src/main/java/software/kes/enhancediterables/FiniteIterable.java
package software.kes.enhancediterables;
import com.jnape.palatable.lambda.adt.Maybe;
import com.jnape.palatable.lambda.adt.coproduct.CoProduct2;
import com.jnape.palatable.lambda.adt.hlist.Tuple2;
import com.jnape.palatable.lambda.functions.Fn1;
import com.jnape.palatable.lambda.functions.Fn2;
import com.jnape.palatable.lambda.functions.builtin.fn1.Inits;
import com.jnape.palatable.lambda.functions.builtin.fn1.Reverse;
import com.jnape.palatable.lambda.functions.builtin.fn1.Tails;
import com.jnape.palatable.lambda.functions.builtin.fn2.CartesianProduct;
import com.jnape.palatable.lambda.functions.builtin.fn2.Cons;
import com.jnape.palatable.lambda.functions.builtin.fn2.Drop;
import com.jnape.palatable.lambda.functions.builtin.fn2.DropWhile;
import com.jnape.palatable.lambda.functions.builtin.fn2.Filter;
import com.jnape.palatable.lambda.functions.builtin.fn2.Intersperse;
import com.jnape.palatable.lambda.functions.builtin.fn2.MagnetizeBy;
import com.jnape.palatable.lambda.functions.builtin.fn2.Map;
import com.jnape.palatable.lambda.functions.builtin.fn2.Partition;
import com.jnape.palatable.lambda.functions.builtin.fn2.PrependAll;
import com.jnape.palatable.lambda.functions.builtin.fn2.Slide;
import com.jnape.palatable.lambda.functions.builtin.fn2.Snoc;
import com.jnape.palatable.lambda.functions.builtin.fn2.Span;
import com.jnape.palatable.lambda.functions.builtin.fn2.TakeWhile;
import com.jnape.palatable.lambda.functions.builtin.fn3.FoldLeft;
import com.jnape.palatable.lambda.functions.builtin.fn3.FoldRight;
import com.jnape.palatable.lambda.functions.builtin.fn3.ZipWith;
import com.jnape.palatable.lambda.functor.builtin.Lazy;
import com.jnape.palatable.lambda.monoid.builtin.Concat;
import java.util.Collection;
import static com.jnape.palatable.lambda.adt.Maybe.just;
import static com.jnape.palatable.lambda.adt.hlist.HList.tuple;
import static java.util.Objects.requireNonNull;
import static software.kes.enhancediterables.EnhancedIterable.enhance;
import static software.kes.enhancediterables.Wrapped.unwrap;
/**
* An {@code EnhancedIterable} that is finite.
*
* @param <A> the element type
*/
public interface FiniteIterable<A> extends EnhancedIterable<A> {
/**
* Lazily appends an element to the end of this {@code FiniteIterable}, yielding a new {@code NonEmptyFiniteIterable}.
*
* @param element the element to append
* @return a {@code NonEmptyFiniteIterable<A>}
*/
@Override
default NonEmptyFiniteIterable<A> append(A element) {
return EnhancedIterables.unsafeNonEmptyFiniteIterable(Snoc.snoc(element, unwrap(this)));
}
/**
* Lazily concatenates another {@code FiniteIterable} to the end of this {@code FiniteIterable},
* yielding a new {@code FiniteIterable}.
*
* @param other the other {@link FiniteIterable}
* @return a {@code FiniteIterable<A>}
*/
default FiniteIterable<A> concat(FiniteIterable<A> other) {
requireNonNull(other);
return EnhancedIterables.finiteIterable(Concat.concat(unwrap(this), unwrap(other)));
}
/**
* Lazily concatenates a {@code Collection} to the end of this {@code FiniteIterable},
* yielding a new {@code FiniteIterable}.
*
* @param other a {@link Collection}
* @return a {@code FiniteIterable<A>}
*/
default FiniteIterable<A> concat(Collection<A> other) {
requireNonNull(other);
return EnhancedIterables.finiteIterable(Concat.concat(unwrap(this), unwrap(other)));
}
/**
* Lazily concatenates a {@code NonEmptyFiniteIterable} to the end of this {@code FiniteIterable},
* yielding a new {@code NonEmptyFiniteIterable}.
*
* @param other a {@link NonEmptyFiniteIterable}
* @return a {@code NonEmptyFiniteIterable<A>}
*/
default NonEmptyFiniteIterable<A> concat(NonEmptyFiniteIterable<A> other) {
requireNonNull(other);
return EnhancedIterables.unsafeNonEmptyFiniteIterable(Concat.concat(unwrap(this), unwrap(other)));
}
/**
* Returns the lazily computed cartesian product of this {@code FiniteIterable} with another {@code FiniteIterable}.
