code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you 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.
   */
  /*
   * $Id$
   */
  package org.apache.xml.dtm;
  
  import org.apache.xml.res.XMLErrorResources;
  import org.apache.xml.res.XMLMessages;
  import org.apache.xml.utils.PrefixResolver;
  import org.apache.xml.utils.XMLStringFactory;
  
  /**
   * A DTMManager instance can be used to create DTM and
   * DTMIterator objects, and manage the DTM objects in the system.
   *
   * <p>The system property that determines which Factory implementation
   * to create is named "org.apache.xml.utils.DTMFactory". This
   * property names a concrete subclass of the DTMFactory abstract
   *  class. If the property is not defined, a platform default is be used.</p>
   *
   * <p>An instance of this class <emph>must</emph> be safe to use across
   * thread instances.  It is expected that a client will create a single instance
   * of a DTMManager to use across multiple threads.  This will allow sharing
   * of DTMs across multiple processes.</p>
   *
   * <p>Note: this class is incomplete right now.  It will be pretty much
   * modeled after javax.xml.transform.TransformerFactory in terms of its
   * factory support.</p>
   *
   * <p>State: In progress!!</p>
   */
  public abstract class DTMManager
  {
  
    /** The default property name to load the manager. */
    private static final String defaultPropName =
      "org.apache.xml.dtm.DTMManager";
    
    /** The default class name to use as the manager. */
    private static String defaultClassName =
      "org.apache.xml.dtm.ref.DTMManagerDefault";
  
    /**
     * Factory for creating XMLString objects.
     *  %TBD% Make this set by the caller.
     */
    protected XMLStringFactory m_xsf = null;
  
    /**
     * Default constructor is protected on purpose.
     */
    protected DTMManager(){}
  
    /**
     * Get the XMLStringFactory used for the DTMs.
     *
     *
     * @return a valid XMLStringFactory object, or null if it hasn't been set yet.
     */
    public XMLStringFactory getXMLStringFactory()
    {
      return m_xsf;
    }
  
    /**
     * Set the XMLStringFactory used for the DTMs.
     *
     *
     * @param xsf a valid XMLStringFactory object, should not be null.
     */
    public void setXMLStringFactory(XMLStringFactory xsf)
    {
      m_xsf = xsf;
    }
  
    /**
     * Obtain a new instance of a <code>DTMManager</code>.
     * This static method creates a new factory instance
     * This method uses the following ordered lookup procedure to determine
     * the <code>DTMManager</code> implementation class to
     * load:
     * <ul>
     * <li>
     * Use the <code>org.apache.xml.dtm.DTMManager</code> system
     * property.
     * </li>
     * <li>
     * Use the JAVA_HOME(the parent directory where jdk is
     * installed)/lib/xalan.properties for a property file that contains the
     * name of the implementation class keyed on the same value as the
     * system property defined above.
     * </li>
     * <li>
     * Use the Services API (as detailed in the JAR specification), if
     * available, to determine the classname. The Services API will look
     * for a classname in the file
     * <code>META-INF/services/org.apache.xml.dtm.DTMManager</code>
     * in jars available to the runtime.
     * </li>
     * <li>
     * Use the default <code>DTMManager</code> classname, which is
     * <code>org.apache.xml.dtm.ref.DTMManagerDefault</code>.
     * </li>
     * </ul>
     *
     * Once an application has obtained a reference to a <code>
     * DTMManager</code> it can use the factory to configure
     * and obtain parser instances.
     *
     * @return new DTMManager instance, never null.
     *
     * @throws DTMConfigurationException
     * if the implementation is not available or cannot be instantiated.
     */
    public static DTMManager newInstance(XMLStringFactory xsf) 
             throws DTMConfigurationException
    {
      DTMManager factoryImpl = null;
      try
      {
        factoryImpl = (DTMManager) ObjectFactory
          .createObject(defaultPropName, defaultClassName);
      }
      catch (ObjectFactory.ConfigurationError e)
      {
        throw new DTMConfigurationException(XMLMessages.createXMLMessage(
          XMLErrorResources.ER_NO_DEFAULT_IMPL, null), e.getException());
          //"No default implementation found");
      }
  
      if (factoryImpl == null)
      {
        throw new DTMConfigurationException(XMLMessages.createXMLMessage(
          XMLErrorResources.ER_NO_DEFAULT_IMPL, null));
          //"No default implementation found");
      }
  
      factoryImpl.setXMLStringFactory(xsf);
  
