A Simple Parser
The Interpreter pattern discussed in Chapter 11 does not cover parsing. An interpreter without a parser is pretty incomplete, unless you persuade your users to write PHP code to invoke the interpreter! Third-party parsers are available that could be deployed to work with the Interpreter pattern, and that would probably be the best choice in a real-world project. This appendix, however, presents a simple object-oriented parser designed to work with the MarkLogic interpreter built in Chapter 11. Be aware that these examples are no more than a proof of concept. They are not designed for use in real-world situations.