com.google.inject.internal.ProviderInternalFactory Maven / Gradle / Ivy

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package com.google.inject.internal;

import com.google.inject.spi.Dependency;

import javax.inject.Provider;

import static com.google.common.base.Preconditions.checkNotNull;

/**
 * Base class for InternalFactories that are used by Providers, to handle
 * circular dependencies.
 *
 */
abstract class ProviderInternalFactory implements InternalFactory {

    protected final Object source;

    ProviderInternalFactory(Object source) {
        this.source = checkNotNull(source, "source");
    }

    protected T circularGet(final Provider provider,
                            InternalContext context,
                            final Dependency dependency,
                            ProvisionListenerStackCallback provisionCallback)
            throws InternalProvisionException {
        final ConstructionContext constructionContext = context.getConstructionContext(this);
        // We have a circular reference between constructors. Return a proxy.
        if (constructionContext.isConstructing()) {
            Class expectedType = dependency.getKey().getTypeLiteral().getRawType();
            // TODO: if we can't proxy this object, can we proxy the other object?
            @SuppressWarnings("unchecked")
            T proxyType = (T) constructionContext.createProxy(context.getInjectorOptions(), expectedType);
            return proxyType;
        }
        // Optimization: Don't go through the callback stack if no one's listening.
        constructionContext.startConstruction();
        try {
            if (!provisionCallback.hasListeners()) {
                return provision(provider, dependency, constructionContext);
            } else {
                return provisionCallback.provision(context, () ->
                        provision(provider, dependency, constructionContext));
            }
        } finally {
            constructionContext.removeCurrentReference();
            constructionContext.finishConstruction();
        }
    }

    /**
     * Provisions a new instance. Subclasses should override this to catch
     * exceptions & rethrow as ErrorsExceptions.
     */
    protected T provision(Provider provider, Dependency dependency,
                          ConstructionContext constructionContext) throws InternalProvisionException {
        T t = provider.get();
        if (t == null && !dependency.isNullable()) {
            InternalProvisionException.onNullInjectedIntoNonNullableDependency(source, dependency);
        }
        constructionContext.setProxyDelegates(t);
        return t;
    }
}