      return factoryImpl;
    }
  
    /**
     * Get an instance of a DTM, loaded with the content from the
     * specified source.  If the unique flag is true, a new instance will
     * always be returned.  Otherwise it is up to the DTMManager to return a
     * new instance or an instance that it already created and may be being used
     * by someone else.
     * 
     * (More parameters may eventually need to be added for error handling
     * and entity resolution, and to better control selection of implementations.)
     *
     * @param source the specification of the source object, which may be null,
     *               in which case it is assumed that node construction will take
     *               by some other means.
     * @param unique true if the returned DTM must be unique, probably because it
     * is going to be mutated.
     * @param whiteSpaceFilter Enables filtering of whitespace nodes, and may
     *                         be null.
     * @param incremental true if the DTM should be built incrementally, if
     *                    possible.
     * @param doIndexing true if the caller considers it worth it to use 
     *                   indexing schemes.
     *
     * @return a non-null DTM reference.
     */
    public abstract DTM getDTM(javax.xml.transform.Source source,
                               boolean unique, DTMWSFilter whiteSpaceFilter,
                               boolean incremental, boolean doIndexing);
  
    /**
     * Get the instance of DTM that "owns" a node handle.
     *
     * @param nodeHandle the nodeHandle.
     *
     * @return a non-null DTM reference.
     */
    public abstract DTM getDTM(int nodeHandle);
  
    /**
     * Given a W3C DOM node, try and return a DTM handle.
     * Note: calling this may be non-optimal.
     *
     * @param node Non-null reference to a DOM node.
     *
     * @return a valid DTM handle.
     */
    public abstract int getDTMHandleFromNode(org.w3c.dom.Node node);
  
    /**
     * Creates a DTM representing an empty <code>DocumentFragment</code> object.
     * @return a non-null DTM reference.
     */
    public abstract DTM createDocumentFragment();
  
    /**
     * Release a DTM either to a lru pool, or completely remove reference.
     * DTMs without system IDs are always hard deleted.
     * State: experimental.
     *
     * @param dtm The DTM to be released.
     * @param shouldHardDelete True if the DTM should be removed no matter what.
     * @return true if the DTM was removed, false if it was put back in a lru pool.
     */
    public abstract boolean release(DTM dtm, boolean shouldHardDelete);
  
    /**
     * Create a new <code>DTMIterator</code> based on an XPath
     * <a href="http://www.w3.org/TR/xpath#NT-LocationPath>LocationPath</a> or
     * a <a href="http://www.w3.org/TR/xpath#NT-UnionExpr">UnionExpr</a>.
     *
     * @param xpathCompiler ??? Somehow we need to pass in a subpart of the
     * expression.  I hate to do this with strings, since the larger expression
     * has already been parsed.
     *
     * @param pos The position in the expression.
     * @return The newly created <code>DTMIterator</code>.
     */
    public abstract DTMIterator createDTMIterator(Object xpathCompiler,
            int pos);
  
    /**
     * Create a new <code>DTMIterator</code> based on an XPath
     * <a href="http://www.w3.org/TR/xpath#NT-LocationPath>LocationPath</a> or
     * a <a href="http://www.w3.org/TR/xpath#NT-UnionExpr">UnionExpr</a>.
     *
     * @param xpathString Must be a valid string expressing a
     * <a href="http://www.w3.org/TR/xpath#NT-LocationPath>LocationPath</a> or
     * a <a href="http://www.w3.org/TR/xpath#NT-UnionExpr">UnionExpr</a>.
     *
     * @param presolver An object that can resolve prefixes to namespace URLs.
     *
     * @return The newly created <code>DTMIterator</code>.
     */
    public abstract DTMIterator createDTMIterator(String xpathString,
            PrefixResolver presolver);
  
    /**
     * Create a new <code>DTMIterator</code> based only on a whatToShow
     * and a DTMFilter.  The traversal semantics are defined as the
     * descendant access.
     * <p>
     * Note that DTMIterators may not be an exact match to DOM
     * NodeIterators. They are initialized and used in much the same way
     * as a NodeIterator, but their response to document mutation is not
     * currently defined.
     *
     * @param whatToShow This flag specifies which node types may appear in
     *   the logical view of the tree presented by the iterator. See the
     *   description of <code>NodeFilter</code> for the set of possible
     *   <code>SHOW_</code> values.These flags can be combined using
     *   <code>OR</code>.
     * @param filter The <code>NodeFilter</code> to be used with this
     *   <code>DTMFilter</code>, or <code>null</code> to indicate no filter.
     * @param entityReferenceExpansion The value of this flag determines
     *   whether entity reference nodes are expanded.
     *
     * @return The newly created <code>DTMIterator</code>.
     */
    public abstract DTMIterator createDTMIterator(int whatToShow,
            DTMFilter filter, boolean entityReferenceExpansion);
  
