From 905a9317a2432beac987c6dba97c714fe67b0c42 Mon Sep 17 00:00:00 2001
From: Alexander Wang <alex@terrastruct.com>
Date: Mon, 26 Jun 2023 10:51:07 -0700
Subject: [PATCH] fix

---
 d2compiler/compile.go                         |   5 +
 d2graph/d2graph.go                            |  15 +-
 .../TestCompile2/nulls/basic/edge.exp.json    | 133 +++++++++++++++++-
 .../TestCompile2/nulls/reappear/edge.exp.json |   2 +-
 4 files changed, 152 insertions(+), 3 deletions(-)

diff --git a/d2compiler/compile.go b/d2compiler/compile.go
index 27f12ed28..d75ceb2f9 100644
--- a/d2compiler/compile.go
+++ b/d2compiler/compile.go
@@ -840,6 +840,11 @@ func (c *compiler) nullify(g *d2graph.Graph) {
 			g.DeleteObject(obj)
 		}
 	}
+	for _, e := range g.Edges {
+		if len(e.References) > 0 && e.References[len(e.References)-1].Nulled() {
+			g.DeleteEdge(e)
+		}
+	}
 }
 
 // TODO add more, e.g. C, bash
diff --git a/d2graph/d2graph.go b/d2graph/d2graph.go
index f86eb8f4e..e140542f1 100644
--- a/d2graph/d2graph.go
+++ b/d2graph/d2graph.go
@@ -95,6 +95,15 @@ func (g *Graph) DeleteObject(obj *Object) {
 	}
 }
 
+func (g *Graph) DeleteEdge(e *Edge) {
+	for i, e2 := range g.Edges {
+		if e == e2 {
+			g.Edges = append(g.Edges[:i], g.Edges[i+1:]...)
+			i--
+		}
+	}
+}
+
 type LayoutGraph func(context.Context, *Graph) error
 
 // TODO consider having different Scalar types
@@ -216,7 +225,7 @@ type Reference struct {
 }
 
 func (r *Reference) Nulled() bool {
-	return r.MapKey != nil && r.MapKey.Value.Null != nil
+	return r.MapKey != nil && len(r.MapKey.Edges) == 0 && r.MapKey.Value.Null != nil
 }
 
 func (r Reference) MapKeyEdgeDest() bool {
@@ -1146,6 +1155,10 @@ type EdgeReference struct {
 	ScopeAST        *d2ast.Map `json:"-"`
 }
 
+func (er *EdgeReference) Nulled() bool {
+	return er.MapKey != nil && er.MapKey.Value.Null != nil
+}
+
 func (e *Edge) GetAstEdge() *d2ast.Edge {
 	return e.References[0].Edge
 }
diff --git a/testdata/d2compiler/TestCompile2/nulls/basic/edge.exp.json b/testdata/d2compiler/TestCompile2/nulls/basic/edge.exp.json
index 842a64237..9f83b57fc 100644
--- a/testdata/d2compiler/TestCompile2/nulls/basic/edge.exp.json
+++ b/testdata/d2compiler/TestCompile2/nulls/basic/edge.exp.json
@@ -132,7 +132,138 @@
       "zIndex": 0
     },
     "edges": null,
-    "objects": null
+    "objects": [
+      {
+        "id": "a",
+        "id_val": "a",
+        "references": [
+          {
+            "key": {
+              "range": "d2/testdata/d2compiler/TestCompile2/nulls/basic/edge.d2,1:0:1-1:1:2",
+              "path": [
+                {
+                  "unquoted_string": {
+                    "range": "d2/testdata/d2compiler/TestCompile2/nulls/basic/edge.d2,1:0:1-1:1:2",
+                    "value": [
+                      {
+                        "string": "a",
+                        "raw_string": "a"
+                      }
+                    ]
+                  }
+                }
+              ]
+            },
+            "key_path_index": 0,
+            "map_key_edge_index": 0
+          },
+          {
+            "key": {
+              "range": "d2/testdata/d2compiler/TestCompile2/nulls/basic/edge.d2,2:1:9-2:2:10",
+              "path": [
+                {
+                  "unquoted_string": {
+                    "range": "d2/testdata/d2compiler/TestCompile2/nulls/basic/edge.d2,2:1:9-2:2:10",
+                    "value": [
+                      {
+                        "string": "a",
+                        "raw_string": "a"
+                      }
+                    ]
+                  }
+                }
+              ]
+            },
+            "key_path_index": 0,
+            "map_key_edge_index": 0
+          }
+        ],
+        "attributes": {
+          "label": {
+            "value": "a"
+          },
+          "labelDimensions": {
+            "width": 0,
+            "height": 0
+          },
+          "style": {},
+          "near_key": null,
+          "shape": {
+            "value": "rectangle"
+          },
+          "direction": {
+            "value": ""
+          },
+          "constraint": null
+        },
+        "zIndex": 0
+      },
+      {
+        "id": "b",
+        "id_val": "b",
+        "references": [
+          {
+            "key": {
+              "range": "d2/testdata/d2compiler/TestCompile2/nulls/basic/edge.d2,1:5:6-1:6:7",
+              "path": [
+                {
+                  "unquoted_string": {
+                    "range": "d2/testdata/d2compiler/TestCompile2/nulls/basic/edge.d2,1:5:6-1:6:7",
+                    "value": [
+                      {
+                        "string": "b",
+                        "raw_string": "b"
+                      }
+                    ]
+                  }
+                }
+              ]
+            },
+            "key_path_index": 0,
+            "map_key_edge_index": 0
+          },
+          {
+            "key": {
+              "range": "d2/testdata/d2compiler/TestCompile2/nulls/basic/edge.d2,2:6:14-2:7:15",
+              "path": [
+                {
+                  "unquoted_string": {
+                    "range": "d2/testdata/d2compiler/TestCompile2/nulls/basic/edge.d2,2:6:14-2:7:15",
+                    "value": [
+                      {
+                        "string": "b",
+                        "raw_string": "b"
+                      }
+                    ]
+                  }
+                }
+              ]
+            },
+            "key_path_index": 0,
+            "map_key_edge_index": 0
+          }
+        ],
+        "attributes": {
+          "label": {
+            "value": "b"
+          },
+          "labelDimensions": {
+            "width": 0,
+            "height": 0
+          },
+          "style": {},
+          "near_key": null,
+          "shape": {
+            "value": "rectangle"
+          },
+          "direction": {
+            "value": ""
+          },
+          "constraint": null
+        },
+        "zIndex": 0
+      }
+    ]
   },
   "err": null
 }
diff --git a/testdata/d2compiler/TestCompile2/nulls/reappear/edge.exp.json b/testdata/d2compiler/TestCompile2/nulls/reappear/edge.exp.json
index 21b584215..726082f0e 100644
--- a/testdata/d2compiler/TestCompile2/nulls/reappear/edge.exp.json
+++ b/testdata/d2compiler/TestCompile2/nulls/reappear/edge.exp.json
@@ -179,7 +179,7 @@
     },
     "edges": [
       {
-        "index": 0,
+        "index": 1,
         "isCurve": false,
         "src_arrow": false,
         "dst_arrow": true,