102 lines
3.7 KiB
Java
102 lines
3.7 KiB
Java
/*
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* Copyright (C) 2014 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.gson.internal;
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import static com.google.common.truth.Truth.assertThat;
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import static org.junit.Assert.assertThrows;
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import java.lang.reflect.ParameterizedType;
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import java.lang.reflect.Type;
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import java.util.List;
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import org.junit.Test;
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@SuppressWarnings("ClassNamedLikeTypeParameter") // for dummy classes A, B, ...
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public final class GsonTypesTest {
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@Test
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public void testNewParameterizedTypeWithoutOwner() throws Exception {
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// List<A>. List is a top-level class
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ParameterizedType type = $Gson$Types.newParameterizedTypeWithOwner(null, List.class, A.class);
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assertThat(type.getOwnerType()).isNull();
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assertThat(type.getRawType()).isEqualTo(List.class);
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assertThat(type.getActualTypeArguments()).asList().containsExactly(A.class);
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// A<B>. A is a static inner class.
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type = $Gson$Types.newParameterizedTypeWithOwner(null, A.class, B.class);
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assertThat(getFirstTypeArgument(type)).isEqualTo(B.class);
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IllegalArgumentException e =
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assertThrows(
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IllegalArgumentException.class,
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// NonStaticInner<A> is not allowed without owner
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() -> $Gson$Types.newParameterizedTypeWithOwner(null, NonStaticInner.class, A.class));
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assertThat(e).hasMessageThat().isEqualTo("Must specify owner type for " + NonStaticInner.class);
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type =
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$Gson$Types.newParameterizedTypeWithOwner(
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GsonTypesTest.class, NonStaticInner.class, A.class);
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assertThat(type.getOwnerType()).isEqualTo(GsonTypesTest.class);
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assertThat(type.getRawType()).isEqualTo(NonStaticInner.class);
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assertThat(type.getActualTypeArguments()).asList().containsExactly(A.class);
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final class D {}
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// D<A> is allowed since D has no owner type
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type = $Gson$Types.newParameterizedTypeWithOwner(null, D.class, A.class);
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assertThat(type.getOwnerType()).isNull();
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assertThat(type.getRawType()).isEqualTo(D.class);
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assertThat(type.getActualTypeArguments()).asList().containsExactly(A.class);
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// A<D> is allowed.
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type = $Gson$Types.newParameterizedTypeWithOwner(null, A.class, D.class);
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assertThat(getFirstTypeArgument(type)).isEqualTo(D.class);
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}
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@Test
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public void testGetFirstTypeArgument() throws Exception {
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assertThat(getFirstTypeArgument(A.class)).isNull();
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Type type = $Gson$Types.newParameterizedTypeWithOwner(null, A.class, B.class, C.class);
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assertThat(getFirstTypeArgument(type)).isEqualTo(B.class);
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}
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private static final class A {}
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private static final class B {}
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private static final class C {}
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@SuppressWarnings({"ClassCanBeStatic", "UnusedTypeParameter"})
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private final class NonStaticInner<T> {}
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/**
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* Given a parameterized type {@code A<B, C>}, returns B. If the specified type is not a generic
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* type, returns null.
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*/
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public static Type getFirstTypeArgument(Type type) throws Exception {
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if (!(type instanceof ParameterizedType)) {
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return null;
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}
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ParameterizedType ptype = (ParameterizedType) type;
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Type[] actualTypeArguments = ptype.getActualTypeArguments();
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if (actualTypeArguments.length == 0) {
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return null;
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}
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return $Gson$Types.canonicalize(actualTypeArguments[0]);
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}
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}
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