*
* @param other a {@code FiniteIterable} of any type
* @param <B> the type of the other {@code FiniteIterable}
* @return a {@code FiniteIterable<Tuple2<A, B>>}
*/
default <B> FiniteIterable<Tuple2<A, B>> cross(FiniteIterable<B> other) {
requireNonNull(other);
return EnhancedIterables.finiteIterable(CartesianProduct.cartesianProduct(unwrap(this), unwrap(other)));
}
/**
* Returns the lazily computed cartesian product of this {@code FiniteIterable} with a {@code Collection}.
*
* @param other a {@link Collection} of any type
* @param <B> the type of the other {@code Collection}
* @return a {@code FiniteIterable<Tuple2<A, B>>}
*/
default <B> FiniteIterable<Tuple2<A, B>> cross(Collection<B> other) {
requireNonNull(other);
return EnhancedIterables.finiteIterable(CartesianProduct.cartesianProduct(unwrap(this), unwrap(other)));
}
/**
* Returns an infinite {@code EnhancedIterable} that repeatedly cycles this {@code FiniteIterable}'s elements,
* in order.
*
* @return an {@code EnhancedIterable<A>}
*/
default EnhancedIterable<A> cycle() {
return EnhancedIterables.cycle(this);
}
/**
* Returns a {@code FiniteIterable} of the distinct values from this {@link FiniteIterable}.
*
* @return a {@code FiniteIterable<A>}
*/
default FiniteIterable<A> distinct() {
return EnhancedIterables.distinct(this);
}
/**
* Returns a new {@code FiniteIterable} that drops the first {@code count} elements of this {@code FiniteIterable}.
*
* @param count the number of elements to drop from this {@code FiniteIterable}.
* Must be >= 0.
* May exceed size of this {@code FiniteIterable}, in which case, the result will be an
* empty {@code FiniteIterable}.
* @return a {@code FiniteIterable<A>}
*/
@Override
default FiniteIterable<A> drop(int count) {
Validation.validateDrop(count);
return EnhancedIterables.finiteIterable(Drop.drop(count, unwrap(this)));
}
/**
* Returns a new {@code FiniteIterable} that skips the first contiguous group of elements of this
* {@code FiniteIterable} that satisfy a predicate.
* <p>
* Iteration begins at the first element for which the predicate evaluates to false.
*
* @param predicate a predicate; should be referentially transparent and not have side-effects
* @return a {@code FiniteIterable<A>}
*/
@Override
default FiniteIterable<A> dropWhile(Fn1<? super A, ? extends Boolean> predicate) {
requireNonNull(predicate);
return EnhancedIterables.finiteIterable(DropWhile.dropWhile(predicate, unwrap(this)));
}
/**
* Returns a new {@code FiniteIterable} that contains all elements of this {@code FiniteIterable}
* that satisfy a predicate.
*
* @param predicate a predicate; should be referentially transparent and not have side-effects
* @return a {@code FiniteIterable<A>}
*/
@Override
default FiniteIterable<A> filter(Fn1<? super A, ? extends Boolean> predicate) {
requireNonNull(predicate);
return EnhancedIterables.finiteIterable(Filter.<A>filter(predicate).apply(unwrap(this)));
}
/**
* Returns a new {@code FiniteIterable} by applying a function to all elements of this {@code FiniteIterable}.
*
* @param f a function from {@code A} to {@code B}.
* This function should be referentially transparent and not perform side-effects.
* It may be called zero or more times for each element.
* @param <B> the type returned by {@code f}
* @return a {@code FiniteIterableonEmptyFiniteIterable<B>}
*/
@Override
default <B> FiniteIterable<B> fmap(Fn1<? super A, ? extends B> f) {
requireNonNull(f);
return EnhancedIterables.finiteIterable(Map.map(f, unwrap(this)));
}
/**
* Applies a binary operator to a start value and all elements of this {@code FiniteIterable}, going left to right.
*
* @param z the start value
* @param op the binary operator
* @param <B> the result type of the binary operator
* @return the result of inserting {@code op} between consecutive elements of this {@code FiniteIterable},
* going left to right with the start value {@code z} on the left:
* <code>
* op(...op(z, x_1), x_2, ..., x_n)
* </code>
* where <code>x,,1,,, ..., x,,n,,</code> are the elements of this {@code FiniteIterable}
* Returns {@code z} if this {@code FiniteIterable} is empty.
