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Code Issues Releases Wiki Activity

Avoid defensive clone() in ParameterizedType.getActualTypeArguments() when possible.

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PiperOrigin-RevId: 347701829
This commit is contained in:
Guice Team
2020-12-15 15:12:54 -08:00
committed by Guice Team
parent 363f568b6d
commit 15ce8eb669
1 changed files with 16 additions and 7 deletions
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core/src/com/google/inject/internal/MoreTypes.java
+16 -7
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@@ -99,7 +99,7 @@ public class MoreTypes {
@SuppressWarnings("unchecked")
TypeLiteral<T> guiceProviderType =
(TypeLiteral<T>)
TypeLiteral.get(Types.providerOf(parameterizedType.getActualTypeArguments()[0]));
TypeLiteral.get(Types.providerOf(getSharedTypeArguments(parameterizedType)[0]));
return guiceProviderType;
}
@@ -151,8 +151,7 @@ public class MoreTypes {
} else if (type instanceof ParameterizedType) {
ParameterizedType p = (ParameterizedType) type;
return new ParameterizedTypeImpl(
p.getOwnerType(), p.getRawType(), p.getActualTypeArguments());
return new ParameterizedTypeImpl(p.getOwnerType(), p.getRawType(), getSharedTypeArguments(p));
} else if (type instanceof GenericArrayType) {
GenericArrayType g = (GenericArrayType) type;
@@ -221,12 +220,11 @@ public class MoreTypes {
return false;
}
// TODO: save a .clone() call
ParameterizedType pa = (ParameterizedType) a;
ParameterizedType pb = (ParameterizedType) b;
return Objects.equal(pa.getOwnerType(), pb.getOwnerType())
&& pa.getRawType().equals(pb.getRawType())
&& Arrays.equals(pa.getActualTypeArguments(), pb.getActualTypeArguments());
&& Arrays.equals(getSharedTypeArguments(pa), getSharedTypeArguments(pb));
} else if (a instanceof GenericArrayType) {
if (!(b instanceof GenericArrayType)) {
@@ -320,7 +318,7 @@ public class MoreTypes {
Type declaredBy = getGenericSupertype(type, rawType, declaredByRaw);
if (declaredBy instanceof ParameterizedType) {
int index = indexOf(declaredByRaw.getTypeParameters(), unknown);
return ((ParameterizedType) declaredBy).getActualTypeArguments()[index];
return getSharedTypeArguments((ParameterizedType) declaredBy)[index];
}
return unknown;
@@ -335,6 +333,17 @@ public class MoreTypes {
throw new NoSuchElementException();
}
/**
* This method is used as a performance optimization to prevent unnecessary clones of
* typeArguments from being made by ParameterizedTypeImpl.
*/
private static Type[] getSharedTypeArguments(ParameterizedType p) {
if (p instanceof ParameterizedTypeImpl) {
return ((ParameterizedTypeImpl) p).typeArguments;
}
return p.getActualTypeArguments();
}
/**
* Returns the declaring class of {@code typeVariable}, or {@code null} if it was not declared by
* a class.
@@ -348,7 +357,7 @@ public class MoreTypes {
implements ParameterizedType, Serializable, CompositeType {
private final Type ownerType;
private final Type rawType;
private final Type[] typeArguments;
final Type[] typeArguments;
public ParameterizedTypeImpl(Type ownerType, Type rawType, Type... typeArguments) {
// require an owner type if the raw type needs it