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Posted to commits@commons.apache.org by gg...@apache.org on 2022/08/12 17:58:30 UTC
[commons-lang] 01/02: Add LangCollectors
This is an automated email from the ASF dual-hosted git repository.
ggregory pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/commons-lang.git
commit 62910e4f329923c77bc8bd2156d56544d1119efd
Author: Gary Gregory <ga...@gmail.com>
AuthorDate: Fri Aug 12 11:33:10 2022 -0400
Add LangCollectors
---
src/changes/changes.xml | 1 +
.../java/org/apache/commons/lang3/StringUtils.java | 21 +--
.../commons/lang3/stream/LangCollectors.java | 167 +++++++++++++++++++++
.../commons/lang3/stream/LangCollectorsTest.java | 141 +++++++++++++++++
4 files changed, 314 insertions(+), 16 deletions(-)
diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index aa1afbda2..f1f71c10d 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -160,6 +160,7 @@ The <action> type attribute can be add,update,fix,remove.
<action issue="LANG-1662" type="add" dev="ggregory" due-to="Daniel Augusto Veronezi Salvador, Gary Gregory, Bruno P. Kinoshita">Let ReflectionToStringBuilder only reflect given field names #849.</action>
<action type="add" dev="ggregory" due-to="Gary Gregory">Add Streams.of(Enumeration<E>).</action>
<action type="add" dev="ggregory" due-to="Gary Gregory">Add Streams.of(Iterable<E>).</action>
+ <action type="add" dev="ggregory" due-to="Gary Gregory">Add LangCollectors.</action>
<!-- UPDATE -->
<action type="update" dev="ggregory" due-to="Dependabot, XenoAmess, Gary Gregory">Bump actions/cache from 2.1.4 to 3.0.7 #742, #752, #764, #833, #867.</action>
<action type="update" dev="ggregory" due-to="Dependabot">Bump actions/checkout from 2 to 3 #819, #825, #859.</action>
diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 8b49f66ab..2960c83f7 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -27,12 +27,13 @@ import java.util.List;
import java.util.Locale;
import java.util.Objects;
import java.util.Set;
-import java.util.StringJoiner;
import java.util.function.Supplier;
import java.util.regex.Pattern;
+import java.util.stream.Stream;
import org.apache.commons.lang3.function.Suppliers;
import org.apache.commons.lang3.function.ToBooleanBiFunction;
+import org.apache.commons.lang3.stream.LangCollectors;
/**
* <p>Operations on {@link java.lang.String} that are
@@ -4705,10 +4706,7 @@ public class StringUtils {
* @return the joined String, {@code null} if null array input
*/
public static String join(final Object[] array, final String delimiter) {
- if (array == null) {
- return null;
- }
- return join(array, delimiter, 0, array.length);
+ return array != null ? join(array, toStringOrEmpty(delimiter), 0, array.length) : null;
}
/**
@@ -4747,17 +4745,8 @@ public class StringUtils {
* {@code endIndex > array.length()}
*/
public static String join(final Object[] array, final String delimiter, final int startIndex, final int endIndex) {
- if (array == null) {
- return null;
- }
- if (endIndex - startIndex <= 0) {
- return EMPTY;
- }
- final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
- for (int i = startIndex; i < endIndex; i++) {
- joiner.add(toStringOrEmpty(array[i]));
- }
- return joiner.toString();
+ return array != null ? Stream.of(array).skip(startIndex).limit(Math.max(0, endIndex - startIndex))
+ .collect(LangCollectors.joining(delimiter, EMPTY, EMPTY, StringUtils::toStringOrEmpty)) : null;
}
/**
diff --git a/src/main/java/org/apache/commons/lang3/stream/LangCollectors.java b/src/main/java/org/apache/commons/lang3/stream/LangCollectors.java
new file mode 100644
index 000000000..abd3b10f8
--- /dev/null
+++ b/src/main/java/org/apache/commons/lang3/stream/LangCollectors.java
@@ -0,0 +1,167 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.lang3.stream;
+
+import java.util.Collections;
+import java.util.Objects;
+import java.util.Set;
+import java.util.StringJoiner;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Collector;
+import java.util.stream.Collectors;
+
+import org.apache.commons.lang3.StringUtils;
+
+/**
+ * Implementations of {@link Collector} that implement various useful reduction operations.
