net.sf.saxon.s9api.streams

Class Step<T extends XdmItem>

java.lang.Object

net.sf.saxon.s9api.streams.Step<T>

Type Parameters:

T - the type of XdmItem that is returned by the step. (Note that we don't parameterize Steps by the type of input item).

All Implemented Interfaces:

Function<XdmItem,Stream<? extends T>>

Direct Known Subclasses:

AxisStep

public abstract class Step<T extends XdmItem>
extends Object
implements Function<XdmItem,Stream<? extends T>>

A Step is a function that can be applied to an item to return a stream of items.

See Also:

Steps

Constructor Summary

Constructors

Constructor and Description
Step()

Method Summary

Modifier and Type	Method and Description
Step<T>	at(long index) Obtain a step that selects the Nth item in the results of this step
Step<T>	cat(Step<T> other) Obtain a Step that concatenates the results of this Step with the result of another Step applied to the same input item.
Step<T>	first() Obtain a step that selects the first item in the results of this step
Step<T>	last() Obtain a step that selects the last item in the results of this step
<U extends XdmItem> Step<U>	then(Step<U> next) Obtain a step that combines the results of this step with the results of another step
Step<T>	where(Predicate<? super T> predicate) Obtain a Step that filters the results of this Step using a supplied predicate.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.function.Function

andThen, apply, compose, identity

Constructor Detail

Step

public Step()

Method Detail

where

public Step<T> where(Predicate<? super T> predicate)

Obtain a Step that filters the results of this Step using a supplied predicate.

For example, CHILD.where(isText()) returns a Step whose effect is to select the text node children of a supplied element or document node.

Parameters:

predicate - the predicate which will be applied to the results of this step

Returns:

a new Step (that is, a function from one Stream of items to another) that filters the results of this step by selecting only the items that satisfy the predicate.

cat

public Step<T> cat(Step<T> other)

Obtain a Step that concatenates the results of this Step with the result of another Step applied to the same input item.

For example, attribute().cat(child()) returns a step whose effect is to select the attributes of a supplied element followed by its children.

Parameters:

other - the step whose results will be concatenated with the results of this step

Returns:

a new Step (that is, a function from one Stream of items to another) that concatenates the results of applying this step to the input item, followed by the results of applying the other step to the input item.

first

public Step<T> first()

Obtain a step that selects the first item in the results of this step

Returns:

a new Step (that is, a function from one Stream of items to another) that filters the results of this step by selecting only the first item.

last

public Step<T> last()

Obtain a step that selects the last item in the results of this step

Returns:

a new Step (that is, a function from one Stream of items to another) that filters the results of this step by selecting only the last item.

at

public Step<T> at(long index)

Obtain a step that selects the Nth item in the results of this step

Parameters:

index - the zero-based index of the item to be selected

Returns:

a new Step (that is, a function from one Stream of items to another) that filters the results of this step by selecting only the items that satisfy the predicate.

then

public <U extends XdmItem> Step<U> then(Step<U> next)

Obtain a step that combines the results of this step with the results of another step

Parameters:

next - the step which will be applied to the results of this step

Returns:

a new Step (that is, a function from one Stream of items to another) that performs this step and the next step in turn. The result is equivalent to the Java {code flatMap()} function or the XPath {code !} operator: there is no sorting of nodes into document order, and no elimination of duplicates.