diff options
Diffstat (limited to 'src/main/java/bjc/optics')
| -rw-r--r-- | src/main/java/bjc/optics/Lens.java | 68 | ||||
| -rw-r--r-- | src/main/java/bjc/optics/LensX.java | 84 | ||||
| -rw-r--r-- | src/main/java/bjc/optics/Lenses.java | 164 | ||||
| -rw-r--r-- | src/main/java/bjc/optics/MutableLens.java | 46 | ||||
| -rw-r--r-- | src/main/java/bjc/optics/Optic.java | 32 | ||||
| -rw-r--r-- | src/main/java/bjc/optics/PrismX.java | 22 | ||||
| -rw-r--r-- | src/main/java/bjc/optics/impl/package-info.java | 18 | ||||
| -rw-r--r-- | src/main/java/bjc/optics/package-info.java | 21 |
8 files changed, 455 insertions, 0 deletions
diff --git a/src/main/java/bjc/optics/Lens.java b/src/main/java/bjc/optics/Lens.java new file mode 100644 index 0000000..be10eef --- /dev/null +++ b/src/main/java/bjc/optics/Lens.java @@ -0,0 +1,68 @@ +/* + * esodata - data structures and other things, of varying utility + * Copyright 2022, Ben Culkin + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +package bjc.optics; + +import java.util.function.Function; +import java.util.function.UnaryOperator; + +import bjc.typeclasses.BiContainer; + +/** + * A type-invariant var Laarhoven lens. + * + * @author bjcul + * + * @param <Whole> The item this lens can focus on + * @param <Part> The field this lens focuses on + */ +public interface Lens<Whole, Part> extends LensX<Whole, Whole, Part, Part>, BiContainer<Whole, Part, Lens<Whole, Part>> { + /** + * Modify a given whole using an operation + * + * @param source The whole to modify. + * @param mod The operation to use for modifying a part + * + * @return A modified whole + */ + default Whole modify(Whole source, UnaryOperator<Part> mod) { + return set(source, mod.apply(get(source))); + } + + /** + * Create a function which sets the part of a given whole. + * + * @param part The part to set + * + * @return A function that sets the given part on a whole. + */ + default Function<Whole, Whole> setting(Part part) { + return (whole) -> set(whole, part); + } + + /** + * Lift a function that modifies parts to one that modifies wholes. + * + * @param f The function which operates on parts + * + * @return A corresponding function which applies the given modification to a part. + */ + default Function<Whole, Whole> lift(UnaryOperator<Part> f) { + // modify will be more efficient for some lenses + return (whole) -> modify(whole, f); + } +} diff --git a/src/main/java/bjc/optics/LensX.java b/src/main/java/bjc/optics/LensX.java new file mode 100644 index 0000000..d0f83be --- /dev/null +++ b/src/main/java/bjc/optics/LensX.java @@ -0,0 +1,84 @@ +/* + * esodata - data structures and other things, of varying utility + * Copyright 2022, Ben Culkin + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +package bjc.optics; + +import static bjc.optics.Lenses.immutable; + +import java.util.function.BiFunction; +import java.util.function.Function; + +/** + * A type-variant lens + * + * @author Ben Culkin + * + * @param <W1> The first type the lens is used on + * @param <W2> The second 'whole' type + * @param <P1> The first 'part' type + * @param <P2> The second 'part' type + */ +public interface LensX<W1, W2, P1, P2> extends Optic<W1, W2, P1, P2> { + /** + * Retrieve the focused value of this lens. + * + * @param source The item to use the lens on. + * + * @return The value from the given whole this lens focuses on. + */ + P1 get(W1 source); + + /** + * Create an updated version of the item this lens focuses on. + * + * @param source The item to use the lens on. + * @param val The new value. + * + * @return The updated item the lens was used on. + */ + W2 set(W1 source, P2 val); + + /** + * Update the focused value. + * + * NOTE: It will often be more efficient to implement this directly. The + * implementation here is provided for convenience. + * + * @param source The item to use the lens on. + * @param action The action to applied to the focused item. + * + * @return The updated item the lens was used on. + */ + default W2 update(W1 source, Function<P1, P2> action) { + return set(source, action.apply(get(source))); + } + + /** + * Compose two type-variant lenses together. + * + * @param <V1> The first type the second lens focuses on + * @param <V2> The second type the second lens focuses on. + * + * @param other The second lens to use. + * + * @return A lens composed from this one and the given one. + */ + default <V1, V2> LensX<W1, W2, V1, V2> compose(LensX<P1, P2, V1, V2> other) { + return immutable((whole) -> other.get(get(whole)), + (whole, val) -> update(whole, (P1 val2) -> other.set(val2, val))); + } +}
