/*
* 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.tools.ant.types;
import java.util.Stack;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.ComponentHelper;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.ProjectComponent;
import org.apache.tools.ant.util.IdentityStack;
/**
* Base class for those classes that can appear inside the build file
* as stand alone data types.
*
* <p>This class handles the common description attribute and provides
* a default implementation for reference handling and checking for
* circular references that is appropriate for types that can not be
* nested inside elements of the same type (i.e. <patternset>
* but not <path>).</p>
*
*/
public abstract class DataType extends ProjectComponent implements Cloneable {
// CheckStyle:VisibilityModifier OFF
/**
* Value to the refid attribute.
*
* @deprecated since 1.7.
* The user should not be directly referencing
* variable. Please use {@link #getRefid} instead.
*/
protected Reference ref;
/**
* Are we sure we don't hold circular references?
*
* <p>Subclasses are responsible for setting this value to false
* if we'd need to investigate this condition (usually because a
* child element has been added that is a subclass of
* DataType).</p>
*
* @deprecated since 1.7.
* The user should not be directly referencing
* variable. Please use {@link #setChecked} or
* {@link #isChecked} instead.
*/
protected boolean checked = true;
// CheckStyle:VisibilityModifier ON
/**
* Has the refid attribute of this element been set?
* @return true if the refid attribute has been set
*/
public boolean isReference() {
return ref != null;
}
/**
* Set the value of the refid attribute.
*
* <p>Subclasses may need to check whether any other attributes
* have been set as well or child elements have been created and
* thus override this method. if they do the must call
* <code>super.setRefid</code>.</p>
* @param ref the reference to use
*/
public void setRefid(final Reference ref) {
this.ref = ref;
checked = false;
}
/**
* Gets as descriptive as possible a name used for this datatype instance.
* @return <code>String</code> name.
*/
protected String getDataTypeName() {
return ComponentHelper.getElementName(getProject(), this, true);
}
/**
* Convenience method.
* @since Ant 1.7
*/
protected void dieOnCircularReference() {
dieOnCircularReference(getProject());
}
/**
* Convenience method.
* @param p the Ant Project instance against which to resolve references.
* @since Ant 1.7
*/
protected void dieOnCircularReference(Project p) {
if (checked || !isReference()) {
return;
}
dieOnCircularReference(new IdentityStack<Object>(this), p);
}
/**
* Check to see whether any DataType we hold references to is
* included in the Stack (which holds all DataType instances that
* directly or indirectly reference this instance, including this
* instance itself).
*
* <p>If one is included, throw a BuildException created by {@link
* #circularReference circularReference}.</p>
*
* <p>This implementation is appropriate only for a DataType that
* cannot hold other DataTypes as children.</p>
*
* <p>The general contract of this method is that it shouldn't do
* anything if {@link #checked <code>checked</code>} is true and
* set it to true on exit.</p>
* @param stack the stack of references to check.
* @param project the project to use to dereference the references.
* @throws BuildException on error.
*/
protected void dieOnCircularReference(final Stack<Object> stack,
final Project project)
throws BuildException {
if (checked || !isReference()) {
return;
}
Object o = ref.getReferencedObject(project);
if (o instanceof DataType) {
IdentityStack<Object> id = IdentityStack.getInstance(stack);
if (id.contains(o)) {
throw circularReference();
} else {
id.push(o);
((DataType) o).dieOnCircularReference(id, project);
id.pop();
}
}
checked = true;
}
/**
* Allow DataTypes outside org.apache.tools.ant.types to indirectly call
* dieOnCircularReference on nested DataTypes.
* @param dt the DataType to check.
* @param stk the stack of references to check.
* @param p the project to use to dereference the references.
* @throws BuildException on error.
* @since Ant 1.7
*/
public static void invokeCircularReferenceCheck(DataType dt, Stack<Object> stk,
Project p) {
dt.dieOnCircularReference(stk, p);
}
/**
* Allow DataTypes outside org.apache.tools.ant.types to indirectly call
* dieOnCircularReference on nested DataTypes.
*
* <p>Pushes dt on the stack, runs dieOnCircularReference and pops
* it again.</p>
* @param dt the DataType to check.
* @param stk the stack of references to check.
* @param p the project to use to dereference the references.
* @throws BuildException on error.
* @since Ant 1.8.0
*/
public static void pushAndInvokeCircularReferenceCheck(DataType dt,
Stack<Object> stk,
Project p) {
stk.push(dt);
dt.dieOnCircularReference(stk, p);
stk.pop();
}
/**
* Performs the check for circular references and returns the
* referenced object.
