/*
* Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 which accompanies this distribution,
* and is available at http://www.eclipse.org/legal/epl-v10.html
*/
package org.opendaylight.yangtools.yang.data.api.schema.xpath;
import com.google.common.annotations.Beta;
import com.google.common.base.Optional;
import com.google.common.util.concurrent.CheckedFuture;
import java.util.concurrent.Future;
import javax.annotation.Nonnull;
import javax.xml.xpath.XPathExpressionException;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
/**
* Asynchronous interface to evaluation. It is functionally the same as an XPathExpression, but allows for asynchronous
* execution of evaluation of the expression.
*
* FIXME: Whether or not the resulting XPathResult can perform blocking calls is up for grabs, but implementations are
* definitely allowed to perform things like on-demand data transformation from foreign object and data models.
*
* @deprecated PREVIEW API. DO NOT IMPLEMENT YET AS THIS NEEDS TO BE VALIDATED FOR USE IN CLIENT APPLICATIONS.
* APPLICATIONS WILLING TO USE THIS API PLEASE CONTACT
* yangtools-dev.
*/
@Beta
@Deprecated
public interface LazyXPathExpression {
/**
* Evaluate this expression at the specified path in a document. If evaluation succeeds, it will return an
* {@link XPathResult} at some point it the future. If it fails to match anything, it {@link Future#get()} will
* return {@link Optional#absent()}.
*
* FIXME: The amount of overhead an implementation can incur on the user as data from the resulting
* {@link XPathResult} is being accessed is left UNDEFINED.
*
* Specifically, the user is expected to store each result returned directly or indirectly in a local
* variable instead of repeated calls to the result's methods, as these may incur CPU processing overhead.
*
* Furthermore all method invocations can throw {@link LazyXPathExpressionException}, which the users are
* expected to handle gracefully. RESILIENT USERS ARE EXPECTED TO CATCH {@link LazyXPathExpressionException}
* AND RECOVER IN THE SAME MANNER THEY WOULD IF AN {@link XPathExpressionException} WOULD HAVE BEEN THROWN.
*
* [ FIXME: would it be appropriate to allow implementations to SneakyThrow {@link XPathExpressionException}
* and not introduce a RuntimeExpcetion ? ]
*
* @param document {@link XPathDocument} on which evaluation should take place
* @param path Path to the node on which to evaluate the expression
* @return An optional {@link XPathResult}
* @throws NullPointerException if any of the arguments are null
* @throws IllegalArgumentException if the path does not match the path at which this expression was compiled
*/
CheckedFuture>, XPathExpressionException> evaluateLazily(
@Nonnull XPathDocument document, @Nonnull YangInstanceIdentifier path);
}