limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 1 | /** |
| 2 | * Copyright (C) 2008 Google Inc. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package com.google.inject.spi; |
| 18 | |
sberlin | b7a02b0 | 2011-07-08 00:34:16 +0000 | [diff] [blame] | 19 | import static com.google.common.base.Preconditions.checkNotNull; |
| 20 | import static com.google.common.base.Preconditions.checkState; |
| 21 | |
Christian Edward Gruber | cade897 | 2014-04-01 15:07:02 -0700 | [diff] [blame] | 22 | import com.google.common.collect.ImmutableSet; |
limpbizkit@gmail.com | 9a227be | 2010-07-03 15:51:31 +0000 | [diff] [blame] | 23 | import com.google.inject.Binder; |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 24 | import com.google.inject.Key; |
| 25 | import com.google.inject.Provider; |
Christian Edward Gruber | cade897 | 2014-04-01 15:07:02 -0700 | [diff] [blame] | 26 | import com.google.inject.util.Types; |
| 27 | |
| 28 | import java.util.Set; |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 29 | |
| 30 | /** |
| 31 | * A lookup of the provider for a type. Lookups are created explicitly in a module using |
| 32 | * {@link com.google.inject.Binder#getProvider(Class) getProvider()} statements: |
| 33 | * <pre> |
| 34 | * Provider<PaymentService> paymentServiceProvider |
| 35 | * = getProvider(PaymentService.class);</pre> |
| 36 | * |
| 37 | * @author jessewilson@google.com (Jesse Wilson) |
limpbizkit | c489adf | 2008-11-18 07:01:33 +0000 | [diff] [blame] | 38 | * @since 2.0 |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 39 | */ |
| 40 | public final class ProviderLookup<T> implements Element { |
| 41 | private final Object source; |
sameb | 9867f9c | 2015-02-02 12:45:25 -0800 | [diff] [blame] | 42 | private final Dependency<T> dependency; |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 43 | private Provider<T> delegate; |
| 44 | |
limpbizkit | 8d62075 | 2009-03-31 22:37:26 +0000 | [diff] [blame] | 45 | public ProviderLookup(Object source, Key<T> key) { |
sameb | 9867f9c | 2015-02-02 12:45:25 -0800 | [diff] [blame] | 46 | this(source, Dependency.get(checkNotNull(key, "key"))); |
| 47 | } |
| 48 | |
| 49 | /** @since 4.0 */ |
| 50 | public ProviderLookup(Object source, Dependency<T> dependency) { |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 51 | this.source = checkNotNull(source, "source"); |
sameb | 9867f9c | 2015-02-02 12:45:25 -0800 | [diff] [blame] | 52 | this.dependency = checkNotNull(dependency, "dependency"); |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 53 | } |
| 54 | |
| 55 | public Object getSource() { |
| 56 | return source; |
| 57 | } |
| 58 | |
| 59 | public Key<T> getKey() { |
sameb | 9867f9c | 2015-02-02 12:45:25 -0800 | [diff] [blame] | 60 | return dependency.getKey(); |
| 61 | } |
| 62 | |
cgdecker | 646e174 | 2015-04-24 12:41:43 -0700 | [diff] [blame^] | 63 | /** @since 4.0 */ |
sameb | 9867f9c | 2015-02-02 12:45:25 -0800 | [diff] [blame] | 64 | public Dependency<T> getDependency() { |
| 65 | return dependency; |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 66 | } |
| 67 | |
limpbizkit | afa4b5d | 2008-08-02 18:40:47 +0000 | [diff] [blame] | 68 | public <T> T acceptVisitor(ElementVisitor<T> visitor) { |
limpbizkit | 03b81a6 | 2009-03-18 05:34:39 +0000 | [diff] [blame] | 69 | return visitor.visit(this); |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 70 | } |
| 71 | |
