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

Generating code for expressions

The easiest code to generate is straight-line code consisting of statements and expressions that execute in sequence with no control flow. As described earlier in this chapter, there are two attributes to compute for each node: the attribute for where to find an expression's value is called addr, while the intermediate code necessary to compute its value is called icode. The values to be computed for these attributes for a subset of the Jzero expression grammar are shown in the following table. The ||| operator refers to list concatenation:

Figure 9.4 – Semantic rules for expressions

The main intermediate code generation algorithm is a bottom-up post-order traversal of the syntax tree. To present it in small chunks, the traversal is broken into the main method, gencode(), and helper methods for each non-terminal. In Unicon, the gencode() method in tree.icn looks as follows:

method gencode()
  every (...