de.christofreichardt.diagnosis.TracerConfigNamespaceContextImpl Maven / Gradle / Ivy

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A trace tool which produces clearly arranged logs by indenting the trace messages depending on the depth of the call stack.

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/*
 * TracerConfigNamespaceContextImpl.java
 */

package de.christofreichardt.diagnosis;

import java.util.Iterator;
import java.util.NoSuchElementException;
import javax.xml.namespace.NamespaceContext;

/**
 * Since the TracerFactory uses XPath to access the XML configuration involving namespaces an implementation of the
 * NamespaceContext interface is necessary. The implementation is simplified as only the namespace "http://www.christofreichardt.de/java/tracer"
 * and the prefix "dns" will be considered.
 * 
 * @author Christof Reichardt
 */
public class TracerConfigNamespaceContextImpl implements NamespaceContext
{
  
  /* =========================
   * inner classes
   * ========================= */
  
  /**
   * Simplified implementation of an iterator.
   */
  public class Iterator implements java.util.Iterator
  {
    boolean flag = true;
    
    /**
     * Returns true if and only if next() hasn't been called yet.
     * 
     * @return true when called once then false.
     */
    @Override
    public boolean hasNext()
    {
      return this.flag;
    }
    
    /**
     * Unsupported operation.
     */
    @Override
    public void remove()
    {
      throw new UnsupportedOperationException();
    }

    /**
     * Returns the next prefix, that is the first call will return "dns" and then a NoSuchElementException will be raised.
     * 
     * @return the next prefix
     */
    @Override
    public String next()
    {
      if (hasNext() == false)
        throw new NoSuchElementException();
      
      this.flag = false;
      
      return "dns";
    }
  }
  
  /* =========================
   * constructors
   * ========================= */
  
  /**
   * default constructor.
   */
  public TracerConfigNamespaceContextImpl()
  {
  }
  
  /* =========================
   * properties
   * ========================= */
  
  /**
   * Returns the fixed namespace URI for the prefix "dns". Other prefixes will cause an IllegalArgumentException.
   * 
   * @param prefix the namespace prefix
   * @return the URI "http://www.christofreichardt.de/java/tracer"
   */
  @Override
  public String getNamespaceURI(String prefix)
  {
    if (prefix == null || !prefix.equals("dns"))
      throw new IllegalArgumentException("Accept only default namespace.");
    
    return "http://www.christofreichardt.de/java/tracer";
  }

  /**
   * Returns the prefix for the fixed namespace "http://www.christofreichardt.de/java/tracer". Other namespaces will cause
   * an IllegalArgumentException.
   * 
   * @param namespaceURI the namespace URI
   * @return the prefix "dns"
   */
  @Override
  public String getPrefix(String namespaceURI)
  {
    if (namespaceURI == null || !namespaceURI.equals("http://www.christofreichardt.de/java/tracer"))
      throw new IllegalArgumentException("Accept only default namespace.");
    
    return "dns";
  }

  /**
   * Returns a special iterator implementation.
   * 
   * @param namespaceURI the namespace URI
   * @return an iterator
   */
  @Override
  public Iterator getPrefixes(String namespaceURI)
  {
    return new TracerConfigNamespaceContextImpl.Iterator();
  }
  
}