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Diffstat (limited to 'gson/src/main/java/com/google/gson/internal/$Gson$Types.java')
| -rw-r--r-- | gson/src/main/java/com/google/gson/internal/$Gson$Types.java | 588 |
1 files changed, 588 insertions, 0 deletions
diff --git a/gson/src/main/java/com/google/gson/internal/$Gson$Types.java b/gson/src/main/java/com/google/gson/internal/$Gson$Types.java new file mode 100644 index 00000000..745d0719 --- /dev/null +++ b/gson/src/main/java/com/google/gson/internal/$Gson$Types.java @@ -0,0 +1,588 @@ +/** + * Copyright (C) 2008 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.gson.internal; + +import static com.google.gson.internal.$Gson$Preconditions.checkArgument; +import static com.google.gson.internal.$Gson$Preconditions.checkNotNull; + +import java.io.Serializable; +import java.lang.reflect.Array; +import java.lang.reflect.GenericArrayType; +import java.lang.reflect.GenericDeclaration; +import java.lang.reflect.Modifier; +import java.lang.reflect.ParameterizedType; +import java.lang.reflect.Type; +import java.lang.reflect.TypeVariable; +import java.lang.reflect.WildcardType; +import java.util.Arrays; +import java.util.Collection; +import java.util.Map; +import java.util.NoSuchElementException; +import java.util.Properties; + +/** + * Static methods for working with types. + * + * @author Bob Lee + * @author Jesse Wilson + */ +public final class $Gson$Types { + static final Type[] EMPTY_TYPE_ARRAY = new Type[] {}; + + private $Gson$Types() { + throw new UnsupportedOperationException(); + } + + /** + * Returns a new parameterized type, applying {@code typeArguments} to + * {@code rawType} and enclosed by {@code ownerType}. + * + * @return a {@link java.io.Serializable serializable} parameterized type. + */ + public static ParameterizedType newParameterizedTypeWithOwner( + Type ownerType, Type rawType, Type... typeArguments) { + return new ParameterizedTypeImpl(ownerType, rawType, typeArguments); + } + + /** + * Returns an array type whose elements are all instances of + * {@code componentType}. + * + * @return a {@link java.io.Serializable serializable} generic array type. + */ + public static GenericArrayType arrayOf(Type componentType) { + return new GenericArrayTypeImpl(componentType); + } + + /** + * Returns a type that represents an unknown type that extends {@code bound}. + * For example, if {@code bound} is {@code CharSequence.class}, this returns + * {@code ? extends CharSequence}. If {@code bound} is {@code Object.class}, + * this returns {@code ?}, which is shorthand for {@code ? extends Object}. + */ + public static WildcardType subtypeOf(Type bound) { + return new WildcardTypeImpl(new Type[] { bound }, EMPTY_TYPE_ARRAY); + } + + /** + * Returns a type that represents an unknown supertype of {@code bound}. For + * example, if {@code bound} is {@code String.class}, this returns {@code ? + * super String}. + */ + public static WildcardType supertypeOf(Type bound) { + return new WildcardTypeImpl(new Type[] { Object.class }, new Type[] { bound }); + } + + /** + * Returns a type that is functionally equal but not necessarily equal + * according to {@link Object#equals(Object) Object.equals()}. The returned + * type is {@link java.io.Serializable}. + */ + public static Type canonicalize(Type type) { + if (type instanceof Class) { + Class<?> c = (Class<?>) type; + return c.isArray() ? new GenericArrayTypeImpl(canonicalize(c.getComponentType())) : c; + + } else if (type instanceof ParameterizedType) { + ParameterizedType p = (ParameterizedType) type; + return new ParameterizedTypeImpl(p.getOwnerType(), + p.getRawType(), p.getActualTypeArguments()); + + } else if (type instanceof GenericArrayType) { + GenericArrayType g = (GenericArrayType) type; + return new GenericArrayTypeImpl(g.getGenericComponentType()); + + } else if (type instanceof WildcardType) { + WildcardType w = (WildcardType) type; + return new WildcardTypeImpl(w.getUpperBounds(), w.getLowerBounds()); + + } else { + // type is either serializable as-is or unsupported + return type; + } + } + + public static Class<?