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Functional Java is an open source library that supports closures for the Java programming language
package fj;
import static fj.Function.compose;
import fj.data.*;
import fj.data.vector.V2;
import fj.data.vector.V3;
import fj.data.vector.V4;
import fj.data.vector.V5;
import fj.data.vector.V6;
import fj.data.vector.V7;
import fj.data.vector.V8;
import java.math.BigDecimal;
import java.math.BigInteger;
/**
* Produces a hash code for an object which should attempt uniqueness.
*
* @version %build.number%
*/
public final class Hash {
private final F f;
private Hash(final F f) {
this.f = f;
}
/**
* Compute the hash of the given value.
*
* @param a The value to compute the hash value for.
* @return The hash value.
*/
public int hash(final A a) {
return f.f(a);
}
/**
* Maps the given function across this hash as a contra-variant functor.
*
* @param g The function to map.
* @return A new hash.
*/
public Hash contramap(final F g) {
return hash(compose(f, g));
}
/**
* Construct a hash with the given hash function.
*
* @param f The function to construct the hash with.
* @return A hash that uses the given function.
*/
public static Hash hash(final F f) {
return new Hash<>(f);
}
/**
* A hash that uses {@link Object#hashCode()}.
*
* @return A hash that uses {@link Object#hashCode()}.
*/
public static Hash anyHash() {
return hash(a -> a.hashCode());
}
/**
* A hash instance for the boolean type.
*/
public static final Hash booleanHash = anyHash();
/**
* A hash instance for the byte type.
*/
public static final Hash byteHash = anyHash();
/**
* A hash instance for the char type.
*/
public static final Hash charHash = anyHash();
/**
* A hash instance for the double type.
*/
public static final Hash doubleHash = anyHash();
/**
* A hash instance for the float type.
*/
public static final Hash floatHash = anyHash();
/**
* A hash instance for the int type.
*/
public static final Hash intHash = anyHash();
/**
* A hash instance for the long type.
*/
public static final Hash longHash = anyHash();
/**
* A hash instance for the short type.
*/
public static final Hash shortHash = anyHash();
/**
* A hash instance for the BigInteger type.
*/
public static final Hash bigintHash = anyHash();
/**
* A hash instance for the BigDecimal type.
*/
public static final Hash bigdecimalHash = anyHash();
/**
* A hash instance for the String type.
*/
public static final Hash stringHash = anyHash();
/**
* A hash instance for the {@link StringBuffer} type.
*/
public static final Hash stringBufferHash = hash(sb -> {
final int p = 419;
int r = 239;
for (int i = 0; i < sb.length(); i++)
r = p * r + sb.charAt(i);
return r;
});
/**
* A hash instance for the {@link StringBuilder} type.
*/
public static final Hash stringBuilderHash = hash(sb -> {
final int p = 419;
int r = 239;
for (int i = 0; i < sb.length(); i++)
r = p * r + sb.charAt(i);
return r;
});
/**
* A hash instance for the {@link Either} type.
*
* @param ha Hash the left side of Either.
* @param hb Hash the right side of Either.
* @return A hash instance for the {@link Either} type.
*/
public static Hash> eitherHash(final Hash ha, final Hash hb) {
return hash(e -> e.isLeft() ? ha.hash(e.left().value()) : hb.hash(e.right().value()));
}
/**
* A hash instance for the {@link Validation} type.
*
* @param ha Hash the failing side of Validation.
* @param hb Hash the succeeding side of Validation.
* @return A hash instance for the {@link Validation} type.
*/
public static Hash> validationHash(final Hash ha, final Hash hb) {
return eitherHash(ha, hb).contramap(Validation.either());
}
/**
* A hash instance for the {@link List} type.
*
* @param ha A hash for the elements of the list.
* @return A hash instance for the {@link List} type.
*/
public static Hash> listHash(final Hash ha) {
return hash(as -> {
final int p = 419;
int r = 239;
List aas = as;
while (!aas.isEmpty()) {
r = p * r + ha.hash(aas.head());
aas = aas.tail();
}
return r;
});
}
/**
* A hash instance for the {@link NonEmptyList} type.
*
* @param ha A hash for the elements of the non-empty list.
* @return A hash instance for the {@link NonEmptyList} type.
*/
public static Hash> nonEmptyListHash(final Hash ha) {
return listHash(ha).contramap(NonEmptyList.toList_());
}
/**
* A hash instance for the {@link Option} type.
*
* @param ha A hash for the element of the optional value.
