All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.google.firebase.database.core.SparseSnapshotTree Maven / Gradle / Ivy

Go to download

This is the official Firebase Admin Java SDK. Build extraordinary native JVM apps in minutes with Firebase. The Firebase platform can power your app’s backend, user authentication, static hosting, and more.

There is a newer version: 9.3.0
Show newest version
/*
 * 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.core;

import com.google.firebase.database.snapshot.ChildKey;
import com.google.firebase.database.snapshot.ChildrenNode;
import com.google.firebase.database.snapshot.Node;

import java.util.HashMap;
import java.util.Map;

class SparseSnapshotTree {

  private Node value;
  private Map children;

  public SparseSnapshotTree() {
    this.value = null;
    this.children = null;
  }

  public void remember(Path path, Node data) {
    if (path.isEmpty()) {
      value = data;
      children = null;
    } else if (value != null) {
      value = value.updateChild(path, data);
    } else {
      if (children == null) {
        children = new HashMap<>();
      }

      ChildKey childKey = path.getFront();
      if (!children.containsKey(childKey)) {
        children.put(childKey, new SparseSnapshotTree());
      }

      SparseSnapshotTree child = children.get(childKey);
      child.remember(path.popFront(), data);
    }
  }

  public boolean forget(final Path path) {
    if (path.isEmpty()) {
      value = null;
      children = null;
      return true;
    } else {
      if (value != null) {
        if (value.isLeafNode()) {
          // non-empty path at leaf. The path leads to nowhere
          return false;
        } else {
          ChildrenNode childrenNode = (ChildrenNode) value;
          value = null;

          childrenNode.forEachChild(
              new ChildrenNode.ChildVisitor() {
                @Override
                public void visitChild(ChildKey name, Node child) {
                  remember(path.child(name), child);
                }
              });

          // We've cleared out the value and set the children. Call this method again
          // to hit the
          // next case
          return forget(path);
        }
      } else if (children != null) {
        ChildKey childKey = path.getFront();
        Path childPath = path.popFront();

        if (children.containsKey(childKey)) {
          SparseSnapshotTree child = children.get(childKey);
          boolean safeToRemove = child.forget(childPath);
          if (safeToRemove) {
            children.remove(childKey);
          }
        }

        if (children.isEmpty()) {
          children = null;
          return true;
        } else {
          return false;
        }
      } else {
        return true;
      }
    }
  }

  public void forEachTree(final Path prefixPath, final SparseSnapshotTreeVisitor visitor) {
    if (value != null) {
      visitor.visitTree(prefixPath, value);
    } else {
      this.forEachChild(
          new SparseSnapshotChildVisitor() {
            @Override
            public void visitChild(ChildKey key, SparseSnapshotTree tree) {
              tree.forEachTree(prefixPath.child(key), visitor);
            }
          });
    }
  }

  public void forEachChild(SparseSnapshotChildVisitor visitor) {
    if (children != null) {
      for (Map.Entry entry : children.entrySet()) {
        visitor.visitChild(entry.getKey(), entry.getValue());
      }
    }
  }

  public interface SparseSnapshotTreeVisitor {

    void visitTree(Path prefixPath, Node tree);
  }

  public interface SparseSnapshotChildVisitor {

    void visitChild(ChildKey key, SparseSnapshotTree tree);
  }
}




© 2015 - 2024 Weber Informatics LLC | Privacy Policy