Let's Create a Compiler (Pt.1)

Introduction

This tutorial will guide you through the initial steps of creating a compiler, as demonstrated in the video series by Pixeled. The focus is on understanding the basics of compiler design, particularly lexical analysis. By the end of this guide, you'll have a foundational understanding of how to set up a simple compiler project and the importance of lexical analysis in the compilation process.

Step 1: Set Up Your Development Environment

Before you start coding, ensure you have the necessary tools installed on your computer. This includes a C++ compiler and a text editor.

• Install a C++ Compiler: You can use GCC or Clang. For Windows, consider installing MinGW or using WSL.
• Choose a Text Editor or IDE: Options like Visual Studio Code, CLion, or even simple editors like Vim can work well.
• Clone the Repository: Access the GitHub repository for the project to get the initial setup:

  git clone https://github.com/orosmatthew/hydrogen-cpp
  

Step 2: Understand Lexical Analysis

Lexical analysis is the first phase of a compiler where the source code is converted into tokens. Understanding this concept is crucial for creating a functional compiler.

• What is a Token?: A token is a string with an assigned meaning. Types of tokens include keywords, operators, identifiers, and literals.

Resources for Learning

• Read about lexical analysis on Wikipedia.
• Refer to the Linux Syscalls documentation for deeper insights into system calls used in compilers.

Step 3: Create a Simple Lexer

A lexer (lexical analyzer) reads the input source code and produces tokens. Here’s how to get started:

• Define the Token Structure: Create a structure to represent a token. For example:

  struct Token {
      enum class Type { Keyword, Identifier, Operator, Literal };
      Type type;
      std::string value;
  };
  

Implement the Lexer Logic

• Read characters from the input.
• Use conditions to identify different token types.
• Store identified tokens in a list.

Example Lexer Function

Here’s a simple example of a lexer function:

std::vector<Token> lexer(const std::string &source) {
    std::vector<Token> tokens;
    // Add logic to parse the source code and fill the tokens vector
    return tokens;
}

Step 4: Test Your Lexer

Once your lexer is implemented, it’s time to test its functionality.

• Create Test Cases: Write various input strings that represent different constructs of your programming language.
• Run the Lexer: Pass the test cases to your lexer to see if it generates the correct tokens.

Debugging Tips: If your lexer fails, check for common issues like

• Incorrect character handling.
• Missing token definitions.

Conclusion

In this first part of creating a compiler, you learned about setting up your development environment, the basics of lexical analysis, and how to implement a simple lexer. These foundational steps are crucial for building a functional compiler.

Next Steps

• Continue with Part 2 of the series to explore parsing and further compiler design concepts.
• Experiment with enhancing your lexer to support more complex token types and error handling.