Consistent return of None across all metrics if either argument is empty.

4 files changed, 10 insertions, 12 deletions

diff --git a/core/source/core/scala/org/hashtree/stringmetric/similarity/LevenshteinMetric.scala b/core/source/core/scala/org/hashtree/stringmetric/similarity/LevenshteinMetric.scala
index 90bb060..945a240 100755
--- a/core/source/core/scala/org/hashtree/stringmetric/similarity/LevenshteinMetric.scala
+++ b/core/source/core/scala/org/hashtree/stringmetric/similarity/LevenshteinMetric.scala
@@ -10,11 +10,10 @@ object LevenshteinMetric extends StringMetric with FilterableStringMetric {
 		(implicit stringFilter: StringFilter): Option[CompareReturn] = {
 
 		val fca1 = stringFilter.filter(charArray1)
-		val fca2 = stringFilter.filter(charArray2)
+		lazy val fca2 = stringFilter.filter(charArray2)
 
-		if (fca1.length == 0 && fca2.length == 0) None
-		else if (fca1.length == 0) Some(fca2.length)
-		else if (fca2.length == 0) Some(fca1.length)
+		if (fca1.length == 0 || fca2.length == 0) None
+		else if (fca1.sameElements(fca2)) Some(0)
 		else Some(levenshtein(fca1, fca2))
 	}
 
diff --git a/core/source/core/scala/org/hashtree/stringmetric/similarity/WeightedLevenshteinMetric.scala b/core/source/core/scala/org/hashtree/stringmetric/similarity/WeightedLevenshteinMetric.scala
index dc16c86..0277430 100755
--- a/core/source/core/scala/org/hashtree/stringmetric/similarity/WeightedLevenshteinMetric.scala
+++ b/core/source/core/scala/org/hashtree/stringmetric/similarity/WeightedLevenshteinMetric.scala
@@ -18,11 +18,9 @@ object WeightedLevenshteinMetric
 			throw new IllegalArgumentException("Expected valid weight options.")
 
 		val fca1 = stringFilter.filter(charArray1)
-		val fca2 = stringFilter.filter(charArray2)
+		lazy val fca2 = stringFilter.filter(charArray2)
 
-		if (fca1.length == 0 && fca2.length == 0) None
-		else if (fca1.length == 0) Some((options._2 * fca2.length).toDouble)
-		else if (fca2.length == 0) Some((options._1 * fca1.length).toDouble)
+		if (fca1.length == 0 || fca2.length == 0) None
 		else if (fca1.sameElements(fca2)) Some(0d)
 		else Some(weightedLevenshtein((fca1, fca2), options).toDouble)
 	}
diff --git a/core/source/test/scala/org/hashtree/stringmetric/similarity/LevenshteinMetricSpec.scala b/core/source/test/scala/org/hashtree/stringmetric/similarity/LevenshteinMetricSpec.scala
index 4a56dcb..c8b5336 100755
--- a/core/source/test/scala/org/hashtree/stringmetric/similarity/LevenshteinMetricSpec.scala
+++ b/core/source/test/scala/org/hashtree/stringmetric/similarity/LevenshteinMetricSpec.scala
@@ -11,6 +11,8 @@ final class LevenshteinMetricSpec extends ScalaTest {
 			"empty arguments" should returns {
 				"None" in {
 					LevenshteinMetric.compare("", "").isDefined should be (false)
+					LevenshteinMetric.compare("abc", "").isDefined should be (false)
+					LevenshteinMetric.compare("", "xyz").isDefined should be (false)
 				}
 			}
 			"equal arguments" should returns {
@@ -21,8 +23,6 @@ final class LevenshteinMetricSpec extends ScalaTest {
 			}
 			"unequal arguments" should returns {
 				"Int indicating distance" in {
-					LevenshteinMetric.compare("abc", "").get should be (3)
-					LevenshteinMetric.compare("", "xyz").get should be (3)
 					LevenshteinMetric.compare("abc", "xyz").get should be (3)
 					LevenshteinMetric.compare("123", "456").get should be (3)
 				}
diff --git a/core/source/test/scala/org/hashtree/stringmetric/similarity/WeightedLevenshteinMetricSpec.scala b/core/source/test/scala/org/hashtree/stringmetric/similarity/WeightedLevenshteinMetricSpec.scala
index 64dec2a..c5f946e 100755
--- a/core/source/test/scala/org/hashtree/stringmetric/similarity/WeightedLevenshteinMetricSpec.scala
+++ b/core/source/test/scala/org/hashtree/stringmetric/similarity/WeightedLevenshteinMetricSpec.scala
@@ -13,6 +13,8 @@ final class WeightedLevenshteinMetricSpec extends ScalaTest {
 			"empty arguments" should returns {
 				"None" in {
 					WeightedLevenshteinMetric.compare("", "")(Options).isDefined should be (false)
+					WeightedLevenshteinMetric.compare("abc", "")(Options).isDefined should be (false)
+					WeightedLevenshteinMetric.compare("", "xyz")(Options).isDefined should be (false)
 				}
 			}
 			"equal arguments" should returns {
@@ -23,8 +25,7 @@ final class WeightedLevenshteinMetricSpec extends ScalaTest {
 			}
 			"unequal arguments" should returns {
 				"Double indicating distance" in {
-					WeightedLevenshteinMetric.compare("abc", "")(Options).get should be (30)
-					WeightedLevenshteinMetric.compare("", "xyz")(Options).get should be (0.3)
+					WeightedLevenshteinMetric.compare("abc", "xyz")(Options).get should be (3)
 					WeightedLevenshteinMetric.compare("123", "456")(Options).get should be (3)
 				}
 			}