dot export: escape \ (#356)

* only logInfo about existing storage if it's non-empty

* dot export: escape `\`

https://discord.com/channels/832209896089976854/832209896089976857/1075959071976464464

* fixup imports

Author: mpollmeier

core/src/main/java/overflowdb/Graph.java

@@ -93,7 +93,10 @@ private Graph(Config config,
   private void initElementCollections(OdbStorage storage) {
     long start = System.currentTimeMillis();
     final Set<Map.Entry<Long, byte[]>> serializedNodes = storage.allNodes();
-    logger.info(String.format("initializing %d nodes from existing storage", serializedNodes.size()));
+    final int serializedNodesCount = serializedNodes.size();
+    if (serializedNodesCount > 0) {
+      logger.info(String.format("initializing %d nodes from existing storage", serializedNodesCount));
+    }
     int importCount = 0;
     long maxId = currentId.get();
 

formats/src/main/scala/overflowdb/formats/dot/DotExporter.scala

@@ -71,8 +71,9 @@ object DotExporter extends Exporter {
   private def encodePropertyValue(value: Object): String = {
     value match {
       case value: String =>
-        // escape double quotes, because we use them to enclose strings
-        val escaped = value.replace("\"", "\\\"")
+        val escaped = value
+          .replace("""\""", """\\""") // escape escape chars - this should come first
+          .replace("\"", "\\\"") // escape double quotes, because we use them to enclose strings
         s"\"$escaped\""
       case list if iterableForList.isDefinedAt(list) =>
         val values = iterableForList(list).mkString(";")

formats/src/test/scala/overflowdb/formats/dot/DotTests.scala

@@ -14,7 +14,7 @@ class DotTests extends AnyWordSpec {
   "Exporter should export valid dot" in {
     val graph = SimpleDomain.newGraph()
 
-    val node2 = graph.addNode(2, TestNode.LABEL, TestNode.STRING_PROPERTY, "string\"Prop2")
+    val node2 = graph.addNode(2, TestNode.LABEL, TestNode.STRING_PROPERTY, """string"Prop2\""")
     val node3 = graph.addNode(3, TestNode.LABEL, TestNode.INT_PROPERTY, 13)
 
     // only allows values defined in FunkyList.funkyWords
@@ -24,7 +24,7 @@ class DotTests extends AnyWordSpec {
     val node1 = graph.addNode(1, TestNode.LABEL,
       TestNode.INT_PROPERTY, 11,
       TestNode.STRING_PROPERTY, "<stringProp1>",
-      TestNode.STRING_LIST_PROPERTY, List("stringListProp1a", "stringListProp1b").asJava,
+      TestNode.STRING_LIST_PROPERTY, List("stringListProp1a", "stringList\\Prop1b").asJava,
       TestNode.FUNKY_LIST_PROPERTY, funkyList,
       TestNode.INT_LIST_PROPERTY, List(21, 31, 41).asJava,
     )
@@ -42,9 +42,9 @@ class DotTests extends AnyWordSpec {
       withClue(s"actual result was: `$result`") {
         result shouldBe
           """digraph {
-             |  2 [label=testNode StringProperty="string\"Prop2"]
+             |  2 [label=testNode StringProperty="string\"Prop2\\"]
              |  3 [label=testNode StringProperty="DEFAULT_STRING_VALUE" IntProperty=13]
-             |  1 [label=testNode FunkyListProperty="apoplectic;bucolic" StringProperty="<stringProp1>" StringListProperty="stringListProp1a;stringListProp1b" IntProperty=11 IntListProperty="21;31;41"]
+             |  1 [label=testNode FunkyListProperty="apoplectic;bucolic" StringProperty="<stringProp1>" StringListProperty="stringListProp1a;stringList\Prop1b" IntProperty=11 IntListProperty="21;31;41"]
              |  2 -> 3 [label=testEdge longProperty=-99]
              |  1 -> 2 [label=testEdge longProperty=9223372036854775807]
              |}""".stripMargin.trim