Simplify Ternary expressions [#203] (#231)

* Simplify Ternary expressions [#203]

* Demonstrate shortcoming with test & partial fix

* Update expectations following change in rewrite

* Add additional test cases; last of which fails currently

* Now expect unwrapped inverted boolean method

* Split tests between changed and unchanged

* Apply suggestions from code review

---------

Co-authored-by: Tim te Beek <[email protected]>
Co-authored-by: Tim te Beek <[email protected]>

build.gradle.kts

@@ -20,6 +20,12 @@ dependencies {
     implementation("org.openrewrite.meta:rewrite-analysis:${rewriteVersion}")
     implementation("org.apache.commons:commons-text:latest.release")
 
+    annotationProcessor("org.openrewrite:rewrite-templating:${rewriteVersion}")
+    implementation("org.openrewrite:rewrite-templating:${rewriteVersion}")
+    compileOnly("com.google.errorprone:error_prone_core:2.19.1:with-dependencies") {
+        exclude("com.google.auto.service", "auto-service-annotations")
+    }
+
     testImplementation("org.jetbrains:annotations:24.+")
     testImplementation("org.openrewrite:rewrite-groovy")
     testImplementation("org.junit-pioneer:junit-pioneer:2.0.1")

src/main/java/org/openrewrite/staticanalysis/SimplifyTernary.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.staticanalysis;
+
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import org.openrewrite.java.template.RecipeDescriptor;
+
+public class SimplifyTernary {
+
+    @RecipeDescriptor(
+            name = "Simplify ternary expressions",
+            description = "Simplify `expr ? true : false` to `expr`."
+    )
+    public static class SimplifyTernaryTrueFalse {
+
+        @BeforeTemplate
+        boolean before(boolean expr) {
+            return expr ? true : false;
+        }
+
+        @AfterTemplate
+        boolean after(boolean expr) {
+            return expr;
+        }
+    }
+
+    @RecipeDescriptor(
+            name = "Simplify ternary expressions",
+            description = "Simplify `expr ? false : true` to `!expr`."
+    )
+    public static class SimplifyTernaryFalseTrue {
+
+        @BeforeTemplate
+        boolean before(boolean expr) {
+            return expr ? false : true;
+        }
+
+        @AfterTemplate
+        boolean after(boolean expr) {
+            return !(expr);
+        }
+    }
+}

src/main/resources/META-INF/rewrite/common-static-analysis.yml

@@ -75,6 +75,7 @@ recipeList:
   - org.openrewrite.staticanalysis.ReplaceStringBuilderWithString
   - org.openrewrite.staticanalysis.SimplifyBooleanExpression
   - org.openrewrite.staticanalysis.SimplifyBooleanReturn
+  - org.openrewrite.staticanalysis.SimplifyTernaryRecipes
   - org.openrewrite.staticanalysis.StaticMethodNotFinal
   - org.openrewrite.staticanalysis.StringLiteralEquality
   - org.openrewrite.staticanalysis.UnnecessaryCloseInTryWithResources

src/test/java/org/openrewrite/staticanalysis/SimplifyTernaryTest.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.staticanalysis;
+
+import org.junit.jupiter.api.Test;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.java.Assertions.java;
+
+class SimplifyTernaryTest implements RewriteTest {
+    @Test
+    void simplified() {
+        rewriteRun(
+          spec -> spec.recipe(new SimplifyTernaryRecipes()),
+          //language=java
+          java(
+            """
+              class Test {
+                  boolean trueCondition1 = true ? true : false;
+                  boolean trueCondition2 = false ? false : true;
+                  boolean trueCondition3 = booleanExpression() ? true : false;
+                  boolean trueCondition4 = trueCondition1 && trueCondition2 ? true : false;
+                  boolean trueCondition5 = !true ? false : true;
+                  boolean trueCondition6 = !false ? true : false;
+                  
+                  boolean falseCondition1 = true ? false : true;
+                  boolean falseCondition2 = !false ? false : true;
+                  boolean falseCondition3 = booleanExpression() ? false : true;
+                  boolean falseCondition4 = trueCondition1 && trueCondition2 ? false : true;
+                  boolean falseCondition5 = !false ? false : true;
+                  boolean falseCondition6 = !true ? true : false;
+                  
+                  boolean binary1 = booleanExpression() && booleanExpression() ? true : false;
+                  boolean binary2 = booleanExpression() && booleanExpression() ? false : true;
+                  boolean binary3 = booleanExpression() || booleanExpression() ? true : false;
+                  boolean binary4 = booleanExpression() || booleanExpression() ? false : true;
+                  
+                  boolean booleanExpression() {
+                    return true;
+                  }
+              }
+              """,
+            """
+              class Test {
+                  boolean trueCondition1 = true;
+                  boolean trueCondition2 = true;
+                  boolean trueCondition3 = booleanExpression();
+                  boolean trueCondition4 = trueCondition1 && trueCondition2;
+                  boolean trueCondition5 = true;
+                  boolean trueCondition6 = true;
+                  
+                  boolean falseCondition1 = false;
+                  boolean falseCondition2 = false;
+                  boolean falseCondition3 = !booleanExpression();
+                  boolean falseCondition4 = !(trueCondition1 && trueCondition2);
+                  boolean falseCondition5 = false;
+                  boolean falseCondition6 = false;
+                  
+                  boolean binary1 = booleanExpression() && booleanExpression();
+                  boolean binary2 = !(booleanExpression() && booleanExpression());
+                  boolean binary3 = booleanExpression() || booleanExpression();
+                  boolean binary4 = !(booleanExpression() || booleanExpression());
+                  
+                  boolean booleanExpression() {
+                    return true;
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void unchanged() {
+        rewriteRun(
+          spec -> spec.recipe(new SimplifyTernaryRecipes()),
+          //language=java
+          java(
+            """
+              class Test {
+                  boolean unchanged1 = booleanExpression() ? booleanExpression() : !booleanExpression();
+                  boolean unchanged2 = booleanExpression() ? true : !booleanExpression();
+                  boolean unchanged3 = booleanExpression() ? booleanExpression() : false;
+                  
+                  boolean booleanExpression() {
+                    return true;
+                  }
+              }
+              """
+          )
+        );
+    }
+}