Class KeyManager

  • All Implemented Interfaces:
    java.io.Serializable

    public class KeyManager
    extends java.lang.Object
    implements java.io.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:
    Serialized Form
    • Constructor Detail

      • KeyManager

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

      • 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 java.util.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