*/
default <B> B foldLeft(Fn2<? super B, ? super A, ? extends B> op, B z) {
requireNonNull(op);
return FoldLeft.<A, B>foldLeft(op, z).apply(unwrap(this));
}
/**
* Applies a binary operator to a start value and all elements of this {@code FiniteIterable}, going right to left.
* <p>
* This method is computationally the iterative inverse of {@link FiniteIterable#foldLeft}, but uses {@code Lazy} to support stack-safe
* execution.
*
* @param z the start value
* @param op the binary operator
* @param <B> the result type of the binary operator
* @return a {@code Lazy<B>} that evaluates to the result of inserting {@code op} between consecutive elements of
* this {@code FiniteIterable}, going right to left with the start value {@code z} on the right:
* <code>
* op(x_1, op(x_2, ... op(x_n, z)...))
* </code>
* where <code>x,,1,,, ..., x,,n,,</code> are the elements of this {@code FiniteIterable}
* Returns {@code z} if this {@code FiniteIterable} is empty.
*/
default <B> Lazy<B> foldRight(Fn2<? super A, ? super Lazy<B>, ? extends Lazy<B>> op, Lazy<B> z) {
requireNonNull(op);
return FoldRight.<A, B>foldRight(op, z).apply(unwrap(this));
}
/**
* Returns a {@code ImmutableNonEmptyIterable} containing all of the subsequences of initial
* elements of this {@code FiniteIterable}, ordered by size, starting with the empty list.
* Example:
*
* <code>FiniteIterable.of(1, 2, 3).inits(); // [[], [1], [1, 2], [1, 2, 3]]</code>
*
* @return a {@code ImmutableNonEmptyFiniteIterable<FiniteIterable<A>>}
*/
default ImmutableNonEmptyFiniteIterable<? extends FiniteIterable<A>> inits() {
return EnhancedIterables.unsafeImmutableNonEmptyFiniteIterable(Map.map(EnhancedIterables::finiteIterable, Inits.inits(unwrap(this))));
}
/**
* Returns a new {@code FiniteIterable} with the provided separator value injected between each value of this
* {@code FiniteIterable}.
* <p>
* If this {@code FiniteIterable} contains fewer than two elements, it is left untouched.
*
* @param separator the separator value
* @return a {@code FiniteIterable<A>}
*/
@Override
default FiniteIterable<A> intersperse(A separator) {
return EnhancedIterables.finiteIterable(Intersperse.intersperse(separator, unwrap(this)));
}
/**
* Returns an {@code Iterable} of contiguous groups of elements in this {@code FiniteIterable} that match a
* predicate pairwise.
*
* @param predicate the predicate function.
* This function should be referentially transparent and not perform side-effects.
* It may be called zero or more times for each element.
* @return a {@code FiniteIterable<NonEmptyFiniteIterable<A>>} containing the contiguous groups
*/
@Override
default FiniteIterable<? extends NonEmptyFiniteIterable<A>> magnetizeBy(Fn2<A, A, Boolean> predicate) {
requireNonNull(predicate);
return EnhancedIterables.finiteIterable(MagnetizeBy.magnetizeBy(predicate, unwrap(this)))
.fmap(EnhancedIterables::unsafeNonEmptyFiniteIterable);
}
/**
* Partitions this {@code FiniteIterable} given a disjoint mapping function.
*
* @param function the mapping function
* @param <B> the output left Iterable element type, as well as the CoProduct2 A type
* @param <C> the output right Iterable element type, as well as the CoProduct2 B type
* @return a {@code Tuple2<FiniteIterable<B>, FiniteIterable<C>>}
*/
@Override
default <B, C> Tuple2<? extends FiniteIterable<B>, ? extends FiniteIterable<C>> partition(
Fn1<? super A, ? extends CoProduct2<B, C, ?>> function) {
requireNonNull(function);
Tuple2<Iterable<B>, Iterable<C>> partitionResult = Partition.partition(function, unwrap(this));
return tuple(EnhancedIterables.finiteIterable(partitionResult._1()),
EnhancedIterables.finiteIterable(partitionResult._2()));
}
/**
* Lazily prepends an element to the front of this {@code FiniteIterable}, yielding a new {@code NonEmptyFiniteIterable}.
*
* @param element the element to prepend
* @return a {@code NonEmptyFiniteIterable<A>}
*/
@Override
default NonEmptyFiniteIterable<A> prepend(A element) {
return EnhancedIterables.unsafeNonEmptyFiniteIterable(Cons.cons(element, unwrap(this)));
}
/**
* Returns a new {@code FiniteIterable} with the provided separator value injected before each value of this
* {@code FiniteIterable}.
