add checks before calling next() when evaluating path segments

fixes #1089

(cherry picked from commit a955c63)

morphia/src/main/java/org/mongodb/morphia/internal/PathTarget.java

@@ -34,6 +34,7 @@
  * @since 1.3
  */
 public class PathTarget {
+    private final String path;
     private final List<String> segments;
     private boolean validateNames = true;
     private int position;
@@ -54,6 +55,7 @@ public PathTarget(final Mapper mapper, final MappedClass root, final String path
         this.root = root;
         segments = asList(path.split("\\."));
         this.mapper = mapper;
+        this.path = path;
     }
 
     /**
@@ -104,6 +106,9 @@ private void resolve() {
             String segment = next();
 
             if (segment.equals("$") || segment.matches("[0-9]+")) {  // array operator
+                if (!hasNext()) {
+                    throw new ValidationException("The given path is invalid: " + path);
+                }
                 segment = next();
             }
             field = resolveField(segment);
@@ -112,7 +117,9 @@ private void resolve() {
                 if (!field.isMap()) {
                     translate(field.getNameToStore());
                 } else {
-                    next();  // consume the map key segment
+                    if (hasNext()) {
+                        next();  // consume the map key segment
+                    }
                 }
             } else {
                 if (validateNames) {

morphia/src/test/java/org/mongodb/morphia/TestUpdateOps.java

@@ -33,11 +33,14 @@
 import org.mongodb.morphia.query.UpdateOpsImpl;
 import org.mongodb.morphia.query.UpdateResults;
 import org.mongodb.morphia.query.ValidationException;
+import org.mongodb.morphia.testmodel.Article;
 import org.mongodb.morphia.testmodel.Circle;
 import org.mongodb.morphia.testmodel.Rectangle;
+import org.mongodb.morphia.testmodel.Translation;
 
 import java.util.ArrayList;
 import java.util.Date;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
@@ -655,23 +658,31 @@ public void testSetOnInsertWhenUpdating() throws Exception {
 
     @Test
     public void testSetUnset() throws Exception {
-        final Key<Circle> key = getDs().save(new Circle(1));
+        Datastore ds = getDs();
+        final Key<Circle> key = ds.save(new Circle(1));
 
-        UpdateResults res = getDs().updateFirst(getDs().find(Circle.class).filter("radius", 1D),
-                                                getDs().createUpdateOperations(Circle.class).set("radius", 2D));
+        assertUpdated(ds.updateFirst(ds.find(Circle.class).filter("radius", 1D),
+                                     ds.createUpdateOperations(Circle.class).set("radius", 2D)), 1);
 
-        assertUpdated(res, 1);
+        assertThat(ds.getByKey(Circle.class, key).getRadius(), is(2D));
 
-        final Circle c = getDs().getByKey(Circle.class, key);
-        assertThat(c.getRadius(), is(2D));
 
+        assertUpdated(ds.updateFirst(ds.find(Circle.class).filter("radius", 2D),
+                                     ds.createUpdateOperations(Circle.class).unset("radius")), 1);
 
-        res = getDs().updateFirst(getDs().find(Circle.class).filter("radius", 2D),
-                                  getDs().createUpdateOperations(Circle.class).unset("radius"));
-        assertUpdated(res, 1);
+        assertThat(ds.getByKey(Circle.class, key).getRadius(), is(0D));
+
+        Article article = new Article();
+
+        ds.save(article);
+
+        ds.update(ds.find(Article.class),
+                  ds.createUpdateOperations(Article.class)
+                 .set("translations", new HashMap<String, Translation>()));
 
-        final Circle c2 = getDs().getByKey(Circle.class, key);
-        assertThat(c2.getRadius(), is(0D));
+        ds.update(ds.find(Article.class),
+                  ds.createUpdateOperations(Article.class)
+                 .unset("translations"));
     }
 
     @Test

morphia/src/test/java/org/mongodb/morphia/internal/PathTargetTest.java

@@ -31,6 +31,10 @@
 import org.mongodb.morphia.mapping.EmbeddedMappingTest.WithNested;
 import org.mongodb.morphia.mapping.MappedClass;
 import org.mongodb.morphia.mapping.Mapper;
+import org.mongodb.morphia.query.ValidationException;
+import org.mongodb.morphia.testmodel.Article;
+
+import static org.junit.Assert.fail;
 
 public class PathTargetTest extends TestBase {
 
@@ -78,17 +82,33 @@ public void arrays() {
         PathTarget pathTarget = new PathTarget(mapper, mappedClass, "listEmbeddedType.1.number");
         Assert.assertEquals("listEmbeddedType.1.number", pathTarget.translatedPath());
         Assert.assertEquals(mapper.getMappedClass(EmbeddedType.class).getMappedFieldByJavaField("number"), pathTarget.getTarget());
+
+        try {
+            new PathTarget(mapper, mappedClass, "listEmbeddedType.$").translatedPath();
+            fail("The dangling $ should have failed.");
+        } catch (ValidationException ignored) {
+
+        }
+
+        try {
+            new PathTarget(mapper, mappedClass, "listEmbeddedType.1").translatedPath();
+            fail("The dangling 1 should have failed.");
+        } catch (ValidationException ignored) {
+        }
     }
 
     @Test
     public void maps() {
-        getMorphia().map(Student.class);
+        getMorphia().map(Student.class, Article.class);
         Mapper mapper = getMorphia().getMapper();
         MappedClass mappedClass = mapper.getMappedClass(Student.class);
 
-        final PathTarget pathTarget = new PathTarget(mapper, mappedClass, "grades.$.data.name");
+        PathTarget pathTarget = new PathTarget(mapper, mappedClass, "grades.$.data.name");
         Assert.assertEquals("grades.$.data.name", pathTarget.translatedPath());
         Assert.assertEquals(mapper.getMappedClass(Grade.class).getMappedFieldByJavaField("data"), pathTarget.getTarget());
+
+        pathTarget = new PathTarget(mapper, mapper.getMappedClass(Article.class), "translations");
+        Assert.assertEquals("translations", pathTarget.translatedPath());
     }
 
     @Test