/*
* Copyright 2010-2016 JetBrains s.r.o.
*
* 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 org.jetbrains.kotlin.resolve.calls.smartcasts;
import org.jetbrains.annotations.
NotNull;
public enum
Nullability {
NULL(true, false),
NOT_NULL(false, true),
UNKNOWN(true, true),
IMPOSSIBLE(false, false);
@
NotNull
public static
Nullability fromFlags(boolean
canBeNull, boolean
canBeNonNull) {
if (!
canBeNull && !
canBeNonNull) return
IMPOSSIBLE;
if (!
canBeNull &&
canBeNonNull) return
NOT_NULL;
if (
canBeNull && !
canBeNonNull) return
NULL;
return
UNKNOWN;
}
private final boolean
canBeNull;
private final boolean
canBeNonNull;
Nullability(boolean
canBeNull, boolean
canBeNonNull) {
this.
canBeNull =
canBeNull;
this.
canBeNonNull =
canBeNonNull;
}
public boolean
canBeNull() {
return
canBeNull;
}
public boolean
canBeNonNull() {
return
canBeNonNull;
}
@
NotNull
public
Nullability refine(@
NotNull Nullability other) {
switch (this) {
case
UNKNOWN:
return
other;
case
IMPOSSIBLE:
return
other;
case
NULL:
switch (
other) {
case
NOT_NULL: return
NOT_NULL;
default: return
NULL;
}
case
NOT_NULL:
switch (
other) {
case
NULL: return
NOT_NULL;
default: return
NOT_NULL;
}
}
throw new
IllegalStateException();
}
@
NotNull
public
Nullability invert() {
switch (this) {
case
NULL:
return
NOT_NULL;
case
NOT_NULL:
return
UNKNOWN;
case
UNKNOWN:
return
UNKNOWN;
case
IMPOSSIBLE:
return
UNKNOWN;
}
throw new
IllegalStateException();
}
@
NotNull
public
Nullability and(@
NotNull Nullability other) {
return
fromFlags(this.
canBeNull &&
other.
canBeNull, this.
canBeNonNull &&
other.
canBeNonNull);
}
@
NotNull
public
Nullability or(@
NotNull Nullability other) {
return
fromFlags(this.
canBeNull ||
other.
canBeNull, this.
canBeNonNull ||
other.
canBeNonNull);
}
}