Make IsEmptyCallOnCollections also support < and > operators

The expressions `c.size() > 0` and `0 < c.size()` can both also be replaced with `!c.isEmpty()`.
openrewrite · Jan 8, 2023 · a04fdda · a04fdda
1 parent cb9654e
commit a04fdda
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Showing 2 changed files with 18 additions and 8 deletions.
diff --git a/...te-java-test/src/test/java/org/openrewrite/java/cleanup/IsEmptyCallOnCollectionsTest.java b/...te-java-test/src/test/java/org/openrewrite/java/cleanup/IsEmptyCallOnCollectionsTest.java
@@ -76,6 +76,10 @@ static void method(List<String> l) {
                           // empty body
                       } else if (l.size() != 0 || 0 != l.size()) {
                           // empty body
+                      } else if (l.size() > 0 || l.size() < 0) {
+                          // empty body
+                      } else if (0 < l.size() || 0 > l.size()) {
+                          // empty body
                       }
                   }
               }
@@ -89,6 +93,10 @@ static void method(List<String> l) {
                           // empty body
                       } else if (!l.isEmpty() || !l.isEmpty()) {
                           // empty body
+                      } else if (!l.isEmpty() || l.size() < 0) {
+                          // empty body
+                      } else if (!l.isEmpty() || 0 > l.size()) {
+                          // empty body
                       }
                   }
               }

diff --git a/rewrite-java/src/main/java/org/openrewrite/java/cleanup/IsEmptyCallOnCollections.java b/rewrite-java/src/main/java/org/openrewrite/java/cleanup/IsEmptyCallOnCollections.java
@@ -68,15 +68,17 @@ public JavaVisitor<ExecutionContext> getVisitor() {
 
             @Override
             public J visitBinary(J.Binary binary, ExecutionContext ctx) {
-                if (binary.getOperator() == J.Binary.Type.Equal || binary.getOperator() == J.Binary.Type.NotEqual) {
-                    if (COLLECTION_SIZE.matches(binary.getLeft()) || COLLECTION_SIZE.matches(binary.getRight())) {
-                        if (isZero(binary.getLeft()) || isZero(binary.getRight())) {
-                            J.MethodInvocation sizeCall = (J.MethodInvocation) (COLLECTION_SIZE.matches(binary.getLeft()) ?
-                                    binary.getLeft() : binary.getRight());
+                if (isZero(binary.getLeft()) || isZero(binary.getRight())) {
+                    boolean zeroRight = isZero(binary.getRight());
+                    J.MethodInvocation maybeSizeCall = (J.MethodInvocation) (zeroRight ? binary.getLeft() : binary.getRight());
+                    if (binary.getOperator() == J.Binary.Type.Equal || binary.getOperator() == J.Binary.Type.NotEqual
+                        || zeroRight && binary.getOperator() == J.Binary.Type.GreaterThan
+                        || !zeroRight && binary.getOperator() == J.Binary.Type.LessThan) {
+                        if (COLLECTION_SIZE.matches(maybeSizeCall)) {
                             String op = binary.getOperator() == J.Binary.Type.Equal ? "" : "!";
-                            return (sizeCall.getSelect() == null ?
-                                sizeCall.withTemplate(isEmptyNoReceiver, sizeCall.getCoordinates().replace(), op) :
-                                sizeCall.withTemplate(isEmpty, sizeCall.getCoordinates().replace(), op, sizeCall.getSelect())
+                            return (maybeSizeCall.getSelect() == null ?
+                                    maybeSizeCall.withTemplate(isEmptyNoReceiver, maybeSizeCall.getCoordinates().replace(), op) :
+                                    maybeSizeCall.withTemplate(isEmpty, maybeSizeCall.getCoordinates().replace(), op, maybeSizeCall.getSelect())
                             ).withPrefix(binary.getPrefix());
                         }
                     }