FnDocumentAvailable.java
/*
* SPDX-FileCopyrightText: none
* SPDX-License-Identifier: CC0-1.0
*/
package gov.nist.secauto.metaschema.core.metapath.function.library;
import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
import gov.nist.secauto.metaschema.core.metapath.ISequence;
import gov.nist.secauto.metaschema.core.metapath.MetapathConstants;
import gov.nist.secauto.metaschema.core.metapath.MetapathException;
import gov.nist.secauto.metaschema.core.metapath.function.DocumentFunctionException;
import gov.nist.secauto.metaschema.core.metapath.function.FunctionUtils;
import gov.nist.secauto.metaschema.core.metapath.function.IArgument;
import gov.nist.secauto.metaschema.core.metapath.function.IFunction;
import gov.nist.secauto.metaschema.core.metapath.item.IItem;
import gov.nist.secauto.metaschema.core.metapath.item.atomic.IAnyUriItem;
import gov.nist.secauto.metaschema.core.metapath.item.atomic.IBooleanItem;
import gov.nist.secauto.metaschema.core.metapath.item.atomic.IStringItem;
import gov.nist.secauto.metaschema.core.util.ObjectUtils;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URLConnection;
import java.util.List;
import edu.umd.cs.findbugs.annotations.NonNull;
public final class FnDocumentAvailable {
@NonNull
static final IFunction SIGNATURE = IFunction.builder()
.name("doc-available")
.namespace(MetapathConstants.NS_METAPATH_FUNCTIONS)
.deterministic()
.contextDependent()
.focusIndependent()
.argument(IArgument.builder()
.name("arg1")
.type(IStringItem.class)
.zeroOrOne()
.build())
.returnType(IBooleanItem.class)
.returnOne()
.functionHandler(FnDocumentAvailable::execute)
.build();
private FnDocumentAvailable() {
// disable construction
}
@SuppressWarnings("unused")
@NonNull
private static ISequence<IBooleanItem> execute(@NonNull IFunction function,
@NonNull List<ISequence<?>> arguments, @NonNull DynamicContext dynamicContext,
IItem focus) {
ISequence<? extends IStringItem> arg = FunctionUtils.asType(ObjectUtils.requireNonNull(arguments.get(0)));
IStringItem item = arg.getFirstItem(true);
return item == null ? ISequence.empty() : ISequence.of(fnDocAvailable(item, dynamicContext));
}
/**
* Test if the document associated with the URI is retrievable.
* <p>
* Based on the XPath 3.1 <a href=
* "https://www.w3.org/TR/xpath-functions-31/#func-doc-available">fn:doc</a>
* function.
*
* @param documentUri
* the resource to load the data from
* @param context
* the Metapath dynamic context
* @return if the document is retrievable
*/
public static IBooleanItem fnDocAvailable(@NonNull IStringItem documentUri, @NonNull DynamicContext context) {
IAnyUriItem uri;
try {
uri = IAnyUriItem.cast(documentUri);
} catch (MetapathException ex) {
throw new DocumentFunctionException(DocumentFunctionException.INVALID_ARGUMENT,
String.format("Invalid URI argument '%s' to fn:doc or fn:doc-available.", documentUri.asString()), ex);
}
return fnDocAvailable(uri, context);
}
/**
* Test if the document associated with the URI is retrievable.
* <p>
* Based on the XPath 3.1 <a href=
* "https://www.w3.org/TR/xpath-functions-31/#func-doc-available">fn:doc</a>
* function.
*
* @param documentUri
* the resource to load the data from
* @param context
* the Metapath dynamic context
* @return if the document is retrievable
*/
public static IBooleanItem fnDocAvailable(@NonNull IAnyUriItem documentUri, @NonNull DynamicContext context) {
// resolve if possible
IAnyUriItem uri = FnResolveUri.fnResolveUri(documentUri, null, context);
if (!uri.isAbsolute() && !uri.isOpaque()) {
throw new DocumentFunctionException(DocumentFunctionException.ERROR_RETRIEVING_RESOURCE, String
.format("No base-uri is available in the static context to resolve the URI '%s'.", documentUri.toString()));
}
boolean retval;
try {
URLConnection connection = uri.asUri().toURL().openConnection();
if (connection instanceof HttpURLConnection) {
HttpURLConnection httpConnection = (HttpURLConnection) connection;
httpConnection.setRequestMethod("HEAD");
httpConnection.connect();
retval = HttpURLConnection.HTTP_OK == httpConnection.getResponseCode();
httpConnection.disconnect();
} else {
connection.connect();
retval = true;
}
return IBooleanItem.valueOf(retval);
} catch (IOException ex) {
throw new DocumentFunctionException(DocumentFunctionException.ERROR_RETRIEVING_RESOURCE, String
.format("Unable to retrieve the resource identified by the URI '%s'.", documentUri.toString()), ex);
}
}
}