Permutation Lower Upper: Generate permutations of chars (capital and not)

This class can generate modified versions of a string by permuting its characters using all combinations of lower and upper case of the letters.

For instance, from a string "ab" the class generates the permutations "ab","Ab","aB","AB" .

This class can be useful when it is necessary to manipulate or change parts of a text string to use with functions that works with regular expressions such as preg_match_all and preg_match and after str_replace.