Merge pull request #36 from digipost/nonemptylist-copyof-loosen-typing

NonEmptyList copy-constructors accept Collection

pom.xml

@@ -49,7 +49,7 @@
  <dependency>
  <groupId>org.junit</groupId>
  <artifactId>junit-bom</artifactId>
- <version>5.10.1</version>
+ <version>5.10.2</version>
  <type>pom</type>
  <scope>import</scope>
  </dependency>
@@ -63,7 +63,7 @@
  <dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>slf4j-bom</artifactId>
- <version>2.0.10</version>
+ <version>2.0.12</version>
  <type>pom</type>
  <scope>import</scope>
  </dependency>
@@ -85,7 +85,7 @@
  <dependency>
  <groupId>nl.jqno.equalsverifier</groupId>
  <artifactId>equalsverifier</artifactId>
- <version>3.15.5</version>
+ <version>3.15.6</version>
  <scope>test</scope>
  </dependency>
  <dependency>
@@ -113,7 +113,7 @@
  <dependency>
  <groupId>no.digipost</groupId>
  <artifactId>jul-to-slf4j-junit-extension</artifactId>
- <version>1.0</version>
+ <version>1.0.1</version>
  <scope>test</scope>
  </dependency>
  <dependency>
@@ -194,7 +194,7 @@
  </plugin>
  <plugin>
  <artifactId>maven-surefire-plugin</artifactId>
- <version>3.2.3</version>
+ <version>3.2.5</version>
  </plugin>
  <plugin>
  <artifactId>maven-deploy-plugin</artifactId>
@@ -244,7 +244,7 @@
  <plugin>
  <groupId>com.github.siom79.japicmp</groupId>
  <artifactId>japicmp-maven-plugin</artifactId>
- <version>0.18.3</version>
+ <version>0.18.5</version>
  <configuration>
  <parameter>
  <includes>

src/main/java/no/digipost/collection/NonEmptyList.java

@@ -18,6 +18,7 @@
 import no.digipost.stream.NonEmptyStream;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
 
@@ -36,7 +37,7 @@
  * relied on.
  * <p>
  * If you need to construct non-empty lists based on another container you
- * need to further mutate, consider using one of the {@link #copyOf(List) copyOf}
+ * need to further mutate, consider using one of the {@link #copyOf(Collection) copyOf}
  * constructors, which will copy the given references so that any subsequent changes to the
  * to the given source container will not be reflected in the created non-empty list. (As usual,
  * this is a shallow copy, meaning that the instances themselves can of course be mutated by anything.)
@@ -190,7 +191,22 @@ static <E> NonEmptyList<E> ofUnsafe(E[] nonEmptyArray) {
  * or {@link Optional#empty()} if the given list is empty
  */
  static <E> Optional<NonEmptyList<E>> copyOf(List<E> list) {
- return firstOf(list).map(first -> NonEmptyList.of(first, new ArrayList<>(list.subList(1, list.size()))));
+ return copyOf((Collection<E>) list);
+ }
+
+
+ /**
+ * Try to construct a non-empty list from copying the elements
+ * of a given collection, which may be empty.
+ *
+ * @param <E> the type of elements in the collection.
+ * @param collection the collection, which may be empty
+ *
+ * @return the resulting non-empty list,
+ * or {@link Optional#empty()} if the given collection is empty
+ */
+ static <E> Optional<NonEmptyList<E>> copyOf(Collection<E> collection) {
+ return of(new ArrayList<>(collection));
  }
 
 
@@ -228,7 +244,30 @@ static <E> Optional<NonEmptyList<E>> copyOf(E[] array) {
  * @see #copyOf(List)
  */
  static <E> NonEmptyList<E> copyOfUnsafe(List<E> nonEmptyList) {
- return copyOf(nonEmptyList).orElseThrow(() -> new IllegalArgumentException("empty list"));
+ return copyOfUnsafe((Collection<E>) nonEmptyList);
+ }
+
+
+ /**
+ * <strong>Unsafe</strong> construction of non-empty list from copying the
+ * elements of a collection assumed to be non-empty.
+ * <p>
+ * This method should only be used when the given collection is <em>guarantied</em>
+ * to be empty, and thus offers a fail-fast way to introduce the non-empty
+ * quality on a type level. Use {@link #copyOf(Collection)} if you need
+ * more flexibility in handling of a possible empty list.
+ *
+ * @param <E> the type of elements in the list.
+ * @param nonEmptyCollection the collection, which is assumed not to be empty
+ *
+ * @return the resulting non-empty list
+ *
+ * @throws IllegalArgumentException if the given list is empty
+ *
+ * @see #copyOf(Collection)
+ */
+ static <E> NonEmptyList<E> copyOfUnsafe(Collection<E> nonEmptyCollection) {
+ return copyOf(nonEmptyCollection).orElseThrow(() -> new IllegalArgumentException("empty list"));
  }