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

Lexemes, lexical categories, and tokens

Programming languages read characters and group adjacent characters together when they are part of the same entity in the language. This can be a multi-character name or reserved word, a constant value, or an operator.

A lexeme is a string of adjacent characters that form a single entity. Most punctuation marks are lexemes unto themselves, in addition to separating what came before from what comes after them. In reasonable languages, whitespace characters such as spaces and tabs are ignored other than to separate lexemes. Almost all languages also have a way of including comments in the source code, and comments are typically treated the same as whitespace: they can be the boundary that separates two lexemes, but they are discarded and not considered further.

Each lexeme has a lexical category. In natural languages, lexical categories are called parts of speech. In a programming language implementation, the lexical category is generally...