Class KeyManager

java.lang.Object
net.sf.saxon.trans.KeyManager
All Implemented Interfaces:
Serializable

public class KeyManager extends Object implements Serializable
KeyManager manages the set of key definitions in a stylesheet, and the indexes associated with these key definitions. It handles xsl:sort-key as well as xsl:key definitions.

The memory management in this class is subtle, with extensive use of weak references. The idea is that an index should continue to exist in memory so long as both the compiled stylesheet and the source document exist in memory: if either is removed, the index should go too. The document itself holds no reference to the index. The compiled stylesheet (which owns the KeyManager) holds a weak reference to the index. The index, of course, holds strong references to the nodes in the document. The Controller holds a strong reference to the list of indexes used for each document, so that indexes remain in memory for the duration of a transformation even if the documents themselves are garbage collected.

Potentially there is a need for more than one index for a given key name, depending on the primitive type of the value provided to the key() function. An index is built corresponding to the type of the requested value; if subsequently the key() function is called with the same name and a different type of value, then a new index is built.

Author:
Michael H. Kay
See Also:
  • Constructor Details

    • KeyManager

      public KeyManager(Configuration config)
      create a KeyManager and initialise variables
  • Method Details

    • addKeyDefinition

      public void addKeyDefinition(int fingerprint, KeyDefinition keydef, Configuration config) throws XPathException
      Register a key definition. Note that multiple key definitions with the same name are allowed
      Parameters:
      fingerprint - Integer representing the name of the key
      keydef - The details of the key's definition
      config - The configuration
      Throws:
      XPathException
    • getKeyDefinitions

      public List getKeyDefinitions(int fingerprint)
      Get all the key definitions that match a particular fingerprint
      Parameters:
      fingerprint - The fingerprint of the name of the required key
      Returns:
      The key definition of the named key if there is one, or null otherwise.
    • selectByKey

      public SequenceIterator selectByKey(int fingerprint, DocumentInfo doc, AtomicValue value, XPathContext context) throws XPathException
      Get the nodes with a given key value
      Parameters:
      fingerprint - The fingerprint of the name of the required key
      doc - The source document in question
      value - The required key value
      context - The dynamic context, needed only the first time when the key is being built
      Returns:
      an enumeration of nodes, always in document order
      Throws:
      XPathException
    • explainKeys

      public void explainKeys(Configuration config)
      Diagnostic output explaining the keys