\ No newline at end of file diff --git a/src/main/java/bjc/optics/Lenses.java b/src/main/java/bjc/optics/Lenses.java new file mode 100644 index 0000000..6cebc84 --- /dev/null +++ b/src/main/java/bjc/optics/Lenses.java @@ -0,0 +1,164 @@ +/* + * esodata - data structures and other things, of varying utility + * Copyright 2022, Ben Culkin + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +package bjc.optics; + +import java.util.function.BiConsumer; +import java.util.function.BiFunction; +import java.util.function.Function; + +import bjc.data.Holder; +import bjc.data.Pair; + +/** + * Utility and constructor functions for lenses + * + * @author bjcul + * + */ +public class Lenses { + /** + * Create an immutable lens from a pair of functions. + * + * @param <W1> The first type the lens is used on + * @param <W2> The second type the lens is used on + * @param <P1> The first type the lens focuses on + * @param <P2> The second type the lens focuses on. + * + * @param getter The getter for the lens + * @param setter The setter for the lens + * + * @return The lens composed from the two given functions + */ + public static <W1, W2, P1, P2> LensX<W1, W2, P1, P2> immutable(Function<W1, P1> getter, + BiFunction<W1, P2, W2> setter) { + return new FunctionalLensX<>(getter, setter); + } + + /** + * Create a mutable lens from a pair of functions. + * + * @param <Whole> The type the lens is used on + * @param <Part> The type the lens is focused on + * + * @param getter The getter for the lens + * @param mutator The mutator for the lens + * + * @return The mutable lens composed from the two given functions + */ + public static <Whole, Part> MutableLens<Whole, Part> mutable(Function<Whole, Part> getter, + BiConsumer<Whole, Part> mutator) { + return new FunctionalMutableLens<>(getter, mutator); + } + + /** + * Create a lens that reflects over the value in a holder + * + * @param <Part1> The first type contained in the holder + * @param <Part2> The second type contained in the holder + * + * @return A lens that focuses on the value of a holder + */ + public static <Part1, Part2> LensX<Holder<Part1>, Holder<Part2>, Part1, Part2> holder() { + return immutable((hld) -> hld.getValue(), (hld, val) -> hld.map((vl) -> val)); + } + + /** + * Create a lens for updating tagged pairs. + * + * TODO: Should this be on a Tagged<T, A> class that is isomorphic to pair + * instead? + * + * @param <A> The first data type + * @param <B> The second data type + * @param <T> The tag type + * + * @return A lens that operates on the value of a tagged pair. + */ + public static <A, B, T> LensX<Pair<T, A>, Pair<T, B>, A, B> tagged() { + return immutable((par) -> par.getRight(), (par, val) -> par.mapRight((vl) -> val)); + } + + /** + * Creates a lens which focuses on a piece of internal state. + * + * @param <A> The first state type + * @param <B> The second state type + * + * @param val The initial state value + * + * @return A lens that focuses on the given internal state. + */ + public static <A, B> LensX<?, ?, A, B> state(A val) { + Holder<A> hold = Holder.of(val); + return immutable((whole) -> hold.getValue(), (whole, vl) -> hold.map((arg) -> vl)); + } + + /** + * Creates a lens which focuses on a piece of mutable internal state. + * + * @param <A> The state type + * + * @param val The initial state value + * + * @return A lens that focuses on the given internal state. + */ + public static <A> MutableLens<?, A> stateM(A val) { + Holder<A> hold = Holder.of(val); + return mutable((whole) -> hold.getValue(), (whole, vl) -> hold.replace(vl)); + } +} + +final class FunctionalLensX<W1, W2, P1, P2> implements LensX<W1, W2, P1, P2> { + private