Fix renames rewriter

Signed-off-by: Dimitry Solovyov <dimitry@solovyov.lv>
opencypher · Jun 4, 2018 · d1e6263 · d1e6263
1 parent 0aaf444
commit d1e6263
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Showing 2 changed files with 38 additions and 2 deletions.
diff --git a/...src/main/scala/org/opencypher/gremlin/translation/ir/rewrite/SimplifyRenamedAliases.scala b/...src/main/scala/org/opencypher/gremlin/translation/ir/rewrite/SimplifyRenamedAliases.scala
@@ -26,10 +26,33 @@ import org.opencypher.gremlin.translation.ir.model._
 object SimplifyRenamedAliases extends GremlinRewriter {
 
   override def apply(steps: Seq[GremlinStep]): Seq[GremlinStep] = {
+    splitAfter({
+      case MapT(Project(_*) :: _) => true
+      case Project(_*)            => true
+      case _                      => false
+    })(steps)
+      .flatMap(rewriteSegment)
+  }
+
+  private def rewriteSegment(steps: Seq[GremlinStep]): Seq[GremlinStep] = {
+    // Find all step labels of vertex start steps
+    val startLabels = extract({
+      case Vertex :: As(asLabel) :: WhereT(SelectK(selectLabel) :: WhereP(Eq(_)) :: Nil) :: _
+          if asLabel == selectLabel =>
+        None
+      case Vertex :: As(stepLabel) :: _ =>
+        Some(stepLabel)
+    })(steps).flatten.toSet
+
     mapTraversals(replace({
       case Vertex :: As(asLabel) :: WhereT(SelectK(selectLabel) :: WhereP(Eq(eqLabel: String)) :: Nil) :: rest
           if asLabel == selectLabel =>
-        SelectK(eqLabel) :: Is(Neq(NULL)) :: rest
+        if (startLabels.contains(eqLabel)) {
+          // Vertex traverser should be non-null
+          SelectK(eqLabel) :: rest
+        } else {
+          SelectK(eqLabel) :: Is(Neq(NULL)) :: rest
+        }
     }))(steps)
   }
 }
diff --git a/...n/src/test/java/org/opencypher/gremlin/translation/ir/rewrite/SimplifyRenamedAliases.java b/...n/src/test/java/org/opencypher/gremlin/translation/ir/rewrite/SimplifyRenamedAliases.java
@@ -44,6 +44,19 @@ public void whereMatchPattern() {
             .withFlavor(flavor)
             .rewritingWith(SimplifyRenamedAliases$.MODULE$)
             .removes(__().V().as("  GENERATED1").where(__().select("  GENERATED1").where(P.isEq("n"))).outE())
-            .adds(__().select("n").is(P.neq(NULL)).outE());
+            .adds(__().select("n").outE());
+    }
+
+    @Test
+    public void whereNonStartMatchPattern() {
+        assertThat(parse(
+            "MATCH (n)-->(m) " +
+                "WHERE (m)-->(:L) " +
+                "RETURN m"
+        ))
+            .withFlavor(flavor)
+            .rewritingWith(SimplifyRenamedAliases$.MODULE$)
+            .removes(__().V().as("  GENERATED1").where(__().select("  GENERATED1").where(P.isEq("m"))).outE())
+            .adds(__().select("m").is(P.neq(NULL)).outE());
     }
 }