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

Improving syntax error messages

Earlier, we saw a bit about the yacc syntax error reporting mechanism. Yacc just calls a function named yyerror(s). Very rarely, this function can be called for an internal error such as a parse stack overflow, but usually when it is called, it is passed the string "parse error" or "syntax error" as its parameter. Neither is adequate for helping programmers find and fix their errors in the real world. If you write a function called yyerror() yourself, you can produce a better error message. The key is to have extra information available that the programmer can use. Usually, that extra information will have to be placed in a global or public static variable in order for yyerror() to access it. Let's look at how to write a better yyerror() function in Unicon, and then in Java.

Adding detail to Unicon syntax error messages

In the Putting together a toy example section earlier in this chapter, you saw a Unicon implementation...