Expand SimplifyBooleanExpressionVisitor to include String comparisons

For openrewrite/rewrite-feature-flags#40
openrewrite · Dec 18, 2024 · 2882fdc · 2882fdc
1 parent 65c9cf1
commit 2882fdc
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diff --git a/...test/src/test/java/org/openrewrite/java/cleanup/SimplifyBooleanExpressionVisitorTest.java b/...test/src/test/java/org/openrewrite/java/cleanup/SimplifyBooleanExpressionVisitorTest.java
@@ -733,4 +733,37 @@ void foo(String a) {
             rewriteRun(java(beforeJava, template.formatted(after)));
         }
     }
+
+    @Issue("https://github.com/openrewrite/rewrite-feature-flags/issues/40")
+    @Test
+    void simplifyStringLiteralEqualsStringLiteral() {
+        rewriteRun(
+          java(
+            """
+              class A {
+                  {
+                      String foo = "foo";
+                      if ("foo".equals("foo")) {}
+                      if (foo.equals(foo)) {}
+                      if (foo.equals("foo")) {}
+                      if ("foo".equals(foo)) {}
+                      if ("foo".equals("bar")) {}
+                  }
+              }
+              """,
+            """
+              class A {
+                  {
+                      String foo = "foo";
+                      if (true) {}
+                      if (true) {}
+                      if (foo.equals("foo")) {}
+                      if ("foo".equals(foo)) {}
+                      if (false) {}
+                  }
+              }
+              """
+          )
+        );
+    }
 }
diff --git a/...ite-java/src/main/java/org/openrewrite/java/cleanup/SimplifyBooleanExpressionVisitor.java b/...ite-java/src/main/java/org/openrewrite/java/cleanup/SimplifyBooleanExpressionVisitor.java
@@ -240,6 +240,7 @@ private J.Binary.Type maybeNegate(J.Binary.Type operator) {
     }
 
     private final MethodMatcher isEmpty = new MethodMatcher("java.lang.String isEmpty()");
+    private final MethodMatcher equals = new MethodMatcher("java.lang.String equals(java.lang.Object)");
 
     @Override
     public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext executionContext) {
@@ -250,6 +251,15 @@ public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext execu
             select instanceof J.Literal &&
             select.getType() == JavaType.Primitive.String) {
             return booleanLiteral(method, J.Literal.isLiteralValue(select, ""));
+        } else if (equals.matches(asMethod)) {
+            Expression arg = asMethod.getArguments().get(0);
+            if (arg instanceof J.Literal && select instanceof J.Literal) {
+                return booleanLiteral(method, ((J.Literal) select).getValue().equals(((J.Literal) arg).getValue()));
+            } else if (arg instanceof J.Identifier && select instanceof J.Identifier) {
+                return booleanLiteral(method, SemanticallyEqual.areEqual(select, arg));
+            } if (arg instanceof J.FieldAccess && select instanceof J.FieldAccess) {
+                return booleanLiteral(method, SemanticallyEqual.areEqual(select, arg));
+            }
         }
         return j;
     }