/*
* Copyright 2012 OmniFaces.
*
* 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 org.omnifaces.el;
import static org.omnifaces.util.Utils.unmodifiableSet;
import java.lang.reflect.Method;
import java.util.Set;
import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ELResolver;
import javax.el.MethodExpression;
import javax.el.MethodInfo;
import javax.el.MethodNotFoundException;
import javax.el.PropertyNotFoundException;
import javax.el.ValueExpression;
import javax.faces.convert.ConverterException;
import javax.faces.validator.ValidatorException;
/**
* This MethodExpression wraps a ValueExpression.
* <p>
* With this wrapper a value expression can be used where a method expression is expected.
* The return value of the method execution will be the value represented by the value expression.
*
* @author Arjan Tijms
*
*/
public class MethodExpressionValueExpressionAdapter extends MethodExpression {
private static final long serialVersionUID = 1L;
private static final Set<RuntimeException> EXCEPTIONS_TO_UNWRAP = unmodifiableSet(
MethodNotFoundException.class, // Needed for proper action listener error handling.
ConverterException.class, // Needed for proper conversion error handling.
ValidatorException.class); // Needed for proper validation error handling.
private final ValueExpression valueExpression;
public MethodExpressionValueExpressionAdapter(ValueExpression valueExpression) {
this.valueExpression = valueExpression;
}
@Override
public Object invoke(ELContext context, Object[] params) {
try {
return valueExpression.getValue(new ValueToInvokeElContext(context, params));
}
catch (ELException e) {
for (Throwable cause = e.getCause(); cause != null; cause = cause.getCause()) {
if (EXCEPTIONS_TO_UNWRAP.contains(cause.getClass())) {
throw (RuntimeException) cause;
}
}
throw e;
}
}
@Override
public MethodInfo getMethodInfo(ELContext context) {
Method method = ExpressionInspector.getMethodReference(context, valueExpression).getMethod();
return new MethodInfo(method.getName(), method.getReturnType(), method.getParameterTypes());
}
@Override
public boolean isLiteralText() {
return false;
}
@Override
public int hashCode() {
return valueExpression.hashCode();
}
@Override
public String getExpressionString() {
return valueExpression.getExpressionString();
}
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (obj instanceof MethodExpressionValueExpressionAdapter) {
return ((MethodExpressionValueExpressionAdapter)obj).getValueExpression().equals(valueExpression);
}
return false;
}
public ValueExpression getValueExpression() {
return valueExpression;
}
/**
* Custom ELContext implementation that wraps a given ELContext to be able to provide a custom
* ElResolver.
*
*/
static class ValueToInvokeElContext extends ELContextWrapper {
// The parameters provided by the client that calls the EL method expression, as opposed to those
// parameters that are bound to the expression when it's created in EL (like #{bean.myMethod(param1, param2)}).
private final Object[] callerProvidedParameters;
public ValueToInvokeElContext(ELContext elContext, Object[] callerProvidedParameters) {
super(elContext);
this.callerProvidedParameters = callerProvidedParameters;
}
@Override
public ELResolver getELResolver() {
return new ValueToInvokeElResolver(super.getELResolver(), callerProvidedParameters);
}
}
/**
* Custom EL Resolver that turns calls for value expression calls (getValue) into method expression calls (invoke).
*
*/
static class ValueToInvokeElResolver extends ELResolverWrapper {
// Null should theoretically be accepted, but some EL implementations want an empty array.
private static final Object[] EMPTY_PARAMETERS = new Object[0];
private final Object[] callerProvidedParameters;
public ValueToInvokeElResolver(ELResolver elResolver, Object[] callerProvidedParameters) {
super(elResolver);
this.callerProvidedParameters = callerProvidedParameters;
}
@Override
public Object getValue(ELContext context, Object base, Object property) {
// If base is null, we're resolving it. Base should always be resolved as a value expression.
if (base == null) {
return super.getValue(context, base, property);
}
// Turn getValue calls into invoke.
// Note 1: We can not directly delegate to invoke() here, since otherwise chained expressions
// "like base.value.value.expression" will not resolve correctly.
//
// Note 2: Some EL implementations call getValue when invoke should be called already. This typically happens when the
// method expression takes no parameters, but is specified with parentheses, e.g. "#{mybean.doAction()}".
try {
return super.getValue(context, base, property);
} catch (PropertyNotFoundException pnfe) {
try {
return super.invoke(context, base, property, null, callerProvidedParameters != null ? callerProvidedParameters : EMPTY_PARAMETERS);
} catch (MethodNotFoundException e) {
// Wrap into new ELException since down the call chain, ElExceptions might be caught, unwrapped one level and then wrapped in
// a new ELException. E.g. Mojarra 2.1's TagValueExpression does the following:
//
// catch (ELException e) {
// throw new ELException(this.attr + ": " + e.getMessage(), e.getCause());
// }
//
// Without wrapping here, we'll then loose this exception.
throw new ELException(e.getMessage(), e);
}
}
}
}
}