/*
* Copyright (C) 2012 Facebook, Inc.
*
* 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 com.facebook.swift.codec.internal.reflection;
import com.facebook.swift.codec.ThriftCodec;
import com.facebook.swift.codec.ThriftCodecManager;
import com.facebook.swift.codec.internal.TProtocolReader;
import com.facebook.swift.codec.internal.TProtocolWriter;
import com.facebook.swift.codec.metadata.ThriftConstructorInjection;
import com.facebook.swift.codec.metadata.ThriftExtraction;
import com.facebook.swift.codec.metadata.ThriftFieldExtractor;
import com.facebook.swift.codec.metadata.ThriftFieldInjection;
import com.facebook.swift.codec.metadata.ThriftFieldMetadata;
import com.facebook.swift.codec.metadata.ThriftInjection;
import com.facebook.swift.codec.metadata.ThriftMethodExtractor;
import com.facebook.swift.codec.metadata.ThriftMethodInjection;
import com.facebook.swift.codec.metadata.ThriftParameterInjection;
import com.facebook.swift.codec.metadata.ThriftStructMetadata;
import com.facebook.swift.codec.metadata.ThriftType;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableSortedMap;
import org.apache.thrift.protocol.TProtocol;
import javax.annotation.concurrent.Immutable;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.Map;
import java.util.SortedMap;
import static java.lang.String.format;
@Immutable
public class ReflectionThriftCodec<T> implements ThriftCodec<T>
{
private final ThriftStructMetadata<T> metadata;
private final SortedMap<Short, ThriftCodec<?>> fields;
public ReflectionThriftCodec(ThriftCodecManager manager, ThriftStructMetadata<T> metadata)
{
this.metadata = metadata;
ImmutableSortedMap.Builder<Short, ThriftCodec<?>> fields = ImmutableSortedMap.naturalOrder();
for (ThriftFieldMetadata fieldMetadata : metadata.getFields()) {
fields.put(fieldMetadata.getId(), manager.getCodec(fieldMetadata.getType()));
}
this.fields = fields.build();
}
@Override
public ThriftType getType()
{
return ThriftType.struct(metadata);
}
@Override
public T read(TProtocol protocol)
throws Exception
{
TProtocolReader reader = new TProtocolReader(protocol);
reader.readStructBegin();
Map<Short, Object> data = new HashMap<>(metadata.getFields().size());
while (reader.nextField()) {
short fieldId = reader.getFieldId();
// do we have a codec for this field
ThriftCodec<?> codec = fields.get(fieldId);
if (codec == null) {
reader.skipFieldData();
continue;
}
// is this field readable
ThriftFieldMetadata field = metadata.getField(fieldId);
if (field.isWriteOnly()) {
reader.skipFieldData();
continue;
}
// read the value
Object value = reader.readField(codec);
if (value == null) {
continue;
}
data.put(fieldId, value);
}
reader.readStructEnd();
// build the struct
return constructStruct(data);
}
@Override
public void write(T instance, TProtocol protocol)
throws Exception
{
TProtocolWriter writer = new TProtocolWriter(protocol);
writer.writeStructBegin(metadata.getStructName());
for (ThriftFieldMetadata fieldMetadata : metadata.getFields()) {
// is the field writable?
if (fieldMetadata.isReadOnly()) {
continue;
}
// get the field value
Object fieldValue = getFieldValue(instance, fieldMetadata);
// write the field
if (fieldValue != null) {
ThriftCodec<Object> codec = (ThriftCodec<Object>) fields.get(fieldMetadata.getId());
writer.writeField(fieldMetadata.getName(), fieldMetadata.getId(), codec, fieldValue);
}
}
writer.writeStructEnd();
}
private T constructStruct(Map<Short, Object> data)
throws Exception
{
// construct instance
Object instance;
{
ThriftConstructorInjection constructor = metadata.getConstructor();
Object[] parametersValues = new Object[constructor.getParameters().size()];
for (ThriftParameterInjection parameter : constructor.getParameters()) {
Object value = data.get(parameter.getId());
parametersValues[parameter.getParameterIndex()] = value;
}
try {
instance = constructor.getConstructor().newInstance(parametersValues);
}
catch (InvocationTargetException e) {
if (e.getTargetException() != null) {
Throwables.propagateIfInstanceOf(e.getTargetException(), Exception.class);
}
throw e;
}
}
// inject fields
for (ThriftFieldMetadata fieldMetadata : metadata.getFields()) {
for (ThriftInjection injection : fieldMetadata.getInjections()) {
if (injection instanceof ThriftFieldInjection) {
ThriftFieldInjection fieldInjection = (ThriftFieldInjection) injection;
Object value = data.get(fieldInjection.getId());
if (value != null) {
fieldInjection.getField().set(instance, value);
}
}
}
}
// inject methods
for (ThriftMethodInjection methodInjection : metadata.getMethodInjections()) {
boolean shouldInvoke = false;
Object[] parametersValues = new Object[methodInjection.getParameters().size()];
for (ThriftParameterInjection parameter : methodInjection.getParameters()) {
Object value = data.get(parameter.getId());
if (value != null) {
parametersValues[parameter.getParameterIndex()] = value;
shouldInvoke = true;
}
}
if (shouldInvoke) {
try {
methodInjection.getMethod().invoke(instance, parametersValues);
}
catch (InvocationTargetException e) {
if (e.getTargetException() != null) {
Throwables.propagateIfInstanceOf(e.getTargetException(), Exception.class);
}
throw e;
}
}
}
// builder method
if (metadata.getBuilderMethod() != null) {
ThriftMethodInjection builderMethod = metadata.getBuilderMethod();
Object[] parametersValues = new Object[builderMethod.getParameters().size()];
for (ThriftParameterInjection parameter : builderMethod.getParameters()) {
Object value = data.get(parameter.getId());
parametersValues[parameter.getParameterIndex()] = value;
}
try {
instance = builderMethod.getMethod().invoke(instance, parametersValues);
if (instance == null) {
throw new IllegalArgumentException("Builder method returned a null instance");
}
if (!metadata.getStructClass().isInstance(instance)) {
throw new IllegalArgumentException(format("Builder method returned instance of type %s, but an instance of %s is required",
instance.getClass().getName(),
metadata.getStructClass().getName()));
}
}
catch (InvocationTargetException e) {
if (e.getTargetException() != null) {
Throwables.propagateIfInstanceOf(e.getTargetException(), Exception.class);
}
throw e;
}
}
return (T) instance;
}
private Object getFieldValue(Object instance, ThriftFieldMetadata field)
throws Exception
{
try {
ThriftExtraction extraction = field.getExtraction();
Object value;
if (extraction instanceof ThriftFieldExtractor) {
ThriftFieldExtractor thriftFieldExtractor = (ThriftFieldExtractor) extraction;
value = thriftFieldExtractor.getField().get(instance);
}
else if (extraction instanceof ThriftMethodExtractor) {
ThriftMethodExtractor thriftMethodExtractor = (ThriftMethodExtractor) extraction;
value = thriftMethodExtractor.getMethod().invoke(instance);
}
else {
throw new IllegalAccessException("Unsupported field extractor type " + extraction.getClass().getName());
}
return value;
}
catch (InvocationTargetException e) {
if (e.getTargetException() != null) {
Throwables.propagateIfInstanceOf(e.getTargetException(), Exception.class);
}
throw e;
}
}
}