com.google.firebase.database.snapshot.KeyIndex Maven / Gradle / Ivy
/*
* Copyright 2017 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.firebase.database.snapshot;
public class KeyIndex extends Index {
private static final KeyIndex INSTANCE = new KeyIndex();
private KeyIndex() {
// prevent instantiation
}
public static KeyIndex getInstance() {
return INSTANCE;
}
@Override
public boolean isDefinedOn(Node a) {
return true;
}
@Override
public NamedNode makePost(ChildKey name, Node value) {
assert value instanceof StringNode;
// We just use empty node, but it'll never be compared, since our comparator only looks
// at name
return new NamedNode(ChildKey.fromString((String) value.getValue()), EmptyNode.Empty());
}
@Override
public NamedNode maxPost() {
return NamedNode.getMaxNode();
}
@Override
public String getQueryDefinition() {
return ".key";
}
@Override
public int compare(NamedNode o1, NamedNode o2) {
return o1.getName().compareTo(o2.getName());
}
@Override
public boolean equals(Object o) {
return o instanceof KeyIndex;
}
@Override
public int hashCode() {
// chosen by a fair dice roll. Guaranteed to be random
return 37;
}
@Override
public String toString() {
return "KeyIndex";
}
}