d4rt

d4rt (pronounced "dart") is an interpreter and runtime for the Dart language, written in Dart.
It allows you to execute Dart code dynamically, bridge native classes, and build advanced scripting or plugin systems in your Dart/Flutter applications.

Features

Dart interpreter: Run Dart code dynamically at runtime.
Full generics support: Complete support for generic classes, functions, and type constraints with runtime validation.
Type bounds checking: Enforce generic type constraints (e.g., T extends num) with dynamic resolution.
Bridging system: Expose your own Dart/Flutter classes, enums, and methods to interpreted code.
Async/await support: Handle asynchronous code and Futures.
Class, enum, and extension support: Use most Dart language features, including classes, inheritance, mixins, enums, and extensions.
Pattern matching: Support for Dart's pattern matching in switch/case and assignments.
Runtime type validation: Validate generic type arguments and method parameters at runtime.
Security sandboxing: Permission-based security system to restrict dangerous operations and prevent malicious code execution.
Custom logging: Integrated, configurable logger for debugging interpreted code.
Extensible: Add your own bridges for custom types and native APIs.

Installation

Add to your pubspec.yaml:

dependencies:
  d4rt: # latest version

Then run:

dart pub get

Usage Example

import 'package:d4rt/d4rt.dart';

void main() {
  final code = '''
    int fib(int n) {
      if (n <= 1) return n;
      return fib(n - 1) + fib(n - 2);
    }
    main() {
      return fib(6);
    }
  ''';

  final interpreter = D4rt();
  final result = interpreter.execute(source: code);
  print('Result: $result'); // Result: 8
}

Security Sandboxing

d4rt includes a comprehensive permission-based security system to prevent malicious code execution. By default, access to dangerous modules like dart:io and dart:isolate is blocked unless explicitly granted.

Granting Permissions

import 'package:d4rt/d4rt.dart';

void main() {
  final interpreter = D4rt();

  // Grant filesystem access
  interpreter.grant(FilesystemPermission.any);

  // Grant network access
  interpreter.grant(NetworkPermission.any);

  // Grant process execution
  interpreter.grant(ProcessRunPermission.any);

  // Grant isolate operations
  interpreter.grant(IsolatePermission.any);

  // Now execute code that uses dangerous operations
  final result = interpreter.execute(source: '''
    import 'dart:io';
    import 'dart:isolate';

    void main() {
      // This code can now access filesystem, network, etc.
      print('Secure execution with granted permissions');
    }
  ''');
}

Permission Types

FilesystemPermission: Controls file and directory operations
- FilesystemPermission.any - Allow all filesystem operations
- FilesystemPermission.read - Allow read-only operations
- FilesystemPermission.write - Allow write operations
- FilesystemPermission.path('/specific/path') - Allow operations on specific paths
NetworkPermission: Controls network operations
- NetworkPermission.any - Allow all network operations
- NetworkPermission.connect('host:port') - Allow connections to specific hosts
ProcessRunPermission: Controls process execution
- ProcessRunPermission.any - Allow execution of any command
- ProcessRunPermission.command('specific-command') - Allow execution of specific commands
IsolatePermission: Controls isolate creation and communication
- IsolatePermission.any - Allow all isolate operations

Permission Management

final interpreter = D4rt();

// Grant permissions
interpreter.grant(FilesystemPermission.any);

// Check permissions
if (interpreter.hasPermission(FilesystemPermission.any)) {
  print('Filesystem access granted');
}

// Revoke permissions
interpreter.revoke(FilesystemPermission.any);

Bridging Native Classes & Enums

You can expose your own Dart classes and enums to the interpreter using the bridge system. Here are minimal examples:

