Book Image

PHP 7 Programming Blueprints

By : Jose Palala, Martin Helmich
Book Image

PHP 7 Programming Blueprints

By: Jose Palala, Martin Helmich

Overview of this book

When it comes to modern web development, performance is everything. The latest version of PHP has been improvised and updated to make it easier to build for performance, improved engine execution, better memory usage, and a new and extended set of tools. If you’re a web developer, what’s not to love? This guide will show you how to make full use of PHP 7 with a range of practical projects that will not only teach you the principles, but also show you how to put them into practice. It will push and extend your skills, helping you to become a more confident and fluent PHP developer. You’ll find out how to build a social newsletter service, a simple blog with a search capability using Elasticsearch, as well as a chat application. We’ll also show you how to create a RESTful web service, a database class to manage a shopping cart on an e-commerce site and how to build an asynchronous microservice architecture. With further guidance on using reactive extensions in PHP, we’re sure that you’ll find everything you need to take full advantage of PHP 7. So dive in now!
Table of Contents (15 chapters)
PHP 7 Programming Blueprints
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
4
Build a Simple Blog with Search Capability using Elasticsearch

Building an Abstract Syntax Tree


Currently, our parser interprets the input code and evaluates it in the same pass. Most compilers and interpreters; however, create an intermediate data structure before actually running the program: an Abstract Syntax Tree (AST). Using an AST offers some interesting possibilities; for example, it provides you with a structured representation of your program that you can then analyze. Also, you can use the AST and transform it back into a text-based program (maybe of another language).

An AST is a tree that represents the structure of a program. The first step to building an AST-based parser is to design the tree's object model: which classes are needed and in which way are they associated to another. The following figure shows the first draft for an object model that can be used to describe mathematical expressions:

The (preliminary) object model for our Abstract Syntax Tree

In this model, nearly all classes implement the Expression interface. This interface...