/*
* Copyright 2010 Google 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.google.gwt.inject.rebind.binding;
import static com.google.inject.internal.Annotations.getKey;
import com.google.gwt.inject.rebind.reflect.MethodLiteral;
import com.google.gwt.inject.rebind.reflect.NoSourceNameException;
import com.google.gwt.inject.rebind.reflect.ReflectUtil;
import com.google.gwt.inject.rebind.util.GuiceUtil;
import com.google.gwt.inject.rebind.util.InjectorMethod;
import com.google.gwt.inject.rebind.util.MethodCallUtil;
import com.google.gwt.inject.rebind.util.NameGenerator;
import com.google.gwt.inject.rebind.util.Preconditions;
import com.google.gwt.inject.rebind.util.PrettyPrinter;
import com.google.gwt.inject.rebind.util.SourceSnippet;
import com.google.gwt.inject.rebind.util.SourceSnippetBuilder;
import com.google.gwt.inject.rebind.util.SourceSnippets;
import com.google.inject.Inject;
import com.google.inject.Key;
import com.google.inject.TypeLiteral;
import com.google.inject.assistedinject.Assisted;
import com.google.inject.assistedinject.AssistedInject;
import com.google.inject.internal.Errors;
import com.google.inject.internal.ErrorsException;
import com.google.inject.spi.InjectionPoint;
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* Binder producing assisted inject factories.
* <p>
* For each method in the factory interface, the binder will determine the
* implementation type from the return type and the provided bindings. It will
* then check all constructors in the implementation type against the method
* parameters (taking named {@literal @}{@link Assisted} annotations into
* account) and pick a matching one (if available). To inject the selected
* constructor the binder will write a common method injection, replacing the
* parameters commonly retrieved through key-specific getter methods with
* values obtained from the matching method arguments. Finally, after an
* instance has been constructed, it will be member-injected before it is
* returned to the caller of the method.
*/
public class FactoryBinding extends AbstractBinding implements Binding {
/**
* If a factory method parameter isn't annotated it gets this annotation.
*/
private static final Assisted DEFAULT_ANNOTATION = new Assisted() {
public String value() {
return "";
}
public Class<? extends Annotation> annotationType() {
return Assisted.class;
}
@Override public boolean equals(Object o) {
return o instanceof Assisted
&& ((Assisted) o).value().equals("");
}
@Override public int hashCode() {
return 127 * "value".hashCode() ^ "".hashCode();
}
@Override public String toString() {
return "@" + Assisted.class.getName() + "(value=)";
}
};
private final List<AssistData> assistData = new ArrayList<AssistData>();
private final Map<Key<?>, TypeLiteral<?>> collector;
private final Key<?> factoryKey;
private final TypeLiteral<?> factoryType;
private final Set<Dependency> dependencies = new LinkedHashSet<Dependency>();
/**
* Collection of all implementations produced by this factory, each annotated
* with @Assisted. This is used to gather all required member-inject methods.
*/
private final Set<TypeLiteral<?>> implementations = new LinkedHashSet<TypeLiteral<?>>();
private final GuiceUtil guiceUtil;
private final MethodCallUtil methodCallUtil;
FactoryBinding(Map<Key<?>, TypeLiteral<?>> collector, Key<?> factoryKey, Context context,
GuiceUtil guiceUtil, MethodCallUtil methodCallUtil) {
super(context, factoryKey);
this.collector = Preconditions.checkNotNull(collector);
this.factoryKey = factoryKey;
this.factoryType = factoryKey.getTypeLiteral();
this.guiceUtil = guiceUtil;
this.methodCallUtil = methodCallUtil;
try {
matchMethods(Preconditions.checkNotNull(factoryKey));
} catch (ErrorsException e) {
e.getErrors().throwConfigurationExceptionIfErrorsExist();
}
}
public SourceSnippet getCreationStatements(NameGenerator nameGenerator,
List<InjectorMethod> methodsOutput) throws NoSourceNameException {
String factoryTypeName = ReflectUtil.getSourceName(factoryType);
SourceSnippetBuilder sb = new SourceSnippetBuilder();
sb.append(factoryTypeName).append(" result = new ").append(factoryTypeName).append("() {");
for (AssistData assisted : assistData) {
// While it might seem that we could just create the return type directly
// in the factory, that won't work. The problem is that the return type
// might have to be created in a different package from the factory: for
// instance, it might inject a package-private object from its own
// package.