limpbizkit | 03b81a6 | 2009-03-18 05:34:39 +0000 | [diff] [blame] | 72 | /** |
| 73 | * Sets the actual provider. |
| 74 | * |
limpbizkit | 03b81a6 | 2009-03-18 05:34:39 +0000 | [diff] [blame] | 75 | * @throws IllegalStateException if the delegate is already set |
limpbizkit | 03b81a6 | 2009-03-18 05:34:39 +0000 | [diff] [blame] | 76 | */ |
| 77 | public void initializeDelegate(Provider<T> delegate) { |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 78 | checkState(this.delegate == null, "delegate already initialized"); |
limpbizkit | 97eac0f | 2009-03-28 18:25:35 +0000 | [diff] [blame] | 79 | this.delegate = checkNotNull(delegate, "delegate"); |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 80 | } |
| 81 | |
limpbizkit | 03b81a6 | 2009-03-18 05:34:39 +0000 | [diff] [blame] | 82 | public void applyTo(Binder binder) { |
sameb | 9867f9c | 2015-02-02 12:45:25 -0800 | [diff] [blame] | 83 | initializeDelegate(binder.withSource(getSource()).getProvider(dependency)); |
limpbizkit | 03b81a6 | 2009-03-18 05:34:39 +0000 | [diff] [blame] | 84 | } |
| 85 | |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 86 | /** |
| 87 | * Returns the delegate provider, or {@code null} if it has not yet been initialized. The delegate |
| 88 | * will be initialized when this element is processed, or otherwise used to create an injector. |
| 89 | */ |
| 90 | public Provider<T> getDelegate() { |
| 91 | return delegate; |
| 92 | } |
limpbizkit | 8d62075 | 2009-03-31 22:37:26 +0000 | [diff] [blame] | 93 | |
| 94 | /** |
| 95 | * Returns the looked up provider. The result is not valid until this lookup has been initialized, |
| 96 | * which usually happens when the injector is created. The provider will throw an {@code |
| 97 | * IllegalStateException} if you try to use it beforehand. |
| 98 | */ |
| 99 | public Provider<T> getProvider() { |
Christian Edward Gruber | cade897 | 2014-04-01 15:07:02 -0700 | [diff] [blame] | 100 | return new ProviderWithDependencies<T>() { |
limpbizkit | 8d62075 | 2009-03-31 22:37:26 +0000 | [diff] [blame] | 101 | public T get() { |
| 102 | checkState(delegate != null, |
| 103 | "This Provider cannot be used until the Injector has been created."); |
| 104 | return delegate.get(); |
| 105 | } |
sameb | 9867f9c | 2015-02-02 12:45:25 -0800 | [diff] [blame] | 106 | |
Christian Edward Gruber | cade897 | 2014-04-01 15:07:02 -0700 | [diff] [blame] | 107 | public Set<Dependency<?>> getDependencies() { |
Christian Edward Gruber | cade897 | 2014-04-01 15:07:02 -0700 | [diff] [blame] | 108 | // We depend on Provider<T>, not T directly. This is an important distinction |
| 109 | // for dependency analysis tools that short-circuit on providers. |
sameb | 9867f9c | 2015-02-02 12:45:25 -0800 | [diff] [blame] | 110 | Key<?> providerKey = getKey().ofType(Types.providerOf(getKey().getTypeLiteral().getType())); |
Christian Edward Gruber | cade897 | 2014-04-01 15:07:02 -0700 | [diff] [blame] | 111 | return ImmutableSet.<Dependency<?>>of(Dependency.get(providerKey)); |
| 112 | } |
limpbizkit | 8d62075 | 2009-03-31 22:37:26 +0000 | [diff] [blame] | 113 | |
| 114 | @Override public String toString() { |
sameb | 9867f9c | 2015-02-02 12:45:25 -0800 | [diff] [blame] | 115 | return "Provider<" + getKey().getTypeLiteral() + ">"; |
limpbizkit | 8d62075 | 2009-03-31 22:37:26 +0000 | [diff] [blame] | 116 | } |
| 117 | }; |
| 118 | } |
limpbizkit | 00ca9f7 | 2008-08-02 17:56:17 +0000 | [diff] [blame] | 119 | } |