org.apache.marmotta.ldpath.template.engine.LDPathDirective Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.marmotta.ldpath.template.engine;
import freemarker.core.Environment;
import freemarker.template.*;
import org.apache.marmotta.ldpath.LDPath;
import org.apache.marmotta.ldpath.api.backend.NodeBackend;
import org.apache.marmotta.ldpath.api.backend.RDFBackend;
import org.apache.marmotta.ldpath.exception.LDPathParseException;
import org.apache.marmotta.ldpath.model.Constants;
import org.apache.marmotta.ldpath.template.model.freemarker.TemplateNodeModel;
import org.apache.marmotta.ldpath.template.model.freemarker.TemplateStackModel;
import org.apache.marmotta.ldpath.template.model.freemarker.TemplateWrapperModel;
import org.apache.marmotta.ldpath.template.model.transformers.*;
import org.apache.marmotta.ldpath.template.util.FormatUtil;
import java.io.IOException;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
/**
* A directive for inserting values retrieved with LDPath. It can be used in several forms:
*
* Value Insertion (without body):
* Allows inserting the value of a path expression. The path expression should specify an XML schema type for the
* type conversion. If no type is given, string conversion is assumed. If the expression would return several values,
* only the first result is taken.
*
*
* <@ldpath path="... :: xsd:type">
*
*
* Value Iteration (with body):
* Allows iterating over result nodes of a path expression. Further path expressions can be used to select the
* values of each result node.
*
*
* <@ldpath path="...">
* ...
* <@ldpath path="...">
* ...
* </@ldpath>
*
*
* If a loop variable is given, it will be bound to the context node. The context node is also implicitly available
* as the variable "context".
*
* Author: Sebastian Schaffert
*/
public class LDPathDirective implements TemplateDirectiveModel {
private LDPath ldpath;
private NodeBackend backend;
public LDPathDirective(RDFBackend backend) {
this.ldpath = new LDPath<>(backend);
this.backend = backend;
// register custom freemarker transformers for the parser so we get the results immediately in the freemarker model
ldpath.registerTransformer(Constants.NS_XSD + "string", new TemplateScalarTransformer());
ldpath.registerTransformer(Constants.NS_XSD + "decimal", new TemplateLongTransformer());
ldpath.registerTransformer(Constants.NS_XSD + "integer", new TemplateIntegerTransformer());
ldpath.registerTransformer(Constants.NS_XSD + "long", new TemplateLongTransformer());
ldpath.registerTransformer(Constants.NS_XSD + "short", new TemplateIntegerTransformer());
ldpath.registerTransformer(Constants.NS_XSD + "double", new TemplateDoubleTransformer());
ldpath.registerTransformer(Constants.NS_XSD + "float", new TemplateFloatTransformer());
ldpath.registerTransformer(Constants.NS_XSD + "dateTime", new TemplateDateTransformer(TemplateDateModel.DATETIME));
ldpath.registerTransformer(Constants.NS_XSD + "date", new TemplateDateTransformer(TemplateDateModel.DATE));
ldpath.registerTransformer(Constants.NS_XSD + "time", new TemplateDateTransformer(TemplateDateModel.TIME));
ldpath.registerTransformer(Constants.NS_XSD + "boolean", new TemplateBooleanTransformer());
ldpath.registerTransformer(Constants.NS_XSD + "anyURI", new TemplateScalarTransformer());
}
/**
* Executes this user-defined directive; called by FreeMarker when the user-defined
* directive is called in the template.
*
* @param env the current processing environment. Note that you can access
* the output {@link java.io.Writer Writer} by {@link freemarker.core.Environment#getOut()}.
* @param params the parameters (if any) passed to the directive as a
* map of key/value pairs where the keys are {@link String}-s and the
* values are {@link freemarker.template.TemplateModel} instances. This is never
* null. If you need to convert the template models to POJOs,
* you can use the utility methods in the {@link freemarker.template.utility.DeepUnwrap} class.
* @param loopVars an array that corresponds to the "loop variables", in
* the order as they appear in the directive call. ("Loop variables" are out-parameters
* that are available to the nested body of the directive; see in the Manual.)
* You set the loop variables by writing this array. The length of the array gives the
* number of loop-variables that the caller has specified.
* Never null, but can be a zero-length array.
* @param body an object that can be used to render the nested content (body) of
* the directive call. If the directive call has no nested content (i.e., it is like
* [@myDirective /] or [@myDirective][/@myDirective]), then this will be
* null.
* @throws freemarker.template.TemplateException
*
* @throws java.io.IOException
*/
@SuppressWarnings("unchecked")
@Override
public void execute(Environment env, @SuppressWarnings("rawtypes") Map params, TemplateModel[] loopVars, TemplateDirectiveBody body) throws TemplateException, IOException {
TemplateStackModel contextStack = (TemplateStackModel)env.getVariable("context");
if(contextStack == null || contextStack.empty()) {
throw new TemplateModelException("error; no context node available");
}
TemplateNodeModel context = (TemplateNodeModel)contextStack.peek();
SimpleScalar pathScalar = (SimpleScalar)params.get("path");
if(pathScalar == null) {
throw new TemplateException("the directive has been called without a path parameter",env);
}
String path = pathScalar.getAsString();
TemplateWrapperModel> namespacesWrapped = (TemplateWrapperModel>)env.getGlobalVariable("namespaces");
Map namespaces;
if(namespacesWrapped == null) {
namespaces = new HashMap<>();
namespacesWrapped = new TemplateWrapperModel>(new HashMap());
env.setGlobalVariable("namespaces",namespacesWrapped);
} else {
namespaces = namespacesWrapped.getAdaptedObject(Map.class);
}
if(body == null) { // value insertion
if(!path.contains("::")) {
path = path + ":: xsd:string";
}
try {
Collection results = ldpath.pathTransform(context.getNode(),path,namespaces);
if(results.size() > 0) {
Object result = results.iterator().next();
if(result instanceof TemplateNumberModel) {
env.getOut().write(FormatUtil.formatNumber( ((TemplateNumberModel)result).getAsNumber() ));
} else if(result instanceof TemplateDateModel) {
switch (((TemplateDateModel)result).getDateType()) {
case TemplateDateModel.DATE:
env.getOut().write(FormatUtil.formatDate(((TemplateDateModel)result).getAsDate()));
break;
case TemplateDateModel.TIME:
env.getOut().write(FormatUtil.formatTime(((TemplateDateModel)result).getAsDate()));
break;
case TemplateDateModel.DATETIME:
env.getOut().write(FormatUtil.formatDateTime(((TemplateDateModel)result).getAsDate()));
break;
default:
env.getOut().write(FormatUtil.formatDateTime(((TemplateDateModel)result).getAsDate()));
}
} else if(result instanceof TemplateScalarModel) {
env.getOut().write( ((TemplateScalarModel)result).getAsString() );
} else if(result instanceof TemplateBooleanModel) {
env.getOut().write( Boolean.toString(((TemplateBooleanModel)result).getAsBoolean()) );
}
} // else write nothing
} catch (LDPathParseException e) {
throw new TemplateException("invalid path for ldpath directive: "+path,e,env);
}
} else {
try {
for(Node node : ldpath.pathQuery(context.getNode(),path,namespaces)) {
contextStack.push(new TemplateNodeModel<>(node, backend));
if(loopVars.length > 0) {
loopVars[0] = new TemplateNodeModel<>(node, backend);
}
body.render(env.getOut());
contextStack.pop();
}
} catch(LDPathParseException ex) {
throw new TemplateException("invalid path for ldpath directive: "+path,ex,env);
}
}
}
}