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Utility classes and methods developed for Brooklyn but not dependendent on Brooklyn or much else
/*
* 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.brooklyn.util.javalang.coerce;
import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.List;
import org.apache.brooklyn.util.exceptions.CompoundRuntimeException;
import org.apache.brooklyn.util.guava.Maybe;
import org.apache.brooklyn.util.javalang.JavaClassNames;
import org.apache.brooklyn.util.javalang.Reflections;
import org.apache.brooklyn.util.text.Strings;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.reflect.TypeToken;
/**
* Defines and registers common generic coercers (e.g. to call a "fromXyz" method, to
* convert from one type to another).
*/
public class CommonAdaptorTryCoercions {
private final TypeCoercerExtensible coercer;
public CommonAdaptorTryCoercions(TypeCoercerExtensible coercer) {
this.coercer = coercer;
}
public CommonAdaptorTryCoercions registerAllAdapters() {
registerAdapter("11-with-from-method", new TryCoercerWithFromMethod());
registerAdapter("12-enum", new TryCoercerToEnum());
registerAdapter("13-toArray", new TryCoercerToArray(coercer));
registerAdapter("15-primitives", new TryCoercerForPrimitivesAndStrings());
return this;
}
/** Registers an adapter for use with type coercion. */
public synchronized void registerAdapter(String nameAndOrder, TryCoercer fn) {
coercer.registerAdapter(nameAndOrder, fn);
}
protected static class TryCoercerWithFromMethod implements TryCoercer {
@Override
@SuppressWarnings("unchecked")
public Maybe tryCoerce(Object input, TypeToken targetType) {
Class rawTargetType = targetType.getRawType();
List exceptions = Lists.newArrayList();
//now look for static TargetType.fromType(Type t) where value instanceof Type
for (Method m: rawTargetType.getMethods()) {
if (((m.getModifiers()&Modifier.STATIC)==Modifier.STATIC) &&
m.getName().startsWith("from") && m.getParameterTypes().length==1 &&
m.getParameterTypes()[0].isInstance(input)) {
if (m.getName().equals("from"+JavaClassNames.verySimpleClassName(m.getParameterTypes()[0]))) {
try {
return Maybe.of((T) m.invoke(null, input));
} catch (Exception e) {
exceptions.add(new ClassCoercionException("Cannot coerce type "+input.getClass()+" to "+rawTargetType.getCanonicalName()+" ("+input+"): "+m.getName()+" adapting failed", e));
}
}
}
}
if (exceptions.isEmpty()) {
return null;
} else if (exceptions.size() == 1) {
return Maybe.absent(exceptions.get(0));
} else {
String errMsg = "Failed coercing type "+input.getClass()+" to "+rawTargetType.getCanonicalName();
return Maybe.absent(new CompoundRuntimeException(errMsg, exceptions));
}
}
}
protected static class TryCoercerToEnum implements TryCoercer {
@Override
@SuppressWarnings("unchecked")
public Maybe tryCoerce(Object input, TypeToken targetType) {
Class rawTargetType = targetType.getRawType();
//for enums call valueOf with the string representation of the value
if (rawTargetType.isEnum()) {
return EnumTypeCoercions.tryCoerceUntyped(Strings.toString(input), (Class)rawTargetType);
} else {
return null;
}
}
}
protected static class TryCoercerToArray implements TryCoercer {
private final TypeCoercerExtensible coercer;
public TryCoercerToArray(TypeCoercerExtensible coercer) {
this.coercer = coercer;
}
@Override
@SuppressWarnings("unchecked")
public Maybe tryCoerce(Object input, TypeToken targetType) {
if (!targetType.isArray()) return null;
TypeToken targetComponentType = targetType.getComponentType();
Iterable castInput;
if (input.getClass().isArray()) {
castInput = Reflections.arrayToList(input);
} else if (Iterable.class.isAssignableFrom(input.getClass())) {
castInput = (Iterable) input;
} else {
return null;
}
Object result = Array.newInstance(targetComponentType.getRawType(), Iterables.size(castInput));
int index = 0;
for (Object member : castInput) {
Maybe coercedMember = coercer.tryCoerce(member, targetComponentType);
if (coercedMember == null || coercedMember.isAbsent()) {
RuntimeException cause = Maybe.Absent.getException(coercedMember);
return Maybe.absent("Array member at index "+index+" cannot be coerced to "+targetComponentType, cause);
}
Array.set(result, index++, coercedMember.get());
}
return (Maybe) Maybe.of(result);
}
}
protected static class TryCoercerForPrimitivesAndStrings implements TryCoercer {
@Override
public Maybe tryCoerce(Object input, TypeToken targetType) {
return PrimitiveStringTypeCoercions.tryCoerce(input, targetType.getRawType());
}
}
}