Любая функция в Ruby определяет разницу между уровнями папок?

Question

Что я пытаюсь сделать, это выяснить, является ли какая-либо папка дочерней / родительской папкой или не связана.

Есть ли какая-либо функция в Ruby File API ?если не как это выяснить?

Например:

real_path_1 = "/Users/amr/Code/xx/zz"
real_path_2 = "/Users/amr/Code/"
# when I have to compare between these paths like:
f_level(real_path_1, real_path_2)
# it should return +2
# that means real_path_1 is **parent** of real_path_2
# with 2 levels depth

Еще один пример:

real_path_1 = "/Users/amr/Code/"
real_path_2 = "/Users/amr/Code/foo/bar/inside"
# when I have to compare between these paths like:
f_level(real_path_1, real_path_2)
# it should return -3
# that means real_path_1 is **child** of real_path_2
# with 3 levels depth

Другой пример:

real_path_1 = "/Users/amr/Code/"
real_path_2 = "/Users/amr/Code/"
# when I have to compare between these paths like:
f_level(real_path_1, real_path_2)
# it should return 0
# that means real_path_1 is **same level** as real_path_2

Когда возвращается ноль :

real_path_1 = "/Users/other/Code/" # or "/folder2/"
real_path_2 = "/Users/amr/Code/" # or "/folder1/"
# when I have to compare between these paths like:
f_level(real_path_1, real_path_2)
# it should return nil
# that means real_path_1 is **not at same level** as real_path_2

Answer 1

Еще одна идея без регулярных выражений:

def f_level(path1_string, path2_string)
  path1, path2 = [path1_string, path2_string].map { |s| s.split(File::SEPARATOR) }  
  minsize = [path1, path2].map(&:size).min
  path1.first(minsize) == path2.first(minsize) ? path1.size - path2.size : nil
end

raise unless f_level("/Users/amr/Code/xx/zz",  "/Users/amr/Code/") == 2
raise unless f_level( "/Users/amr/Code/", "/Users/amr/Code/foo/bar/inside") == -3
raise unless f_level("/Users/amr/Code/", "/Users/amr/Code/") == 0 
raise unless f_level("/Users/other/Code/", "/Users/amr/Code/") == nil

Answer 2

def f_level a,b
    if a[/^#{b}/] && (b[-1,1] == '/' || $'[0,1] == '/')
        $'.scan(/[^\/]+/).size
    elsif b[/^#{a}/] && (a[-1,1] == '/' || $'[0,1] == '/')
        -($'.scan(/[^\/]+/).size)
    end
end

"/Users/amr/Code/xx/zz"
"/Users/amr/Code/"
2
"/Users/amr/Code/"
"/Users/amr/Code/xx/zz"
-2
"/Users/amr/Code/"
"/Users/amr/Code/"
0
"/Users/other/Code/"
"/Users/amr/Code/"
nil