final BiFunction<W1, P2, W2> setter; + private final Function<W1, P1> getter; + + FunctionalLensX(Function<W1, P1> getter, BiFunction<W1, P2, W2> setter) { + this.setter = setter; + this.getter = getter; + } + + @Override + public P1 get(W1 source) { + return getter.apply(source); + } + + @Override + public W2 set(W1 source, P2 val) { + return setter.apply(source, val); + } +} + +final class FunctionalMutableLens<Whole, Part> implements MutableLens<Whole, Part> { + private final BiConsumer<Whole, Part> mutator; + private final Function<Whole, Part> getter; + + FunctionalMutableLens(Function<Whole, Part> getter, BiConsumer<Whole, Part> mutator) { + this.mutator = mutator; + this.getter = getter; + } + + @Override + public Part get(Whole source) { + return getter.apply(source); + } + + @Override + public void mutate(Whole source, Part val) { + mutator.accept(source, val); + } +} diff --git a/src/main/java/bjc/optics/MutableLens.java b/src/main/java/bjc/optics/MutableLens.java new file mode 100644 index 0000000..88eca04 --- /dev/null +++ b/src/main/java/bjc/optics/MutableLens.java @@ -0,0 +1,46 @@ +/* + * esodata - data structures and other things, of varying utility + * Copyright 2022, Ben Culkin + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +package bjc.optics; + +/** + * A type-invariant lens for mutating objects. + * + * Note that there is no type-variant version, because that wouldn't make much sense. + * + * Also, mixing mutable and immutable lenses may lead to confusion. + * + * @author bjcul + * + * @param <Whole> The type the lens is used on + * @param <Part> The type the lens is focused on + */ +public interface MutableLens<Whole, Part> extends Lens<Whole, Part> { + /** + * Apply a mutation to an item. + * + * @param source The item to use the lens on. + * @param val The new value for the focused field. + */ + void mutate(Whole source, Part val); + + @Override + default Whole set(Whole source, Part val) { + mutate(source, val); + return source; + } +} diff --git a/src/main/java/bjc/optics/Optic.java b/src/main/java/bjc/optics/Optic.java new file mode 100644 index 0000000..389da21 --- /dev/null +++ b/src/main/java/bjc/optics/Optic.java @@ -0,0 +1,32 @@ +/* + * esodata - data structures and other things, of varying utility + * Copyright 2022, Ben Culkin + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +package bjc.optics; + +/** + * General interface for optics of varying sorts + * + * @author bjcul + * + * @param <W1> The first item the optic is used on + * @param <W2> The second item the optic is used on + * @param <P1> The first item the optic focuses on + * @param <P2> The second item the optic focuses on + */ +public interface Optic<W1, W2, P1, P2> { + // Marker interface +} diff --git a/src/main/java/bjc/optics/PrismX.java b/src/main/java/bjc/optics/PrismX.java new file mode 100644 index 0000000..b4986cf --- /dev/null +++ b/src/main/java/bjc/optics/PrismX.java @@ -0,0 +1,22 @@ +/* + * esodata - data structures and other things, of varying utility + * Copyright 2022, Ben Culkin + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +package bjc.optics; + +public interface PrismX<W1, W2, P1, P2> extends Optic<W1, W2, P1, P2> { + +} diff --git a/src/main/java/bjc/optics/impl/package-info.java b/src/main/java/bjc/optics/impl/package-info.java new file mode 100644 index 0000000..b147877 --- /dev/null +++ b/src/main/java/bjc/optics/impl/package-info.java @@ -0,0 +1,18 @@ +/* + * esodata - data structures and other things, of varying utility + * Copyright 2022, Ben Culkin + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +package bjc.optics.impl;
\ No newline at end of file diff --git a/src/main/java/bjc/optics/package-info.java b/src/main/java/bjc/optics/package-info.java new file mode 100644 index 0000000..241b565 --- /dev/null +++ b/src/main/java/bjc/optics/package-info.java @@ -0,0 +1,21 @@ +/* + * esodata - data structures and other things, of varying utility + * Copyright 2022, Ben Culkin + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +/** + * + */ +package bjc.optics;
\ No newline at end of file |