net.sf.saxon.s9api

Class XPathExecutable

java.lang.Object

net.sf.saxon.s9api.XPathExecutable

public class XPathExecutable
extends java.lang.Object

An XPathExecutable represents the compiled form of an XPath expression. To evaluate the expression, it must first be loaded to form an XPathSelector.

An XPathExecutable is immutable, and therefore thread-safe. It is simplest to load a new XPathSelector each time the expression is to be evaluated. However, the XPathSelector is serially reusable within a single thread.

An XPathExecutable is created by using the XPathCompiler.compile(java.lang.String) method on the XPathCompiler class.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	XPathExecutable(XPathExpression exp, Processor processor, IndependentContext env)

Method Summary

Modifier and Type	Method and Description
Step<XdmItem>	asStep() Treat the compiled XPath expression as a Step, so that it can be used in a call on XdmValue.select(net.sf.saxon.s9api.streams.Step<T>).
OccurrenceIndicator	getRequiredCardinalityForVariable(QName variableName) Get the required cardinality of a declared variable in the static context of the expression.
ItemType	getRequiredItemTypeForVariable(QName variableName) Get the required item type of a declared variable in the static context of the expression.
OccurrenceIndicator	getResultCardinality() Get the statically-determined cardinality of the result of the expression.
ItemType	getResultItemType() Get the ItemType of the items in the result of the expression, as determined by static analysis.
XPathExpression	getUnderlyingExpression() Get the underlying implementation object representing the compiled XPath expression.
StaticContext	getUnderlyingStaticContext() Get the underlying implementation object representing the static context of the compiled XPath expression.
java.util.Iterator<QName>	iterateExternalVariables() Get an iterator over the names of all the external variables.
XPathSelector	load() Load the compiled XPath expression to prepare it for execution.

Methods inherited from class java.lang.Object

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

Constructor Detail

XPathExecutable

protected XPathExecutable(XPathExpression exp,
                          Processor processor,
                          IndependentContext env)

Method Detail

load

public XPathSelector load()

Load the compiled XPath expression to prepare it for execution.

Returns:

An XPathSelector. The returned XPathSelector can be used to set up the dynamic context, and then to evaluate the expression.

asStep

public Step<XdmItem> asStep()

Treat the compiled XPath expression as a Step, so that it can be used in a call on XdmValue.select(net.sf.saxon.s9api.streams.Step<T>).

Example usage: node.select(c.compile(".//x[a=b+2]").asStep()).asXdmValue()

Returns:

a Step, whose effect is to evaluate the XPath expression (with the origin item as the initial context item)

getResultItemType

public ItemType getResultItemType()

Get the ItemType of the items in the result of the expression, as determined by static analysis. This is the most precise ItemType that the processor is able to determine from static examination of the expression; the actual items in the expression result are guaranteed to belong to this ItemType or to a subtype of this ItemType.

Returns:

the statically-determined ItemType of the result of the expression

Since:

9.1

getResultCardinality

public OccurrenceIndicator getResultCardinality()

Get the statically-determined cardinality of the result of the expression. This is the most precise cardinality that the processor is able to determine from static examination of the expression.

Returns:

the statically-determined cardinality of the result of the expression

Since:

9.1

iterateExternalVariables

public java.util.Iterator<QName> iterateExternalVariables()

Get an iterator over the names of all the external variables. This includes both variables that have been explicitly declared using a call to declareVariable(), and variables that are implicitly declared by reference in the case where the allowUndeclaredVariables option is set. It does not include range variables bound in a for, some, or every expression.

If the allowUndeclaredVariables option is set, this method allows discovery of the variable references that appear in the compiled expression.

Returns:

an iterator over the names of the external variables defined in the XPath expression

Since:

9.2

getRequiredItemTypeForVariable

public ItemType getRequiredItemTypeForVariable(QName variableName)

Get the required item type of a declared variable in the static context of the expression.

Parameters:

variableName - the name of a declared variable

Returns:

the required item type.

If the variable was explicitly declared, this will be the item type that was set when the variable was declared. If no item type was set, it will be ItemType.ANY_ITEM.

If the variable was implicitly declared by reference (which can happen only when the allowUndeclaredVariables option is set), the returned type will be ItemType.ANY_ITEM.

If no variable with the specified QName has been declared either explicitly or implicitly, the method returns null.

Since:

9.2

getRequiredCardinalityForVariable

public OccurrenceIndicator getRequiredCardinalityForVariable(QName variableName)

Get the required cardinality of a declared variable in the static context of the expression.

Parameters:

variableName - the name of a declared variable

Returns:

the required cardinality.

If the variable was explicitly declared, this will be the occurrence indicator that was set when the variable was declared. If no item type was set, it will be OccurrenceIndicator.ZERO_OR_MORE.

If the variable was implicitly declared by reference (which can happen only when the allowUndeclaredVariables option is set), the returned type will be OccurrenceIndicator.ZERO_OR_MORE.

If no variable with the specified QName has been declared either explicitly or implicitly, the method returns null.

Since:

9.2

getUnderlyingExpression

public XPathExpression getUnderlyingExpression()

Get the underlying implementation object representing the compiled XPath expression. This method provides access to lower-level Saxon classes and methods which may be subject to change from one release to the next.

Returns:

the underlying compiled XPath expression.

getUnderlyingStaticContext

public StaticContext getUnderlyingStaticContext()

Get the underlying implementation object representing the static context of the compiled XPath expression. This method provides access to lower-level Saxon classes and methods which may be subject to change from one release to the next.

Returns:

the underlying static context.