⚙️ Mini Compiler (C++)

A lightweight, education-oriented compiler designed to transform infix arithmetic expressions into stack-based assembly instructions. This project demonstrates the core phases of compilation, from lexical analysis to code generation, with built-in AST optimizations.

✨ Features

• Lexical Analysis (Tokenizer): Converts raw source code into a stream of typed tokens (Identifiers, Numbers, Operators).
• Abstract Syntax Tree (AST): Builds a hierarchical representation of expressions to preserve operator precedence.
• Constant Folding Optimization: Automatically evaluates constant expressions at compile-time (e.g., 5 * 2 becomes 10) to improve runtime efficiency.
• Stack-based Code Generation: Produces VM-style instructions (PUSH, LOAD, ADD, STORE) suitable for stack machines.

🚀 Getting Started

Prerequisites

• GCC/G++ Compiler

Compilation

Build the compiler using the following command:

g++ main.cpp lexer.cpp parser.cpp codegen.cpp -o compiler

Usage

1. Define your expression in input.txt (Example: a = b + 5 * 2)
2. Run the compiler:

./compiler

📊 Sample Transformation

Input (input.txt):

a = b + 5 * 2

Output (Instructions):

LOAD b
PUSH 10
ADD
STORE a

Note how 5 * 2 was optimized to 10 via constant folding.

🧠 Architectural Overview

1. Lexer: Scans input for valid symbols.
2. Parser: Recursively constructs an AST and applies fold() to simplify nodes.
3. Generator: Recursively traverses the optimized AST to emit postfix-style instructions.

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Developed as a pedagogical tool for understanding compiler construction and optimization.