> getRawType(Type type) { + if (type instanceof Class<?>) { + // type is a normal class. + return (Class<?>) type; + + } else if (type instanceof ParameterizedType) { + ParameterizedType parameterizedType = (ParameterizedType) type; + + // I'm not exactly sure why getRawType() returns Type instead of Class. + // Neal isn't either but suspects some pathological case related + // to nested classes exists. + Type rawType = parameterizedType.getRawType(); + checkArgument(rawType instanceof Class); + return (Class<?>) rawType; + + } else if (type instanceof GenericArrayType) { + Type componentType = ((GenericArrayType)type).getGenericComponentType(); + return Array.newInstance(getRawType(componentType), 0).getClass(); + + } else if (type instanceof TypeVariable) { + // we could use the variable's bounds, but that won't work if there are multiple. + // having a raw type that's more general than necessary is okay + return Object.class; + + } else if (type instanceof WildcardType) { + return getRawType(((WildcardType) type).getUpperBounds()[0]); + + } else { + String className = type == null ? "null" : type.getClass().getName(); + throw new IllegalArgumentException("Expected a Class, ParameterizedType, or " + + "GenericArrayType, but <" + type + "> is of type " + className); + } + } + + static boolean equal(Object a, Object b) { + return a == b || (a != null && a.equals(b)); + } + + /** + * Returns true if {@code a} and {@code b} are equal. + */ + public static boolean equals(Type a, Type b) { + if (a == b) { + // also handles (a == null && b == null) + return true; + + } else if (a instanceof Class) { + // Class already specifies equals(). + return a.equals(b); + + } else if (a instanceof ParameterizedType) { + if (!(b instanceof ParameterizedType)) { + return false; + } + + // TODO: save a .clone() call + ParameterizedType pa = (ParameterizedType) a; + ParameterizedType pb = (ParameterizedType) b; + return equal(pa.getOwnerType(), pb.getOwnerType()) + && pa.getRawType().equals(pb.getRawType()) + && Arrays.equals(pa.getActualTypeArguments(), pb.getActualTypeArguments()); + + } else if (a instanceof GenericArrayType) { + if (!(b instanceof GenericArrayType)) { + return false; + } + + GenericArrayType ga = (GenericArrayType) a; + GenericArrayType gb = (GenericArrayType) b; + return equals(ga.getGenericComponentType(), gb.getGenericComponentType()); + + } else if (a instanceof WildcardType) { + if (!(b instanceof WildcardType)) { + return false; + } + + WildcardType wa = (WildcardType) a; + WildcardType wb = (WildcardType) b; + return Arrays.equals(wa.getUpperBounds(), wb.getUpperBounds()) + && Arrays.equals(wa.getLowerBounds(), wb.getLowerBounds()); + + } else if (a instanceof TypeVariable) { + if (!(b instanceof TypeVariable)) { + return false; + } + TypeVariable<?> va = (TypeVariable<?>) a; + TypeVariable<?> vb = (TypeVariable<?>) b; + return va.getGenericDeclaration() == vb.getGenericDeclaration() + && va.getName().equals(vb.getName()); + + } else { + // This isn't a type we support. Could be a generic array type, wildcard type, etc. + return false; + } + } + + private static int hashCodeOrZero(Object o) { + return o != null ? o.hashCode() : 0; + } + + public static String typeToString(Type type) { + return type instanceof Class ? ((Class<?>) type).getName() : type.toString(); + } + + /** + * Returns the generic supertype for {@code supertype}. For example, given a class {@code + * IntegerSet}, the result for when supertype is {@code Set.class} is {@code Set<Integer>} and the + * result when the supertype is {@code Collection.class} is {@code Collection<Integer>}. + */ + static Type getGenericSupertype(Type context, Class<?