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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package com.sun.javafx.binding;

import java.util.Objects;
import java.util.function.Function;

import javafx.beans.value.ObservableValue;
import javafx.util.Subscription;

public class MappedBinding extends LazyObjectBinding {

    private final ObservableValue source;
    private final Function mapper;

    public MappedBinding(ObservableValue source, Function mapper) {
        this.source = Objects.requireNonNull(source, "source cannot be null");
        this.mapper = Objects.requireNonNull(mapper, "mapper cannot be null");
    }

    @Override
    protected T computeValue() {
        S value = source.getValue();

        return value == null ? null : mapper.apply(value);
    }

    @Override
    protected Subscription observeSources() {
        return source.subscribe(this::invalidate); // start observing source
    }
}