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The module for FunctionalJ Core.
// ============================================================================
// Copyright (c) 2017-2021 Nawapunth Manusitthipol (NawaMan - http://nawaman.net).
// ----------------------------------------------------------------------------
// MIT License
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
// ============================================================================
package functionalj.ref;
import static java.util.Objects.requireNonNull;
import java.util.Objects;
import java.util.function.BiPredicate;
import java.util.function.Supplier;
import lombok.val;
@FunctionalInterface
public interface RetainChecker {
public static final RetainChecker forever = new Forever();
public static final RetainChecker never = new Never();
public boolean stillValid();
//== Sub classes ==
public static class Forever implements RetainChecker {
@Override
public boolean stillValid() {
return true;
}
@Override
public String toString() {
return "FOREVER";
}
}
public static class Never implements RetainChecker {
@Override
public boolean stillValid() {
return false;
}
@Override
public String toString() {
return "NEVER";
}
}
// Time relative
// Time relative with different first time period
// Time absolute
public static class RefBoolean implements RetainChecker {
private final Ref ref;
public RefBoolean(Ref ref) {
this.ref = (ref != null) ? ref : Ref.ofValue(false);
}
@Override
public boolean stillValid() {
return ref.value();
}
}
public static class SuppliedValueCheck implements RetainChecker {
private final Holder state;
private final Supplier stateSupplier;
private final BiPredicate changeCheck;
private final StateUpdater stateUpdater;
SuppliedValueCheck(
boolean isLocal,
Supplier initialStateSupplier,
Supplier stateSupplier,
BiPredicate changeCheck,
StateUpdater stateUpdater) {
this.state = new Holder<>(isLocal);
val initialState
= (initialStateSupplier != null)
? initialStateSupplier.get()
: stateSupplier.get();
this.state.set(initialState, initialState);
this.stateSupplier = requireNonNull(stateSupplier);
this.changeCheck = (changeCheck != null) ? changeCheck : new WhenNotEqual();
this.stateUpdater = (stateUpdater != null) ? stateUpdater : new UpdateOnChanged();
}
@Override
public final boolean stillValid() {
val newValue = stateSupplier.get();
val oldState = state.get();
val isChanged = isChanged(newValue, oldState);
val newState = newState(isChanged, oldState, newValue);
state.set(oldState, newState);
return !isChanged;
}
protected boolean isChanged(STATE newState, STATE oldState) {
return changeCheck.test(oldState, newState);
}
protected STATE newState(boolean isChanged, STATE oldState, STATE newValue) {
return stateUpdater.getNewState(isChanged, oldState, newValue);
}
@Override
public String toString() {
return "SuppliedValueCheck ["
+ "state=" + state + ", "
+ "stateSupplier=" + stateSupplier + ", "
+ "changeCheck=" + changeCheck + ", "
+ "stateUpdater=" + stateUpdater
+ "]";
}
}
//== Aux classes ==
public static class WhenNotSame implements BiPredicate {
@Override
public boolean test(S oldState, S newState) {
return oldState != newState;
}
@Override
public String toString() {
return "WHEN_NOT_SAME";
}
}
public static class WhenNotEqual implements BiPredicate {
@Override
public boolean test(S oldState, S newState) {
return !Objects.equals(oldState, newState);
}
@Override
public String toString() {
return "WHEN_NOT_EQUAL";
}
}
@FunctionalInterface
public static interface StateUpdater {
public S getNewState(boolean isChanged, S oldState, S newValue);
}
public static class UpdateOnChanged implements StateUpdater {
@Override
public S getNewState(boolean isChanged, S oldState, S newValue) {
return isChanged ? newValue : oldState;
}
@Override
public String toString() {
return "WHEN_CHANGE";
}
}
public static class UpdateAlways implements StateUpdater {
@Override
public S getNewState(boolean isChanged, S oldState, S newValue) {
return newValue;
}
@Override
public String toString() {
return "ALWAYS";
}
}
public static class UpdateNever implements StateUpdater {
@Override
public S getNewState(boolean isChanged, S oldState, S newValue) {
return oldState;
}
@Override
public String toString() {
return "NEVER";
}
}
}