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package bjc.dicelang.neodice;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;
import bjc.esodata.*;
/**
* Represents a single polyhedral die.
* @author Ben Culkin
*
* @param <SideType> The type of value represented by this die.
*
*/
@FunctionalInterface
public interface Die<SideType> {
/**
* Rolls this die.
*
* @param rng The source for random numbers
*
* @return The result of rolling the die.
*/
public SideType roll(Random rng);
/**
* Returns a die pool which rolls this die the specified number of times.
*
* @param numTimes The number of times to roll this die.
*
* @return A die pool that rolls this die the specified number of times.
*/
default DiePool<SideType> times(int numTimes) {
return new ExpandDiePool<>(this, (die, rng) -> {
return Stream.generate(() -> die.roll(rng))
.limit(numTimes);
});
};
/**
* Returns a die which will reroll this die as long as the provided condition is true.
*
* @param comparer The thing to use to compare die values.
* @param condition The condition to reroll the die on.
*
* @return A die that rerolls when the given condition is met.
*/
default Die<SideType> reroll(
Comparator<SideType> comparer,
Predicate<SideType> condition) {
return RerollDie.create(comparer, this, condition,
(list) -> list.get(list.size()));
}
/**
* Returns a die which will reroll this die up to a specified number of times,
* as long as the provided condition is true.
*
* @param comparer The thing to use to compare die values.
* @param condition The condition to reroll the die on.
* @param limit The maximum number of times to reroll the die.
*
* @return A die that rerolls when the given condition is met.
*/
default Die<SideType> reroll(
Comparator<SideType> comparer,
Predicate<SideType> condition,
int limit) {
return RerollDie.create(comparer, this, condition,
(list) -> list.get(list.size()), limit);
}
/**
* Create an stream which gives rolls of this dice.
*
* @param rng The source for random numbers.
*
* @return An iterator which gives rolls of this dice.
*/
default Stream<SideType> stream(Random rng) {
return Stream.generate(() -> this.roll(rng));
}
/**
* Create a new transforming die.
*
* @param <NewType> The new type of the die.
*
* @param mapper The function to use for mapping.
*
* @return A die that transforms with the given mapping.
*/
default <NewType> Die<NewType> transform(Function<SideType, NewType> mapper) {
return (rng) -> mapper.apply(this.roll(rng));
}
/**
* Create a simple polyhedral die with a fixed number of sides.
*
* @param sides The number of sides for the die.
*
* @return A die which returns a result from 1 to sides.
*/
static Die<Integer> polyhedral(int sides) {
return new PolyhedralDie(sides);
}
}
class PolyhedralDie implements Die<Integer> {
private final int sides;
public PolyhedralDie(int sides) {
this.sides = sides;
}
@Override
public Integer roll(Random rng) {
// Dice are one-based, not zero-based.
return rng.nextInt(sides) + 1;
}
@Override
public String toString() {
return String.format("d%d", sides);
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + sides;
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj == null) return false;
if (getClass() != obj.getClass()) return false;
PolyhedralDie other = (PolyhedralDie) obj;
if (sides != other.sides) return false;
else return true;
}
}
class RerollDie<SideType> implements Die<SideType> {
private final Die<SideType> contained;
private final Predicate<SideType> condition;
private final Function<MinMaxList<SideType>, SideType> chooser;
private final Comparator<SideType> comparer;
private int limit = Integer.MAX_VALUE;
private RerollDie(
Comparator<SideType> comparer,
Die<SideType> contained,
Predicate<SideType> condition,
Function<MinMaxList<SideType>, SideType> chooser) {
this.comparer = comparer;
this.contained = contained;
this.condition = condition;
this.chooser = chooser;
}
private RerollDie(
Comparator<SideType> comparer,
Die<SideType> contained,
Predicate<SideType> condition,
Function<MinMaxList<SideType>, SideType> chooser,
int limit) {
this(comparer, contained, condition, chooser);
this.limit = limit;
}
@Override
public SideType roll(Random rng) {
SideType roll = contained.roll(rng);
MinMaxList<SideType> newRolls = new MinMaxList<>(comparer, roll);
int rerollCount = 0;
while (condition.test(roll) && rerollCount < limit) {
roll = contained.roll(rng);
newRolls.add(roll);
rerollCount += 1;
}
return chooser.apply(newRolls);
}
public static <Side extends Comparable<Side>> Die<Side> create(
Die<Side> contained,
Predicate<Side> condition,
Function<MinMaxList<Side>, Side> chooser) {
return new RerollDie<>(Comparator.naturalOrder(), contained, condition, chooser);
}
public static <Side extends Comparable<Side>> Die<Side> create(
Die<Side> contained,
Predicate<Side> condition,
Function<MinMaxList<Side>, Side> chooser,
int limit) {
return new RerollDie<>(Comparator.naturalOrder(), contained, condition, chooser, limit);
}
public static <Side> Die<Side> create(
Comparator<Side> comparer,
Die<Side> contained,
Predicate<Side> condition,
Function<MinMaxList<Side>, Side> chooser) {
return new RerollDie<>(comparer, contained, condition, chooser);
}
public static <Side> Die<Side> create(
Comparator<Side> comparer,
Die<Side> contained,
Predicate<Side> condition,
Function<MinMaxList<Side>, Side> chooser,
int limit) {
return new RerollDie<>(comparer, contained, condition, chooser, limit);
}
}
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