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The core XML data binding framework with support for marshalling Java objects to and unmarshalling from XML documents.
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/*
 * Copyright 2011 Jakub Narloch
 *
 * 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 org.exolab.castor.xml;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.xml.sax.helpers.AttributeListImpl;

/**
 * This class is an actual namespace stack implementation, responsible for adding and removing
 * namespace scopes, as well as resolving namespace urls and prefixes by traversing all the
 * namespace stack.
 * 
 * @author Jakub Narloch
 * @since 1.3.3
 */
@SuppressWarnings("deprecation")
public class NamespacesStack {

  private final Log logger = LogFactory.getLog(this.getClass());

  /**
   * Represents the string used for indicating default namespace, by default empty string is used.
   */
  private static final String DEFAULT_NAMESPACE = "";

  /**
   * Represents a stack of namespaces.
   */
  private List namespaceStack = new ArrayList();

  /**
   * Adds a namespace to current scope.
   * 
   * @param namespacePrefix the namespace prefix
   * @param namespaceUri the namespace uri
   */
  public void addNamespace(String namespacePrefix, String namespaceUri) {
    Namespaces namespaces = getCurrentNamespaceScope();
    if (namespaces != null) {
      namespaces.addNamespace(namespacePrefix, namespaceUri);
    }
  }

  /**
   * Adds the default namespace to current scope.
   * 
   * @param namespaceUri the namespace uri
   */
  public void addDefaultNamespace(String namespaceUri) {
    addNamespace(DEFAULT_NAMESPACE, namespaceUri);
  }

  /**
   * Removes the namespace from current scope using the namespace prefix
   * 
   * @param namespacePrefix the prefix of the namespace to remove
   */
  public void removeNamespace(String namespacePrefix) {
    getCurrentNamespaceScope().removeNamespace(namespacePrefix);
  }

  /**
   * Retrieves the namespace uri bound to specified prefix.
   * 
   * @param namespacePrefix the namespace prefix
   * 
   * @return the namespace uri bound to the prefix, or null if no namespace has been bound for the
   *         given prefix
   */
  public String getNamespaceURI(String namespacePrefix) {
    String namespaceUri = null;
    for (int ind = namespaceStack.size() - 1; ind >= 0 && namespaceUri == null; ind--) {
      namespaceUri = namespaceStack.get(ind).getNamespaceURI(namespacePrefix);
    }
    return namespaceUri;
  }

  /**
   * Declares the namespaces using the attribute list.
   * 
   * @param attributeList the list of attributes containing the namespaces
   * @param localOnly whether the namespaces will only registered in current namespace context or in
   *        entire stack
   */
  @SuppressWarnings("deprecation")
  public void declareAsAttributes(AttributeListImpl attributeList, boolean localOnly) {
    getCurrentNamespaceScope().declareAsAttributes(attributeList);
    if (!localOnly) {
      for (int ind = namespaceStack.size() - 1; ind >= 0; ind--) {

        namespaceStack.get(ind).declareAsAttributes(attributeList);
      }
    }
  }

  /**
   * Retrieves the default namespace namespace uri.
   * 
   * @return the default namespace uri
   */
  public String getDefaultNamespaceURI() {
    return getNamespaceURI(DEFAULT_NAMESPACE);
  }

  /**
   * Retrieves the namespace prefix for the given namespace uri.
   * 
   * @param namespaceUri the namespace uri
   * 
   * @return the
   */
  public String getNamespacePrefix(String namespaceUri) {
    String namespacePrefix = null;
    for (int ind = namespaceStack.size() - 1; ind >= 0 && namespacePrefix == null; ind--) {
      namespacePrefix = namespaceStack.get(ind).getNamespacePrefix(namespaceUri);
    }
    return namespacePrefix;
  }

  /**
   * Retrieves the non default namespace prefix for the given namespace uri.
   * 
   * @param namespaceUri the namespace uri
   * 
   * @return the
   */
  public String getNonDefaultNamespacePrefix(String namespaceUri) {
    String namespacePrefix = null;
    for (int ind = namespaceStack.size() - 1; ind >= 0 && namespacePrefix == null; ind--) {
      namespacePrefix = namespaceStack.get(ind).getNonDefaultNamespacePrefix(namespaceUri);
    }
    return namespacePrefix;
  }

  /**
   * Retrieves the namespace prefixes registered in current scope.
   * 
   * @return the enumeration of namespace prefixes
   */
  public Enumeration getLocalNamespacePrefixes() {
    Namespaces namespaces = getCurrentNamespaceScope();
    return namespaces != null ? namespaces.getLocalNamespacePrefixes() : null;
  }

  /**
   * Adds a new namespace scope.
   */
  public void addNewNamespaceScope() {
    namespaceStack.add(new Namespaces());
  }

  /**
   * Removes the namespace scope.
   */
  public void removeNamespaceScope() {
    // removes the current namespace
    if (!namespaceStack.isEmpty()) {
      namespaceStack.remove(namespaceStack.size() - 1);
    } else {
      this.logger.error("Trying to remove a namespaces scope from an empty stack of Namespaces");
    }
  }

  /**
   * Retrieves the current namespace scope.
   * 
   * @return the current namespace scope.
   */
  public Namespaces getCurrentNamespaceScope() {
    if (namespaceStack.isEmpty()) {
      addNewNamespaceScope();
    }
    return namespaceStack.get(namespaceStack.size() - 1);
  }
}