com.google.web.bindery.requestfactory.apt.TypeSimplifier Maven / Gradle / Ivy
/*
* Copyright 2011 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.web.bindery.requestfactory.apt;
import java.util.ArrayList;
import java.util.List;
import javax.lang.model.element.TypeElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.NoType;
import javax.lang.model.type.PrimitiveType;
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.type.TypeVariable;
import javax.lang.model.type.WildcardType;
import javax.lang.model.util.SimpleTypeVisitor6;
/**
* Utility type for reducing complex type declarations to ones suitable for
* determining assignability based on RequestFactory's type-mapping semantics.
*
* Rules:
*
* - primitive type {@code ->} boxed type (optional)
* - {@code void -> Void} (optional)
* - {@code
-> Foo}
* - {@code ? extends Foo -> Foo}
* - {@code Foo
-> Foo}
*
*/
public class TypeSimplifier extends SimpleTypeVisitor6 {
public static TypeMirror simplify(TypeMirror toBox, boolean boxPrimitives, State state) {
if (toBox == null) {
return null;
}
return toBox.accept(new TypeSimplifier(boxPrimitives), state);
}
private final boolean boxPrimitives;
private TypeSimplifier(boolean boxPrimitives) {
this.boxPrimitives = boxPrimitives;
}
@Override
public TypeMirror visitDeclared(DeclaredType x, State state) {
if (x.getTypeArguments().isEmpty()) {
return x;
}
List newArgs = new ArrayList(x.getTypeArguments().size());
for (TypeMirror original : x.getTypeArguments()) {
// Are we looking at a self-parameterized type like Foo>?
if (original.getKind().equals(TypeKind.TYPEVAR) && state.types.isAssignable(original, x)) {
// If so, return a raw type
return state.types.getDeclaredType((TypeElement) x.asElement());
} else {
newArgs.add(original.accept(this, state));
}
}
return state.types.getDeclaredType((TypeElement) x.asElement(), newArgs
.toArray(new TypeMirror[newArgs.size()]));
}
@Override
public TypeMirror visitNoType(NoType x, State state) {
if (boxPrimitives) {
return state.findType(Void.class);
}
return x;
}
@Override
public TypeMirror visitPrimitive(PrimitiveType x, State state) {
if (boxPrimitives) {
return state.types.boxedClass(x).asType();
}
return x;
}
@Override
public TypeMirror visitTypeVariable(TypeVariable x, State state) {
if (x.equals(x.getUpperBound())) {
// See comment in TransportableTypeVisitor
return state.types.erasure(x);
}
return x.getUpperBound().accept(this, state);
}
@Override
public TypeMirror visitWildcard(WildcardType x, State state) {
return state.types.erasure(x).accept(this, state);
}
@Override
protected TypeMirror defaultAction(TypeMirror x, State state) {
return state.types.getNoType(TypeKind.NONE);
}
}