io.camunda.zeebe.model.bpmn.traversal.ModelWalker Maven / Gradle / Ivy
/*
* Copyright © 2017 camunda services GmbH ([email protected])
*
* Licensed 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 io.camunda.zeebe.model.bpmn.traversal;
import io.camunda.zeebe.model.bpmn.BpmnModelInstance;
import io.camunda.zeebe.model.bpmn.impl.BpmnModelInstanceImpl;
import io.camunda.zeebe.model.bpmn.instance.BpmnModelElementInstance;
import io.camunda.zeebe.model.bpmn.instance.Definitions;
import io.camunda.zeebe.model.bpmn.instance.Process;
import java.util.Collection;
import java.util.Deque;
import java.util.LinkedList;
import org.camunda.bpm.model.xml.impl.util.ModelUtil;
import org.camunda.bpm.model.xml.instance.ModelElementInstance;
import org.camunda.bpm.model.xml.type.ModelElementType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Walks the elements of a {@link BpmnModelInstance} and invokes the provided {@link
* ModelElementVisitor} for every element.
*
* The following order is guaranteed (anything that is not listed here is not guaranteed):
*
*
* - An element is visited only after its parent has been visited (top-down)
*
- An element's child is visisted before any not yet visited sibling (depth-first)
*
*
* We can add more constraints to this as we see fit (e.g. certain BPMN elements in the same
* scope can be visited in a defined order to make transformation more convenient)
*
*
Depth-first is nice for transformation so we can have some kind of stack with transformation
* state.
*/
public class ModelWalker {
private static final Logger LOG = LoggerFactory.getLogger(ModelWalker.class);
private final BpmnModelInstanceImpl modelInstance;
private final Deque elementsToVisit = new LinkedList<>();
public ModelWalker(final BpmnModelInstance modelInstance) {
this.modelInstance = (BpmnModelInstanceImpl) modelInstance;
}
public void walk(final ModelElementVisitor visitor) {
final Definitions rootElement = modelInstance.getDefinitions();
elementsToVisit.add(rootElement); // top-down
BpmnModelElementInstance currentElement;
while ((currentElement = elementsToVisit.poll()) != null) {
// add a new check here for ignore non-executable processes
if (isNonExecutableProcess(currentElement)) {
continue;
}
visitor.visit(currentElement);
final Collection children = getChildElements(currentElement);
children.forEach(
c -> {
if (c instanceof BpmnModelElementInstance) {
elementsToVisit.addFirst((BpmnModelElementInstance) c);
} else {
final ModelElementType elementType = c.getElementType();
LOG.debug(
"Ignoring unknown BPMN element '{}:{}'",
elementType.getTypeNamespace(),
elementType.getTypeName());
}
}); // depth-first
}
}
private Collection getChildElements(
final BpmnModelElementInstance element) {
return ModelUtil.getModelElementCollection(
element.getDomElement().getChildElements(), modelInstance);
}
private boolean isNonExecutableProcess(final BpmnModelElementInstance element) {
if (element instanceof Process) {
final Process process = (Process) element;
return !process.isExecutable();
} else {
return false;
}
}
}