Description:

Technically, PPI is short for Parse::Perl::Isolated. In
acknowledgement that someone may some day come up with a valid
solution for the grammar problem, it was decided to leave the
Parse::Perl namespace free.

The purpose of this parser is not to parse Perl code, but to parse
Perl documents. In most cases, a single file is valid as both. By
treating the problem this way, we can parse a single file containing
Perl source isolated from any other resources, such as the libraries
upon which the code may depend, and without needing to run an instance
of Perl alongside or inside the parser (a possible solution for
Parse::Perl that is investigated from time to time).