//
// So here's the strategy: we generate a separate injector method that,
// given the assisted parameters, creates the return value and performs
// member injection on it, named "assistedCreate_FACTORY_RETURNTYPE".
// Then we create a factory method that dispatches to that injector method
// (which, again, may be in some other injector fragment).
String returnName = ReflectUtil.getSourceName(assisted.implementation);
String signature = ReflectUtil.signatureBuilder(assisted.method)
.removeAbstractModifier()
.build();
SourceSnippet methodCall = methodCallUtil.createMethodCallWithInjection(
assisted.constructor, null, assisted.parameterNames, nameGenerator, methodsOutput);
SourceSnippet assistedCreateCall = callAssistedCreate(assisted, nameGenerator, methodsOutput);
sb.append("\n\n ").append(signature).append(" {")
.append("\n return ").append(assistedCreateCall).append(";")
.append("\n }"); // End method.
}
sb.append("\n};"); // End factory implementation.
return sb.build();
}
private SourceSnippet callAssistedCreate(AssistData assisted, NameGenerator nameGenerator,
List<InjectorMethod> methodsOutput) throws NoSourceNameException {
String returnTypeName = ReflectUtil.getSourceName(assisted.implementation);
String packageName = ReflectUtil.getUserPackageName(assisted.implementation);
String factoryTypeName = ReflectUtil.getSourceName(factoryType);
String assistedInjectMethodName =
nameGenerator.getAssistedInjectMethodName(factoryKey, assisted.method.getName());
String assistedInjectSignature = ReflectUtil.signatureBuilder(assisted.method)
.withMethodName(assistedInjectMethodName)
.removeAbstractModifier()
.build();
SourceSnippet memberInjectCall =
SourceSnippets.callMemberInject(assisted.implementation, "result");
SourceSnippet methodCall = methodCallUtil.createMethodCallWithInjection(
assisted.constructor, null, assisted.parameterNames, nameGenerator, methodsOutput);
SourceSnippet assistedInjectMethodBody = new SourceSnippetBuilder()
.append(returnTypeName).append(" result = ").append(methodCall)
.append("\n").append(memberInjectCall)
.append("\nreturn result;")
.build();
methodsOutput.add(SourceSnippets.asMethod(false, assistedInjectSignature, packageName,
assistedInjectMethodBody));
List<String> parameterNames = new ArrayList<String>();
for (int i = 0; i < assisted.method.getParameterKeys().size(); ++i) {
parameterNames.add(ReflectUtil.formatParameterName(i));
}
return SourceSnippets.callMethod(assistedInjectMethodName, packageName, parameterNames);
}
public Collection<Dependency> getDependencies() {
return dependencies;
}
@Override
public Collection<TypeLiteral<?>> getMemberInjectRequests() {
return Collections.unmodifiableCollection(implementations);
}
private void matchMethods(Key<?> factoryKey) throws ErrorsException {
Errors errors = new Errors();
dependencies.add(new Dependency(Dependency.GINJECTOR, factoryKey, getContext()));
Class<?> factoryRawType = factoryType.getRawType();
// getMethods() includes inherited methods from super-interfaces.
for (Method method : factoryRawType.getMethods()) {
Key<?> returnType = getKey(factoryType.getReturnType(method), method,
method.getAnnotations(), errors);
// Get parameters with annotations.
List<TypeLiteral<?>> params = factoryType.getParameterTypes(method);
Annotation[][] paramAnnotations = method.getParameterAnnotations();
int p = 0;
List<Key<?>> paramList = new ArrayList<Key<?>>();
for (TypeLiteral<?> param : params) {
Key<?> paramKey = getKey(param, method, paramAnnotations[p++], errors);
paramList.add(assistKey(method, paramKey, errors));
}
// Try to match up the method to the constructor.
