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

Checking operations on array types

An array is a sequence of elements that are all of the same type. Up to this point, the Jzero language hasn't really supported array types, other than to allow enough syntax for main() to declare its array of the String parameter. Now, it is time to add support for the remainder of the Jzero array operations, which are a small subset of what Java arrays can do. Jzero arrays are limited to single-dimension arrays created without initializers. In order to check array operations properly, we will modify the code from the previous chapters so that we can recognize array variables when they are declared, and then check all uses on these arrays to only allow legal operations. Let's begin with array variable declarations.

Handling array variable declarations

The idea that a variable will hold a reference to an array is attached to the variable's type in the recursive grammar rule, in j0gram.y, for the non-terminal VarDeclarator. The...