> rawType, Class<?> toResolve) { + if (toResolve == rawType) { + return context; + } + + // we skip searching through interfaces if unknown is an interface + if (toResolve.isInterface()) { + Class<?>[] interfaces = rawType.getInterfaces(); + for (int i = 0, length = interfaces.length; i < length; i++) { + if (interfaces[i] == toResolve) { + return rawType.getGenericInterfaces()[i]; + } else if (toResolve.isAssignableFrom(interfaces[i])) { + return getGenericSupertype(rawType.getGenericInterfaces()[i], interfaces[i], toResolve); + } + } + } + + // check our supertypes + if (!rawType.isInterface()) { + while (rawType != Object.class) { + Class<?> rawSupertype = rawType.getSuperclass(); + if (rawSupertype == toResolve) { + return rawType.getGenericSuperclass(); + } else if (toResolve.isAssignableFrom(rawSupertype)) { + return getGenericSupertype(rawType.getGenericSuperclass(), rawSupertype, toResolve); + } + rawType = rawSupertype; + } + } + + // we can't resolve this further + return toResolve; + } + + /** + * Returns the generic form of {@code supertype}. For example, if this is {@code + * ArrayList<String>}, this returns {@code Iterable<String>} given the input {@code + * Iterable.class}. + * + * @param supertype a superclass of, or interface implemented by, this. + */ + static Type getSupertype(Type context, Class<?> contextRawType, Class<?> supertype) { + checkArgument(supertype.isAssignableFrom(contextRawType)); + return resolve(context, contextRawType, + $Gson$Types.getGenericSupertype(context, contextRawType, supertype)); + } + + /** + * Returns the component type of this array type. + * @throws ClassCastException if this type is not an array. + */ + public static Type getArrayComponentType(Type array) { + return array instanceof GenericArrayType + ? ((GenericArrayType) array).getGenericComponentType() + : ((Class<?>) array).getComponentType(); + } + + /** + * Returns the element type of this collection type. + * @throws IllegalArgumentException if this type is not a collection. + */ + public static Type getCollectionElementType(Type context, Class<?> contextRawType) { + Type collectionType = getSupertype(context, contextRawType, Collection.class); + + if (collectionType instanceof WildcardType) { + collectionType = ((WildcardType)collectionType).getUpperBounds()[0]; + } + if (collectionType instanceof ParameterizedType) { + return ((ParameterizedType) collectionType).getActualTypeArguments()[0]; + } + return Object.class; + } + + /** + * Returns a two element array containing this map's key and value types in + * positions 0 and 1 respectively. + */ + public static Type[] getMapKeyAndValueTypes(Type context, Class<?> contextRawType) { + /* + * Work around a problem with the declaration of java.util.Properties. That + * class should extend Hashtable<String, String>, but it's declared to + * extend Hashtable<Object, Object>. + */ + if (context == Properties.class) { + return new Type[] { String.class, String.class }; // TODO: test subclasses of Properties! + } + + Type mapType = getSupertype(context, contextRawType, Map.class); + // TODO: strip wildcards? + if (mapType instanceof ParameterizedType) { + ParameterizedType mapParameterizedType = (ParameterizedType) mapType; + return mapParameterizedType.getActualTypeArguments(); + } + return new Type[] { Object.class, Object.class }; + } + + public static Type resolve(Type context, Class<?> contextRawType, Type toResolve) { + // this implementation is made a little more complicated in an attempt to avoid object-creation + while (true) { + if (toResolve instanceof TypeVariable) { + TypeVariable<?> typeVariable = (TypeVariable<?>) toResolve; + toResolve = resolveTypeVariable(context, contextRawType, typeVariable); + if (toResolve == typeVariable) { + return toResolve; + } + + } else if (toResolve instanceof Class && ((Class<?>) toResolve).isArray()) { + Class<?