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package bjc.utils.funcutils;
import java.util.function.BiFunction;
import java.util.function.BiPredicate;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.UnaryOperator;
/**
* Utility things for functions.
*
* @author ben
*/
public class FuncUtils {
/**
* Convert a binary function into a unary function that returns a function.
*
* @param <A>
* The initial type of the function.
*
* @param <B>
* The intermediate type of the function.
*
* @param <C>
* The terminal type of the function.
*
* @param func
* The function to transform.
*
* @return The function transformed into a unary function returning a function.
*/
public static <A, B, C> Function<A, Function<B, C>> curry2(
final BiFunction<A, B, C> func)
{
return arg1 ->
arg2 ->
func.apply(arg1, arg2);
}
/**
* Do the specified action the specified number of times.
*
* @param nTimes
* The number of times to do the action.
*
* @param cons
* The action to perform.
*/
public static void doTimes(
final int nTimes,
final Consumer<Integer> cons)
{
for (int i = 0; i < nTimes; i++) cons.accept(i);
}
/**
* Return an operator that executes until it converges.
*
* @param <T> The type the operator is on.
*
* @param op
* The operator to execute.
*
* @param maxTries
* The maximum amount of times to apply the function in an
* attempt to cause it to converge.
*
* @return The requested operator.
*/
public static <T> UnaryOperator<T> converge(final UnaryOperator<T> op,
final int maxTries)
{
return converge(op, Object::equals, maxTries);
}
/**
* Return an operator that executes until it converges.
*
* @param <T> The type the operator is on.
*
* @param op
* The operator to execute.
* @param converged
* The predicate to execute to check if the function has
* converged.
*
* @param maxTries
* The maximum amount of times to apply the function in an
* attempt to cause it to converge.
*
* @return The requested operator.
*/
public static <T> UnaryOperator<T> converge(
final UnaryOperator<T> op,
final BiPredicate<T, T> converged,
final int maxTries)
{
return val -> {
T newVal = op.apply(val);
T oldVal = newVal;
int tries = 0;
do {
oldVal = newVal;
newVal = op.apply(newVal);
tries += 1;
} while (!converged.test(newVal, oldVal) && tries < maxTries);
return newVal;
};
}
}
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