Introduce Comparators{Min,Max} Refaster templates (#270)

PicnicSupermarket · Sep 29, 2022 · aa5ad4d · aa5ad4d
1 parent 8c0041a
commit aa5ad4d
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diff --git a/...e-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ComparatorTemplates.java b/...e-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ComparatorTemplates.java
@@ -19,6 +19,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.function.ToDoubleFunction;
 import java.util.function.ToIntFunction;
@@ -259,4 +260,36 @@ T after(T value1, T value2, Comparator<T> cmp) {
       return Comparators.max(value1, value2, cmp);
     }
   }
+
+  /**
+   * Prefer a method reference to {@link Comparators#min(Comparable, Comparable)} over calling
+   * {@link BinaryOperator#minBy(Comparator)} with {@link Comparator#naturalOrder()}.
+   */
+  static final class ComparatorsMin<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    BinaryOperator<T> before() {
+      return BinaryOperator.minBy(naturalOrder());
+    }
+
+    @AfterTemplate
+    BinaryOperator<T> after() {
+      return Comparators::min;
+    }
+  }
+
+  /**
+   * Prefer a method reference to {@link Comparators#max(Comparable, Comparable)} over calling
+   * {@link BinaryOperator#minBy(Comparator)} with {@link Comparator#naturalOrder()}.
+   */
+  static final class ComparatorsMax<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    BinaryOperator<T> before() {
+      return BinaryOperator.maxBy(naturalOrder());
+    }
+
+    @AfterTemplate
+    BinaryOperator<T> after() {
+      return Comparators::max;
+    }
+  }
 }
diff --git a/...test/resources/tech/picnic/errorprone/refastertemplates/ComparatorTemplatesTestInput.java b/...test/resources/tech/picnic/errorprone/refastertemplates/ComparatorTemplatesTestInput.java
@@ -1,5 +1,6 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static java.util.Comparator.naturalOrder;
 import static java.util.Comparator.reverseOrder;
 import static java.util.function.Function.identity;
 
@@ -8,6 +9,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.function.BinaryOperator;
 import tech.picnic.errorprone.refaster.test.RefasterTemplateTestCase;
 
 final class ComparatorTemplatesTest implements RefasterTemplateTestCase {
@@ -102,4 +104,12 @@ ImmutableSet<Object> testMaxOfPairCustomOrder() {
         Collections.max(ImmutableList.of(new Object(), new Object()), (a, b) -> 0),
         Collections.max(ImmutableSet.of(new Object(), new Object()), (a, b) -> 1));
   }
+
+  BinaryOperator<String> testComparatorsMin() {
+    return BinaryOperator.minBy(naturalOrder());
+  }
+
+  BinaryOperator<String> testComparatorsMax() {
+    return BinaryOperator.maxBy(naturalOrder());
+  }
 }
diff --git a/...est/resources/tech/picnic/errorprone/refastertemplates/ComparatorTemplatesTestOutput.java b/...est/resources/tech/picnic/errorprone/refastertemplates/ComparatorTemplatesTestOutput.java
@@ -10,6 +10,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.function.BinaryOperator;
 import tech.picnic.errorprone.refaster.test.RefasterTemplateTestCase;
 
 final class ComparatorTemplatesTest implements RefasterTemplateTestCase {
@@ -90,4 +91,12 @@ ImmutableSet<Object> testMaxOfPairCustomOrder() {
         Comparators.max(new Object(), new Object(), (a, b) -> 0),
         Comparators.max(new Object(), new Object(), (a, b) -> 1));
   }
+
+  BinaryOperator<String> testComparatorsMin() {
+    return Comparators::min;
+  }
+
+  BinaryOperator<String> testComparatorsMax() {
+    return Comparators::max;
+  }
 }