An implementation of the Pattern interface for Perl5 regular expressions.
This class is compatible with the Perl5Compiler and Perl5Matcher
classes. When a Perl5Compiler instance compiles a regular expression
pattern, it produces a Perl5Pattern instance containing internal
data structures used by Perl5Matcher to perform pattern matches.
This class cannot be subclassed and
cannot be directly instantiated by the programmer as it would not
make sense. Perl5Pattern instances should only be created through calls
to a Perl5Compiler instance's compile() methods. The class implements
the Serializable interface so that instances may be pre-compiled and
saved to disk if desired.