1, string.len(start)) == start
-    end
-
     -- do nothing if we are on a letter, i.e. not at len + 1 or on a space
     if cur_pos ~= #command + 1 and command:sub(cur_pos, cur_pos) ~= " " then
         return command, cur_pos
@@ -160,7 +157,7 @@ function completion.shell(command, cur_pos, ncomp, shell)
         while true do
             local line = c:read("*line")
             if not line then break end
-            if str_starts(line, "./") and gfs.is_dir(line) then
+            if gstring.startswith(line, "./") and gfs.is_dir(line) then
                 line = line .. "/"
             end
             table.insert(output, bash_escape(line))

lib/gears/string.lua

@@ -106,4 +106,22 @@ function gstring.split(str, delimiter)
     return result
 end
 
+--- Check if a string starts with another string
+-- @class function
+-- @name startswith
+-- @tparam string str String to search
+-- @tparam string sub String to check for
+function gstring.startswith(str, sub)
+	return string.sub(str, 1, string.len(sub)) == sub
+end
+
+--- Check if a string ends with another string
+-- @class function
+-- @name endswith
+-- @tparam string str String to search
+-- @tparam string sub String to check for
+function gstring.endswith(str, sub)
+	return sub == "" or string.sub(str,-string.len(sub)) == sub
+end
+
 return gstring