src/org/apache/xml/dtm/ref/xni2dtm/DTM_XSequence.java

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package org.apache.xml.dtm.ref.xni2dtm;

import org.apache.xml.dtm.DTMSequence;

/** This class provides an API representation for the XPath 2 Data Model's "Sequences"
 * -- which are the basic representation for typed values. Only built-in types, 
 * types derived from built-ins, and sets thereof are returned directly by the XPath2
 * DM; complex schema-types must be accessed through the document tree.
 * 
 * %REVIEW% Should we have a more compact empty-sequence? (Probably not worth
 * the effort, since XNI2DTM will use a stored instance.)
 * */
public class DTM_XSequence 
implements DTMSequence
{
  Object[] values;
  
  // We currently expect all elements in schema-produced sequencs to have
  // the same type. This may need to be enhanced at some point in the future.
  XPath2Type type;

  /** Create a sequence.
   * 
   * @param value Object representation of the primitive value. May be array.
   * @param type Datatype being represented. May be list-of type.
   * */
  public DTM_XSequence(Object value,XPath2Type type)
  {   
    // If it's a list-of type, we want to unwrap that and resport
    // the type of the individual element...

    XPath2Type itemType=type.getItemType();
    
    if(itemType==null)
    {
      // Creating the array is a bit wasteful. Special-case this?
      this.values=new Object[1];
      this.values[0]=value;
      this.type=type;
    }
    else
    {
      this.values=(Object[])value;
      this.type=itemType;
    }
  }
  
  /** @return the number of members in this sequence. */
  public int getLength()
  {
    return values.length;
  }
  
  /** Retrieve the value for this member of the sequence. Since values may be
   * a heterogenous mix, and their type may not be known until they're examined,
   * they're returned as Objects. This is storage-inefficient if the value(s)
   * is/are builtins that map to Java primitives. Tough.
   * 
   * @param index 0-based index into the sequence.
   * @return the specified value
   * @throws exception if index <0 or >=length   
   * */
  public Object getValue(int index)
  {
    return values[index];
  }
  
  /** Retrieve the datatype namespace URI for this member of the sequence.
   * 
   * @param index 0-based index into the sequence.
   * @return the namespace for the specified value's type
   * @throws exception if index <0 or >=length   
   * */
  public String getTypeNS(int index)
  {
    return type.getTargetNamespace();
  }
  
  /** Retrieve the datatype namespace URI for this member of the sequence.
   * 
   * %REVIEW% Do we really need type -- 
   * or can we just tell folks to do instanceOf on the Java value objects?  
   * 
   * @param index 0-based index into the sequence.
   * @return the localname of the specified value's type
   * @throws exception if index <0 or >=length   
   * */
  public String getTypeLocalName(int index)
  {
    return type.getTypeName();
  }
  
  /** Ask whether this member's datatype equals or is derived from a specified
   * schema NSURI/localname pair.
   * 
   * @param index 0-based index into the sequence.
   * @return true if the type is an instance of this schema datatype,
   * false if it isn't.
   * @throws exception if index <0 or >=length   
   * */
  public boolean isSchemaType(int index, String namespace, String localname)
  {
    return type.derivedFrom(namespace,localname);
  }
  
  /** %REVIEW% Format not yet firmly settled. Primarily for debugging purposes!
   * */
  public String toString()
  {
    StringBuffer b=new StringBuffer("Sequence[");
    String start="";
    
    for(int i=0;i<values.length;++i)
    {
      b.append(start)
          .append(type.getTargetNamespace()).append(':').append(type.getTypeName())
          .append(" = ");
          
      if(values[i] instanceof int[])
      {
      	int[] v=(int[])values[i];
      	b.append('[');
      	if(v.length>0)
      		b.append(v[0]);
      	for(int j=1;j<v.length;++j)
	      	b.append(',').append(v[j]);
      	b.append(']');
      }
      else
        b.append(values[i]);
        
      if(values[i]!=null)
          b.append(" {"+values[i].getClass().getName()+"}");
      start=", ";
    }
    return b.append(']').toString();
  }
}