    /**
     * Create a new <code>DTMIterator</code> that holds exactly one node.
     *
     * @param node The node handle that the DTMIterator will iterate to.
     *
     * @return The newly created <code>DTMIterator</code>.
     */
    public abstract DTMIterator createDTMIterator(int node);
    
    /* Flag indicating whether an incremental transform is desired */
    public boolean m_incremental = false;
    
    /*
     * Flag set by FEATURE_SOURCE_LOCATION.
     * This feature specifies whether the transformation phase should
     * keep track of line and column numbers for the input source
     * document. 
     */
    public boolean m_source_location = false; 
    
    /**
     * Get a flag indicating whether an incremental transform is desired 
     * @return incremental boolean.
     *
     */
    public boolean getIncremental()
    {
      return m_incremental;  
    }
    
    /**
     * Set a flag indicating whether an incremental transform is desired
     * This flag should have the same value as the FEATURE_INCREMENTAL feature
     * which is set by the TransformerFactory.setAttribut() method before a
     * DTMManager is created
     * @param incremental boolean to use to set m_incremental.
     *
     */
    public void setIncremental(boolean incremental)
    {
      m_incremental = incremental;  
    }
    
    /**
     * Get a flag indicating whether the transformation phase should
     * keep track of line and column numbers for the input source
     * document.
     * @return source location boolean
     *
     */
    public boolean getSource_location()
    {
      return m_source_location;  
    }  
    
    /**
     * Set a flag indicating whether the transformation phase should
     * keep track of line and column numbers for the input source
     * document.
     * This flag should have the same value as the FEATURE_SOURCE_LOCATION feature
     * which is set by the TransformerFactory.setAttribut() method before a
     * DTMManager is created
     * @param sourceLocation boolean to use to set m_source_location
     */
    public void setSource_location(boolean sourceLocation){
      m_source_location = sourceLocation;
    }
    
  
    // -------------------- private methods --------------------
  
     /**
     * Temp debug code - this will be removed after we test everything
     */
    private static boolean debug;
  
    static
    {
      try
      {
        debug = System.getProperty("dtm.debug") != null;
      }
      catch (SecurityException ex){}
    }
  
    /** This value, set at compile time, controls how many bits of the
     * DTM node identifier numbers are used to identify a node within a
     * document, and thus sets the maximum number of nodes per
     * document. The remaining bits are used to identify the DTM
     * document which contains this node.
     *
     * If you change IDENT_DTM_NODE_BITS, be sure to rebuild _ALL_ the
     * files which use it... including the IDKey testcases.
     *
     * (FuncGenerateKey currently uses the node identifier directly and
     * thus is affected when this changes. The IDKEY results will still be
     * _correct_ (presuming no other breakage), but simple equality
     * comparison against the previous "golden" files will probably
     * complain.)
     * */
    public static final int IDENT_DTM_NODE_BITS = 16;
      
  
    /** When this bitmask is ANDed with a DTM node handle number, the result
     * is the low bits of the node's index number within that DTM. To obtain
     * the high bits, add the DTM ID portion's offset as assigned in the DTM 
     * Manager.
     */
    public static final int IDENT_NODE_DEFAULT = (1<<IDENT_DTM_NODE_BITS)-1;
  
  
    /** When this bitmask is ANDed with a DTM node handle number, the result
     * is the DTM's document identity number.
     */
    public static final int IDENT_DTM_DEFAULT = ~IDENT_NODE_DEFAULT;
  
    /** This is the maximum number of DTMs available.  The highest DTM is
      * one less than this.
     */
    public static final int IDENT_MAX_DTMS = (IDENT_DTM_DEFAULT >>> IDENT_DTM_NODE_BITS) + 1;
  
  
    /**
     * %TBD% Doc
     *
     * NEEDSDOC @param dtm
     *
     * NEEDSDOC ($objectName$) @return
     */
    public abstract int getDTMIdentity(DTM dtm);
  
    /**
     * %TBD% Doc
     *
     * NEEDSDOC ($objectName$) @return
     */
    public int getDTMIdentityMask()
    {
      return IDENT_DTM_DEFAULT;
    }
  
    /**
     * %TBD% Doc
     *
     * NEEDSDOC ($objectName$) @return
     */
    public int getNodeIdentityMask()
    {
      return IDENT_NODE_DEFAULT;
    }
  
  }
  