/*
* Copyright 2003-2016 JetBrains s.r.o.
*
* 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 jetbrains.mps.nodeEditor.menus;
import org.apache.log4j.Logger;
import org.jetbrains.annotations.NotNull;
import java.util.ArrayDeque;
import java.util.Collections;
import java.util.List;
/**
* Wraps a {@link MenuItemFactory} and returns an empty list of items if {@link #createItems} is called with the same parameters several times.
*/
public class RecursionSafeMenuItemFactory<ItemT, ContextT, MenuLookupT> implements MenuItemFactory<ItemT, ContextT, MenuLookupT> {
private static final Logger LOG = Logger.getLogger(RecursionSafeMenuItemFactory.class);
private final ArrayDeque<Key> myKeyStack = new ArrayDeque<>();
private final MenuItemFactory<ItemT, ContextT, MenuLookupT> myFactory;
public RecursionSafeMenuItemFactory(MenuItemFactory<ItemT, ContextT, MenuLookupT> factory) {
myFactory = factory;
}
@Override
@NotNull
public List<ItemT> createItems(@NotNull ContextT context, @NotNull MenuLookupT menuLookup) {
Key<ContextT, MenuLookupT> key = new Key<>(context, menuLookup);
if (myKeyStack.contains(key)) {
LOG.error("Menu for key '" + key + "' requested more than once, returning empty menu to prevent endless recursion");
LOG.error("Current menu key stack: " + myKeyStack);
return Collections.emptyList();
}
myKeyStack.addLast(key);
try {
return myFactory.createItems(context, menuLookup);
} finally {
myKeyStack.removeLast();
}
}
private static class Key<ContextT, MenuLookupT> {
@NotNull
private final ContextT myContext;
@NotNull
private final MenuLookupT myLookup;
public Key(@NotNull ContextT context, @NotNull MenuLookupT lookup) {
myLookup = lookup;
myContext = context;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Key<ContextT, MenuLookupT> key = (Key<ContextT, MenuLookupT>) o;
return myContext.equals(key.myContext) && myLookup.equals(key.myLookup);
}
@Override
public int hashCode() {
int result = myContext.hashCode();
result = 31 * result + myLookup.hashCode();
return result;
}
@Override
public String toString() {
return "(lookup=" + myLookup +
", context=" + myContext + ')';
}
}
}