From: Pit Capitain <pit@...>
Date: 2002-04-27T01:11:09+09:00
Subject: RE: expand_path and overlap

On 27 Apr 2002, at 0:20, Morris, Chris
gave some unit tests for collapse_path

>   assert_equal("/a/b/c", collapse_path("b/c", "/a/b/c/d/e"))
>   assert_equal("/a/b", collapse_path("b", "/a/b/c/d/e"))
>   assert_equal("/a/b/c/f", collapse_path("b/c/f", "/a/b/c/d/e"))
>   assert_equal("/a/b/c/d/e/m/n/o", collapse_path("m/n/o", "/a/b/c/d/e"))
>   assert_equal("/a/b/c/a/b/d", collapse_path("a/b/d", "/a/b/c/a/b/c"))

Here are the modified implementations according to the unit tests. 
The result of collapse_path( "b/c/f", "/a/b/c/d/e/b/x/g/h" ) should be 
specified, too.

def collapse_path1( path, base )
  abs_path = '/' + path
  pattern = Regexp.quote( abs_path.sub( /(.)\/.*/, '\1' ) )
  base.sub( /(.*)#{pattern}(\/|$).*/, '\1' ) + abs_path
end

def collapse_path2( path, base )
  abs_path = '/' + path
  pattern = Regexp.quote( abs_path )
  while pattern
    return $1 + abs_path if base =~ /(.*)#{pattern}(\/|$)/
    pattern.sub!( /(.*)\/.*/, '\1' )
  end
  return base + abs_path
end

Regards,
Pit