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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.yolean.chain;
import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
/**
* @author tonytv
* @author gjoranv
*/
public class Dependencies<T> {
final Order<T> before;
final Order<T> after;
final List<String> provided;
private Dependencies(Order<T> before, Order<T> after, String[] provided) {
this.before = before;
this.after = after;
this.provided = copyList(provided);
}
@SafeVarargs
public static <T> Dependencies<T> before(T... components) {
return new Dependencies<>(new Order<>(components, null, null), Order.<T>emptyOrder(), null);
}
@SafeVarargs
public static <T> Dependencies<T> before(Class<? extends T>... classes) {
return new Dependencies<>(new Order<>(null, classes, null), Order.<T>emptyOrder(), null);
}
public static <T> Dependencies<T> before(String... providedNames) {
return new Dependencies<>(new Order<T>(null, null, providedNames), Order.<T>emptyOrder(), null);
}
@SafeVarargs
public static <T> Dependencies<T> after(T... components) {
return new Dependencies<>(Order.<T>emptyOrder(), new Order<>(components, null, null), null);
}
@SafeVarargs
public static <T> Dependencies<T> after(Class<? extends T>... classes) {
return new Dependencies<>(Order.<T>emptyOrder(), new Order<>(null, classes, null), null);
}
public static <T> Dependencies<T> after(String... providedNames) {
return new Dependencies<>(Order.<T>emptyOrder(), new Order<T>(null, null, providedNames), null);
}
public static <T> Dependencies<T> provides(String... names) {
return new Dependencies<>(Order.<T>emptyOrder(), Order.<T>emptyOrder(), names);
}
public static <T> Dependencies<T> emptyDependencies() {
return new Dependencies<>(Order.<T>emptyOrder(), Order.<T>emptyOrder(), null);
}
@SuppressWarnings("unchecked")
static <T> Dependencies<T> union(List<Dependencies<? extends T>> dependenciesList) {
if (dependenciesList.size() > 1) {
Dependencies<T> result = emptyDependencies();
for (Dependencies<? extends T> dependencies : dependenciesList) {
result = result.union(dependencies);
}
return result;
} else if (dependenciesList.size() == 0) {
return emptyDependencies();
} else {
return (Dependencies<T>)dependenciesList.get(0); // Dependencies<T> is covariant for T, the cast is valid.
}
}
private Dependencies<T> union(Dependencies<? extends T> other) {
List<String> lst = listUnion(provided, other.provided);
return new Dependencies<>(before.union(other.before),
after.union(other.after),
lst.toArray(new String[lst.size()]));
}
private static <T> List<T> listUnion(List<? extends T> list1, List<? extends T> list2) {
List<T> union = new ArrayList<>(list1);
union.removeAll(list2);
union.addAll(list2);
return union;
}
static <T> Dependencies<T> getAnnotatedDependencies(T component) {
return new Dependencies<>(
new Order<T>(null, null, getSymbols(component, Before.class)),
new Order<T>(null, null, getSymbols(component, After.class)),
getProvidedSymbols(component));
}
private static <T> String[] getProvidedSymbols(T component) {
List<String> lst = allOf(getSymbols(component, Provides.class), component.getClass().getName());
return lst.toArray(new String[lst.size()]);
}
@SafeVarargs
static <T> List<T> allOf(List<T> elements, T... otherElements) {
List<T> result = new ArrayList<>(elements);
result.addAll(Arrays.asList(otherElements));
return result;
}
@SafeVarargs
static <T> List<T> allOf(T[] elements, T... otherElements) {
return allOf(Arrays.asList(elements), otherElements);
}
private static <T> List<String> getSymbols(T component, Class<? extends Annotation> annotationClass) {
List<String> result = new ArrayList<>();
result.addAll(annotationSymbols(component, annotationClass));
return result;
}
private static <T> Collection<String> annotationSymbols(T component, Class<? extends Annotation> annotationClass) {
try {
List<String> values = new ArrayList<>();
Class<?> clazz = component.getClass();
while (clazz != null) {
Annotation annotation = clazz.getAnnotation(annotationClass);
if (annotation != null) {
values.addAll(Arrays.asList((String[])annotationClass.getMethod("value").invoke(annotation)));
}
clazz = clazz.getSuperclass();
}
return values;
} catch (IllegalAccessException | NoSuchMethodException | InvocationTargetException e) {
throw new RuntimeException(e);
}
}
private static <U> List<U> copyList(List<U> list) {
return list == null ?
Collections.<U>emptyList() :
new ArrayList<>(list);
}
private static <U> List<U> copyList(U[] array) {
return array == null ?
Collections.<U>emptyList() :
new ArrayList<>(Arrays.<U>asList(array));
}
static final class Order<T> {
final List<T> instances;
final List<Class<? extends T>> classes;
final List<String> providedNames;
private Order(T[] instances, Class<? extends T>[] classes, String[] providedNames) {
this.instances = copyList(instances);
this.classes = copyList(classes);
this.providedNames = copyList(providedNames);
}
private Order(List<T> instances, List<Class<? extends T>> classes, List<String> providedNames) {
this.instances = copyList(instances);
this.classes = copyList(classes);
this.providedNames = copyList(providedNames);
}
// TODO: unit test
private Order<T> union(Order<? extends T> other) {
return new Order<>(
listUnion(instances, other.instances),
listUnion(classes, other.classes),
listUnion(providedNames, other.providedNames));
}
// TODO: try to make it possible to use 'null' Order in Dependencies instead.
private static <U> Order<U> emptyOrder() {
return new Order<>((U[])null, null, null);
}
}
}
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