/**
* Converts theory to one about a different type using the given function retaining all precursor
* values
*
* @param <N> type to convert to
* @param mapping Function from type T to type N
* @return a Subject2 relating to the state of a theory involving two values
*/
public <N> Subject2<P, N> asWithPrecursor(Function<T, N> mapping) {
Generator<Pair<P, N>> g =
(prng, step) -> {
P p = this.ps.next(prng, step);
T t = this.conversion.apply(p);
return Pair.of(p, mapping.apply(t));
};
Shrink<Pair<P, N>> s =
(original, context) ->
ps.shrink(original._1, context)
.map(p -> Pair.of(p, conversion.andThen(mapping).apply(p)));
Source<Pair<P, N>> gen = Source.of(g).withShrinker(s);
return new PrecursorTheoryBuilder1<P, N>(state, gen, assumptions);
}
private <N> Generator<Pair<P, T>> generatorFunction() {
return (prng, step) -> {
P p = ps.next(prng, step);
return Pair.of(p, conversion.apply(p));
};
}
private <N> Shrink<Pair<P, T>> shrinker() {
return (pair, context) ->
ps.shrink(pair._1, context).map(pre -> Pair.of(pre, conversion.apply(pre)));
}