Package com.saxonica.ee.trans

Class AncestorPatternOptimizer

java.lang.Object

com.saxonica.ee.trans.PatternOptimizer

com.saxonica.ee.trans.AncestorPatternOptimizer

public class AncestorPatternOptimizer
extends PatternOptimizer

A PatternOptimizer is an agent responsible for optimizing a particular class of patterns. It has two parts: a meta-pattern which determines which kinds of pattern it recognizes, and an action part which extracts characteristics and preconditions whose evaluation can be shared by all the rules in a rule chain

Constructor Summary

Constructors

Constructor	Description
AncestorPatternOptimizer()

Method Summary

Modifier and Type	Method	Description
boolean	appliesTo(Pattern pattern)	Ask whether this pattern optimizer is applicable to a particular pattern
static AncestorPatternOptimizer	getInstance()
void	process(RuleEE rule, Pattern pattern, Map<Precondition,List<RuleEE>> preconditions, Map<Characteristic,Characteristic> characteristics)	Process a particular pattern, potentially adding to the list of preconditions and characteristics maintained when processing a set of rules

Methods inherited from class com.saxonica.ee.trans.PatternOptimizer

addPrecondition, allocateCharacteristic

Methods inherited from class java.lang.Object

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

Constructor Details

AncestorPatternOptimizer

public AncestorPatternOptimizer()

Method Details

getInstance

public static AncestorPatternOptimizer getInstance()

appliesTo

public boolean appliesTo(Pattern pattern)

Description copied from class: PatternOptimizer

Ask whether this pattern optimizer is applicable to a particular pattern

Specified by:

appliesTo in class PatternOptimizer

Parameters:

pattern - the pattern in question

Returns:

true if this pattern optimizer is applicable to this pattern

process

public void process(RuleEE rule,
 Pattern pattern,
 Map<Precondition,List<RuleEE>> preconditions,
 Map<Characteristic,Characteristic> characteristics)

Description copied from class: PatternOptimizer

Process a particular pattern, potentially adding to the list of preconditions and characteristics maintained when processing a set of rules

Specified by:

process in class PatternOptimizer

Parameters:

rule - the rule to be processed

pattern - the pattern used by this rule

preconditions - a collection of preconditions maintained for a set of rules

characteristics - a collection of characteristics maintained for a set of rules. This is maintained as a map from characteristics to characteristics in which the key and the value are always the same; the reason for this curious structure is that when an equivalent characteristic is already present in the map, we want to return the existing characteristic to replace the new one; a Java Set does not have any (efficient) operation to "find the existing value in the set that is equal to X".