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graph_resolver › Classes › GraphResolver

GraphResolver ​

class GraphResolver

Resolves the module import graph and initializes dependencies concurrently.

For each import declared by a Module, the resolver:

  1. Checks for circular dependencies using a per-branch resolutionStack.
  2. Looks up (or creates) a ModuleController in the shared registry to avoid duplicate initialization.
  3. Initializes the controller if it has not started yet, or waits for an in-progress initialization triggered by a concurrent branch.

All import branches are resolved in parallel via Future.wait, maximizing throughput for large module graphs.

See also:

Constructors ​

GraphResolver() ​

GraphResolver()

Properties ​

hashCode no setter inherited ​

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

Implementation
dart
external int get hashCode;

runtimeType no setter inherited ​

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation
dart
external Type get runtimeType;

Methods ​

noSuchMethod() inherited ​

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dart
dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

dart
class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation
dart
@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

resolveAndInitImports() ​

Future<List<ModuleController>> resolveAndInitImports(dynamic module, Map<ModuleRegistryKey, ModuleController> registry, dynamic binderFactory, {Set<Type>? resolutionStack, List<dynamic> interceptors = const [], ModuleOverrideScope? overrideScope})

Recursively resolves and initializes the imports of module.

Returns the list of ModuleControllers for the direct imports. Throws CircularDependencyException or ModuleLifecycleException if resolution fails.

Implementation
dart
Future<List<ModuleController>> resolveAndInitImports(
  Module module,
  Map<ModuleRegistryKey, ModuleController> registry,
  BinderFactory binderFactory, {
  Set<Type>? resolutionStack,
  List<ModuleInterceptor> interceptors = const [],
  ModuleOverrideScope? overrideScope,
}) async {
  final currentStack = resolutionStack ?? {module.runtimeType};

  &#47;&#47; 1. Prepare all tasks (Futures) and launch them concurrently
  final futures = module.imports.map((importModule) async {
    final type = importModule.runtimeType;

    &#47;&#47; Check Circular Dependency (Immediate Fail-Fast)
    if (currentStack.contains(type)) {
      throw CircularDependencyException(
        'Circular dependency detected: ${currentStack.join(' -> ')} -> $type',
        dependencyChain: [...currentStack, type],
      );
    }

    &#47;&#47; --- CRITICAL SECTION START (Synchronous) ---
    &#47;&#47; Important: Getting or creating the controller must be atomic
    &#47;&#47; so that concurrent branches don't create duplicates.
    &#47;&#47; In Dart this block won't be preempted as long as there's no await.
    final childScope = overrideScope?.childFor(type);
    final registryKey = ModuleRegistryKey(
      moduleType: type,
      overrideScope: childScope,
    );
    ModuleController? controller = registry[registryKey];

    if (controller == null) {
      controller = ModuleController(
        importModule,
        binderFactory: binderFactory,
        overrideScopeTree: childScope,
        interceptors: interceptors,
      );
      registry[registryKey] = controller;
    }
    &#47;&#47; --- CRITICAL SECTION END ---

    &#47;&#47; Branch A and Branch B each get their own copy of the stack.
    &#47;&#47; This allows safe cycle detection across concurrent branches.
    final newStack = {...currentStack, type};

    &#47;&#47; Now it's safe to await (yield execution)
    if (controller.currentStatus == ModuleStatus.initial) {
      await controller.initialize(registry, resolutionStack: newStack);
    } else if (controller.currentStatus == ModuleStatus.loading) {
      &#47;&#47; If the module is already loading (triggered by another branch), just wait.
      &#47;&#47; Check for cycles in THIS branch
      if (currentStack.contains(type)) {
        throw CircularDependencyException(
          'Circular dependency detected (during loading): ${currentStack.join(' -> ')} -> $type',
          dependencyChain: [...currentStack, type],
        );
      }
      &#47;&#47; Smart Wait: Wait until the other branch finishes
      await controller.status.firstWhere(
        (s) =>
            s == ModuleStatus.loaded ||
            s == ModuleStatus.error ||
            s == ModuleStatus.disposed,
      );

      if (controller.currentStatus == ModuleStatus.error) {
        throw ModuleLifecycleException(
          'Dependent module $type failed to load: ${controller.lastError}',
          moduleType: type,
          state: ModuleStatus.error,
        );
      }
      if (controller.currentStatus == ModuleStatus.disposed) {
        throw ModuleLifecycleException(
          'Dependent module $type was disposed during initialization.',
          moduleType: type,
          state: ModuleStatus.disposed,
        );
      }
    } else if (controller.currentStatus == ModuleStatus.error) {
      throw ModuleLifecycleException(
        'Dependent module $type failed to load: ${controller.lastError}',
        moduleType: type,
        state: ModuleStatus.error,
      );
    }

    return controller;
  });

  &#47;&#47; 2. Await all branches concurrently
  final resolvedControllers = await Future.wait(futures);

  return resolvedControllers;
}

toString() inherited ​

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

Implementation
dart
external String toString();

Operators ​

operator ==() inherited ​

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

  • Total: It must return a boolean for all arguments. It should never throw.

  • Reflexive: For all objects o, o == o must be true.

  • Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

  • Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

Implementation
dart
external bool operator ==(Object other);