1 /* 2 * Copyright (C) 2018 The Dagger Authors. 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 dagger.internal.codegen; 18 19 import com.google.common.collect.ImmutableSet; 20 21 /** 22 * A label for a binding indicating whether, and how, it may be redefined across implementations of 23 * a subcomponent. 24 * 25 * <p>A subcomponent has multiple implementations only when generating ahead-of-time subcomponents. 26 * Specifically, each subcomponent type in a component hierarchy is implemented as an abstract 27 * class, and descendent components are implemented as abstract inner classes. A consequence of this 28 * is that a given subcomponent has an implementation for each ancestor component. Each 29 * implementation represents a different sub-binding-graph of the full subcomponent. A binding is 30 * modifiable if it's definition may change depending on the characteristics of its ancestor 31 * components. 32 */ 33 enum ModifiableBindingType { 34 /** A binding that is not modifiable */ 35 NONE, 36 37 /** 38 * A binding that is missing when generating the abstract base class implementation of a 39 * subcomponent. 40 */ 41 MISSING, 42 43 /** 44 * A binding that requires an instance of a generated type. These binding are modifiable in the 45 * sense that they are encapsulated in a method when they are first required, possibly in an 46 * abstract implementation of a subcomponent, where, in general, no concrete instances of 47 * generated types are available, and the method is satisfied in a final concrete implementation. 48 */ 49 GENERATED_INSTANCE, 50 51 /** 52 * Multibindings may have contributions come from any ancestor component. Therefore, each 53 * implementation of a subcomponent may have newly available contributions, and so the binding 54 * method is reimplemented with each subcomponent implementation. 55 */ 56 MULTIBINDING, 57 58 /** 59 * A Optional binding that may be empty when looking at a partial binding graph, but bound to a 60 * value when considering the complete binding graph, thus modifiable across subcomponent 61 * implementations. 62 */ 63 OPTIONAL, 64 65 /** 66 * If a binding is defined according to an {@code @Inject} annotated constructor on the object it 67 * is valid for that binding to be redefined a single time by an {@code @Provides} annotated 68 * module method. It is possible that the {@code @Provides} binding isn't available in a partial 69 * binding graph, but becomes available when considering a more complete binding graph, therefore 70 * such bindings are modifiable across subcomponent implementations. 71 */ 72 INJECTION, 73 74 /** 75 * A {@link dagger.Binds} method whose dependency is {@link #MISSING}. 76 * 77 * <p>There's not much to do for @Binds bindings if the dependency is missing - at best, if the 78 * dependency is a weaker scope/unscoped, we save only a few lines that implement the scoping. But 79 * it's also possible, if the dependency is the same or stronger scope, that no extra code is 80 * necessary, in which case we'd be overriding a method that just returns another. 81 */ 82 BINDS_METHOD_WITH_MISSING_DEPENDENCY, 83 ; 84 85 private static final ImmutableSet<ModifiableBindingType> TYPES_WITH_BASE_CLASS_IMPLEMENTATIONS = 86 ImmutableSet.of(NONE, INJECTION, MULTIBINDING, OPTIONAL); 87 isModifiable()88 boolean isModifiable() { 89 return !equals(NONE); 90 } 91 92 /** 93 * Returns true if the method encapsulating the modifiable binding should have a concrete 94 * implementation in the abstract base class for a subcomponent. 95 */ hasBaseClassImplementation()96 boolean hasBaseClassImplementation() { 97 return TYPES_WITH_BASE_CLASS_IMPLEMENTATIONS.contains(this); 98 } 99 } 100