+ * <p>
+ * This class is called {@code LangCollectors} instead of {@code Collectors} to avoid clashes with {@link Collectors}.
+ * </p>
+ *
+ * @since 3.13.0
+ */
+public final class LangCollectors {
+
+ /**
+ * Simple implementation class for {@code Collector}.
+ *
+ * @param <T> the type of elements to be collected
+ * @param <R> the type of the result
+ */
+ private static class SimpleCollector<T, A, R> implements Collector<T, A, R> {
+
+ private final BiConsumer<A, T> accumulator;
+ private final Set<Characteristics> characteristics;
+ private final BinaryOperator<A> combiner;
+ private final Function<A, R> finisher;
+ private final Supplier<A> supplier;
+
+ private SimpleCollector(final Supplier<A> supplier, final BiConsumer<A, T> accumulator, final BinaryOperator<A> combiner, final Function<A, R> finisher,
+ final Set<Characteristics> characteristics) {
+ this.supplier = supplier;
+ this.accumulator = accumulator;
+ this.combiner = combiner;
+ this.finisher = finisher;
+ this.characteristics = characteristics;
+ }
+
+ @Override
+ public BiConsumer<A, T> accumulator() {
+ return accumulator;
+ }
+
+ @Override
+ public Set<Characteristics> characteristics() {
+ return characteristics;
+ }
+
+ @Override
+ public BinaryOperator<A> combiner() {
+ return combiner;
+ }
+
+ @Override
+ public Function<A, R> finisher() {
+ return finisher;
+ }
+
+ @Override
+ public Supplier<A> supplier() {
+ return supplier;
+ }
+ }
+
+ private static final Set<Collector.Characteristics> CH_NOID = Collections.emptySet();
+
+ /**
+ * Returns a {@code Collector} that concatenates the input elements, separated by the specified delimiter, in encounter
+ * order.
+ * <p>
+ * This is a variation of {@link Collectors#joining()} that works with any element class, not just {@code CharSequence}.
+ * </p>
+ *
+ * @return A {@code Collector} which concatenates Object elements, separated by the specified delimiter, in encounter
+ * order.
+ */
+ public static Collector<Object, ?, String> joining() {
+ return new SimpleCollector<>(StringBuilder::new, StringBuilder::append, StringBuilder::append, StringBuilder::toString, CH_NOID);
+ }
+
+ /**
+ * Returns a {@code Collector} that concatenates the input elements, separated by the specified delimiter, in encounter
+ * order.
+ * <p>
+ * This is a variation of {@link Collectors#joining(CharSequence)} that works with any element class, not just
+ * {@code CharSequence}.
+ * </p>
+ *
+ * @param delimiter the delimiter to be used between each element.
+ * @return A {@code Collector} which concatenates Object elements, separated by the specified delimiter, in encounter
+ * order.
+ */
+ public static Collector<Object, ?, String> joining(final CharSequence delimiter) {
+ return joining(delimiter, StringUtils.EMPTY, StringUtils.EMPTY);
+ }
+
+ /**
+ * Returns a {@code Collector} that concatenates the input elements, separated by the specified delimiter, with the
+ * specified prefix and suffix, in encounter order.
+ * <p>
+ * This is a variation of {@link Collectors#joining(CharSequence, CharSequence, CharSequence)} that works with any
+ * element class, not just {@code CharSequence}.
+ * </p>
+ *
+ * @param delimiter the delimiter to be used between each element
+ * @param prefix the sequence of characters to be used at the beginning of the joined result
+ * @param suffix the sequence of characters to be used at the end of the joined result
+ * @return A {@code Collector} which concatenates CharSequence elements, separated by the specified delimiter, in
+ * encounter order
+ */
+ public static Collector<Object, ?, String> joining(final CharSequence delimiter, final CharSequence prefix, final CharSequence suffix) {
+ return joining(delimiter, prefix, suffix, Objects::toString);
+ }
+
+ /**
+ * Returns a {@code Collector} that concatenates the input elements, separated by the specified delimiter, with the
+ * specified prefix and suffix, in encounter order.
