com.saxonica.ee.pattern.preconditions

Class ComparisonPredicateIndex.IndexBase

java.lang.Object

com.saxonica.ee.pattern.preconditions.ComparisonPredicateIndex.IndexBase

Enclosing class:

ComparisonPredicateIndex

public abstract class ComparisonPredicateIndex.IndexBase
extends Object

A class that is used to index sets of rules with common forms, such as patt[expr = value] where patt - the base pattern and expr - the LHS of a comparison are common By matching instances of this class we can group rules that have similar 'left hand sides' for indexation

Field Summary

Fields

Modifier and Type	Field and Description
Pattern	basePattern
AtomicComparer	comparer
Expression	comparisonLHS

Constructor Summary

Constructors

Constructor and Description
ComparisonPredicateIndex.IndexBase()

Method Summary

Methods

Modifier and Type	Method and Description
abstract boolean	equals(Object other)
abstract SequenceIterator	eval(Item item, XPathContext context) Evaluate this 'common LHS' against a context node to generate a possible iterator.
void	explain(ExpressionPresenter out)
int	hashCode()
SequenceIterator	makeIterator(Item item, XPathContext context) Make an iterator for a given item and context

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

basePattern

public Pattern basePattern

comparisonLHS

public Expression comparisonLHS

comparer

public AtomicComparer comparer

Constructor Detail

ComparisonPredicateIndex.IndexBase

public ComparisonPredicateIndex.IndexBase()

Method Detail

equals

public abstract boolean equals(Object other)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

eval

public abstract SequenceIterator eval(Item item,
                    XPathContext context)
                               throws XPathException

Evaluate this 'common LHS' against a context node to generate a possible iterator. Firstly context node must match against any base (and ancestral) patterns required, then the comparison expression LHS is evaluated in context to generate a (possibly empty) sequence of values that will then be used for rule index lookup.

Parameters:

item - the context item

context - the XPath context

Returns:

a sequence iterator over the LHS values, or null if the node doesn't match the required patterns

Throws:

XPathException

makeIterator

public SequenceIterator makeIterator(Item item,
                            XPathContext context)
                              throws XPathException

Make an iterator for a given item and context

Parameters:

item - the item to be iterated over

context - the dynamic context

Returns:

an iterator over the members of the sequence

Throws:

XPathException

explain

public void explain(ExpressionPresenter out)