Book Image

Build Your Own Programming Language

By : Clinton L. Jeffery
Book Image

Build Your Own Programming Language

By: Clinton L. Jeffery

Overview of this book

The need for different types of computer languages is growing rapidly and developers prefer creating domain-specific languages for solving specific application domain problems. Building your own programming language has its advantages. It can be your antidote to the ever-increasing size and complexity of software. In this book, you’ll start with implementing the frontend of a compiler for your language, including a lexical analyzer and parser. The book covers a series of traversals of syntax trees, culminating with code generation for a bytecode virtual machine. Moving ahead, you’ll learn how domain-specific language features are often best represented by operators and functions that are built into the language, rather than library functions. We’ll conclude with how to implement garbage collection, including reference counting and mark-and-sweep garbage collection. Throughout the book, Dr. Jeffery weaves in his experience of building the Unicon programming language to give better context to the concepts where relevant examples are provided in both Unicon and Java so that you can follow the code of your choice of either a very high-level language with advanced features, or a mainstream language. By the end of this book, you’ll be able to build and deploy your own domain-specific languages, capable of compiling and running programs.
Table of Contents (25 chapters)
1
Section 1: Programming Language Frontends
7
Section 2: Syntax Tree Traversals
13
Section 3: Code Generation and Runtime Systems
21
Section 4: Appendix

Chapter 3: Scanning Source Code

The first step in any programming language is reading the individual characters of input source code and figuring out which characters are grouped. In a natural language, this would include looking at the adjacent sequences of letters to identify the words. In a programming language, clusters of characters form variable names, reserved words, or sometimes operators or punctuation marks that are several characters long. This chapter will teach you how to use pattern matching to read in source code and identify the words and punctuation from the raw characters.

In this chapter, we're going to cover the following main topics:

  • Lexemes, lexical categories, and tokens
  • Regular expressions
  • Using UFlex and JFlex
  • Writing a scanner for Jzero
  • Regular expressions are not always enough

First, let's look at the several kinds of words that appear in program source code. Just as a natural language reader must distinguish the...