* <p>
* If this {@code FiniteIterable} is empty, it is left untouched.
*
* @param separator the separator value
* @return a {@code FiniteIterable<A>}
*/
@Override
default FiniteIterable<A> prependAll(A separator) {
return EnhancedIterables.finiteIterable(PrependAll.prependAll(separator, unwrap(this)));
}
/**
* Returns a reversed representation of this {@code FiniteIterable}.
* <p>
* Note that reversing is deferred until the returned {@code Iterable} is iterated.
*
* @return a {@code FiniteIterable<A>}
*/
default FiniteIterable<A> reverse() {
return EnhancedIterables.finiteIterable(Reverse.reverse(unwrap(this)));
}
/**
* Returns the number of elements in this {@code FiniteIterable}.
* <p>
* If this {@code FiniteIterable} contains more than <code>Integer.MAX_VALUE</code> elements, returns
* <code>Integer.MAX_VALUE</code>.
*
* @return the number of elements in this {@code FiniteIterable}
*/
default int size() {
return EnhancedIterables.size(this);
}
/**
* "Slides" a window of {@code k} elements across the {@code FiniteIterable} by one element at a time.
* <p>
* Example:
*
* <code>FiniteIterable.of(1, 2, 3, 4, 5).slide(2); // [[1, 2], [2, 3], [3, 4], [4, 5]]</code>
*
* @param k the number of elements in the sliding window. Must be >= 1.
* @return a {@code FiniteIterable<NonEmptyFiniteIterable<A>>}
*/
@Override
default FiniteIterable<? extends NonEmptyFiniteIterable<A>> slide(int k) {
Validation.validateSlide(k);
return EnhancedIterables.finiteIterable(Map.map(EnhancedIterables::unsafeNonEmptyFiniteIterable,
Slide.slide(k, unwrap(this))));
}
/**
* Returns a {@code Tuple2} where the first slot is the front contiguous elements of this
* {@code FiniteIterable} matching a predicate and the second slot is all the remaining elements.
*
* @param predicate a predicate; should be referentially transparent and not have side-effects
* @return a {@code Tuple2<FiniteIterable<B>, FiniteIterable<C>>}
*/
@Override
default Tuple2<? extends FiniteIterable<A>, ? extends FiniteIterable<A>> span(Fn1<? super A, ? extends Boolean> predicate) {
requireNonNull(predicate);
Tuple2<Iterable<A>, Iterable<A>> spanResult = Span.<A>span(predicate).apply(unwrap(this));
return tuple(EnhancedIterables.finiteIterable(spanResult._1()),
EnhancedIterables.finiteIterable(spanResult._2()));
}
/**
* Returns an {@code ImmutableNonEmptyIterable} containing all of the subsequences of tail
* elements of this {@code FiniteIterable}, ordered by size, starting with the full list.
* Example:
*
* <code>FiniteIterable.of(1, 2, 3).tails(); // [[1, 2, 3], [2, 3], [3], []]</code>
*
* @return an {@code ImmutableNonEmptyIterable<FiniteIterable<A>>}
*/
@Override
default ImmutableNonEmptyIterable<? extends FiniteIterable<A>> tails() {
return EnhancedIterables.unsafeImmutableNonEmptyIterable(Map.map(EnhancedIterables::finiteIterable, Tails.tails(unwrap(this))));
}
/**
* Returns a new {@code FiniteIterable} that limits to the first contiguous group of elements of this
* {@code FiniteIterable} that satisfy a predicate.
* <p>
* Iteration ends at, but does not include, the first element for which the predicate evaluates to false.
*
* @param predicate a predicate; should be referentially transparent and not have side-effects
* @return a {@code FiniteIterable<A>}
*/
@Override
default FiniteIterable<A> takeWhile(Fn1<? super A, ? extends Boolean> predicate) {
requireNonNull(predicate);
return EnhancedIterables.finiteIterable(TakeWhile.takeWhile(predicate, unwrap(this)));
}
/**
* Always succeeds because {@code FiniteIterable}s are always finite.
*
* @return this {@code FiniteIterable} wrapped in a `just`
*/
@Override
default Maybe<? extends FiniteIterable<A>> toFinite() {
return just(this);
}
/**
* Converts this {@code FiniteIterable} to a {@code NonEmptyFiniteIterable} if it contains
* one or more elements.
