Building a custom batch compiler is a fantastic way to understand how source code transforms into executable binaries or scripts without manual intervention. A batch compiler automatically processes source files in bulk—sequentially or in parallel—running them through traditional compiler pipeline phases.
The essential pipeline for designing and building your very first custom batch compiler is outlined below. Step 1: Define the Source Syntax and Target Language
Before writing any code, determine what your input language looks like and what your output language will be.
Source Language: Design a simple, restricted grammar (e.g., variable assignments, basic math, and if statements).
Target Output: Instead of emitting complex machine-code binaries from scratch, compile your code into C or JavaScript. This approach, known as a transpiler, allows you to let an existing ecosystem (like GCC or Node.js) handle final execution. Step 2: Build the Lexer (Tokenization)
The lexer reads your source code file as a raw text string and breaks it down into individual, meaningful units called tokens. The text x = 5 + 10 is processed character by character.
It outputs a flat array of categorized objects:[Identifier: “x”, Assignment: “=”, Number: “5”, Operator: “+”, Number: “10”]. Step 3: Implement the Parser (AST Generation)
The parser takes the flat list of tokens from your lexer and converts it into a hierarchical data structure called an Abstract Syntax Tree (AST).
It validates the structure against your grammar rules. For example, ensuring an equal sign is preceded by a valid variable name.
It groups operations by order of operations, establishing parent-child relationships for math and logic blocks. Step 4: Create the Code Generator (Emitter)
The code generator traverses your AST and maps each structural node into corresponding strings of your target language.
Leave a Reply