/*
* 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.cocoon.components.modules.input;
import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.component.ComponentSelector;
import org.apache.avalon.framework.thread.ThreadSafe;
import java.util.Map;
import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
/**
* This modules allows to "chain" several other modules. If a module
* returns "null" as attribute value, the next module in the chain is
* queried until either a value can be obtained or the end of the
* chain is reached.
*
* <p>A typical example would be to "chain" request parameters,
* session attributes, and constants in this order. This way, an
* application could have a default skin that could be overridden by a
* user in her/his profile stored in the session. In addition, the
* user could request a different skin through passing a request
* parameter.</p>
*
* <p>Usage:</p>
*
* <p> Any number of <input-module/> blocks may appear in the
* component configuration. The @name attribute is used as the name of
* the requested input module. The complete <input-module/>
* block is passed at run-time to the module and thus can contain any
* configuration data for that particular module.</p>
*
* <p>Configuration:</p>
*
* <p>It can be controlled whether it returns a flat or a deep view,
* i.e. whether only values from the first module are returned if
* non-null or they are merged with values from other modules
* <code><all-values>true</all-values></code>. The same is
* possible for the attribute names
* (<code><all-names/></code>). In addition, empty strings could
* be treated the same as null values
* (<code><empty-as-null/></code>).</p>
*
* @author <a href="mailto:haul@apache.org">Christian Haul</a>
* @version CVS $Id$
*/
public class ChainMetaModule extends AbstractMetaModule implements ThreadSafe {
private ModuleHolder[] inputs = null;
private boolean emptyAsNull = false;
private boolean allNames = false;
private boolean allValues = false;
public void configure(Configuration config) throws ConfigurationException {
Configuration[] confs = config.getChildren("input-module");
if (confs.length > 0) {
this.inputs = new ModuleHolder[confs.length];
int j = 0;
for (int i=0; i<confs.length; i++) {
ModuleHolder module = new ModuleHolder();
module.name = confs[i].getAttribute("name",null);
if (module.name == null) {
if (getLogger().isErrorEnabled())
getLogger().error("No name attribute for module configuration. Skipping.");
continue;
}
module.config = confs[i];
this.inputs[j]=module;
j++;
}
}
this.emptyAsNull = config.getChild("empty-as-null").getValueAsBoolean(this.emptyAsNull);
this.allNames = config.getChild("all-names").getValueAsBoolean(this.allNames);
this.allValues = config.getChild("all-values").getValueAsBoolean(this.allValues);
}
public synchronized void lazy_initialize() {
try {
// obtain input modules
if (!this.initialized) {
this.inputSelector=(ComponentSelector) this.manager.lookup(INPUT_MODULE_SELECTOR);
if (this.inputSelector != null && this.inputSelector instanceof ThreadSafe) {
for (int i=0; i<this.inputs.length; i++) {
if (this.inputs[i].name != null)
this.inputs[i].input = obtainModule(this.inputs[i].name);
}
} else if (!(this.inputSelector instanceof ThreadSafe) ) {
this.manager.release(this.inputSelector);
this.inputSelector = null;
}
this.initialized = true;
}
} catch (Exception e) {
if (getLogger().isWarnEnabled())
getLogger().warn("A problem occurred setting up input modules :'" + e.getMessage());
}
}
public void dispose() {
if (this.inputSelector != null) {
for (int i=0; i<this.inputs.length; i++) {
if (this.inputs[i].input != null)
this.inputSelector.release(this.inputs[i].input);
}
this.manager.release(this.inputSelector);
}
}
public Object[] getAttributeValues( String attr, Configuration modeConf, Map objectModel )
throws ConfigurationException {
if (!this.initialized) {
this.lazy_initialize();
}
// obtain correct configuration objects
// default vs dynamic
Configuration[] inputConfigs = null;
boolean allValues = this.allValues;
boolean emptyAsNull = this.emptyAsNull;
