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

Chapter 5

  1. The yylex() lexical analyzer allocates a leaf and stores it in yylval for each terminal symbol that it returns to yyparse().
  2. When a production rule in the grammar is reduced, the semantic action code in the parser allocates an internal node and initializes its children to refer to the leaves and internal nodes corresponding to symbols on the right-hand side of that production rule.
  3. yyparse() maintains a value stack that grows and shrinks in lock-step with the parse stack during parsing. Leaves and internal nodes are stored on the value stack until they are inserted as children into a containing internal node.
  4. A value stack is fully generic and can contain any type of value. In C, this is done using a union type, which is type-unsafe. In Java, it is done using a parserVal class that contains the tree nodes in a generic way. In Unicon and other dynamic languages, no wrapping or unwrapping is needed.