+ * <p>
+ * This is a variation of {@link Collectors#joining(CharSequence, CharSequence, CharSequence)} that works with any
+ * element class, not just {@code CharSequence}.
+ * </p>
+ *
+ * @param delimiter the delimiter to be used between each element
+ * @param prefix the sequence of characters to be used at the beginning of the joined result
+ * @param suffix the sequence of characters to be used at the end of the joined result
+ * @param toString A function that takes an Object and returns a non-null String.
+ * @return A {@code Collector} which concatenates CharSequence elements, separated by the specified delimiter, in
+ * encounter order
+ */
+ public static Collector<Object, ?, String> joining(final CharSequence delimiter, final CharSequence prefix, final CharSequence suffix,
+ final Function<Object, String> toString) {
+ return new SimpleCollector<>(() -> new StringJoiner(delimiter, prefix, suffix), (a, t) -> a.add(toString.apply(t)), StringJoiner::merge,
+ StringJoiner::toString, CH_NOID);
+ }
+
+ private LangCollectors() {
+ // No instance
+ }
+
+}
diff --git a/src/test/java/org/apache/commons/lang3/stream/LangCollectorsTest.java b/src/test/java/org/apache/commons/lang3/stream/LangCollectorsTest.java
new file mode 100644
index 000000000..e8f408498
--- /dev/null
+++ b/src/test/java/org/apache/commons/lang3/stream/LangCollectorsTest.java
@@ -0,0 +1,141 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.lang3.stream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Objects;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Function;
+import java.util.stream.Collector;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests {@link LangCollectors}
+ */
+public class LangCollectorsTest {
+
+ private static class Fixture {
+ int value;
+
+ private Fixture(final int value) {
+ this.value = value;
+ }
+
+ @Override
+ public String toString() {
+ return Integer.toString(value);
+ }
+ }
+
+ private static final Long _1L = Long.valueOf(1);
+ private static final Long _2L = Long.valueOf(2);
+ private static final Long _3L = Long.valueOf(3);
+
+ private static final Function<Object, String> TO_STRING = Objects::toString;
+
+ private static final Collector<Object, ?, String> JOINING_0 = LangCollectors.joining();
+ private static final Collector<Object, ?, String> JOINING_1 = LangCollectors.joining("-");
+ private static final Collector<Object, ?, String> JOINING_3 = LangCollectors.joining("-", "<", ">");
+ private static final Collector<Object, ?, String> JOINING_4 = LangCollectors.joining("-", "<", ">", TO_STRING);
+ private static final Collector<Object, ?, String> JOINING_4_NUL = LangCollectors.joining("-", "<", ">", o -> Objects.toString(o, "NUL"));
+
+ @Test
+ public void testJoiningNonStrings0Arg() {
+ assertEquals("", Stream.of().collect(JOINING_0));
+ assertEquals("1", Stream.of(_1L).collect(JOINING_0));
+ assertEquals("12", Stream.of(_1L, _2L).collect(JOINING_0));
+ assertEquals("123", Stream.of(_1L, _2L, _3L).collect(JOINING_0));
+ assertEquals("1null3", Stream.of(_1L, null, _3L).collect(JOINING_0));
+ assertEquals("12", Stream.of(new AtomicLong(1), new AtomicLong(2)).collect(JOINING_0));
+ assertEquals("12", Stream.of(new Fixture(1), new Fixture(2)).collect(JOINING_0));
+ }
+
+ @Test
+ public void testJoiningNonStrings1Arg() {
