To minimise memory usage, a Flyweight shares as much as possible memory with similar objects. It is needed when a large amount of objects is used that don't differ much in state. A common practice is to hold state in external data structures and pass them to the flyweight object when needed.
You can also find this code on GitHub
Text.php
Text.php
Word.php
Word.php
Character.php
Character.php
TextFactory.php
TextFactory.php
Tests/FlyweightTest.php
Tests/FlyweightTest.php