> original = (Class<?>) toResolve; + Type componentType = original.getComponentType(); + Type newComponentType = resolve(context, contextRawType, componentType); + return componentType == newComponentType + ? original + : arrayOf(newComponentType); + + } else if (toResolve instanceof GenericArrayType) { + GenericArrayType original = (GenericArrayType) toResolve; + Type componentType = original.getGenericComponentType(); + Type newComponentType = resolve(context, contextRawType, componentType); + return componentType == newComponentType + ? original + : arrayOf(newComponentType); + + } else if (toResolve instanceof ParameterizedType) { + ParameterizedType original = (ParameterizedType) toResolve; + Type ownerType = original.getOwnerType(); + Type newOwnerType = resolve(context, contextRawType, ownerType); + boolean changed = newOwnerType != ownerType; + + Type[] args = original.getActualTypeArguments(); + for (int t = 0, length = args.length; t < length; t++) { + Type resolvedTypeArgument = resolve(context, contextRawType, args[t]); + if (resolvedTypeArgument != args[t]) { + if (!changed) { + args = args.clone(); + changed = true; + } + args[t] = resolvedTypeArgument; + } + } + + return changed + ? newParameterizedTypeWithOwner(newOwnerType, original.getRawType(), args) + : original; + + } else if (toResolve instanceof WildcardType) { + WildcardType original = (WildcardType) toResolve; + Type[] originalLowerBound = original.getLowerBounds(); + Type[] originalUpperBound = original.getUpperBounds(); + + if (originalLowerBound.length == 1) { + Type lowerBound = resolve(context, contextRawType, originalLowerBound[0]); + if (lowerBound != originalLowerBound[0]) { + return supertypeOf(lowerBound); + } + } else if (originalUpperBound.length == 1) { + Type upperBound = resolve(context, contextRawType, originalUpperBound[0]); + if (upperBound != originalUpperBound[0]) { + return subtypeOf(upperBound); + } + } + return original; + + } else { + return toResolve; + } + } + } + + static Type resolveTypeVariable(Type context, Class<?> contextRawType, TypeVariable<?> unknown) { + Class<?> declaredByRaw = declaringClassOf(unknown); + + // we can't reduce this further + if (declaredByRaw == null) { + return unknown; + } + + Type declaredBy = getGenericSupertype(context, contextRawType, declaredByRaw); + if (declaredBy instanceof ParameterizedType) { + int index = indexOf(declaredByRaw.getTypeParameters(), unknown); + return ((ParameterizedType) declaredBy).getActualTypeArguments()[index]; + } + + return unknown; + } + + private static int indexOf(Object[] array, Object toFind) { + for (int i = 0; i < array.length; i++) { + if (toFind.equals(array[i])) { + return i; + } + } + throw new NoSuchElementException(); + } + + /** + * Returns the declaring class of {@code typeVariable}, or {@code null} if it was not declared by + * a class. + */ + private static Class<?> declaringClassOf(TypeVariable<?> typeVariable) { + GenericDeclaration genericDeclaration = typeVariable.getGenericDeclaration(); + return genericDeclaration instanceof Class + ? (Class<?>) genericDeclaration + : null; + } + + private static void checkNotPrimitive(Type type) { + checkArgument(!(type instanceof Class<?>) || !((Class<?>) type).isPrimitive()); + } + + private static final class ParameterizedTypeImpl implements ParameterizedType, Serializable { + private final Type ownerType; + private final Type rawType; + private final Type[] typeArguments; + + public ParameterizedTypeImpl(Type ownerType, Type rawType, Type... typeArguments) { + // require an owner type if the raw type needs it + if (rawType instanceof Class<?>) { + Class<?> rawTypeAsClass = (Class<?