* @return the dereferenced object.
* @throws BuildException if the reference is invalid (circular ref, wrong class, etc).
* @since Ant 1.7
*/
protected Object getCheckedRef() {
return getCheckedRef(getProject());
}
/**
* Performs the check for circular references and returns the
* referenced object.
* @param p the Ant Project instance against which to resolve references.
* @return the dereferenced object.
* @throws BuildException if the reference is invalid (circular ref, wrong class, etc).
* @since Ant 1.7
*/
protected Object getCheckedRef(Project p) {
return getCheckedRef(getClass(), getDataTypeName(), p);
}
/**
* Performs the check for circular references and returns the
* referenced object.
* @param requiredClass the class that this reference should be a subclass of.
* @param dataTypeName the name of the datatype that the reference should be
* (error message use only).
* @return the dereferenced object.
* @throws BuildException if the reference is invalid (circular ref, wrong class, etc).
*/
protected <T> T getCheckedRef(final Class<T> requiredClass,
final String dataTypeName) {
return getCheckedRef(requiredClass, dataTypeName, getProject());
}
/**
* Performs the check for circular references and returns the
* referenced object. This version allows the fallback Project instance to be specified.
* @param requiredClass the class that this reference should be a subclass of.
* @param dataTypeName the name of the datatype that the reference should be
* (error message use only).
* @param project the fallback Project instance for dereferencing.
* @return the dereferenced object.
* @throws BuildException if the reference is invalid (circular ref, wrong class, etc),
* or if <code>project</code> is <code>null</code>.
* @since Ant 1.7
*/
protected <T> T getCheckedRef(final Class<T> requiredClass,
final String dataTypeName, final Project project) {
if (project == null) {
throw new BuildException("No Project specified");
}
dieOnCircularReference(project);
Object o = ref.getReferencedObject(project);
if (!(requiredClass.isAssignableFrom(o.getClass()))) {
log("Class " + displayName(o.getClass())
+ " is not a subclass of "
+ displayName(requiredClass),
Project.MSG_VERBOSE);
String msg = ref.getRefId() + " doesn\'t denote a " + dataTypeName;
throw new BuildException(msg);
}
@SuppressWarnings("unchecked")
final T result = (T) o;
return result;
}
/**
* Creates an exception that indicates that refid has to be the
* only attribute if it is set.
* @return the exception to throw
*/
protected BuildException tooManyAttributes() {
return new BuildException("You must not specify more than one "
+ "attribute when using refid");
}
/**
* Creates an exception that indicates that this XML element must
* not have child elements if the refid attribute is set.
* @return the exception to throw
*/
protected BuildException noChildrenAllowed() {
return new BuildException("You must not specify nested elements "
+ "when using refid");
}
/**
* Creates an exception that indicates the user has generated a
* loop of data types referencing each other.
* @return the exception to throw
*/
protected BuildException circularReference() {
return new BuildException("This data type contains a circular "
+ "reference.");
}
/**
* The flag that is used to indicate that circular references have been checked.
* @return true if circular references have been checked
*/
protected boolean isChecked() {
return checked;
}
/**
* Set the flag that is used to indicate that circular references have been checked.
* @param checked if true, if circular references have been checked
*/
protected void setChecked(final boolean checked) {
this.checked = checked;
}
/**
* get the reference set on this object
* @return the reference or null
*/
public Reference getRefid() {
return ref;
}
/**
* check that it is ok to set attributes, i.e that no reference is defined
* @since Ant 1.6
* @throws BuildException if not allowed
*/
protected void checkAttributesAllowed() {
if (isReference()) {
throw tooManyAttributes();
}
}
/**
* check that it is ok to add children, i.e that no reference is defined
* @since Ant 1.6
* @throws BuildException if not allowed
*/
protected void checkChildrenAllowed() {
if (isReference()) {
throw noChildrenAllowed();
}
}
/**
* Basic DataType toString().
* @return this DataType formatted as a String.
*/
@Override
public String toString() {
String d = getDescription();
return d == null ? getDataTypeName() : getDataTypeName() + " " + d;
}
/**
* @since Ant 1.7
* @return a shallow copy of this DataType.
* @throws CloneNotSupportedException if there is a problem.
*/
@Override
public Object clone() throws CloneNotSupportedException {
DataType dt = (DataType) super.clone();
dt.setDescription(getDescription());
if (getRefid() != null) {
dt.setRefid(getRefid());
}
dt.setChecked(isChecked());
return dt;
}
private String displayName(Class<?> clazz) {
return clazz.getName() + " (loaded via " + clazz.getClassLoader() +")";
}
}