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      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.internal;
     18 
     19 import static com.google.common.base.Preconditions.checkNotNull;
     20 
     21 import com.google.inject.Binder;
     22 import com.google.inject.Key;
     23 import com.google.inject.Scope;
     24 import com.google.inject.spi.Element;
     25 import com.google.inject.spi.InstanceBinding;
     26 
     27 import java.lang.annotation.Annotation;
     28 import java.util.List;
     29 
     30 /**
     31  * Bind a value or constant.
     32  *
     33  * @author jessewilson (at) google.com (Jesse Wilson)
     34  */
     35 public abstract class AbstractBindingBuilder<T> {
     36 
     37   public static final String IMPLEMENTATION_ALREADY_SET = "Implementation is set more than once.";
     38   public static final String SINGLE_INSTANCE_AND_SCOPE
     39       = "Setting the scope is not permitted when binding to a single instance.";
     40   public static final String SCOPE_ALREADY_SET = "Scope is set more than once.";
     41   public static final String BINDING_TO_NULL = "Binding to null instances is not allowed. "
     42       + "Use toProvider(Providers.of(null)) if this is your intended behaviour.";
     43   public static final String CONSTANT_VALUE_ALREADY_SET = "Constant value is set more than once.";
     44   public static final String ANNOTATION_ALREADY_SPECIFIED
     45       = "More than one annotation is specified for this binding.";
     46 
     47   protected static final Key<?> NULL_KEY = Key.get(Void.class);
     48 
     49   protected List<Element> elements;
     50   protected int position;
     51   protected final Binder binder;
     52   private BindingImpl<T> binding;
     53 
     54   public AbstractBindingBuilder(Binder binder, List<Element> elements, Object source, Key<T> key) {
     55     this.binder = binder;
     56     this.elements = elements;
     57     this.position = elements.size();
     58     this.binding = new UntargettedBindingImpl<T>(source, key, Scoping.UNSCOPED);
     59     elements.add(position, this.binding);
     60   }
     61 
     62   protected BindingImpl<T> getBinding() {
     63     return binding;
     64   }
     65 
     66   protected BindingImpl<T> setBinding(BindingImpl<T> binding) {
     67     this.binding = binding;
     68     elements.set(position, binding);
     69     return binding;
     70   }
     71 
     72   /** Sets the binding to a copy with the specified annotation on the bound key */
     73   protected BindingImpl<T> annotatedWithInternal(Class<? extends Annotation> annotationType) {
     74     checkNotNull(annotationType, "annotationType");
     75     checkNotAnnotated();
     76     return setBinding(binding.withKey(
     77         Key.get(this.binding.getKey().getTypeLiteral(), annotationType)));
     78   }
     79 
     80   /** Sets the binding to a copy with the specified annotation on the bound key */
     81   protected BindingImpl<T> annotatedWithInternal(Annotation annotation) {
     82     checkNotNull(annotation, "annotation");
     83     checkNotAnnotated();
     84     return setBinding(binding.withKey(
     85         Key.get(this.binding.getKey().getTypeLiteral(), annotation)));
     86   }
     87 
     88   public void in(final Class<? extends Annotation> scopeAnnotation) {
     89     checkNotNull(scopeAnnotation, "scopeAnnotation");
     90     checkNotScoped();
     91     setBinding(getBinding().withScoping(Scoping.forAnnotation(scopeAnnotation)));
     92   }
     93 
     94   public void in(final Scope scope) {
     95     checkNotNull(scope, "scope");
     96     checkNotScoped();
     97     setBinding(getBinding().withScoping(Scoping.forInstance(scope)));
     98   }
     99 
    100   public void asEagerSingleton() {
    101     checkNotScoped();
    102     setBinding(getBinding().withScoping(Scoping.EAGER_SINGLETON));
    103   }
    104 
    105   protected boolean keyTypeIsSet() {
    106     return !Void.class.equals(binding.getKey().getTypeLiteral().getType());
    107   }
    108 
    109   protected void checkNotTargetted() {
    110     if (!(binding instanceof UntargettedBindingImpl)) {
    111       binder.addError(IMPLEMENTATION_ALREADY_SET);
    112     }
    113   }
    114 
    115   protected void checkNotAnnotated() {
    116     if (binding.getKey().getAnnotationType() != null) {
    117       binder.addError(ANNOTATION_ALREADY_SPECIFIED);
    118     }
    119   }
    120 
    121   protected void checkNotScoped() {
    122     // Scoping isn't allowed when we have only one instance.
    123     if (binding instanceof InstanceBinding) {
    124       binder.addError(SINGLE_INSTANCE_AND_SCOPE);
    125       return;
    126     }
    127 
    128     if (binding.getScoping().isExplicitlyScoped()) {
    129       binder.addError(SCOPE_ALREADY_SET);
    130     }
    131   }
    132 }