[sis] 02/02: Add a `MapValue.putIfAbsent` method for efficiency. It is used in various places.

[desruisseaux]

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desruisseaux pushed a commit to branch geoapi-4.0
in repository https://gitbox.apache.org/repos/asf/sis.git

commit 281a020ec5f7e47acac28961cdb6a80a4bb28e39
Author: Martin Desruisseaux <martin.desruisse...@geomatys.com>
AuthorDate: Thu Jan 27 12:30:38 2022 +0100

    Add a `MapValue.putIfAbsent` method for efficiency. It is used in various 
places.
---
 .../main/java/org/apache/sis/metadata/ValueMap.java  | 20 +++++++++++++++++++-
 .../java/org/apache/sis/metadata/ValueMapTest.java   | 15 ++++++++++++++-
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git 
a/core/sis-metadata/src/main/java/org/apache/sis/metadata/ValueMap.java 
b/core/sis-metadata/src/main/java/org/apache/sis/metadata/ValueMap.java
index a68fdae..3538fe0 100644
--- a/core/sis-metadata/src/main/java/org/apache/sis/metadata/ValueMap.java
+++ b/core/sis-metadata/src/main/java/org/apache/sis/metadata/ValueMap.java
@@ -31,7 +31,7 @@ import static 
org.apache.sis.metadata.PropertyAccessor.RETURN_PREVIOUS;
  * are the value returned by the {@code getFoo()} method using reflection.
  *
  * @author  Martin Desruisseaux (Geomatys)
- * @version 0.3
+ * @version 1.2
  *
  * @see MetadataStandard#asValueMap(Object, Class, KeyNamePolicy, 
ValueExistencePolicy)
  *
@@ -118,6 +118,24 @@ final class ValueMap extends PropertyMap<Object> {
     }
 
     /**
+     * Associates the specified value with the specified key in this map if no 
value is currently associated.
+     *
+     * @throws IllegalArgumentException if the given key is not the name of a 
property in the metadata.
+     * @throws ClassCastException if the given value is not of the expected 
type.
+     * @throws UnmodifiableMetadataException if the property for the given key 
is read-only.
+     */
+    @Override
+    public Object putIfAbsent(final String key, final Object value) {
+        final int index = accessor.indexOf(key, true);
+        final Object old = accessor.get(index, metadata);
+        if (old == null || valuePolicy.isSkipped(old)) {
+            return accessor.set(index, metadata, value, RETURN_NULL);
+        } else {
+            return old;
+        }
+    }
+
+    /**
      * Puts every entries from the given map. This method is overloaded for 
performance reasons
      * since we are not interested in the return value of the {@link 
#put(String, Object)} method.
      *
diff --git 
a/core/sis-metadata/src/test/java/org/apache/sis/metadata/ValueMapTest.java 
b/core/sis-metadata/src/test/java/org/apache/sis/metadata/ValueMapTest.java
index 64b0577..a5d58b5 100644
--- a/core/sis-metadata/src/test/java/org/apache/sis/metadata/ValueMapTest.java
+++ b/core/sis-metadata/src/test/java/org/apache/sis/metadata/ValueMapTest.java
@@ -46,7 +46,7 @@ import static org.apache.sis.test.TestUtilities.getSingleton;
  * Unless otherwise specified, all tests use the {@link 
MetadataStandard#ISO_19115} constant.
  *
  * @author  Martin Desruisseaux (Geomatys)
- * @version 1.0
+ * @version 1.2
  *
  * @see MetadataStandardTest#testValueMap()
  *
@@ -305,4 +305,17 @@ public final strictfp class ValueMapTest extends TestCase {
             new SimpleEntry<>("ISBN",                    "9782505004509")
         }, map.entrySet().toArray());
     }
+
+    /**
+     * Tests {@link ValueMap#putIfAbsent(String, Object)}.
+     */
+    @Test
+    public void testPutIfAbsent() {
+        final Map<String, Object> citation = createCitation();
+        assertEquals("Undercurrent", 
String.valueOf(citation.putIfAbsent("title", "A new title")));
+        assertEquals("Undercurrent", String.valueOf(citation.get("title")));
+        assertEquals("Undercurrent", String.valueOf(citation.remove("title")));
+        assertNull(citation.putIfAbsent("title", "A new title"));
+        assertEquals("A new title",  String.valueOf(citation.get("title")));
+    }
 }