1 /*
2 * Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
1865 }
1866
1867 /**
1868 * Returns a {@code Collector} which applies an {@code double}-producing
1869 * mapping function to each input element, and returns summary statistics
1870 * for the resulting values.
1871 *
1872 * @param <T> the type of the input elements
1873 * @param mapper a mapping function to apply to each element
1874 * @return a {@code Collector} implementing the summary-statistics reduction
1875 *
1876 * @see #summarizingLong(ToLongFunction)
1877 * @see #summarizingInt(ToIntFunction)
1878 */
1879 public static <T>
1880 Collector<T, ?, DoubleSummaryStatistics> summarizingDouble(ToDoubleFunction<? super T> mapper) {
1881 return new CollectorImpl<T, DoubleSummaryStatistics, DoubleSummaryStatistics>(
1882 DoubleSummaryStatistics::new,
1883 (r, t) -> r.accept(mapper.applyAsDouble(t)),
1884 (l, r) -> { l.combine(r); return l; }, CH_ID);
1885 }
1886
1887 /**
1888 * Implementation class used by partitioningBy.
1889 */
1890 private static final class Partition<T>
1891 extends AbstractMap<Boolean, T>
1892 implements Map<Boolean, T> {
1893 final T forTrue;
1894 final T forFalse;
1895
1896 Partition(T forTrue, T forFalse) {
1897 this.forTrue = forTrue;
1898 this.forFalse = forFalse;
1899 }
1900
1901 @Override
1902 public Set<Map.Entry<Boolean, T>> entrySet() {
1903 return new AbstractSet<>() {
1904 @Override
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1 /*
2 * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
1865 }
1866
1867 /**
1868 * Returns a {@code Collector} which applies an {@code double}-producing
1869 * mapping function to each input element, and returns summary statistics
1870 * for the resulting values.
1871 *
1872 * @param <T> the type of the input elements
1873 * @param mapper a mapping function to apply to each element
1874 * @return a {@code Collector} implementing the summary-statistics reduction
1875 *
1876 * @see #summarizingLong(ToLongFunction)
1877 * @see #summarizingInt(ToIntFunction)
1878 */
1879 public static <T>
1880 Collector<T, ?, DoubleSummaryStatistics> summarizingDouble(ToDoubleFunction<? super T> mapper) {
1881 return new CollectorImpl<T, DoubleSummaryStatistics, DoubleSummaryStatistics>(
1882 DoubleSummaryStatistics::new,
1883 (r, t) -> r.accept(mapper.applyAsDouble(t)),
1884 (l, r) -> { l.combine(r); return l; }, CH_ID);
1885 }
1886
1887 /**
1888 * Returns a {@code Collector} that passes the input elements to two specified collectors
1889 * and merges their results with the specified merge function.
1890 *
1891 * <p>The resulting collector is {@link Collector.Characteristics#UNORDERED} if both supplied
1892 * collectors are unordered and {@link Collector.Characteristics#CONCURRENT} if both supplied
1893 * collectors are concurrent.
1894 *
1895 * @param <T> the type of the input elements
1896 * @param <R1> the result type of the first collector
1897 * @param <R2> the result type of the second collector
1898 * @param <R> the final result type
1899 * @param c1 the first collector
1900 * @param c2 the second collector
1901 * @param merger the function which merges two results into the single one
1902 * @return a {@code Collector} which aggregates the results of two supplied collectors.
1903 * @since 12
1904 */
1905 public static <T, R1, R2, R>
1906 Collector<T, ?, R> teeingAndThen(Collector<? super T, ?, R1> c1,
1907 Collector<? super T, ?, R2> c2,
1908 BiFunction<? super R1, ? super R2, ? extends R> merger) {
1909 return teeingAndThen0(c1, c2, merger);
1910 }
1911
1912 private static <T, A1, A2, R1, R2, R>
1913 Collector<T, ?, R> teeingAndThen0(Collector<? super T, A1, R1> c1,
1914 Collector<? super T, A2, R2> c2,
1915 BiFunction<? super R1, ? super R2, ? extends R> merger) {
1916 Objects.requireNonNull(c1, "c1");
1917 Objects.requireNonNull(c2, "c2");
1918 Objects.requireNonNull(merger, "merger");
1919
1920 Supplier<A1> c1Supplier = Objects.requireNonNull(c1.supplier(), "c1 supplier");
1921 Supplier<A2> c2Supplier = Objects.requireNonNull(c2.supplier(), "c2 supplier");
1922 BiConsumer<A1, ? super T> c1Accumulator = Objects.requireNonNull(c1.accumulator(), "c1 accumulator");
1923 BiConsumer<A2, ? super T> c2Accumulator = Objects.requireNonNull(c2.accumulator(), "c2 accumulator");
1924 BinaryOperator<A1> c1Combiner = Objects.requireNonNull(c1.combiner(), "c1 combiner");
1925 BinaryOperator<A2> c2Combiner = Objects.requireNonNull(c2.combiner(), "c2 combiner");
1926 Function<A1, R1> c1Finisher = Objects.requireNonNull(c1.finisher(), "c1 finisher");
1927 Function<A2, R2> c2Finisher = Objects.requireNonNull(c2.finisher(), "c2 finisher");
1928
1929 Set<Collector.Characteristics> characteristics;
1930 Set<Collector.Characteristics> c1Characteristics = c1.characteristics();
1931 Set<Collector.Characteristics> c2Characteristics = c2.characteristics();
1932 if (CH_ID.containsAll(c1Characteristics) || CH_ID.containsAll(c2Characteristics)) {
1933 characteristics = CH_NOID;
1934 } else {
1935 EnumSet<Collector.Characteristics> c = EnumSet.noneOf(Collector.Characteristics.class);
1936 c.addAll(c1Characteristics);
1937 c.retainAll(c2Characteristics);
1938 c.remove(Collector.Characteristics.IDENTITY_FINISH);
1939 characteristics = Collections.unmodifiableSet(c);
1940 }
1941
1942 class PairBox {
1943 A1 left = c1Supplier.get();
1944 A2 right = c2Supplier.get();
1945
1946 void add(T t) {
1947 c1Accumulator.accept(left, t);
1948 c2Accumulator.accept(right, t);
1949 }
1950
1951 PairBox combine(PairBox other) {
1952 left = c1Combiner.apply(left, other.left);
1953 right = c2Combiner.apply(right, other.right);
1954 return this;
1955 }
1956
1957 R get() {
1958 R1 r1 = c1Finisher.apply(left);
1959 R2 r2 = c2Finisher.apply(right);
1960 return merger.apply(r1, r2);
1961 }
1962 }
1963
1964 return new CollectorImpl<>(PairBox::new, PairBox::add, PairBox::combine, PairBox::get, characteristics);
1965 }
1966
1967 /**
1968 * Implementation class used by partitioningBy.
1969 */
1970 private static final class Partition<T>
1971 extends AbstractMap<Boolean, T>
1972 implements Map<Boolean, T> {
1973 final T forTrue;
1974 final T forFalse;
1975
1976 Partition(T forTrue, T forFalse) {
1977 this.forTrue = forTrue;
1978 this.forFalse = forFalse;
1979 }
1980
1981 @Override
1982 public Set<Map.Entry<Boolean, T>> entrySet() {
1983 return new AbstractSet<>() {
1984 @Override
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