15. Fanta Revisited (continued)

• Here is how the NFA engine would work:

    Position in the regex | Position in the string
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^                    |^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^                    | ^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^                    |  ^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^                    |   ^
    ----------------------------------------------------------------
  
    etc.
  
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^                    |            ^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^                   |            ^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^                  |            ^^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^                 |            ^^^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^^                |            ^^^^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^^ ^^             |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^^ ^^ ^           |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ----------------------------------------------------------------
  

• Oops! That's no good. But no worries - the NFA engine will now happily backtrack, and force the ".*" to give up characters:

    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^^ ^^             |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^^ ^^ ^           |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^^ ^^             |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^^ ^^ ^           |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^^ ^^             |            ^^^^^^^^^^^^^^^^^^^^^^^^^^
    ----------------------------------------------------------------
     fanta(.*)n           | This isn't fantastic, let's drink fanta!
     ^^^^^ ^^ ^           |            ^^^^^^^^^^^^^^^^^^^^^^^^^^
    ----------------------------------------------------------------
  

• So, what's the big deal? Why does it matter how the regex engine works? They seem to do the same thing, just in different ways. Right?