ELContext.java
/*
* 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 javax.el;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
public abstract class ELContext {
private Locale locale;
private Map<Class<?>,Object> map;
private boolean resolved;
private ImportHandler importHandler = null;
private List<EvaluationListener> listeners;
private Deque<Map<String,Object>> lambdaArguments = new ArrayDeque<>();
public ELContext() {
this.resolved = false;
}
public void setPropertyResolved(boolean resolved) {
this.resolved = resolved;
}
/**
* Mark the given property as resolved and notify any interested listeners.
*
* @param base The base object on which the property was found
* @param property The property that was resolved
*
* @since EL 3.0
*/
public void setPropertyResolved(Object base, Object property) {
setPropertyResolved(true);
notifyPropertyResolved(base, property);
}
public boolean isPropertyResolved() {
return this.resolved;
}
// Can't use Class<?> because API needs to match specification
/**
* Add an object to this EL context under the given key.
*
* @param key The key under which to store the object
* @param contextObject The object to add
*
* @throws NullPointerException If the supplied key or context is <code>null</code>
*/
public void putContext(@SuppressWarnings("rawtypes") Class key, Object contextObject) {
Objects.requireNonNull(key);
Objects.requireNonNull(contextObject);
if (this.map == null) {
this.map = new HashMap<>();
}
this.map.put(key, contextObject);
}
// Can't use Class<?> because API needs to match specification
/**
* Obtain the context object for the given key.
*
* @param key The key of the required context object
*
* @return The value of the context object associated with the given key
*
* @throws NullPointerException If the supplied key is <code>null</code>
*/
public Object getContext(@SuppressWarnings("rawtypes") Class key) {
Objects.requireNonNull(key);
if (this.map == null) {
return null;
}
return this.map.get(key);
}
public abstract ELResolver getELResolver();
/**
* Obtain the ImportHandler for this ELContext, creating one if necessary. This method is not thread-safe.
*
* @return the ImportHandler for this ELContext.
*
* @since EL 3.0
*/
public ImportHandler getImportHandler() {
if (importHandler == null) {
importHandler = new ImportHandler();
}
return importHandler;
}
public abstract FunctionMapper getFunctionMapper();
public Locale getLocale() {
return this.locale;
}
public void setLocale(Locale locale) {
this.locale = locale;
}
public abstract VariableMapper getVariableMapper();
/**
* Register an EvaluationListener with this ELContext.
*
* @param listener The EvaluationListener to register
*
* @since EL 3.0
*/
public void addEvaluationListener(EvaluationListener listener) {
if (listeners == null) {
listeners = new ArrayList<>();
}
listeners.add(listener);
}
/**
* Obtain the list of registered EvaluationListeners.
*
* @return A list of the EvaluationListener registered with this ELContext
*
* @since EL 3.0
*/
public List<EvaluationListener> getEvaluationListeners() {
if (listeners == null) {
return Collections.emptyList();
} else {
return listeners;
}
}
/**
* Notify interested listeners that an expression will be evaluated.
*
* @param expression The expression that will be evaluated
*
* @since EL 3.0
*/
public void notifyBeforeEvaluation(String expression) {
if (listeners == null) {
return;
}
for (EvaluationListener listener : listeners) {
try {
listener.beforeEvaluation(this, expression);
} catch (Throwable t) {
Util.handleThrowable(t);
// Ignore - no option to log
}
}
}
/**
* Notify interested listeners that an expression has been evaluated.
*
* @param expression The expression that was evaluated
*
* @since EL 3.0
*/
public void notifyAfterEvaluation(String expression) {
if (listeners == null) {
return;
}
for (EvaluationListener listener : listeners) {
try {
listener.afterEvaluation(this, expression);
} catch (Throwable t) {
Util.handleThrowable(t);
// Ignore - no option to log
}
}
}
/**
* Notify interested listeners that a property has been resolved.
*
* @param base The object on which the property was resolved
* @param property The property that was resolved
*
* @since EL 3.0
*/
public void notifyPropertyResolved(Object base, Object property) {
if (listeners == null) {
return;
}
for (EvaluationListener listener : listeners) {
try {
listener.propertyResolved(this, base, property);
} catch (Throwable t) {
Util.handleThrowable(t);
// Ignore - no option to log
}
}
}
/**
* Determine if the specified name is recognised as the name of a lambda argument.
*
* @param name The name of the lambda argument
*
* @return <code>true</code> if the name is recognised as the name of a lambda argument, otherwise
* <code>false</code>
*
* @since EL 3.0
*/
public boolean isLambdaArgument(String name) {
for (Map<String,Object> arguments : lambdaArguments) {
if (arguments.containsKey(name)) {
return true;
}
}
return false;
}
/**
* Obtain the value of the lambda argument with the given name.
*
* @param name The name of the lambda argument
*
* @return The value of the specified argument
*
* @since EL 3.0
*/
public Object getLambdaArgument(String name) {
for (Map<String,Object> arguments : lambdaArguments) {
Object result = arguments.get(name);
if (result != null) {
return result;
}
}
return null;
}
/**
* Called when starting to evaluate a lambda expression so that the arguments are available to the EL context during
* evaluation.
*
* @param arguments The arguments in scope for the current lambda expression.
*
* @since EL 3.0
*/
public void enterLambdaScope(Map<String,Object> arguments) {
lambdaArguments.push(arguments);
}
/**
* Called after evaluating a lambda expression to signal that the arguments are no longer required.
*
* @since EL 3.0
*/
public void exitLambdaScope() {
lambdaArguments.pop();
}
/**
* Coerce the supplied object to the requested type.
*
* @param obj The object to be coerced
* @param type The type to which the object should be coerced
*
* @return An instance of the requested type.
*
* @throws ELException If the conversion fails
*
* @since EL 3.0
*/
public Object convertToType(Object obj, Class<?> type) {
boolean originalResolved = isPropertyResolved();
setPropertyResolved(false);
try {
ELResolver resolver = getELResolver();
if (resolver != null) {
Object result = resolver.convertToType(this, obj, type);
if (isPropertyResolved()) {
return result;
}
}
} finally {
setPropertyResolved(originalResolved);
}
return ELManager.getExpressionFactory().coerceToType(obj, type);
}
}