public static MethodHandle identity(Wrapper wrap) {
EnumMap<Wrapper, MethodHandle> cache = CONSTANT_FUNCTIONS[1];
MethodHandle mh = cache.get(wrap);
if (mh != null) {
return mh;
}
// slow path
MethodType type = MethodType.methodType(wrap.primitiveType());
if (wrap != Wrapper.VOID) type = type.appendParameterTypes(wrap.primitiveType());
try {
mh = IMPL_LOOKUP.findStatic(THIS_CLASS, "identity", type);
} catch (ReflectiveOperationException ex) {
mh = null;
}
if (mh == null && wrap == Wrapper.VOID) {
mh = EMPTY; // #(){} : #()void
}
if (mh != null) {
cache.put(wrap, mh);
return mh;
}
if (mh != null) {
cache.put(wrap, mh);
return mh;
}
throw new IllegalArgumentException("cannot find identity for " + wrap);
}
public static MethodHandle convertPrimitive(Wrapper wsrc, Wrapper wdst) {
EnumMap<Wrapper, MethodHandle> cache = CONVERT_PRIMITIVE_FUNCTIONS[wsrc.ordinal()];
MethodHandle mh = cache.get(wdst);
if (mh != null) {
return mh;
}
// slow path
Class<?> src = wsrc.primitiveType();
Class<?> dst = wdst.primitiveType();
MethodType type =
src == void.class ? MethodType.methodType(dst) : MethodType.methodType(dst, src);
if (wsrc == wdst) {
mh = identity(src);
} else if (wsrc == Wrapper.VOID) {
mh = zeroConstantFunction(wdst);
} else if (wdst == Wrapper.VOID) {
mh = MethodHandles.dropArguments(EMPTY, 0, src); // Defer back to MethodHandles.
} else if (wsrc == Wrapper.OBJECT) {
mh = unboxCast(dst);
} else if (wdst == Wrapper.OBJECT) {
mh = box(src);
} else {
assert (src.isPrimitive() && dst.isPrimitive());
try {
mh =
IMPL_LOOKUP.findStatic(
THIS_CLASS, src.getSimpleName() + "To" + capitalize(dst.getSimpleName()), type);
} catch (ReflectiveOperationException ex) {
mh = null;
}
}
if (mh != null) {
assert (mh.type() == type) : mh;
cache.put(wdst, mh);
return mh;
}
throw new IllegalArgumentException(
"cannot find primitive conversion function for "
+ src.getSimpleName()
+ " -> "
+ dst.getSimpleName());
}
public static MethodHandle zeroConstantFunction(Wrapper wrap) {
EnumMap<Wrapper, MethodHandle> cache = CONSTANT_FUNCTIONS[0];
MethodHandle mh = cache.get(wrap);
if (mh != null) {
return mh;
}
// slow path
MethodType type = MethodType.methodType(wrap.primitiveType());
switch (wrap) {
case VOID:
mh = EMPTY;
break;
case OBJECT:
case INT:
case LONG:
case FLOAT:
case DOUBLE:
try {
mh = IMPL_LOOKUP.findStatic(THIS_CLASS, "zero" + wrap.wrapperSimpleName(), type);
} catch (ReflectiveOperationException ex) {
mh = null;
}
break;
}
if (mh != null) {
cache.put(wrap, mh);
return mh;
}
// use zeroInt and cast the result
if (wrap.isSubwordOrInt() && wrap != Wrapper.INT) {
mh = MethodHandles.explicitCastArguments(zeroConstantFunction(Wrapper.INT), type);
cache.put(wrap, mh);
return mh;
}
throw new IllegalArgumentException("cannot find zero constant for " + wrap);
}
private static MethodType boxType(Wrapper wrap) {
// be exact, since return casts are hard to compose
Class<?> boxType = wrap.wrapperType();
return MethodType.methodType(boxType, wrap.primitiveType());
}
private static MethodType unboxType(Wrapper wrap) {
return MethodType.methodType(wrap.primitiveType(), Object.class, boolean.class);
}