package com.google.gson.internal;
import java.lang.reflect.Type;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* Contains static utility methods pertaining to primitive types and their corresponding wrapper
* types.
*
* @author Kevin Bourrillion
*/
public final class Primitives {
private Primitives() {}
/** A map from primitive types to their corresponding wrapper types. */
private static final Map<Class<?>, Class<?>> PRIMITIVE_TO_WRAPPER_TYPE;
/** A map from wrapper types to their corresponding primitive types. */
private static final Map<Class<?>, Class<?>> WRAPPER_TO_PRIMITIVE_TYPE;
// Sad that we can't use a BiMap. :(
static {
Map<Class<?>, Class<?>> primToWrap = new HashMap<Class<?>, Class<?>>(16);
Map<Class<?>, Class<?>> wrapToPrim = new HashMap<Class<?>, Class<?>>(16);
add(primToWrap, wrapToPrim, boolean.class, Boolean.class);
add(primToWrap, wrapToPrim, byte.class, Byte.class);
add(primToWrap, wrapToPrim, char.class, Character.class);
add(primToWrap, wrapToPrim, double.class, Double.class);
add(primToWrap, wrapToPrim, float.class, Float.class);
add(primToWrap, wrapToPrim, int.class, Integer.class);
add(primToWrap, wrapToPrim, long.class, Long.class);
add(primToWrap, wrapToPrim, short.class, Short.class);
add(primToWrap, wrapToPrim, void.class, Void.class);
PRIMITIVE_TO_WRAPPER_TYPE = Collections.unmodifiableMap(primToWrap);
WRAPPER_TO_PRIMITIVE_TYPE = Collections.unmodifiableMap(wrapToPrim);
}
private static void add(Map<Class<?>, Class<?>> forward, Map<Class<?>, Class<?>> backward, Class<?> key, Class<?> value) {
forward.put(key, value);
backward.put(value, key);
}
/**
* Returns true if this type is a primitive.
*/
public static boolean isPrimitive(Type type) {
return PRIMITIVE_TO_WRAPPER_TYPE.containsKey(type);
}
/**
* Returns {@code true} if {@code type} is one of the nine primitive-wrapper types, such as
* {@link Integer}.
*
* @see Class#isPrimitive
*/
public static boolean isWrapperType(Type type) {
return WRAPPER_TO_PRIMITIVE_TYPE.containsKey(Preconditions.checkNotNull(type));
}
/**
* Returns the corresponding wrapper type of {@code type} if it is a primitive type; otherwise
* returns {@code type} itself. Idempotent.
*
* <pre>
* wrap(int.class) == Integer.class
* wrap(Integer.class) == Integer.class
* wrap(String.class) == String.class
* </pre>
*/
public static <T> Class<T> wrap(Class<T> type) {
// cast is safe: long.class and Long.class are both of type Class<Long>
@SuppressWarnings("unchecked")
Class<T> wrapped = (Class<T>) PRIMITIVE_TO_WRAPPER_TYPE.get(Preconditions.checkNotNull(type));
return (wrapped == null) ? type : wrapped;
}
/**
* Returns the corresponding primitive type of {@code type} if it is a wrapper type; otherwise
* returns {@code type} itself. Idempotent.
*
* <pre>
* unwrap(Integer.class) == int.class
* unwrap(int.class) == int.class
* unwrap(String.class) == String.class
* </pre>
*/
public static <T> Class<T> unwrap(Class<T> type) {
// cast is safe: long.class and Long.class are both of type Class<Long>
@SuppressWarnings("unchecked")
Class<T> unwrapped = (Class<T>) WRAPPER_TO_PRIMITIVE_TYPE.get(Preconditions.checkNotNull(type));
return (unwrapped == null) ? type : unwrapped;
}
}