guice/src/main/java/com/google/inject/internal/InstanceBindingImpl.java

package com.google.inject.internal;

import com.google.common.base.MoreObjects;
import com.google.common.base.Objects;
import com.google.common.collect.ImmutableSet;
import com.google.inject.Binder;
import com.google.inject.Key;
import com.google.inject.Provider;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.HasDependencies;
import com.google.inject.spi.InjectionPoint;
import com.google.inject.spi.InstanceBinding;
import com.google.inject.util.Providers;

import java.util.Set;

final class InstanceBindingImpl<T> extends BindingImpl<T> implements InstanceBinding<T> {

    final T instance;
    final Provider<T> provider;
    final ImmutableSet<InjectionPoint> injectionPoints;

    public InstanceBindingImpl(InjectorImpl injector, Key<T> key, Object source,
                               InternalFactory<? extends T> internalFactory, Set<InjectionPoint> injectionPoints,
                               T instance) {
        super(injector, key, source, internalFactory, Scoping.EAGER_SINGLETON);
        this.injectionPoints = ImmutableSet.copyOf(injectionPoints);
        this.instance = instance;
        this.provider = Providers.of(instance);
    }

    public InstanceBindingImpl(Object source, Key<T> key, Scoping scoping,
                               Set<InjectionPoint> injectionPoints, T instance) {
        super(source, key, scoping);
        this.injectionPoints = ImmutableSet.copyOf(injectionPoints);
        this.instance = instance;
        this.provider = Providers.of(instance);
    }

    @Override
    public Provider<T> getProvider() {
        return this.provider;
    }

    public <V> V acceptTargetVisitor(BindingTargetVisitor<? super T, V> visitor) {
        return visitor.visit(this);
    }

    public T getInstance() {
        return instance;
    }

    public Set<InjectionPoint> getInjectionPoints() {
        return injectionPoints;
    }

    public Set<Dependency<?>> getDependencies() {
        return instance instanceof HasDependencies
                ? ImmutableSet.copyOf(((HasDependencies) instance).getDependencies())
                : Dependency.forInjectionPoints(injectionPoints);
    }

    public BindingImpl<T> withScoping(Scoping scoping) {
        return new InstanceBindingImpl<T>(getSource(), getKey(), scoping, injectionPoints, instance);
    }

    public BindingImpl<T> withKey(Key<T> key) {
        return new InstanceBindingImpl<T>(getSource(), key, getScoping(), injectionPoints, instance);
    }

    public void applyTo(Binder binder) {
        // instance bindings aren't scoped
        binder.withSource(getSource()).bind(getKey()).toInstance(instance);
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(InstanceBinding.class)
                .add("key", getKey())
                .add("source", getSource())
                .add("instance", instance)
                .toString();
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof InstanceBindingImpl) {
            InstanceBindingImpl<?> o = (InstanceBindingImpl<?>) obj;
            return getKey().equals(o.getKey())
                    && getScoping().equals(o.getScoping())
                    && Objects.equal(instance, o.instance);
        } else {
            return false;
        }
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(getKey(), getScoping());
    }
}