com.google.gwt.inject.rebind.binding.Dependency Maven / Gradle / Ivy
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/*
* Copyright 2011 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.inject.rebind.binding;
import com.google.gwt.inject.rebind.GuiceBindingVisitor;
import com.google.gwt.inject.rebind.util.Preconditions;
import com.google.gwt.inject.rebind.util.PrettyPrinter;
import com.google.inject.Key;
import com.google.inject.Provider;
/**
* Representation of a dependency edge. Contains information about the source and target
* {@code Key}s, as well as the properties of the edge (optional/requried, lazy/eager).
*
* Dependencies also store the context in which the dependency arose. This
* is not part of the dependency's identity from the point of view of equals()
* and hashCode(), which ultimately means that if the same dependency arises in
* several different contexts, we will pick an arbitrary instance (specifically,
* the first one encountered, see {@link DependencyGraph}).
*/
public class Dependency {
private static final class GinjectorSourceClass {}
/**
* A unique key used to indicate that a dependency originated in the Ginjector; for instance,
* keys produced by the root Ginjector, or while visiting bindings in {@link GuiceBindingVisitor}
* often have as their source {@link Dependency#GINJECTOR}.
*/
public static final Key GINJECTOR = Key.get(GinjectorSourceClass.class);
private final Key source;
private final Key target;
private final boolean optional;
private final boolean lazy;
private final Context context;
/**
* Construct a dependency edge from the given source to target keys. Creates a required, eager
* edge.
*
* @param source The key that depends on target. Can use {@link Dependency#GINJECTOR} as
* described above.
* @param target the key that is depended on
* @param context a brief description of the context of the dependency (e.g., Foo.java:123)
* @param contextArgs arguments to pretty-print into the context as with
* {@link PrettyPrinter#format}
*/
public Dependency(Key source, Key target, String context, Object... contextArgs) {
this(source, target, false, false, context, contextArgs);
}
/**
* Construct a dependency edge from the given source to target keys. Creates a required, eager
* edge.
*
* @param source The key that depends on target. Can use {@link Dependency#GINJECTOR} as
* described above.
* @param target the key that is depended on
* @param context the context of the dependency (e.g., Foo.java:123)
*/
public Dependency(Key source, Key target, Context context) {
this(source, target, false, false, context);
}
/**
* Construct a dependency edge from the given source to target keys.
*
* @param source The key that depends on the target. Can use {@link Dependency#GINJECTOR} as
* described above.
* @param target the key that is depended on
* @param optional {@code true} iff the dependency is optional. Errors will not be reported if
* the target is unavailable.
* @param lazy {@code true} iff the dependency is only needed on-demand (eg, by calling
* {@link Provider#get}). A cycle is only a problem if none of the edges are lazy.
* @param context a brief description of the context of the dependency (e.g., Foo.java:123)
* @param contextArgs arguments to pretty-print into the context as with
* {@link PrettyPrinter#format}
*/
public Dependency(Key source, Key target, boolean optional, boolean lazy, String context,
Object... contextArgs) {
this(source, target, optional, lazy, Context.format(context, (Object[]) contextArgs));
Preconditions.checkArgument(!context.isEmpty(), "dependency context must not be empty");
}
/**
* Construct a dependency edge from the given source to target keys.
*
* @param source The key that depends on the target. Can use {@link Dependency#GINJECTOR} as
* described above.
* @param target the key that is depended on
* @param optional {@code true} iff the dependency is optional. Errors will not be reported if
* the target is unavailable.
* @param lazy {@code true} iff the dependency is only needed on-demand (eg, by calling
* {@link Provider#get}). A cycle is only a problem if none of the edges are lazy.
* @param context the context of the dependency (e.g., Foo.java:123)
*/
public Dependency(Key source, Key target, boolean optional, boolean lazy, Context context) {
Preconditions.checkArgument(source != null, "null is not supported as the source");
Preconditions.checkArgument(target != null && !target.equals(GINJECTOR),
"null and GINJECTOR are not supported as the target.");
Preconditions.checkArgument(context != null, "dependency context must not be null");
this.source = source;
this.target = target;
this.optional = optional;
this.lazy = lazy;
this.context = context;
}
public Context getContext() {
return context;
}
public Key getTarget() {
return target;
}
public Key getSource() {
return source;
}
public boolean isOptional() {
return optional;
}
public boolean isLazy() {
return lazy;
}
@Override
public String toString() {
return String.format("%s -> %s [context: %s, optional: %s, lazy: %s]",
source, target, context, optional, lazy);
}
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (obj == null) {
return false;
}
if (obj instanceof Dependency) {
Dependency other = (Dependency) obj;
return optional == other.optional
&& lazy == other.lazy
&& (target == null ? other.target == null : target.equals(other.target))
&& (source == null ? other.source == null : source.equals(other.source));
}
return false;
}
@Override
public int hashCode() {
int hashCode = source.hashCode();
hashCode = hashCode * 31 + target.hashCode();
hashCode = hashCode * 31 + (optional ? 2 : 0) + (lazy ? 1 : 0);
return hashCode;
}
}