TypeLiteral<?> implementation = collector.get(returnType);
if (implementation == null) {
implementation = returnType.getTypeLiteral();
}
Constructor<?> constructor =
findMatchingConstructor(method, implementation, paramList, errors);
if (constructor == null) {
continue; // Errors are collected and thrown below.
}
// Calculate a map from method to constructor parameters and required
// keys.
String[] parameterNames = extractConstructorParameters(factoryKey,
implementation, constructor, paramList, errors, dependencies);
TypeLiteral<?> methodDeclaringType = factoryType.getSupertype(method.getDeclaringClass());
assistData.add(new AssistData(implementation, MethodLiteral.get(constructor, implementation),
MethodLiteral.get(method, methodDeclaringType), parameterNames));
implementations.add(implementation);
dependencies.addAll(guiceUtil.getMemberInjectionDependencies(factoryKey, implementation));
}
errors.throwConfigurationExceptionIfErrorsExist();
}
/**
* Matches constructor parameters to method parameters for injection and
* records remaining parameters as required keys.
*/
private String[] extractConstructorParameters(Key<?> factoryKey, TypeLiteral<?> implementation,
Constructor constructor, List<Key<?>> methodParams, Errors errors,
Set<Dependency> dependencyCollector) throws ErrorsException {
// Get parameters with annotations.
List<TypeLiteral<?>> ctorParams = implementation.getParameterTypes(constructor);
Annotation[][] ctorParamAnnotations = constructor.getParameterAnnotations();
int p = 0;
String[] parameterNames = new String[ctorParams.size()];
Set<Key<?>> keySet = new LinkedHashSet<Key<?>>();
for (TypeLiteral<?> ctorParam : ctorParams) {
Key<?> ctorParamKey = getKey(ctorParam, constructor, ctorParamAnnotations[p], errors);
if (ctorParamKey.getAnnotationType() == Assisted.class) {
if (!keySet.add(ctorParamKey)) {
errors.addMessage(PrettyPrinter.format(
"%s has more than one parameter of type %s annotated with @Assisted(\"%s\"). " +
"Please specify a unique value with the annotation to avoid confusion.",
implementation, ctorParamKey.getTypeLiteral().getType(),
((Assisted) ctorParamKey.getAnnotation()).value()));
}
int location = methodParams.indexOf(ctorParamKey);
// This should never happen since the constructor was already checked
// in #[inject]constructorHasMatchingParams(..).
Preconditions.checkState(location != -1);
parameterNames[p] = ReflectUtil.formatParameterName(location);
} else {
dependencyCollector.add(new Dependency(factoryKey, ctorParamKey, false, true,
constructor.toString()));
}
p++;
}
return parameterNames;
}
/**
* Finds a constructor suitable for the method. If the implementation
* contained any constructors marked with {@link AssistedInject}, this
* requires all {@link Assisted} parameters to exactly match the parameters
* (in any order) listed in the method. Otherwise, if no
* {@link AssistedInject} constructors exist, this will default to looking
* for a {@literal @}{@link Inject} constructor.
*/
private Constructor findMatchingConstructor(Method method, TypeLiteral<?> implementation,
List<Key<?>> paramList, Errors errors) throws ErrorsException {
Constructor<?> matchingConstructor = null;
boolean anyAssistedInjectConstructors = false;
// Look for AssistedInject constructors...
for (Constructor<?> constructor : implementation.getRawType().getDeclaredConstructors()) {
if (constructor.isAnnotationPresent(AssistedInject.class)) {
anyAssistedInjectConstructors = true;
if (constructorHasMatchingParams(implementation, constructor, paramList, errors)) {
if (matchingConstructor != null) {
errors.addMessage(PrettyPrinter.format(
"%s has more than one constructor annotated with @AssistedInject "
+ "that matches the parameters in method %s.",
implementation, method));
return null;
} else {
matchingConstructor = constructor;
}
}
}
}
if (matchingConstructor != null) {
return matchingConstructor;
}
if (anyAssistedInjectConstructors) {
errors.addMessage(PrettyPrinter.format(
"%s has @AssistedInject constructors, but none of them match the "
+ "parameters in method %s.", implementation, method));
return null;
}
// Look for @Inject constructors...
