#1340 - Added Links.and(Stream<Link>).

Added equivalent overloads of merge(…) as well.

src/main/java/org/springframework/hateoas/Links.java

@@ -136,7 +136,7 @@ public class Links implements Iterable<Link> {
 
 	/**
 	 * Adds the given links if the given condition is {@literal true}. The given {@link Supplier}s will only be resolved
-	 * if the given condition is true. Essentially syntactic sugar to write:<br />
+	 * if the given condition is {@literal true}. Essentially syntactic sugar to write:<br />
 	 * <code>
 	 * if (a > 3) {
 	 *   links = links.and(…);
@@ -154,9 +154,29 @@ public class Links implements Iterable<Link> {
 
 		Assert.notNull(links, "Links must not be null!");
 
-		return condition //
-				? and(Arrays.stream(links).map(Supplier::get).collect(Collectors.toList())) //
-				: this;
+		return andIf(condition, Stream.of(links).map(Supplier::get));
+	}
+
+	/**
+	 * Adds the given links if the given condition is {@literal true}. The given {@link Stream} will only be resolved if
+	 * the given condition is {@literal true}. Essentially syntactic sugar to write:<br />
+	 * <code>
+	 * if (a > 3) {
+	 *   links = links.and(…);
+	 * }
+	 * </code> as <code>
+	 * links = link.andIf(a > 3, …);
+	 * </code>
+	 *
+	 * @param condition
+	 * @param links must not be {@literal null}.
+	 * @return
+	 */
+	public final Links andIf(boolean condition, Stream<Link> links) {
+
+		Assert.notNull(links, "Links must not be null!");
+
+		return condition ? and(links.collect(Collectors.toList())) : this;
 	}
 
 	/**
@@ -176,6 +196,19 @@ public class Links implements Iterable<Link> {
 		return Links.of(newLinks);
 	}
 
+	/**
+	 * Creates a new {@link Links} instance with all given {@link Link}s added. For conditional adding see
+	 * {@link #merge(Iterable)}.
+	 *
+	 * @param links must not be {@literal null}.
+	 * @return
+	 * @see #merge(Iterable)
+	 * @see #merge(MergeMode, Iterable)
+	 */
+	public Links and(Stream<Link> links) {
+		return and(links.collect(Collectors.toList()));
+	}
+
 	/**
 	 * Merges the current {@link Links} with the given ones, skipping {@link Link}s already contained in the current
 	 * instance. For unconditional combination see {@link #and(Link...)}.
@@ -191,12 +224,25 @@ public class Links implements Iterable<Link> {
 
 	/**
 	 * Merges the current {@link Links} with the given ones, skipping {@link Link}s already contained in the current
-	 * instance. For unconditional combination see {@link #and(Link...)}.
+	 * instance. For unconditional combination see {@link #and(Stream)}.
 	 *
 	 * @param links the {@link Link}s to be merged, must not be {@literal null}.
 	 * @return
 	 * @see MergeMode#SKIP_BY_EQUALITY
-	 * @see #and(Link...)
+	 * @see #and(Stream)
+	 */
+	public Links merge(Stream<Link> links) {
+		return merge(links.collect(Collectors.toList()));
+	}
+
+	/**
+	 * Merges the current {@link Links} with the given ones, skipping {@link Link}s already contained in the current
+	 * instance. For unconditional combination see {@link #and(Iterable)}.
+	 *
+	 * @param links the {@link Link}s to be merged, must not be {@literal null}.
+	 * @return
+	 * @see MergeMode#SKIP_BY_EQUALITY
+	 * @see #and(Iterable)
 	 */
 	public Links merge(Iterable<Link> links) {
 		return merge(MergeMode.SKIP_BY_EQUALITY, links);
@@ -213,6 +259,17 @@ public class Links implements Iterable<Link> {
 		return merge(mode, Arrays.asList(links));
 	}
 
+	/**
+	 * Merges the current {@link Links} with the given ones applying the given {@link MergeMode}.
+	 *
+	 * @param mode must not be {@literal null}.
+	 * @param links must not be {@literal null}.
+	 * @return
+	 */
+	public Links merge(MergeMode mode, Stream<Link> links) {
+		return merge(mode, links.collect(Collectors.toList()));
+	}
+
 	/**
 	 * Merges the current {@link Links} with the given ones applying the given {@link MergeMode}.
 	 *

src/test/java/org/springframework/hateoas/LinksUnitTest.java

@@ -17,10 +17,17 @@ package org.springframework.hateoas;
 
 import static org.assertj.core.api.Assertions.*;
 
-import java.util.Arrays;
-import java.util.Optional;
+import lombok.Value;
 
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.DynamicTest;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestFactory;
+import org.springframework.hateoas.Links.MergeMode;
 import org.springframework.util.StringUtils;
 
 /**
@@ -151,4 +158,43 @@ class LinksUnitTest {
 			throw new IllegalStateException();
 		})).doesNotThrowAnyException();
 	}
+
+	@TestFactory // #1340
+	Stream<DynamicTest> addsStreamOfLinks() {
+
+		Links links = Links.NONE;
+		Link link = Link.of("/foo");
+
+		List<NamedLinks> sources = Arrays.asList(//
+				NamedLinks.of("via varargs", links.and(link)), //
+				NamedLinks.of("via Iterable", links.and(Arrays.asList(link))), //
+				NamedLinks.of("via Stream", links.and(Stream.of(link))));
+
+		return DynamicTest.stream(sources.iterator(), NamedLinks::getName,
+				it -> assertThat(it.links.getRequiredLink(IanaLinkRelations.SELF)).isNotNull());
+	}
+
+	@TestFactory // #1340
+	Stream<DynamicTest> mergesStreamOfLinks() {
+
+		Links links = Links.NONE.and(Link.of("/foo"));
+		Link same = Link.of("/foo");
+		Link sameRel = Link.of("/bar");
+
+		List<NamedLinks> sources = Arrays.asList(//
+				NamedLinks.of("merge same via varargs", links.merge(same)),
+				NamedLinks.of("merge same rel via varargs", links.merge(MergeMode.SKIP_BY_REL, sameRel)),
+				NamedLinks.of("merge same via Stream", links.merge(Stream.of(same))),
+				NamedLinks.of("merge same rel via Stream", links.merge(MergeMode.SKIP_BY_REL, Stream.of(sameRel))));
+
+		return DynamicTest.stream(sources.iterator(), NamedLinks::getName,
+				it -> assertThat(it.links).hasSize(1) //
+						.element(0).extracting(Link::getHref).isEqualTo("/foo"));
+	}
+
+	@Value(staticConstructor = "of")
+	static class NamedLinks {
+		String name;
+		Links links;
+	}
 }