support * notation for all types of link traversals #323

dashjoin-core/src/main/java/org/dashjoin/util/OpenCypher.java

@@ -34,6 +34,8 @@ static class Relation {
     String name;
     String variable;
     Boolean left2right;
+    Integer from;
+    Integer to;
   }
 
   /**
@@ -81,7 +83,6 @@ Table parseTable(OpenCypherQuery.Table t) {
    * query constructor - parsing is done in old code
    */
   public OpenCypher(OpenCypherQuery query) {
-    System.out.println(query);
     this.query = query;
 
     patterns = new ArrayList<>();
@@ -103,6 +104,13 @@ public OpenCypher(OpenCypherQuery query) {
       p.right = parseTable(i.table);
       p.right.key = i.table.key;
       p.right.value = i.table.value;
+      if (i.edge.star) {
+        p.relation.from = i.edge.from == null ? 1 : i.edge.from;
+        p.relation.to = i.edge.to == null ? 5 : i.edge.to;
+      } else {
+        p.relation.from = 1;
+        p.relation.to = 1;
+      }
       left = p.right;
     }
     patterns.get(patterns.size() - 1).isLast = true;
@@ -149,20 +157,56 @@ class Path {
     List<Binding> bindings;
 
     boolean isSolution() {
+      Pattern last = bindings.get(bindings.size() - 1).pattern;
+      if (last.isLast)
+        if (last.relation != null)
+          if (numberOfMatches() < last.relation.from)
+            return false;
       return bindings.get(bindings.size() - 1).pattern.isLast;
     }
 
+    /**
+     * how often did the last pattern match
+     */
+    int numberOfMatches() {
+
+      Pattern last = bindings.get(bindings.size() - 1).pattern;
+
+      int count = 0;
+      for (Binding b : bindings)
+        if (b.pattern == last)
+          count++;
+
+      return count;
+    }
+
     /**
      * given the current partial result, return the list of possible next patterns to traverse. This
      * can be a list, because there are constructs like "traverse this link 1 or 2 times"
      */
     List<Pattern> candidatePatterns() {
-      // TODO: only take next pattern for now
-      Pattern next = bindings.get(bindings.size() - 1).pattern.next;
-      if (next == null)
-        return Arrays.asList();
-      else
+
+      Pattern last = bindings.get(bindings.size() - 1).pattern;
+      Pattern next = last.next;
+
+      int count = 0;
+      for (Binding b : bindings)
+        if (b.pattern == last)
+          count++;
+
+      if (last.relation == null)
+        // we are at the start, return next if there is one
         return Arrays.asList(next);
+
+      if (last.relation.from < count)
+        // we still need more edges with this relation
+        return Arrays.asList(last);
+
+      if (count < last.relation.to)
+        // we can either add another hop of the last relation or jump to the next
+        return Arrays.asList(last, next);
+
+      return Arrays.asList(next);
     }
 
     /**
@@ -187,6 +231,8 @@ void search(List<Map<String, Object>> res) throws Exception {
         res.add(OpenCypher.this.query.project(r, path));
       }
       for (Pattern pattern : candidatePatterns()) {
+        if (pattern == null)
+          continue;
         Binding b = bindings.get(bindings.size() - 1);
 
         if (pattern.relation.left2right == null || pattern.relation.left2right) {

dashjoin-core/src/main/java/org/dashjoin/util/OpenCypherQuery.java

@@ -240,7 +240,7 @@ public static class Step {
     public Map<String, Object> edge;
   }
 
-  public boolean newEngine = false;
+  public boolean newEngine = true;
 
   /**
    * name of the path variable: MATCH path=(...

dashjoin-core/src/test/java/org/dashjoin/util/OpenCypherQueryTest.java

@@ -7,7 +7,6 @@
 import org.dashjoin.service.Services;
 import org.dashjoin.util.OpenCypherQuery.Table;
 import org.junit.jupiter.api.Assertions;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentMatchers;
 import org.mockito.Mockito;
@@ -283,18 +282,17 @@ public void testRange() throws Exception {
     Assertions.assertEquals("[{from.ID=4, to.ID=1}]", res.toString());
   }
 
-  @Disabled
   @Test
   public void testRange2() throws Exception {
     List<Map<String, Object>> res =
         run("MATCH (from:`dj/junit/NODE`)<-[*]-(to) RETURN from.ID, to.ID");
     Assertions.assertEquals(4, res.size());
 
     res = run("MATCH (from:`dj/junit/NODE` {ID:1})<-[*2..2]-(to) RETURN from.ID, to.ID");
-    Assertions.assertEquals("[{from.ID=4, to.ID=1}]", res.toString());
+    Assertions.assertEquals("[{from.ID=1, to.ID=4}]", res.toString());
 
     res = run(
-        "MATCH (from:`dj/junit/NODE` {ID:4})<-[dj/junit/NODE/REL`*2..2]-(to) RETURN from.ID, to.ID");
-    Assertions.assertEquals("[{from.ID=4, to.ID=1}]", res.toString());
+        "MATCH (from:`dj/junit/NODE` {ID:1})<-[`dj/junit/NODE/REL`*2..2]-(to) RETURN from.ID, to.ID");
+    Assertions.assertEquals("[{from.ID=1, to.ID=4}]", res.toString());
   }
 }