if (modeConf!=null && modeConf.getChildren().length > 0) {
inputConfigs = modeConf.getChildren("input-module");
emptyAsNull = modeConf.getChild("empty-as-null").getValueAsBoolean(emptyAsNull);
allValues = modeConf.getChild("all-values").getValueAsBoolean(allValues);
if (inputConfigs.length == 0) inputConfigs = null;
}
Object[] value = null;
boolean debug = getLogger().isDebugEnabled();
List values = null;
if (allValues) values = new ArrayList();
if (inputConfigs == null) {
// static configuration branch
int i = 0;
while (i < this.inputs.length && (value == null || allValues)) {
if (this.inputs[i].name != null) {
value = getValues(attr, objectModel, this.inputs[i].input, this.inputs[i].name, this.inputs[i].config);
if (emptyAsNull && value != null && value.length == 0) value = null;
if (emptyAsNull && value != null && value.length == 1 &&
value[0] instanceof String && value[0].equals("")) value = null;
if (debug) getLogger().debug("read from "+this.inputs[i].name+" attribute "+attr+" as "+value);
if (allValues && value != null) values.addAll(Arrays.asList(value));
}
i++;
}
} else {
// run-time configuration branch
int i = 0;
while (i < inputConfigs.length && (value == null || allValues)) {
String name = inputConfigs[i].getAttribute("name",null);
if (name != null) {
value = getValues(attr, objectModel, null, name, inputConfigs[i]);
if (emptyAsNull && value != null && value.length == 0) value = null;
if (emptyAsNull && value != null && value.length == 1 &&
value[0] instanceof String && value[0].equals("")) value = null;
if (debug) getLogger().debug("read from "+name+" attribute "+attr+" as "+value);
if (allValues && value != null) values.addAll(Arrays.asList(value));
}
i++;
}
}
if (debug) getLogger().debug("result chaining for "+attr+" is "+(allValues? values.toArray() : value));
return (allValues? values.toArray() : value);
}
private void addIterator(Collection col, Iterator iter) {
while (iter != null && iter.hasNext())
col.add(iter.next());
}
public Iterator getAttributeNames( Configuration modeConf, Map objectModel )
throws ConfigurationException {
if (!this.initialized) {
this.lazy_initialize();
}
// obtain correct configuration objects
// default vs dynamic
Configuration[] inputConfigs = null;
boolean emptyAsNull = this.emptyAsNull;
boolean allNames = this.allNames;
if (modeConf!=null && modeConf.getChildren().length > 0) {
inputConfigs = modeConf.getChildren("input-module");
emptyAsNull = modeConf.getChild("empty-as-null").getValueAsBoolean(emptyAsNull);
allNames = modeConf.getChild("all-names").getValueAsBoolean(allNames);
if (inputConfigs.length == 0) inputConfigs = null;
}
Iterator value = null;
Collection values = null;
if (allNames) values = new ArrayList();
boolean debug = getLogger().isDebugEnabled();
if (inputConfigs == null) {
// static configuration branch
int i = 0;
while (i < this.inputs.length && (value == null || allNames)) {
if (this.inputs[i].name != null) {
value = getNames(objectModel, this.inputs[i].input, this.inputs[i].name, this.inputs[i].config);
if (debug) getLogger().debug("read from "+this.inputs[i].name+" AttributeNames as "+value);
if (allNames && value != null) addIterator(values, value);
}
i++;
}
} else {
// run-time configuration branch
int i = 0;
while (i < inputConfigs.length && value == null) {
String name = inputConfigs[i].getAttribute("name",null);
if (name != null) {
value = getNames(objectModel, null, name, inputConfigs[i]);
if (debug) getLogger().debug("read from "+name+" AttributeNames as "+value);
if (allNames && value != null) addIterator(values, value);
}
i++;
}
}
if (debug) getLogger().debug("result chaining names is "+(allNames? values.iterator() : value));
return (allNames? values.iterator() : value);
}
public Object getAttribute( String attr, Configuration modeConf, Map objectModel )
throws ConfigurationException {
Object[] values = this.getAttributeValues(attr,modeConf,objectModel);
if (getLogger().isDebugEnabled()) getLogger().debug("result chaining single for "+attr+" is "+(values != null? values[0] : "null"));
return (values != null? values[0] : null);
}
}