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/*
* esodata - data structures and other things, of varying utility
* Copyright 2022, Ben Culkin
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package bjc.functypes;
import java.util.Optional;
import java.util.function.Consumer;
import java.util.function.Function;
/**
* 'Grammar' type used for making certain types of conditional processing read
* easier.
*
* @author bjcul
*
* @param <Input> The input type
* @param <Output> The output type
*/
@FunctionalInterface
public interface ElseFunction<Input, Output> extends Function<Input, Output> {
/**
* Apply the alternative.
*
* Defaults to just applying this function
*
* @param x The input
*
* @return The result of applying the function
*/
public default Output elseApply(Input x) {
return apply(x);
}
/**
* Handle a value present in an optional.
*
* @param <Input> The type contained in the optional.
*
* @param val The optional
*
* @return A function for processing the optional
*/
public static <Input> ElseFunction<Consumer<Input>, ElseFunction<Runnable, Void>> ifPresent(Optional<Input> val) {
return (f) -> (g) -> {
if (val.isPresent())
f.accept(val.get());
else
g.run();
return null;
};
}
/**
* Handle a value not present in an optional.
*
* @param <Input> The type contained in the optional.
*
* @param val The optional
*
* @return A function for processing the optional
*/
public static <Input> ElseFunction<Runnable, ElseFunction<Consumer<Input>, Void>> ifNotPresent(Optional<Input> val) {
return (f) -> (g) -> {
if (val.isPresent())
g.accept(val.get());
else
f.run();
return null;
};
}
}
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