*
* @return a {@code Maybe<NonEmptyFiniteIterable<A>}
*/
@Override
default Maybe<? extends NonEmptyFiniteIterable<A>> toNonEmpty() {
return EnhancedIterables.maybeNonEmpty(this)
.fmap(EnhancedIterables::unsafeNonEmptyFiniteIterable);
}
/**
* Zips together this {@code FiniteIterable} with another {@code Iterable} by applying a zipping function.
* <p>
* Applies the function to the successive elements of each {@code Iterable} until one of them runs out of elements.
*
* @param fn the zipping function.
* Not null.
* This function should be referentially transparent and not perform side-effects.
* It may be called zero or more times for each element.
* @param other the other {@code Iterable}
* @param <B> the element type of the other {@code Iterable}
* @param <C> the element type of the result
* @return an {@code FiniteIterable<C>}
*/
default <B, C> FiniteIterable<C> zipWith(Fn2<A, B, C> fn, Iterable<B> other) {
requireNonNull(fn);
requireNonNull(other);
return EnhancedIterables.finiteIterable(ZipWith.zipWith(fn, unwrap(this), unwrap(other)));
}
/**
* Creates an {@code ImmutableFiniteIterable} by copying elements from a {@code FiniteIterable}.
* <p>
* If {@code source} is already an {@code ImmutableFiniteIterable}, this method will return it without copying.
*
* @param source the source to copy from
* @param <A> the element type
* @return an {@code ImmutableFiniteIterable<A>}
*/
static <A> ImmutableFiniteIterable<A> copyFrom(FiniteIterable<A> source) {
return EnhancedIterables.copyFrom(source);
}
/**
* Creates an {@code ImmutableFiniteIterable} by copying elements from a {@code Collection}.
*
* @param source the source to copy from
* @param <A> the element type
* @return an {@code ImmutableFiniteIterable<A>}
*/
static <A> ImmutableFiniteIterable<A> copyFrom(Collection<A> source) {
return EnhancedIterables.copyFrom(source);
}
/**
* Creates an {@code ImmutableFiniteIterable} by copying elements from an {@code Iterable}.
* <p>
* If {@code source} is already an {@code ImmutableIterable}, no copying will be performed.
*
* @param maxCount the maximum number of elements to take from the supplied {@link Iterable}.
* Must be >= 0.
* May exceed size of the {@code Iterable}, in which case, the result will contain
* as many elements available.
* @param source the source to copy from
* @param <A> the element type
* @return an {@code ImmutableFiniteIterable<A>}
*/
static <A> ImmutableFiniteIterable<A> copyFrom(int maxCount, Iterable<A> source) {
return EnhancedIterables.copyFrom(maxCount, source);
}
/**
* Creates an empty {@code FiniteIterable}.
*
* @param <A> the element type
* @return an {@code ImmutableFiniteIterable<A>}
*/
static <A> ImmutableFiniteIterable<A> emptyFiniteIterable() {
return EnhancedIterables.emptyEnhancedIterable();
}
/**
* Creates a {@code FiniteIterable} by wrapping a {@code Collection}.
* <p>
* Does not make a copy of the {@link Collection}.
*
* @param collection the source {@code Collection}
* @param <A> the element type
* @return a {@code FiniteIterable<A>}
*/
static <A> FiniteIterable<A> finiteIterable(Collection<A> collection) {
requireNonNull(collection);
return EnhancedIterables.finiteIterable(collection);
}
/**
* Creates a {@code FiniteIterable} by wrapping an {@code Iterable}.
*
* @param maxCount the maximum number of elements to take from the supplied {@link Iterable}.
* Must be >= 0.
* May exceed size of the {@code Iterable}, in which case, the result will contain
* as many elements available.
* @param iterable the source {@code Iterable}
* @param <A> the element type
* @return a {@code FiniteIterable<A>}
*/
static <A> FiniteIterable<A> finiteIterable(int maxCount, Iterable<A> iterable) {
return enhance(iterable).take(maxCount);
}
/**
* Creates a {@code FiniteIterable} containing the given elements.
* <p>
* Note that this method actually returns an {@link ImmutableNonEmptyFiniteIterable}, which is
* also a {@link FiniteIterable}.
*
* @param first the first element
* @param more the remaining elements
* @param <A> the element type
* @return an {@code ImmutableNonEmptyFiniteIterable<A>}
*/
@SuppressWarnings("varargs")
@SafeVarargs
static <A> ImmutableNonEmptyFiniteIterable<A> of(A first, A... more) {
if (more.length > 0) {
return EnhancedIterables.of(first, more);
} else {
return EnhancedIterables.singleton(first);
}
}
}