/foo  # Match starting at foo
 (         # Capture
 (?:       # Complex expression:
   (?!baz) #   make sure we're not at the beginning of baz 
   .       #   accept any character
 )*        # any number of times
 )         # End capture
 bar  # and ending at bar
/x;

##</code><code>##

 (?:       # Complex expression:
   (?!Lib) #   make sure we're not at the beginning of Lib
   [^\n]       #   accept any character
 )+        # any positive number of times