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.
For XSLT-defined keys, equality matching follows the rules of the eq operator, which means that untypedAtomic values are treated as strings. In backwards compatibility mode, all values are converted to strings.
This class is also used for internal indexes constructed (a) to support the idref() function, and (b) (in Saxon-EE only) to support filter expressions of the form /a/b/c[d=e], where the path expression being filtered must be a single-document context-free path rooted at a document node, where exactly one of d and e must be dependent on the focus, and where certain other conditions apply such as the filter predicate not being positional. The operator in this case may be either "=" or "eq". If it is "eq", then the semantics are very similar to xsl:key indexes, except that use of non-comparable types gives an error rather than a non-match. If the operator is "=", however, then the rules for handling untypedAtomic values are different: these must be converted to the type of the other operand. In this situation the following rules apply. Assume that the predicate is [use=value], where use is dependent on the focus (the indexed value), and value is the sought value.
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.
For XSLT-defined keys, equality matching follows the rules of the eq operator, which means that untypedAtomic values are treated as strings. In backwards compatibility mode, all values are converted to strings.
This class is also used for internal indexes constructed (a) to support the idref() function, and (b) (in Saxon-EE only) to support filter expressions of the form /a/b/c[d=e], where the path expression being filtered must be a single-document context-free path rooted at a document node, where exactly one of d and e must be dependent on the focus, and where certain other conditions apply such as the filter predicate not being positional. The operator in this case may be either "=" or "eq". If it is "eq", then the semantics are very similar to xsl:key indexes, except that use of non-comparable types gives an error rather than a non-match. If the operator is "=", however, then the rules for handling untypedAtomic values are different: these must be converted to the type of the other operand. In this situation the following rules apply. Assume that the predicate is [use=value], where use is dependent on the focus (the indexed value), and value is the sought value.
"key()" function.
@author Dmitri Plotnikov
@version $Revision: 1.3 $ $Date: 2003/03/11 00:59:12 $
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.
For XSLT-defined keys, equality matching follows the rules of the eq operator, which means that untypedAtomic values are treated as strings. In backwards compatibility mode, all values are converted to strings.
This class is also used for internal indexes constructed (a) to support the idref() function, and (b) (in Saxon-SA only) to support filter expressions of the form /a/b/c[d=e], where the path expression being filtered must be a single-document context-free path rooted at a document node, where exactly one of d and e must be dependent on the focus, and where certain other conditions apply such as the filter predicate not being positional. The operator in this case may be either "=" or "eq". If it is "eq", then the semantics are very similar to xsl:key indexes, except that use of non-comparable types gives an error rather than a non-match. If the operator is "=", however, then the rules for handling untypedAtomic values are different: these must be converted to the type of the other operand. In this situation the following rules apply. Assume that the predicate is [use=value], where use is dependent on the focus (the indexed value), and value is the sought value.
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