MiniJava Compiler Project

This project implements a compiler for MiniJava, including a MiniC subset, using JavaCC for parsing and the Visitor pattern for compiler phases. The compiler transforms MiniJava source code through multiple stages such as syntax tree construction, pretty printing, type checking, and x86-64 assembly code generation.

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🚀 Features

• Parses MiniJava and MiniC programs using JavaCC
• Builds Abstract Syntax Trees (AST)
• Pretty prints MiniJava source code
• Converts C code to equivalent Python code
• Generates x86-64 assembly code
• Constructs symbol tables for scope and type tracking
• Performs type checking for type safety

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🧩 Components

🔹 Parser (Compiler.jj)

• Tokenizes MiniJava/MiniC syntax
• Defines grammar rules for expressions, statements, and method declarations
• Builds the AST representing the program structure
• Generate the following files that compile and parse the program
  • Compiler.java
  • CompilerConstants.java
  • CompilerTokenManager.java
  • ParseException.java
  • SimpleCharStream.java
  • Token.java
  • TokenMgrError.java

🔹 Visitor Implementations

AST_Visitor

• Traverses the AST and prints its structure with indentation
• Displays node class names, hierarchy, and literal values

public Object visit(Program node, Object data){
    System.out.println(indentString() + getClassName(node));
    ++indent;
    node.m.accept(this,data);
    if (node.c!=null){
        node.c.accept(this,data);
    }
    --indent;
    return data;
}

PP_Visitor (Demo)

• Pretty prints MiniJava programs with proper formatting

C2Python_Visitor (Demo)

• Converts C code to Python, handling:
  • Function declarations
  • Control structures (if, while)
  • Expressions and type conversions

public Object visit(MethodDecl node, Object data){
    int indent = (int) data; 
    String id = (String) node.i.accept(this,indent);
    String formalList = "";
    if (node.f!=null){
        formalList = (String) node.f.accept(this,indent);
    }
    // ...
    return indentString(indent) + "def " + id + "(" + formalList + "):\n" + 
           statementList + indentString(indent+1) + "return " + expr;
} 

CodeGen_Visitor_Tiara (Demo)

• Generates x86-64 assembly code
• Manages:
  • Register allocation
  • Stack frame setup
  • Procedure calls
  • Array access
  • Control flow

public Object visit(Print node, Object data){ 
    Exp e=node.e;
    String expCode = (String) node.e.accept(this, data);

    String result = 
        expCode
    + "# "+node.accept(ppVisitor, 0)
    +   "popq %rdi\n"
    +   "movb	$0, %al\n"  
    +   "callq print\n";

    return result;
}

SymbolTableVisitor (Demo)

• Builds symbol tables for:
  • Variable declarations
  • Method signatures
  • Class scopes and types

TypeCheckingVisitor (Demo)

• Validates type correctness throughout the AST

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🧪 MiniJava Language Support

MiniJava (Full Subset)

• Classes with methods and instance variables
• Integer, boolean, and array types
• If/else and while control structures
• Binary operations: +, -, *, <, &&
• Method calls

MiniC (Restricted Subset)

• No classes or instance variables
• Only method declarations
• Integer and boolean types
• Limited expressions: <, +, -, *, literals, and identifiers
• Statements: assignment, if, and print

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🛠️ Build & Run

The project includes several build scripts:

build.sh: Compiles the Java files and runs a demo

clean.sh: Cleans generated files and preserves visitor implementations

🔧 Testing

The tests directory contains various test files including:

• hello.c: Simple C program that calculates and prints a square
• print.c: Support code for print functionality
• Other test cases for different language features

🗂️ Project Structure

• src: Java source files for visitors and compiler logic
• bin: Compiled classes and JavaCC grammar file
• tests: Test input files and generated outputs
• syntaxtree: AST node classes

🌳 Abstract Syntax Tree

The AST represents programs as a hierarchy of node types:

• Program
  Top-level node containing MainClass and class declarations
• MainClass
  Entry point with main method
• Statement nodes
  • Block
  • If
  • While
  • Print
  • Assign
• Expression nodes
  • Plus
  • Minus
  • Times
  • LessThan
  • …etc.
• Type nodes
  • IntegerType
  • BooleanType
  • IntArrayType
• Lists
  • StatementList
  • ExpList
  • VarDeclList
  • …etc.