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

Understanding context-free grammars

In this section, we will define the notation used by programming language inventors to describe the syntax of their language. You will be able to use what you learn in this section to supply syntax rules as input to the parser generators used in the next section. Let's begin by understanding what context-free grammars are.

Context-free grammars are the most widely used notation for describing the syntax allowed in a programming language in terms of patterns of lexemes. They are formulated from very simple rules that are easy to understand. Context-free grammars are built from the following components:

  • Terminal symbols: A set of input symbols are called terminal symbols. Terminal symbols in a grammar are read in from a scanner such as the one we produced in the last chapter. Although they are referred to as symbols, terminal symbols correspond to an entire word, operator, or punctuation mark; a terminal symbol identifies the category...