Bridge a Dart Class (Minimal)

import 'package:d4rt/d4rt.dart';

class MyClass {
  int value;
  MyClass(this.value);
  int doubleValue() => value * 2;
}

final myClassBridge = BridgedClass(
  nativeType: MyClass,
  name: 'MyClass',
  constructors: {
    '': (InterpreterVisitor visitor, List<Object?> positionalArgs, Map<String, Object?> namedArgs) {
      if (positionalArgs.length == 1 && positionalArgs[0] is int) {
        return MyClass(positionalArgs[0] as int);
      }
      throw ArgumentError('MyClass constructor expects one integer argument.');
    },
  },
  methods: {
    'doubleValue': (InterpreterVisitor visitor, Object target, List<Object?> positionalArgs, Map<String, Object?> namedArgs) {
      if (target is MyClass) {
        return target.doubleValue();
      }
      throw TypeError();
    },
  },
  getters: {
    'value': (InterpreterVisitor? visitor, Object target) {
      if (target is MyClass) {
        return target.value;
      }
      throw TypeError();
    },
  },
);

void main() {
  final interpreter = D4rt();
  interpreter.registerBridgedClass(myClassBridge, 'package:example/my_class_library.dart');

  final code = '''
    import 'package:example/my_class_library.dart';

    main() {
      var obj = MyClass(21);
      return obj.doubleValue();
    }
  ''';

  final result = interpreter.execute(source: code);
  print(result); // 42
}

Bridge a Dart Enum (Minimal)

import 'package:d4rt/d4rt.dart';

enum Color { red, green, blue }

final colorEnumBridge = BridgedEnumDefinition<Color>(
  name: 'Color',
  values: Color.values,
);

void main() {
  final interpreter = D4rt();
  interpreter.registerBridgedEnum(colorEnumBridge, 'package:example/my_enum_library.dart');

  final code = '''
    import 'package:example/my_enum_library.dart';

    main() {
      var favoriteColor = Color.green;
      print('My favorite color is \${favoriteColor.name}');
      return favoriteColor.index;
    }
  ''';

  final result = interpreter.execute(source: code);
  print(result); // 1
}

Supported Features

Feature	Status / Notes
Classes & Inheritance	✅ Full support (abstract, inheritance, mixins, interfaces, sealed, base, final)
Enums	✅ Full support (fields, methods, static, named values, index, name)
Mixins	✅ Supported (declaration, application, on clause, constraints)
Extensions	✅ Supported (methods, getters, setters, operators)
Async/await	✅ Supported (async functions, await, Futures)
Pattern matching	✅ Supported (switch/case, if-case, destructuring, list/map/record patterns)
Collections (List, Map, Set)	✅ Supported (literals, spread, if/for, nested, null-aware, records)
Top-level functions	✅ Supported (named, anonymous, closures, nested)
Getters/Setters	✅ Supported (instance, static, extension, bridge)
Static members	✅ Supported (fields, methods, getters/setters, bridge)
Switch/case	✅ Supported (classic, pattern, default, fallthrough, exhaustive checks)
Try/catch/finally	✅ Supported (multiple catch, on/type, rethrow, stacktrace)
Imports	✅ Supported (URIs, show/hide clauses for libraries defined in `sources`)
Generics	✅ Full support (generic classes/functions, type constraints, runtime validation)
Operator overloading	✅ Full support
FFI	🚫 Not supported
Isolates	✅ Full support
Reflection/Mirrors	🚫 Not supported
Records	✅ Supported (positional, named, pattern matching)
String interpolation	✅ Supported
Cascade notation (`..`)	✅ Supported
Null safety	✅ Supported (null-aware ops, checks, patterns)
Type tests (`is`, `as`)	✅ Supported
Exception handling	✅ Supported (throw, rethrow, custom errors)

See the documentation for details and limitations.

Limitations

Operator overloading is partially supported (via extensions, not via class operator methods).
Some advanced Dart features (FFI, mirrors) are not available.
The interpreter is not a full Dart VM: some language features may behave differently.

Documentation

Contributing

Contributions are welcome!
Feel free to open issues, suggest features, or submit pull requests.

License

MIT License. See LICENSE.

About the Name

d4rt is a play on the word "dart", using "4" as a stylized "A".
It is pronounced exactly like "dart".