org.opendaylight.yangtools.yang.data.api.schema.xpath

Interface XPathExpression

All Known Subinterfaces:

OptimizableXPathExpression, RelocatableXPathExpression

@Beta
public interface XPathExpression

A compiled XPath expression. Each instance is bound to a particular XPathSchemaContext and may not be evaluated on XPathDocuments from other context.

Method Summary

Modifier and Type	Method and Description
Optional<? extends XPathResult<?>>	evaluate(@NonNull XPathDocument document, @NonNull YangInstanceIdentifier path) Evaluate this expression at the specified path in a document.
@NonNull SchemaPath	getApexPath() Return the SchemaPath of the topmost node which affects the result of evaluation of this expression.
@NonNull SchemaPath	getEvaluationPath() Return the evaluation context SchemaPath of this expression.

Method Detail

evaluate

Optional<? extends XPathResult<?>> evaluate(@NonNull XPathDocument document,
                                            @NonNull YangInstanceIdentifier path)
                                     throws XPathExpressionException

Evaluate this expression at the specified path in a document. If evaluation succeeds, it will return an XPathResult. If it fails to match anything, it will return Optional.empty(). Implementations of this method are expected to perform complete evaluation such that accessing data via the resulting XPathResult will not incur large overhead.

Parameters:

document - XPathDocument on which evaluation should take place

path - Path to the node on which to evaluate the expression

Returns:

An optional XPathResult

Throws:

NullPointerException - if any of the arguments are null

XPathExpressionException - if the expression cannot be evaluated

IllegalArgumentException - if the path does not match the path at which this expression was compiled

getEvaluationPath

@NonNull SchemaPath getEvaluationPath()

Return the evaluation context SchemaPath of this expression. This is corresponds to the SchemaPath at which this expression was compiled at, or relocated to via RelocatableXPathExpression.relocateExpression().

Returns:

The evaluation SchemaPath

getApexPath

@NonNull SchemaPath getApexPath()

Return the SchemaPath of the topmost node which affects the result of evaluation of this expression. This information is useful for large evolving documents (such as DataTree implementations) to minimize the frequency of evaluation. The apex can be either logically higher or lower in the SchemaPath tree than getEvaluationPath().

Returns:

The apex node evaluation of this expression can reference, or SchemaPath.ROOT if it cannot cannot be conclusively determined.