com.saxonica.stream.feed

Class GroupStartingFeed

java.lang.Object

com.saxonica.stream.feed.ItemFeed

com.saxonica.stream.feed.GroupingFeed

com.saxonica.stream.feed.GroupStartingFeed

All Implemented Interfaces:

Feed

public class GroupStartingFeed
extends GroupingFeed

This class implements GroupingFeed when the group-starting-with option is used. It contains the logic to decide whether an item starts a new group, based on evaluating the group-starting-with pattern

Constructor Summary

Constructors

Constructor and Description
GroupStartingFeed(GroupVariableReference expression, Feed result, Stack<XPathContext> contextStack)

Method Summary

Methods

Modifier and Type	Method and Description
protected boolean	isStartOfNewGroup(boolean atStart, XPathContext context) Determine whether the current item is the start of a new group
void	open() Called at the start of the for-each-group instruction

Methods inherited from class com.saxonica.stream.feed.GroupingFeed

append, close, getControllingExpression, getLocalContext, setControllingExpression, setOuterFeed

Methods inherited from class com.saxonica.stream.feed.ItemFeed

getContext, getContextStack, getExpression, getPipelineConfiguration, getResult, setPipelineConfiguration

Methods inherited from class java.lang.Object

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

Constructor Detail

GroupStartingFeed

public GroupStartingFeed(GroupVariableReference expression,
                 Feed result,
                 Stack<XPathContext> contextStack)

Method Detail

open

public void open()
          throws XPathException

Called at the start of the for-each-group instruction

Specified by:

open in interface Feed

Overrides:

open in class GroupingFeed

Throws:

XPathException

isStartOfNewGroup

protected boolean isStartOfNewGroup(boolean atStart,
                        XPathContext context)
                             throws XPathException

Determine whether the current item is the start of a new group

Specified by:

isStartOfNewGroup in class GroupingFeed

Parameters:

atStart - true if this item is the first in the population

context - the evaluation context. The item in question will be the context item

Returns:

true if this item is to be the first in a new group

Throws:

XPathException - if a dynamic error occurs