/*
* Copyright 2013 The Netty Project
*
* The Netty Project 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 io.netty.util.internal;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.Modifier;
import java.lang.reflect.Method;
final class JavassistTypeParameterMatcherGenerator {
private static final InternalLogger logger =
InternalLoggerFactory.getInstance(JavassistTypeParameterMatcherGenerator.class);
private static final ClassPool classPool = new ClassPool(true);
static TypeParameterMatcher generate(Class<?> type) {
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
if (classLoader == null) {
classLoader = ClassLoader.getSystemClassLoader();
}
return generate(type, classLoader);
}
static TypeParameterMatcher generate(Class<?> type, ClassLoader classLoader) {
final String typeName = typeName(type);
final String className = "io.netty.util.internal.__matchers__." + typeName + "Matcher";
try {
try {
return (TypeParameterMatcher) Class.forName(className, true, classLoader).newInstance();
} catch (Exception e) {
// Not defined in the specified class loader.
}
CtClass c = classPool.getAndRename(NoOpTypeParameterMatcher.class.getName(), className);
c.setModifiers(c.getModifiers() | Modifier.FINAL);
c.getDeclaredMethod("match").setBody("{ return $1 instanceof " + typeName + "; }");
byte[] byteCode = c.toBytecode();
c.detach();
Method method = ClassLoader.class.getDeclaredMethod(
"defineClass", String.class, byte[].class, int.class, int.class);
method.setAccessible(true);
Class<?> generated = (Class<?>) method.invoke(classLoader, className, byteCode, 0, byteCode.length);
logger.debug("Generated: {}", generated.getName());
return (TypeParameterMatcher) generated.newInstance();
} catch (RuntimeException e) {
throw e;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private static String typeName(Class<?> type) {
if (type.isArray()) {
return typeName(type.getComponentType()) + "[]";
}
return type.getName();
}
private JavassistTypeParameterMatcherGenerator() { }
}