[#757] Add validator that detects the cyclic imports. Add print methods in Graph

Author: opatrascoiu

dmn-core/src/main/java/com/gs/dmn/Graph.java

@@ -14,7 +14,12 @@
 
 import com.gs.dmn.runtime.Pair;
 
+import java.io.IOException;
+import java.io.StringWriter;
+import java.io.Writer;
 import java.util.*;
+import java.util.function.Function;
+import java.util.function.Predicate;
 
 public class Graph<T> {
     private final Set<T> nodes = new LinkedHashSet<>();
@@ -144,4 +149,34 @@ private void collectCyclesDFS(T node, Set<T> visited, Stack<T> stack, List<List<
         }
         stack.pop();
     }
+
+    public void printNodes(Writer writer, Function<T, String> nodeInfo) throws IOException {
+        for (T node : nodes) {
+            writer.write(nodeInfo.apply(node) + "\n");
+        }
+    }
+
+    public void printBF(T rootNode, StringWriter writer, Function<T, String> nodeInfo) {
+        printBF(rootNode, writer, nodeInfo, x -> true);
+    }
+
+    public void printBF(T rootNode, StringWriter writer, Function<T, String> nodeInfo, Predicate<T> filter) {
+        Set<T> visited = new LinkedHashSet<>();
+        if (filter.test(rootNode)) {
+            printBF(rootNode, writer, nodeInfo, filter, 0, visited);
+        }
+    }
+
+    private void printBF(T node, StringWriter writer, Function<T, String> nodeInfo, Predicate<T> filter, int level, Set<T> visited) {
+        String indent = "\t".repeat(level);
+        writer.write(indent + nodeInfo.apply(node) + "\n");
+        if (!visited.contains(node)) {
+            visited.add(node);
+            for (T child : getChildren(node)) {
+                if (filter.test(child)) {
+                    printBF(child, writer, nodeInfo, filter, level + 1, visited);
+                }
+            }
+        }
+    }
 }

dmn-core/src/test/java/com/gs/dmn/GraphTest.java

@@ -15,6 +15,8 @@
 import com.gs.dmn.runtime.Pair;
 import org.junit.jupiter.api.Test;
 
+import java.io.IOException;
+import java.io.StringWriter;
 import java.util.List;
 import java.util.Set;
 
@@ -133,4 +135,46 @@ void testFindCyclesWhenSelfLoop() {
 
         assertEquals(List.of(List.of(1, 1)), graph.findCycles());
     }
+
+    @Test
+    void testPrintNodes() throws IOException {
+        Graph<Integer> graph = new Graph<>();
+        graph.addEdge(1, 2);
+        graph.addEdge(2, 3);
+        graph.addEdge(3, 1); // Cycle 1-2-3-1
+        graph.addEdge(3, 4);
+        graph.addEdge(4, 2); // Cycle 2-3-4-2
+
+        StringWriter writer = new StringWriter();
+        graph.printNodes(writer, this::nodeInfo);
+        String expectedNodes = "1\n2\n3\n4\n";
+        assertEquals(expectedNodes, writer.getBuffer().toString());
+    }
+
+    @Test
+    void testPrintTree() {
+        Graph<Integer> graph = new Graph<>();
+        graph.addEdge(1, 2);
+        graph.addEdge(2, 3);
+        graph.addEdge(3, 1); // Cycle 1-2-3-1
+        graph.addEdge(3, 4);
+        graph.addEdge(4, 2); // Cycle 2-3-4-2
+
+        StringWriter writer = new StringWriter();
+        graph.printBF(1, writer, this::nodeInfo);
+        String expectedNodes =
+                """
+                        1
+                        \t2
+                        \t\t3
+                        \t\t\t1
+                        \t\t\t4
+                        \t\t\t\t2
+                        """;
+        assertEquals(expectedNodes, writer.getBuffer().toString());
+    }
+
+    private String nodeInfo(Integer node) {
+        return "" + node;
+    }
 }