* @return A hash instance for the {@link Option} type.
*/
public static Hash> optionHash(final Hash ha) {
return hash(o -> o.isNone() ? 0 : ha.hash(o.some()));
}
public static Hash> seqHash(final Hash h) {
return hash(s -> streamHash(h).hash(s.toStream()));
}
public static Hash> setHash(final Hash h) {
return hash(s -> streamHash(h).hash(s.toStream()));
}
/**
* A hash instance for the {@link Stream} type.
*
* @param ha A hash for the elements of the stream.
* @return A hash instance for the {@link Stream} type.
*/
public static Hash> streamHash(final Hash ha) {
return hash(as -> {
final int p = 419;
int r = 239;
Stream aas = as;
while (!aas.isEmpty()) {
r = p * r + ha.hash(aas.head());
aas = aas.tail()._1();
}
return r;
});
}
/**
* A hash instance for the {@link Array} type.
*
* @param ha A hash for the elements of the array.
* @return A hash instance for the {@link Array} type.
*/
public static Hash> arrayHash(final Hash ha) {
return hash(as -> {
final int p = 419;
int r = 239;
for (int i = 0; i < as.length(); i++) {
r = p * r + ha.hash(as.get(i));
}
return r;
});
}
/**
* A hash instance for the {@link Tree} type.
*
* @param ha A hash for the elements of the tree.
* @return A hash instance for the {@link Tree} type.
*/
public static Hash> treeHash(final Hash ha) {
return streamHash(ha).contramap(Tree.flatten_());
}
public static Hash> treeMapHash(final Hash h, final Hash v) {
return hash(t -> streamHash(Hash.p2Hash(h, v)).hash(t.toStream()));
}
/**
* A hash instance for a product-1.
*
* @param ha A hash for the first element of the product.
* @return A hash instance for a product-1.
*/
public static Hash> p1Hash(final Hash ha) {
return ha.contramap(P1.__1());
}
/**
* A hash instance for a product-2.
*
* @param ha A hash for the first element of the product.
* @param hb A hash for the second element of the product.
* @return A hash instance for a product-2.
*/
public static Hash> p2Hash(final Hash ha, final Hash hb) {
return hash(p2 -> {
final int p = 419;
int r = 239;
r = p * r + ha.hash(p2._1());
r = p * r + hb.hash(p2._2());
return r;
});
}
/**
* A hash instance for a product-3.
*
* @param ha A hash for the first element of the product.
* @param hb A hash for the second element of the product.
* @param hc A hash for the third element of the product.
* @return A hash instance for a product-3.
*/
public static Hash> p3Hash(final Hash ha, final Hash hb, final Hash hc) {
return hash(p3 -> {
final int p = 419;
int r = 239;
r = p * r + ha.hash(p3._1());
r = p * r + hb.hash(p3._2());
r = p * r + hc.hash(p3._3());
return r;
});
}
/**
* A hash instance for a product-4.
*
* @param ha A hash for the first element of the product.
* @param hb A hash for the second element of the product.
* @param hc A hash for the third element of the product.
* @param hd A hash for the fourth element of the product.
* @return A hash instance for a product-4.
*/
public static Hash> p4Hash(final Hash ha, final Hash hb, final Hash hc,
final Hash hd) {
return hash(p4 -> {
final int p = 419;
int r = 239;
r = p * r + ha.hash(p4._1());
r = p * r + hb.hash(p4._2());
r = p * r + hc.hash(p4._3());
r = p * r + hd.hash(p4._4());
return r;
});
}
/**
* A hash instance for a product-5.
*
* @param ha A hash for the first element of the product.
* @param hb A hash for the second element of the product.
* @param hc A hash for the third element of the product.
* @param hd A hash for the fourth element of the product.
* @param he A hash for the fifth element of the product.
* @return A hash instance for a product-5.
*/
public static Hash> p5Hash(final Hash ha, final Hash hb, final Hash hc,
final Hash hd, final Hash he) {
return hash(p5 -> {
final int p = 419;
int r = 239;
r = p * r + ha.hash(p5._1());
r = p * r + hb.hash(p5._2());
r = p * r + hc.hash(p5._3());
r = p * r + hd.hash(p5._4());
r = p * r + he.hash(p5._5());
return r;
});
}
/**
* A hash instance for a product-6.
*
* @param ha A hash for the first element of the product.
* @param hb A hash for the second element of the product.
* @param hc A hash for the third element of the product.
* @param hd A hash for the fourth element of the product.
