IronJava

IronJava is a native .NET library that parses Java source files and provides a strongly-typed Abstract Syntax Tree (AST) accessible in C#. Built for .NET 9, it supports Java 17 syntax with comprehensive visitor pattern implementation, AST transformations, and JSON serialization.

Features

• Full Java 17 Support: Parse modern Java syntax including records, sealed classes, and pattern matching
• Strongly-Typed AST: Over 70+ typed AST node classes representing all Java constructs
• Visitor Pattern: Dual visitor interfaces for traversing and transforming the AST
• AST Transformations: Built-in transformers for renaming, modifier changes, and node removal
• LINQ-Style Queries: Search and filter AST nodes with fluent query syntax
• JSON Serialization: Export AST to JSON for interoperability
• Cross-Platform: Works on Windows, Linux, and macOS
• Container-Ready: Optimized for use in Docker containers and cloud environments

Requirements

• .NET 9.0 or later
• Cross-platform: Windows, Linux, macOS

Installation

Install IronJava via NuGet:

dotnet add package IronJava

Or via Package Manager Console:

Install-Package IronJava

Quick Start

using MarketAlly.IronJava.Core;
using MarketAlly.IronJava.Core.AST.Nodes;
using MarketAlly.IronJava.Core.AST.Query;

// Parse Java source code
var parser = new JavaParser();
var result = parser.Parse(@"
    public class HelloWorld {
        public static void main(String[] args) {
            System.out.println(""Hello, World!"");
        }
    }
");

if (result.Success)
{
    var ast = result.CompilationUnit;
    
    // Find all method declarations
    var methods = ast.FindAll<MethodDeclaration>();
    
    // Query for the main method
    var mainMethod = ast.Query<MethodDeclaration>()
        .WithName("main")
        .WithModifier(Modifiers.Public | Modifiers.Static)
        .ExecuteFirst();
    
    Console.WriteLine($"Found main method: {mainMethod?.Name}");
}

Core Concepts

AST Structure

IronJava provides a comprehensive typed AST hierarchy:

CompilationUnit
├── PackageDeclaration
├── ImportDeclaration[]
└── TypeDeclaration[]
    ├── ClassDeclaration
    │   ├── Members[]
    │   └── NestedTypes[]
    ├── InterfaceDeclaration
    │   ├── Members[]
    │   └── NestedTypes[]
    ├── EnumDeclaration
    │   ├── Constants[]
    │   ├── Members[]
    │   └── NestedTypes[]
    └── AnnotationDeclaration
        └── Members[]

Visitor Pattern

Use visitors to traverse and analyze the AST:

public class MethodCounter : JavaVisitorBase
{
    public int Count { get; private set; }
    
    public override void VisitMethodDeclaration(MethodDeclaration node)
    {
        Count++;
        base.VisitMethodDeclaration(node);
    }
}

// Usage
var counter = new MethodCounter();
ast.Accept(counter);
Console.WriteLine($"Total methods: {counter.Count}");

AST Transformations

Transform your code programmatically:

// Rename all occurrences of a variable
var renamer = new IdentifierRenamer("oldName", "newName");
var transformed = ast.Accept(renamer);

// Add final modifier to all classes
var modifier = ModifierTransformer.AddModifier(Modifiers.Final);
var finalClasses = ast.Accept(modifier);

// Chain multiple transformations
var transformer = new TransformationBuilder()
    .AddModifier(Modifiers.Final)
    .RenameIdentifier("oldVar", "newVar")
    .RemoveNodes(node => node is JavaDoc)
    .Build();
    
var result = transformer.Transform(ast);

LINQ-Style Queries

Search the AST with powerful query expressions:

// Find all public static methods
var publicStaticMethods = ast
    .FindAll<MethodDeclaration>()
    .Where(m => m.Modifiers.IsPublic() && m.Modifiers.IsStatic());

// Find all classes implementing Serializable
var serializableClasses = ast
    .QueryClasses()
    .Where(c => c.Interfaces.Any(i => i.Name == "Serializable"))
    .Execute();

// Find getter methods
var getters = ast
    .FindAll<MethodDeclaration>()
    .Where(m => m.IsGetter());

// Access nested types
var outerClass = ast.Types.OfType<ClassDeclaration>().First();
foreach (var nestedType in outerClass.NestedTypes)
{
    Console.WriteLine($"Nested: {nestedType.Name} ({nestedType.GetType().Name})");
}

JSON Serialization

Export AST to JSON for external tools:

var serializer = new AstJsonSerializer();
string json = serializer.Serialize(ast);

// Output:
// {
//   "nodeType": "CompilationUnit",
//   "types": [{
//     "nodeType": "ClassDeclaration",
//     "name": "HelloWorld",
//     "modifiers": ["public"],
//     ...
//   }]
// }

Advanced Usage

Error Handling

var result = parser.Parse(javaSource);

if (!result.Success)
{
    foreach (var error in result.Errors)
    {
        Console.WriteLine($"Error at {error.Location}: {error.Message}");
    }
}

AST Comparison

var comparer = new AstEqualityComparer(
    ignoreLocation: true,
    ignoreJavaDoc: true
);

bool areEqual = comparer.Equals(ast1, ast2);

// Compute differences
var differ = new AstDiffer();
var diff = differ.ComputeDiff(original, modified);

Console.WriteLine($"Added: {diff.Additions.Count()}");
Console.WriteLine($"Deleted: {diff.Deletions.Count()}");
Console.WriteLine($"Modified: {diff.Modifications.Count()}");

Pattern Matching

// Check if a class follows singleton pattern
bool isSingleton = classDecl.IsSingletonClass();

// Find all main methods
var mainMethods = ast
    .FindAll<MethodDeclaration>()
    .Where(m => m.IsMainMethod());

Supported Java Features

• ✅ Classes, Interfaces, Enums, Records
• ✅ Annotations and Annotation Types
• ✅ Generics and Type Parameters
• ✅ Lambda Expressions
• ✅ Method References
• ✅ Switch Expressions
• ✅ Pattern Matching
• ✅ Sealed Classes
• ✅ Text Blocks
• ✅ var/Local Type Inference
• ✅ Modules (Java 9+)

Performance

IronJava is designed for performance:

• Immutable AST nodes for thread safety
• Efficient visitor pattern implementation
• Minimal allocations during parsing
• Optimized for large codebases

Contributing

We welcome contributions! Please see our Contributing Guide for details.

License

IronJava is licensed under the MIT License. See LICENSE for details.

Acknowledgments

• Built on ANTLR4 with the official Java grammar
• Inspired by JavaParser and Spoon

Support

• 📖 Documentation
• 🐛 Issue Tracker
• 💬 Discussions
• 📧 Email: dev@marketally.com