Constructor<?> injectConstructor =
(Constructor) InjectionPoint.forConstructorOf(implementation).getMember();
if (injectConstructorHasMatchingParams(implementation, injectConstructor, paramList, errors)) {
return injectConstructor;
}
// No matching constructor exists, complain.
errors.addMessage(PrettyPrinter.format(
"%s has no constructors matching the parameters in method %s.",
implementation, method));
return null;
}
/**
* Matching logic for {@literal @}{@link AssistedInject} constructor and
* method parameters.
*
* This returns true if and only if all @Assisted parameters in the
* constructor exactly match (in any order) all @Assisted parameters the
* method's parameter.
*/
private boolean constructorHasMatchingParams(TypeLiteral<?> type, Constructor<?> constructor,
List<Key<?>> paramList, Errors errors) throws ErrorsException {
List<TypeLiteral<?>> params = type.getParameterTypes(constructor);
Annotation[][] paramAnnotations = constructor.getParameterAnnotations();
int p = 0;
List<Key<?>> constructorKeys = new ArrayList<Key<?>>();
for (TypeLiteral<?> param : params) {
constructorKeys.add(getKey(param, constructor, paramAnnotations[p++], errors));
}
// Require that every key exist in the constructor to match up exactly.
for (Key<?> key : paramList) {
// If it didn't exist in the constructor set, we can't use it.
if (!constructorKeys.remove(key)) {
return false;
}
}
// If any keys remain and their annotation is Assisted, we can't use it.
for (Key<?> key : constructorKeys) {
if (key.getAnnotationType() == Assisted.class) {
return false;
}
}
// All @Assisted params match up to the method's parameters.
return true;
}
/**
* Matching logic for {@literal @}{@link Inject} constructor and method
* parameters.
*
* This returns true if all assisted parameters required by the constructor
* are provided by the factory method.
*/
private boolean injectConstructorHasMatchingParams(TypeLiteral<?> type,
Constructor<?> constructor, List<Key<?>> paramList, Errors errors) throws ErrorsException {
List<TypeLiteral<?>> params = type.getParameterTypes(constructor);
Annotation[][] paramAnnotations = constructor.getParameterAnnotations();
int p = 0;
for (TypeLiteral<?> param : params) {
Key<?> paramKey = getKey(param, constructor, paramAnnotations[p++], errors);
if(paramKey.getAnnotationType() == Assisted.class && !paramList.contains(paramKey)) {
return false;
}
}
return true;
}
/**
* Returns a key similar to {@code key}, but with an {@literal @}Assisted
* binding annotation.
*
* This fails if another binding annotation is clobbered in the process. If
* the key already has the {@literal @}Assisted annotation, it is returned
* as-is to preserve any String value.
*/
private <T> Key<T> assistKey(Method method, Key<T> key, Errors errors) throws ErrorsException {
if (key.getAnnotationType() == null) {
return Key.get(key.getTypeLiteral(), DEFAULT_ANNOTATION);
} else if (key.getAnnotationType() == Assisted.class) {
return key;
} else {
errors.withSource(method).addMessage(PrettyPrinter.format(
"Only @Assisted is allowed for factory parameters, but found @%s",
key.getAnnotationType()));
throw errors.toException();
}
}
private static class AssistData {
final TypeLiteral<?> implementation;
final MethodLiteral<?, Constructor<?>> constructor;
final MethodLiteral<?, Method> method;
final String[] parameterNames;
private AssistData(TypeLiteral<?> implementation, MethodLiteral<?, Constructor<?>> constructor,
MethodLiteral<?, Method> method, String[] parameterNames) {
this.implementation = implementation;
this.parameterNames = parameterNames;
this.method = method;
this.constructor = constructor;
}
}
}