Added regular_expressions/heregexes

Removed heregexes from wanted recipes

Author: JohnFord

chapters/regular_expressions/heregexes.textile

@@ -0,0 +1,27 @@
+---
+layout: recipe
+title: Using Heregexes
+chapter: Regular Expressions
+---
+
+h2. Problem
+
+You need to write a complex regular expression.
+
+h2. Solution
+
+Use Coffeescript's "heregexes" -- extended regular expressions that ignore internal whitespace and can contain comments.
+
+{% highlight coffeescript %}
+pattern = ///
+  ^\(?(\d{3})\)? # Capture area code, ignore optional parens
+  [-\s]?(\d{3})  # Capture prefix, ignore optional dash or space
+  -?(\d{4})      # Capture line-number, ignore optional dash
+///
+[area_code, prefix, line] = "(555)123-4567".match(pattern)[1..3]
+# => ['555', '123', '4567']
+{% endhighlight %}
+
+h2. Discussion
+
+Breaking up your complex regular expressions and commenting key sections makes them a lot more decipherable and maintainable. For example, changing this regex to allow an optional space between the prefix and line number would now be fairly obvious.

wanted-recipes.textile

@@ -113,7 +113,6 @@ h2. Regular Expressions
 * Searching for substrings # "foo bar baz".match(/ba./) # => [ 'bar', index: 4, input: 'foo bar baz' ]
 * Searching for substrings # "foo bar baz".search(/ba./) # => 4
 * Replacing substrings # "foo bar baz".replace( /ba./, 'foo') # => "foo foo baz"
-* Extended "heregexes"
 
 h2. AJAX