%!PS

% begin included library code
% see https://github.com/Firedrake/postscript-libraries/
/apush.right { % [a b] c -> [a b c]
    exch
    [ exch aload length 2 add -1 roll ]
} bind def

/reduce { % array proc -> value
    2 dict begin
    /p exch def
    /a exch def
    a 0 get
    1 1 a length 1 sub {
        a exch get
        p
    } for
    end
} bind def

/deepeq {
    2 dict begin
    /a exch def
    /b exch def
    a type b type eq {
        a type /dicttype eq {
            a length b length eq {
                <<
                    a {
                        pop
                        true
                    } forall
                    b {
                        pop
                        true
                    } forall
                >>
                true exch
                {
                    pop
                    dup a exch known {
                        dup b exch known {
                            dup a exch get exch b exch get deepeq not {
                                pop false
                            } if
                        } {
                            false
                        } ifelse
                    } {
                        false
                    } ifelse
                } forall
            } {
                false
            } ifelse
        } {
            a type dup /arraytype eq exch /stringtype eq or {
                a length b length eq {
                    true
                    0 1 a length 1 sub {
                        dup a exch get exch b exch get deepeq not {
                            pop false
                            exit
                        } if
                    } for
                } {
                    false
                } ifelse
            } {
                a b eq
            } ifelse
        } ifelse
    } {
        false
    } ifelse
    end
} bind def

/listmin {
    { min } reduce
} bind def

/test {
    /test.count test.count 1 add def
    {
        /test.pass test.pass 1 add def
    } {
        ( ) print
        test.count (....) cvs print
        (-fail) print
    } ifelse
} bind def

/test.end {
    ( ) print
    test.count 0 gt {
        (Passed ) print
        test.pass (...) cvs print
        (/) print
        test.count (...) cvs print
        ( \() print
        test.pass 100 mul test.count idiv (...) cvs print
        (%\)) print
        (\r\n) print
    } if
} bind def

/apush { apush.right } bind def

/strconcat % (a) (b) -> (ab)  
{ exch dup length
  2 index length add string
  dup dup 4 2 roll copy length
  4 -1 roll putinterval
} bind def

/strsplit % (ajbjc) (j) -> [ (a) (b) (c) ]
{
    1 dict begin
    /sep exch def
    [ exch
      {
          dup length 0 eq {
              pop
              exit
          } {
              sep search {
                  exch pop
                  dup length 0 eq {
                      pop
                  } {
                      exch
                  } ifelse
              } {
                  ()
              } ifelse
          } ifelse
      } loop
    ]
    end
} bind def

/test.start {
    print (:) print
    /test.pass 0 def
    /test.count 0 def
} bind def

/strjoin % [(a) (b) (c)] (j) -> (ajbjc)
{
    3 dict begin
    /j exch def
    dup 0 get /out exch def
    /first true def
    {
        first {
            pop
            /first false def
        } {
            out j strconcat
            exch strconcat
            /out exch def
        } ifelse
    } forall
    out
    end
} bind def


% end included library code

/commonpath {
    6 dict begin
    /pa 0 array def
    /pl 0 array def
    {
        (/) strsplit /q exch def
        /pl pl q length apush def
        /pa pa q apush def
    } forall
    /out [ () ] def
    0 1 pl listmin 1 sub {
        /cl exch def
        /ex false def
        /tx pa 0 get cl get def
        pa {
            cl get tx deepeq not {
                /ex true def
                exit
            } if
        } forall
        ex {
            exit
        } if
        /out out tx apush def
    } for
    out (/) strjoin
    end
} bind def

(commonpath) test.start
[
    (/a/b/c/1/x.pl)
    (/a/b/c/d/e/2/x.pl)
    (/a/b/c/d/3/x.pl)
    (/a/b/c/4/x.pl)
    (/a/b/c/d/5/x.pl)
] commonpath (/a/b/c) deepeq test
test.end