feat: add aghead and agtail (#105)

cgraph/cgraph.go

@@ -528,6 +528,22 @@ func (e *Edge) SetNode(v *Node) {
 	e.wasm.SetNode(v.getWasm())
 }
 
+func (e *Edge) Head() (*Node, error) {
+	n, err := e.wasm.Head(context.Background())
+	if err != nil {
+		return nil, err
+	}
+	return toNode(n), nil
+}
+
+func (e *Edge) Tail() (*Node, error) {
+	n, err := e.wasm.Tail(context.Background())
+	if err != nil {
+		return nil, err
+	}
+	return toNode(n), nil
+}
+
 func (c *CommonFields) Disc() *Disc {
 	return toDisc(c.wasm.GetDisc())
 }

graphviz_test.go

@@ -288,3 +288,65 @@ func TestNodeDegree(t *testing.T) {
 		}
 	}
 }
+
+func TestEdgeSourceAndTarget(t *testing.T) {
+	ctx := context.Background()
+	graph, err := graphviz.New(ctx)
+	if err != nil {
+		t.Fatalf("Error: %+v", err)
+	}
+
+	g, err := graph.Graph()
+	if err != nil {
+		t.Fatalf("Error: %+v", err)
+	}
+
+	nodeA, err := g.CreateNodeByName("a")
+	if err != nil {
+		t.Fatalf("Error: %+v", err)
+	}
+
+	nodeB, err := g.CreateNodeByName("b")
+	if err != nil {
+		t.Fatalf("Error: %+v", err)
+	}
+
+	edge, err := g.CreateEdgeByName("edge", nodeA, nodeB)
+	if err != nil {
+		t.Fatalf("Error: %+v", err)
+	}
+
+	head, err := edge.Head()
+	if err != nil {
+		t.Fatalf("Error: %+v", err)
+	}
+	if head == nil {
+		t.Fatalf("Source is nil")
+	}
+
+	headName, err := head.Name()
+	if err != nil {
+		t.Fatalf("Error: %+v", err)
+	}
+
+	if headName != "b" {
+		t.Fatalf("Expected source name to be 'b', got '%s'", headName)
+	}
+
+	target, err := edge.Tail()
+	if err != nil {
+		t.Fatalf("Error: %+v", err)
+	}
+	if target == nil {
+		t.Fatalf("Target is nil")
+	}
+
+	tailName, err := target.Name()
+	if err != nil {
+		t.Fatalf("Error: %+v", err)
+	}
+
+	if tailName != "a" {
+		t.Fatalf("Expected target name to be 'a', got '%s'", tailName)
+	}
+}

internal/wasm/bind.proto

@@ -690,6 +690,26 @@ option (nori.file).export = {
       pointer: 1
     }
   }
+  method {
+    recv: "Edge"
+    name: "head"
+    alias: "aghead"
+    return {
+      kind: STRUCT
+      ref: "Node"
+      pointer: 1
+    }
+  }
+  method {
+    recv: "Edge"
+    name: "tail"
+    alias: "agtail"
+    return {
+      kind: STRUCT
+      ref: "Node"
+      pointer: 1
+    }
+  }
   method {
     recv: "Graph"
     name: "idEdge"

internal/wasm/build/bind.c

@@ -5690,6 +5690,26 @@ void wasm_bridge_Graph_edge(void * _arg0, void * _arg1, void * _arg2, void * _ar
   *_arg5 = v;
 }
 
+void wasm_bridge_Edge_head(void * _arg0, void ** _arg1) {
+  Agedge_t * arg0;
+  arg0 = (Agedge_t *)_arg0;
+  Agnode_t * ret = aghead(
+    arg0
+  );
+  Agnode_t * v = (Agnode_t *)ret;
+  *_arg1 = v;
+}
+
+void wasm_bridge_Edge_tail(void * _arg0, void ** _arg1) {
+  Agedge_t * arg0;
+  arg0 = (Agedge_t *)_arg0;
+  Agnode_t * ret = agtail(
+    arg0
+  );
+  Agnode_t * v = (Agnode_t *)ret;
+  *_arg1 = v;
+}
+
 void wasm_bridge_Graph_idEdge(void * _arg0, void * _arg1, void * _arg2, unsigned long long int _arg3, int _arg4, void ** _arg5) {
   Agraph_t * arg0;
   arg0 = (Agraph_t *)_arg0;