package org.jdbi.v3.core.collector;
import java.util.function.Function;
import java.util.function.Supplier;
class OptionalBuilder<T, O> {
private final Supplier<O> empty;
private final Function<T, O> factory;
boolean set;
T value;
OptionalBuilder(Supplier<O> empty, Function<T, O> factory) {
this.empty = empty;
this.factory = factory;
}
void set(T value) {
if (set) {
throw tooManyValues(this.value, value);
}
this.value = value;
this.set = true;
}
O build() {
return value == null ? empty.get() : factory.apply(value);
}
static <T, OPT_T> OptionalBuilder<T, OPT_T> combine(OptionalBuilder<T, OPT_T> left, OptionalBuilder<T, OPT_T> right) {
if (left.set && right.set) {
throw tooManyValues(left.value, right.value);
}
return left.set ? left : right;
}
private static <T> IllegalStateException tooManyValues(T first, T second) {
return new IllegalStateException(
String.format("Multiple values for optional: [%s, %s, ...]",
stringify(first),
stringify(second)));
}
private static String stringify(Object value) {
return value == null ? null : "'" + value + "'";
}
}