* @param he A hash for the fifth element of the product.
* @param hf A hash for the sixth element of the product.
* @return A hash instance for a product-6.
*/
public static Hash> p6Hash(final Hash ha, final Hash hb,
final Hash hc, final Hash hd,
final Hash he, final Hash hf) {
return hash(p6 -> {
final int p = 419;
int r = 239;
r = p * r + ha.hash(p6._1());
r = p * r + hb.hash(p6._2());
r = p * r + hc.hash(p6._3());
r = p * r + hd.hash(p6._4());
r = p * r + he.hash(p6._5());
r = p * r + hf.hash(p6._6());
return r;
});
}
/**
* A hash instance for a product-7.
*
* @param ha A hash for the first element of the product.
* @param hb A hash for the second element of the product.
* @param hc A hash for the third element of the product.
* @param hd A hash for the fourth element of the product.
* @param he A hash for the fifth element of the product.
* @param hf A hash for the sixth element of the product.
* @param hg A hash for the seventh element of the product.
* @return A hash instance for a product-7.
*/
public static Hash> p7Hash(final Hash ha, final Hash hb,
final Hash hc, final Hash hd,
final Hash he, final Hash hf,
final Hash hg) {
return hash(p7 -> {
final int p = 419;
int r = 239;
r = p * r + ha.hash(p7._1());
r = p * r + hb.hash(p7._2());
r = p * r + hc.hash(p7._3());
r = p * r + hd.hash(p7._4());
r = p * r + he.hash(p7._5());
r = p * r + hf.hash(p7._6());
r = p * r + hg.hash(p7._7());
return r;
});
}
/**
* A hash instance for a product-8.
*
* @param ha A hash for the first element of the product.
* @param hb A hash for the second element of the product.
* @param hc A hash for the third element of the product.
* @param hd A hash for the fourth element of the product.
* @param he A hash for the fifth element of the product.
* @param hf A hash for the sixth element of the product.
* @param hg A hash for the seventh element of the product.
* @param hh A hash for the eighth element of the product.
* @return A hash instance for a product-8.
*/
public static Hash> p8Hash(final Hash ha, final Hash hb,
final Hash hc, final Hash hd,
final Hash he, final Hash hf,
final Hash hg, final Hash hh) {
return hash(p8 -> {
final int p = 419;
int r = 239;
r = p * r + ha.hash(p8._1());
r = p * r + hb.hash(p8._2());
r = p * r + hc.hash(p8._3());
r = p * r + hd.hash(p8._4());
r = p * r + he.hash(p8._5());
r = p * r + hf.hash(p8._6());
r = p * r + hg.hash(p8._7());
r = p * r + hh.hash(p8._8());
return r;
});
}
/**
* A hash instance for a vector-2.
*
* @param ea A hash for the elements of the vector.
* @return A hash instance for a vector-2.
*/
public static Hash> v2Hash(final Hash ea) {
return streamHash(ea).contramap(V2.toStream_());
}
/**
* A hash instance for a vector-3.
*
* @param ea A hash for the elements of the vector.
* @return A hash instance for a vector-3.
*/
public static Hash> v3Hash(final Hash ea) {
return streamHash(ea).contramap(V3.toStream_());
}
/**
* A hash instance for a vector-4.
*
* @param ea A hash for the elements of the vector.
* @return A hash instance for a vector-4.
*/
public static Hash> v4Hash(final Hash ea) {
return streamHash(ea).contramap(V4.toStream_());
}
/**
* A hash instance for a vector-5.
*
* @param ea A hash for the elements of the vector.
* @return A hash instance for a vector-5.
*/
public static Hash> v5Hash(final Hash ea) {
return streamHash(ea).contramap(V5.toStream_());
}
/**
* A hash instance for a vector-6.
*
* @param ea A hash for the elements of the vector.
* @return A hash instance for a vector-6.
*/
public static Hash> v6Hash(final Hash ea) {
return streamHash(ea).contramap(V6.toStream_());
}
/**
* A hash instance for a vector-7.
*
* @param ea A hash for the elements of the vector.
* @return A hash instance for a vector-7.
*/
public static Hash> v7Hash(final Hash ea) {
return streamHash(ea).contramap(V7.toStream_());
}
/**
* A hash instance for a vector-8.
*
* @param ea A hash for the elements of the vector.
* @return A hash instance for a vector-8.
*/
public static Hash> v8Hash(final Hash ea) {
return streamHash(ea).contramap(V8.toStream_());
}
}