%!PS

% begin included library code
% see https://codeberg.org/Firedrake/postscript-libraries/
/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

/c.islower {
    dup 97 ge exch 122 le and
} 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

/c.isupper {
    dup 65 ge exch 90 le and
} bind def

/apush.right { % [a b] c -> [a b c]
    exch
    [ exch aload length 2 add -1 roll ]
} bind def

/rotor {
    5 dict begin
    /delta exch def
    /size exch def
    dup length /len exch def
    /ar exch def
    /ix 0 def
    [
        {
            ix size add len gt {
                exit
            } if
            ar ix size getinterval
            /ix ix size delta add add def
        } loop
    ]
    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

/s2a {
    [ exch { } forall ]
} bind def

/a2s {
    2 dict begin
    /i exch def
    i length dup string /o exch def
    1 sub 0 exch 1 exch {
        dup i 3 -1 roll get o 3 1 roll put
    } for
    o
    end
} bind def

/c.isalpha {
    dup c.islower exch c.isupper or
} bind def

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


% end included library code

/findthird {
    0 dict begin
    /b exch def
    /a exch def
    /ss 0 array def
    /sa 0 array def
    s2a {
        /c exch def
        c c.isalpha {
            /sa sa c apush.right def
        } {
            sa length 0 gt {
                /ss ss sa a2s apush.right def
                /sa 0 array def
            } if
        } ifelse
    } forall
    sa length 0 gt {
        /ss ss sa a2s apush.right def
    } if
    [
        ss 3 -2 rotor {
            /p exch def
            p 0 get a deepeq
            p 1 get b deepeq and {
                p 2 get
            } if
        } forall
    ]
    end
} bind def

(findthird) test.start
(Perl is a my favourite language but Python is my favourite too.) (my) (favourite) findthird [(language) (too)] deepeq test
(Barbie is a beautiful doll also also a beautiful princess.) (a) (beautiful) findthird [(doll) (princess)] deepeq test
(we will we will rock you rock you.) (we) (will) findthird [(we) (rock)] deepeq test
test.end