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

Determining the type at each syntax tree node

Within the syntax tree, the nodes associated with actual code expressions in the method bodies have a type associated with the value that the expression computes. For example, if a tree node corresponds to the sum of adding two numbers, the tree node's type is determined by the types of the operands and the rules of the language for the addition operator. Our goal for this section is to spell out how this type information can be calculated.

As you saw in the Type representation in the compiler section, the class for syntax tree nodes has an attribute to store that node's type, if there is one. The type attribute is calculated bottom-up, during a post-order tree traversal. There is a similarity here to checking for undeclared variables, which we did in the previous chapter, in that type checking expressions only occur in the bodies of functions. The call to invoke this type checking tree traversal, starting at the root of the...