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'rapiddweller Common' is an open source Java library forked from Databene Commons by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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.rapiddweller.common.context;

import com.rapiddweller.common.Assert;
import com.rapiddweller.common.Context;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.util.HashSet;
import java.util.Map.Entry;
import java.util.Set;
import java.util.Stack;

/**
 * Combines several contexts to a {@link Stack}, querying recursively in the {@link #get(String)} method
 * until an entry is found or the stack is completely iterated.
 * Created: 09.01.2013 13:06:13
 *
 * @author Volker Bergmann
 * @since 0.5.21
 */
public class SimpleContextStack implements ContextStack {

  private static final Logger logger = LogManager.getLogger(ContextStack.class);

  /**
   * The Contexts.
   */
  protected Stack contexts;

  /**
   * Instantiates a new Simple context stack.
   *
   * @param contexts the contexts
   */
  public SimpleContextStack(Context... contexts) {
    this.contexts = new Stack<>();
    for (Context c : contexts) {
      this.contexts.push(c);
    }
  }

  @Override
  public Object get(String key) {
    for (int i = contexts.size() - 1; i >= 0; i--) {
      Object result = contexts.get(i).get(key);
      if (result != null) {
        return result;
      }
    }
    return null;
  }

  @Override
  public boolean contains(String key) {
    for (int i = contexts.size() - 1; i >= 0; i--) {
      Context c = contexts.get(i);
      if (c.contains(key)) {
        return true;
      }
    }
    return false;
  }

  @Override
  public Set keySet() {
    Set keySet = new HashSet<>();
    for (int i = contexts.size() - 1; i >= 0; i--) {
      Context c = contexts.get(i);
      keySet.addAll(c.keySet());
    }
    return keySet;
  }

  @Override
  public Set> entrySet() {
    Set> entrySet = new HashSet<>();
    for (Context c : contexts) {
      entrySet.addAll(c.entrySet());
    }
    return entrySet;
  }

  @Override
  public void remove(String key) {
    if (contexts.size() > 0) {
      contexts.peek().remove(key);
    }
  }

  @Override
  public void set(String key, Object value) {
    Assert.notNull(key, "key");
    if (contexts.size() > 0) {
      contexts.peek().set(key, value);
    } else {
      logger.warn("ContextStack is empty, ignoring element: " + key);
    }
  }

  @Override
  public void push(Context context) {
    this.contexts.push(context);
  }

  @Override
  public Context pop() {
    return this.contexts.pop();
  }

}