src/main/java/org/shedlang/compiler/util/Lazy.java


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package org.shedlang.compiler.util;

import java.util.Optional;
import java.util.function.Supplier;

public class Lazy<T> {
    public static <T> Lazy<T> of(Supplier<T> supplier) {
        return new Lazy<>(supplier);
    }

    private final Supplier<T> supplier;
    private Optional<T> value;

    private Lazy(Supplier<T> supplier) {
        this.supplier = supplier;
        this.value = Optional.empty();
    }

    public T get() {
        if (this.value.isEmpty()) {
            this.value = Optional.of(this.supplier.get());
        }

        return this.value.get();
    }
}