CompositeELResolver.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.beans.FeatureDescriptor;
import java.util.HashSet;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.Set;
public class CompositeELResolver extends ELResolver {
private static final Class<?> SCOPED_ATTRIBUTE_EL_RESOLVER;
private static final Set<String> KNOWN_NON_TYPE_CONVERTING_RESOLVERS = new HashSet<>();
static {
Class<?> clazz = null;
try {
clazz = Class.forName("javax.servlet.jsp.el.ScopedAttributeELResolver");
} catch (ClassNotFoundException e) {
// Ignore. This is expected if using the EL stand-alone
}
SCOPED_ATTRIBUTE_EL_RESOLVER = clazz;
// EL API Resolvers
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add(ArrayELResolver.class.getName());
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add(BeanELResolver.class.getName());
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add(BeanNameELResolver.class.getName());
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add(ListELResolver.class.getName());
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add(MapELResolver.class.getName());
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add(ResourceBundleELResolver.class.getName());
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add(StaticFieldELResolver.class.getName());
// JSP API Resolvers - referenced by name to avoid creating dependency
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add("jakarta.servlet.jsp.el.ImplicitObjectELResolver");
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add("jakarta.servlet.jsp.el.ScopedAttributeELResolver");
// Tomcat internal resolvers - referenced by name to avoid creating dependency
KNOWN_NON_TYPE_CONVERTING_RESOLVERS.add("org.apache.el.stream.StreamELResolverImpl");
}
private int resolversSize;
private ELResolver[] resolvers;
/*
* Use a separate array for ELResolvers that might implement type conversion as a performance optimisation. See
* https://bz.apache.org/bugzilla/show_bug.cgi?id=68119
*/
private int typeConvertersSize;
private ELResolver[] typeConverters;
public CompositeELResolver() {
resolversSize = 0;
resolvers = new ELResolver[8];
typeConvertersSize = 0;
typeConverters = new ELResolver[0];
}
public void add(ELResolver elResolver) {
Objects.requireNonNull(elResolver);
/*
* resolversSize should never be larger than resolvers.length. If it ever is, the code will fail when execution
* reaches System.arraycopy with an IndexOutOfBoundsException.
*/
if (resolversSize >= resolvers.length) {
ELResolver[] nr = new ELResolver[resolversSize * 2];
System.arraycopy(resolvers, 0, nr, 0, resolversSize);
resolvers = nr;
}
resolvers[resolversSize++] = elResolver;
if (KNOWN_NON_TYPE_CONVERTING_RESOLVERS.contains(elResolver.getClass().getName())) {
// Performance optimisation. ELResolver known not to perform type conversion
return;
}
if (typeConvertersSize == 0) {
typeConverters = new ELResolver[1];
} else if (typeConvertersSize == typeConverters.length) {
ELResolver[] expandedTypeConverters = new ELResolver[typeConvertersSize * 2];
System.arraycopy(typeConverters, 0, expandedTypeConverters, 0, typeConvertersSize);
typeConverters = expandedTypeConverters;
}
typeConverters[typeConvertersSize++] = elResolver;
}
@Override
public Object getValue(ELContext context, Object base, Object property) {
context.setPropertyResolved(false);
int sz = resolversSize;
for (int i = 0; i < sz; i++) {
Object result = resolvers[i].getValue(context, base, property);
if (context.isPropertyResolved()) {
return result;
}
}
return null;
}
@Override
public Object invoke(ELContext context, Object base, Object method, Class<?>[] paramTypes, Object[] params) {
context.setPropertyResolved(false);
int sz = this.resolversSize;
for (int i = 0; i < sz; i++) {
Object obj = this.resolvers[i].invoke(context, base, method, paramTypes, params);
if (context.isPropertyResolved()) {
return obj;
}
}
return null;
}
@Override
public Class<?> getType(ELContext context, Object base, Object property) {
context.setPropertyResolved(false);
int sz = this.resolversSize;
for (int i = 0; i < sz; i++) {
Class<?> type = this.resolvers[i].getType(context, base, property);
if (context.isPropertyResolved()) {
if (SCOPED_ATTRIBUTE_EL_RESOLVER != null &&
SCOPED_ATTRIBUTE_EL_RESOLVER.isAssignableFrom(resolvers[i].getClass())) {
// Special case since
// javax.servlet.jsp.el.ScopedAttributeELResolver will
// always return Object.class for type
Object value = resolvers[i].getValue(context, base, property);
if (value != null) {
return value.getClass();
}
}
return type;
}
}
return null;
}
@Override
public void setValue(ELContext context, Object base, Object property, Object value) {
context.setPropertyResolved(false);
int sz = this.resolversSize;
for (int i = 0; i < sz; i++) {
this.resolvers[i].setValue(context, base, property, value);
if (context.isPropertyResolved()) {
return;
}
}
}
@Override
public boolean isReadOnly(ELContext context, Object base, Object property) {
context.setPropertyResolved(false);
int sz = this.resolversSize;
for (int i = 0; i < sz; i++) {
boolean readOnly = this.resolvers[i].isReadOnly(context, base, property);
if (context.isPropertyResolved()) {
return readOnly;
}
}
return false;
}
@Override
public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
return new FeatureIterator(context, base, this.resolvers, this.resolversSize);
}
@Override
public Class<?> getCommonPropertyType(ELContext context, Object base) {
Class<?> commonType = null;
int sz = this.resolversSize;
for (int i = 0; i < sz; i++) {
Class<?> type = this.resolvers[i].getCommonPropertyType(context, base);
if (type != null && (commonType == null || commonType.isAssignableFrom(type))) {
commonType = type;
}
}
return commonType;
}
@Override
public Object convertToType(ELContext context, Object obj, Class<?> type) {
context.setPropertyResolved(false);
int sz = typeConvertersSize;
for (int i = 0; i < sz; i++) {
Object result = this.typeConverters[i].convertToType(context, obj, type);
if (context.isPropertyResolved()) {
return result;
}
}
return null;
}
private static final class FeatureIterator implements Iterator<FeatureDescriptor> {
private final ELContext context;
private final Object base;
private final ELResolver[] resolvers;
private final int size;
private Iterator<FeatureDescriptor> itr;
private int idx;
private FeatureDescriptor next;
FeatureIterator(ELContext context, Object base, ELResolver[] resolvers, int size) {
this.context = context;
this.base = base;
this.resolvers = resolvers;
this.size = size;
this.idx = 0;
this.guaranteeIterator();
}
private void guaranteeIterator() {
while (this.itr == null && this.idx < this.size) {
this.itr = this.resolvers[this.idx].getFeatureDescriptors(this.context, this.base);
this.idx++;
}
}
@Override
public boolean hasNext() {
if (this.next != null) {
return true;
}
if (this.itr != null) {
while (this.next == null && itr.hasNext()) {
this.next = itr.next();
}
} else {
return false;
}
if (this.next == null) {
this.itr = null;
this.guaranteeIterator();
}
return hasNext();
}
@Override
public FeatureDescriptor next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
FeatureDescriptor result = this.next;
this.next = null;
return result;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}
}