org.glowroot.instrumentation.engine.weaving.Accessor Maven / Gradle / Ivy
/*
* Copyright 2014-2019 the original author or authors.
*
* 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.glowroot.instrumentation.engine.weaving;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import org.checkerframework.checker.nullness.qual.Nullable;
import static org.glowroot.instrumentation.test.harness.shaded.com.google.common.base.Preconditions.checkNotNull;
class Accessor {
private final AccessorType accessorType;
private final @Nullable Method method;
private final @Nullable Field field;
static Accessor fromMethod(Method method) {
return new Accessor(method);
}
static Accessor fromField(Field field) {
return new Accessor(field);
}
static Accessor arrayLength() {
return new Accessor();
}
private Accessor(Method method) {
accessorType = AccessorType.METHOD;
this.method = method;
this.field = null;
}
private Accessor(Field field) {
accessorType = AccessorType.FIELD;
this.method = null;
this.field = field;
}
private Accessor() {
accessorType = AccessorType.ARRAY_LENGTH;
this.method = null;
this.field = null;
}
Class getValueType() {
switch (accessorType) {
case METHOD:
checkNotNull(method);
return method.getReturnType();
case FIELD:
checkNotNull(field);
return field.getType();
case ARRAY_LENGTH:
return int.class;
default:
throw new AssertionError("Unexpected accessor type: " + accessorType);
}
}
@Nullable
Object evaluate(Object object) throws Exception {
if (isArrayEvaluation(object)) {
return evaluateArray((/*@Nullable*/ Object[]) object);
}
switch (accessorType) {
case METHOD:
checkNotNull(method);
return method.invoke(object);
case FIELD:
checkNotNull(field);
return field.get(object);
case ARRAY_LENGTH:
return Array.getLength(object);
default:
throw new AssertionError("Unexpected accessor type: " + accessorType);
}
}
private boolean isArrayEvaluation(Object object) {
return object instanceof Object[] && accessorType != AccessorType.ARRAY_LENGTH;
}
private Object evaluateArray(/*@Nullable*/ Object[] array) throws Exception {
/*@Nullable*/ Object[] values = new Object[array.length];
for (int i = 0; i < array.length; i++) {
Object item = array[i];
values[i] = item == null ? null : evaluate(item);
}
return values;
}
private enum AccessorType {
METHOD, FIELD, ARRAY_LENGTH
}
}