====== Regular Expressions ======

==== Matching type ====
^Code       ^Meaning                      ^
|\w         |Alphanumeric Character       |
|\W         |Non-Alphanumeric Characters  |
|\s         |White Space                  |
|\S         |Non-White Space              |
|\d         |Digits                       |
|\D         |Non-Digits                   |
|\b         |Word Boundary                |
|\B         |Non-Word Boundary            |
|\A or caret|At the Beginning of a String |
|\Z or $    |At the End of a String       |
|.          |Match Any Single Character   |

==== Modifiers ====
^Code               ^Meaning                                  ^
|*                  |Zero or More Occurrences                 |
|?                  |Zero or One Occurrence                   |
|+                  |One or More Occurrences                  |
|{ N }              |Exactly N Occurrences                    |
|{ N,M }            |Between N and M Occurrences              |
|.* <thingy>        |Greedy Match, up to the last thingy      |
|.*? <thingy>       |Non-Greedy Match, up to the first thingy |
|[ set_of_things ]  |Match Any Item in the Set                |
|[ caret set_of_things ]|Does Not Match Anything in the Set       |
|( some_expression )|Tag an Expression                        |
|$1..$N             |Tagged Expressions used in Substitutions |

==== References ====
  * Quickref 1 - http://www.tjhsst.edu/~dhyatt/perl/exA.html
  * Quickref 2 - http://www.kichwa.com/quik_ref/expressions.html
  * Explanation In depth - http://www.troubleshooters.com/codecorn/littperl/perlreg.htm