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

Creating and populating symbol tables for each scope

A symbol table contains a record of all the names that are declared for a scope. There is one symbol table for each scope. A symbol table provides a means of looking up symbols by their name to obtain information about them. If a variable was declared, the symbol table lookup returns a record with all the information known about that symbol: where it was declared, what its data type is, whether it is public or private, and so on. All this information can be found in the syntax tree. If we also place it in a table, the goal is to access the information directly, from anywhere else that information is needed.

The traditional implementation of a symbol table is a hash table, which provides a very fast information lookup. Your compiler could use any data structure that allows you to store or retrieve information associated with a symbol, even a linked list. But hash tables are the best for this, and they are standard in Unicon and...