+ assertEquals("", Stream.of().collect(JOINING_1));
+ assertEquals("1", Stream.of(_1L).collect(JOINING_1));
+ assertEquals("1-2", Stream.of(_1L, _2L).collect(JOINING_1));
+ assertEquals("1-2-3", Stream.of(_1L, _2L, _3L).collect(JOINING_1));
+ assertEquals("1-null-3", Stream.of(_1L, null, _3L).collect(JOINING_1));
+ assertEquals("1-2", Stream.of(new AtomicLong(1), new AtomicLong(2)).collect(JOINING_1));
+ assertEquals("1-2", Stream.of(new Fixture(1), new Fixture(2)).collect(JOINING_1));
+ }
+
+ @Test
+ public void testJoiningNonStrings3Args() {
+ assertEquals("<>", Stream.of().collect(JOINING_3));
+ assertEquals("<1>", Stream.of(_1L).collect(JOINING_3));
+ assertEquals("<1-2>", Stream.of(_1L, _2L).collect(JOINING_3));
+ assertEquals("<1-2-3>", Stream.of(_1L, _2L, _3L).collect(JOINING_3));
+ assertEquals("<1-null-3>", Stream.of(_1L, null, _3L).collect(JOINING_3));
+ assertEquals("<1-2>", Stream.of(new AtomicLong(1), new AtomicLong(2)).collect(JOINING_3));
+ assertEquals("<1-2>", Stream.of(new Fixture(1), new Fixture(2)).collect(JOINING_3));
+ }
+
+ @Test
+ public void testJoiningNonStrings4Args() {
+ assertEquals("<>", Stream.of().collect(JOINING_4));
+ assertEquals("<1>", Stream.of(_1L).collect(JOINING_4));
+ assertEquals("<1-2>", Stream.of(_1L, _2L).collect(JOINING_4));
+ assertEquals("<1-2-3>", Stream.of(_1L, _2L, _3L).collect(JOINING_4));
+ assertEquals("<1-null-3>", Stream.of(_1L, null, _3L).collect(JOINING_4));
+ assertEquals("<1-NUL-3>", Stream.of(_1L, null, _3L).collect(JOINING_4_NUL));
+ assertEquals("<1-2>", Stream.of(new AtomicLong(1), new AtomicLong(2)).collect(JOINING_4));
+ assertEquals("<1-2>", Stream.of(new Fixture(1), new Fixture(2)).collect(JOINING_4));
+ }
+
+ @Test
+ public void testJoiningStrings0Arg() {
+ assertEquals("", Stream.of().collect(JOINING_0));
+ assertEquals("1", Stream.of("1").collect(JOINING_0));
+ assertEquals("12", Stream.of("1", "2").collect(JOINING_0));
+ assertEquals("123", Stream.of("1", "2", "3").collect(JOINING_0));
+ assertEquals("1null3", Stream.of("1", null, "3").collect(JOINING_0));
+ }
+
+ @Test
+ public void testJoiningStrings1Arg() {
+ assertEquals("", Stream.of().collect(JOINING_1));
+ assertEquals("1", Stream.of("1").collect(JOINING_1));
+ assertEquals("1-2", Stream.of("1", "2").collect(JOINING_1));
+ assertEquals("1-2-3", Stream.of("1", "2", "3").collect(JOINING_1));
+ assertEquals("1-null-3", Stream.of("1", null, "3").collect(JOINING_1));
+ }
+
+ @Test
+ public void testJoiningStrings3Args() {
+ assertEquals("<>", Stream.of().collect(JOINING_3));
+ assertEquals("<1>", Stream.of("1").collect(JOINING_3));
+ assertEquals("<1-2>", Stream.of("1", "2").collect(JOINING_3));
+ assertEquals("<1-2-3>", Stream.of("1", "2", "3").collect(JOINING_3));
+ assertEquals("<1-null-3>", Stream.of("1", null, "3").collect(JOINING_3));
+ }
+
+ @Test
+ public void testJoiningStrings4Args() {
+ assertEquals("<>", Stream.of().collect(JOINING_4));
+ assertEquals("<1>", Stream.of("1").collect(JOINING_4));
+ assertEquals("<1-2>", Stream.of("1", "2").collect(JOINING_4));
+ assertEquals("<1-2-3>", Stream.of("1", "2", "3").collect(JOINING_4));
+ assertEquals("<1-null-3>", Stream.of("1", null, "3").collect(JOINING_4));
+ assertEquals("<1-NUL-3>", Stream.of("1", null, "3").collect(JOINING_4_NUL));
+ }
+}