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 3

  1. A first approximation of the regular expression is [0-3][0-9]"/"[01][0-9]"/"[0-9]{4}. While it is possible to write a regular expression that matches only legal dates, such an expression is impractically long, especially considering leap years. In such cases, it makes sense to use the regular expression that provides the simplest close approximation of correctness, and then check correctness in the semantic action or a subsequent semantic analysis phase.
  2. yylex() returns an integer category for use in syntax analysis, while yytext is a string that contains the symbols matched and yylval holds an object called a token that contains all the lexical attributes of that lexeme.
  3. When a regular expression does not return a value, the characters that it matched are discarded and the yylex() function continues with a new match, starting with the next character in the input.
  4. Flex matches the longest string that it can; it breaks ties among multiple...