>) rawType; + boolean isStaticOrTopLevelClass = Modifier.isStatic(rawTypeAsClass.getModifiers()) + || rawTypeAsClass.getEnclosingClass() == null; + checkArgument(ownerType != null || isStaticOrTopLevelClass); + } + + this.ownerType = ownerType == null ? null : canonicalize(ownerType); + this.rawType = canonicalize(rawType); + this.typeArguments = typeArguments.clone(); + for (int t = 0; t < this.typeArguments.length; t++) { + checkNotNull(this.typeArguments[t]); + checkNotPrimitive(this.typeArguments[t]); + this.typeArguments[t] = canonicalize(this.typeArguments[t]); + } + } + + public Type[] getActualTypeArguments() { + return typeArguments.clone(); + } + + public Type getRawType() { + return rawType; + } + + public Type getOwnerType() { + return ownerType; + } + + @Override public boolean equals(Object other) { + return other instanceof ParameterizedType + && $Gson$Types.equals(this, (ParameterizedType) other); + } + + @Override public int hashCode() { + return Arrays.hashCode(typeArguments) + ^ rawType.hashCode() + ^ hashCodeOrZero(ownerType); + } + + @Override public String toString() { + StringBuilder stringBuilder = new StringBuilder(30 * (typeArguments.length + 1)); + stringBuilder.append(typeToString(rawType)); + + if (typeArguments.length == 0) { + return stringBuilder.toString(); + } + + stringBuilder.append("<").append(typeToString(typeArguments[0])); + for (int i = 1; i < typeArguments.length; i++) { + stringBuilder.append(", ").append(typeToString(typeArguments[i])); + } + return stringBuilder.append(">").toString(); + } + + private static final long serialVersionUID = 0; + } + + private static final class GenericArrayTypeImpl implements GenericArrayType, Serializable { + private final Type componentType; + + public GenericArrayTypeImpl(Type componentType) { + this.componentType = canonicalize(componentType); + } + + public Type getGenericComponentType() { + return componentType; + } + + @Override public boolean equals(Object o) { + return o instanceof GenericArrayType + && $Gson$Types.equals(this, (GenericArrayType) o); + } + + @Override public int hashCode() { + return componentType.hashCode(); + } + + @Override public String toString() { + return typeToString(componentType) + "[]"; + } + + private static final long serialVersionUID = 0; + } + + /** + * The WildcardType interface supports multiple upper bounds and multiple + * lower bounds. We only support what the Java 6 language needs - at most one + * bound. If a lower bound is set, the upper bound must be Object.class. + */ + private static final class WildcardTypeImpl implements WildcardType, Serializable { + private final Type upperBound; + private final Type lowerBound; + + public WildcardTypeImpl(Type[] upperBounds, Type[] lowerBounds) { + checkArgument(lowerBounds.length <= 1); + checkArgument(upperBounds.length == 1); + + if (lowerBounds.length == 1) { + checkNotNull(lowerBounds[0]); + checkNotPrimitive(lowerBounds[0]); + checkArgument(upperBounds[0] == Object.class); + this.lowerBound = canonicalize(lowerBounds[0]); + this.upperBound = Object.class; + + } else { + checkNotNull(upperBounds[0]); + checkNotPrimitive(upperBounds[0]); + this.lowerBound = null; + this.upperBound = canonicalize(upperBounds[0]); + } + } + + public Type[] getUpperBounds() { + return new Type[] { upperBound }; + } + + public Type[] getLowerBounds() { + return lowerBound != null ? new Type[] { lowerBound } : EMPTY_TYPE_ARRAY; + } + + @Override public boolean equals(Object other) { + return other instanceof WildcardType + && $Gson$Types.equals(this, (WildcardType) other); + } + + @Override public int hashCode() { + // this equals Arrays.hashCode(getLowerBounds()) ^ Arrays.hashCode(getUpperBounds()); + return (lowerBound != null ? 31 + lowerBound.hashCode() : 1) + ^ (31 + upperBound.hashCode()); + } + + @Override public String toString() { + if (lowerBound != null) { + return "? super " + typeToString(lowerBound); + } else if (upperBound == Object.class) { + return "?"; + } else { + return "? extends " + typeToString(upperBound); + } + } + + private static final long serialVersionUID = 0; + } +} |