feat: add utility class for handling RO-Crate graph operations

Author: Pfeil

src/main/java/edu/kit/datamanager/ro_crate/util/Graph.java

@@ -0,0 +1,56 @@
+package edu.kit.datamanager.ro_crate.util;
+
+import com.fasterxml.jackson.databind.JsonNode;
+
+import java.util.stream.StreamSupport;
+
+/**
+ * Utility class for handling operations on RO-Crate graphs.
+ * Provides methods to find entities by ID or type within a graph.
+ * <p>
+ * {@see JsonUtilFunctions}.
+ */
+public class Graph {
+    /**
+     * Finds an entity in the graph by its ID.
+     *
+     * @param graph The JSON node representing the graph.
+     * @param id    The ID of the entity to find.
+     * @return The entity as a JsonNode if found, null otherwise.
+     */
+    public static JsonNode findEntityById(JsonNode graph, String id) {
+        for (JsonNode entity : graph) {
+            if (entity.has("@id") && entity.get("@id").asText().equals(id)) {
+                return entity;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Finds an entity in the graph by its type.
+     *
+     * @param graph The JSON node representing the graph.
+     * @param type  The type of the entity to find.
+     * @return The entity as a JsonNode if found, null otherwise.
+     */
+    public static JsonNode findEntityByType(JsonNode graph, String type) {
+        return StreamSupport.stream(graph.spliterator(), false)
+                .filter(entity -> entity.path("@type").asText().equals(type))
+                .findFirst()
+                .orElse(null);
+    }
+
+    /**
+     * Finds all entities in the graph by their type.
+     *
+     * @param graph The JSON node representing the graph.
+     * @param type  The type of the entities to find.
+     * @return An array of JsonNode containing all entities of the specified type.
+     */
+    public static JsonNode[] findEntitiesByType(JsonNode graph, String type) {
+        return StreamSupport.stream(graph.spliterator(), false)
+                .filter(entity -> entity.path("@type").asText().equals(type))
+                .toArray(JsonNode[]::new);
+    }
+}

src/test/java/edu/kit/datamanager/ro_crate/writer/RoCrateMetadataGenerationTest.java

@@ -14,8 +14,8 @@
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.stream.StreamSupport;
 
+import static edu.kit.datamanager.ro_crate.util.Graph.*;
 import static org.junit.jupiter.api.Assertions.*;
 
 class RoCrateMetadataGenerationTest {
@@ -401,28 +401,4 @@ void should_PreserveExistingProvenance_When_ModifyingCrate(@TempDir Path tempDir
         assertEquals(2, roCrateJavaEntity.get("Action").size(),
             "should have both actions");
     }
-
-    private JsonNode findEntityById(JsonNode graph, String id) {
-        for (JsonNode entity : graph) {
-            if (entity.has("@id") && entity.get("@id").asText().equals(id)) {
-                return entity;
-            }
-        }
-        return null;
-    }
-
-    private JsonNode findEntityByType(JsonNode graph, String type) {
-        for (JsonNode entity : graph) {
-            if (entity.has("@type") && entity.get("@type").asText().equals(type)) {
-                return entity;
-            }
-        }
-        return null;
-    }
-
-    private JsonNode[] findEntitiesByType(JsonNode graph, String type) {
-        return StreamSupport.stream(graph.spliterator(), false)
-            .filter(entity -> entity.has("@type") && entity.get("@type").asText().equals(type))
-            .toArray(JsonNode[]::new);
-    }
 }