net.sf.saxon.trans
public class KeyManager extends Object implements Serializable
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.
Constructor Summary | |
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KeyManager(Configuration config)
create a KeyManager and initialise variables |
Method Summary | |
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void | addKeyDefinition(int fingerprint, KeyDefinition keydef, NamePool namePool)
Register a key definition. |
List | getKeyDefinitions(int fingerprint)
Get all the key definitions that match a particular fingerprint |
SequenceIterator | selectByKey(int fingerprint, DocumentInfo doc, AtomicValue value, XPathContext context)
Get the nodes with a given key value |
Parameters: fingerprint Integer representing the name of the key keydef The details of the key's definition namePool
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.
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