[Dart] Use Object.hash and Object.hashAll if supported

Dart/src/com/jetbrains/lang/dart/ide/generation/CreateEqualsAndHashcodeFix.java

@@ -6,6 +6,7 @@
 import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.NlsContexts;
+import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.psi.PsiElement;
 import com.jetbrains.lang.dart.DartBundle;
@@ -14,6 +15,7 @@
 import com.jetbrains.lang.dart.psi.DartClass;
 import com.jetbrains.lang.dart.psi.DartComponent;
 import com.jetbrains.lang.dart.psi.DartComponentName;
+import com.jetbrains.lang.dart.sdk.DartSdk;
 import org.dartlang.analysis.server.protocol.TypeHierarchyItem;
 import org.jetbrains.annotations.NotNull;
 
@@ -23,6 +25,7 @@
 public class CreateEqualsAndHashcodeFix extends BaseCreateMethodsFix<DartComponent> {
 
   private boolean mySuperclassOverridesEqualEqualAndHashCode;
+  private boolean supportsObjectHashMethods = false;
 
   public CreateEqualsAndHashcodeFix(@NotNull final DartClass dartClass) {
     super(dartClass);
@@ -32,6 +35,9 @@ public CreateEqualsAndHashcodeFix(@NotNull final DartClass dartClass) {
   public void beforeInvoke(@NotNull Project project, Editor editor, PsiElement file) {
     super.beforeInvoke(project, editor, file);
     mySuperclassOverridesEqualEqualAndHashCode = doesSuperclassOverrideEqualEqualAndHashCode(myDartClass);
+
+    final DartSdk sdk = DartSdk.getDartSdk(project);
+    supportsObjectHashMethods = sdk != null && StringUtil.compareVersionNumbers(sdk.getVersion(), "2.14") >= 0;
   }
 
   @Override
@@ -94,20 +100,54 @@ protected Template buildFunctionsText(TemplateManager templateManager, @NotNull
 
     template.addTextSegment("@override\n");
     template.addTextSegment("int get hashCode => ");
-    boolean firstItem = true;
-    if (mySuperclassOverridesEqualEqualAndHashCode) {
-      template.addTextSegment("super.hashCode");
-      firstItem = false;
+
+    final int totalItems = elementsToProcess.size() + (mySuperclassOverridesEqualEqualAndHashCode ? 1 : 0);
+    if (totalItems <= 0) {
+      template.addTextSegment("0");
     }
-    for (DartComponent component : elementsToProcess) {
-      if (!firstItem) {
-        template.addTextSegment(" ^ ");
+    else if (supportsObjectHashMethods && totalItems > 1) {
+      final boolean useHashAll = totalItems > 20;
+      if (useHashAll) {
+        template.addTextSegment("Object.hashAll(");
+        template.addTextSegment("[");
+      }
+      else {
+        template.addTextSegment("Object.hash(");
+      }
+
+      boolean shouldPrependComma = false;
+      if (mySuperclassOverridesEqualEqualAndHashCode) {
+        template.addTextSegment("super.hashCode");
+        shouldPrependComma = true;
+      }
+
+      for (final DartComponent component : elementsToProcess) {
+        if (shouldPrependComma) {
+          template.addTextSegment(",");
+        }
+        template.addTextSegment(String.valueOf(component.getName()));
+        shouldPrependComma = true;
       }
-      template.addTextSegment(component.getName() + ".hashCode");
-      firstItem = false;
+
+      if (useHashAll) {
+        template.addTextSegment("]");
+      }
+
+      template.addTextSegment(")");
     }
-    if (!mySuperclassOverridesEqualEqualAndHashCode && elementsToProcess.isEmpty()) {
-      template.addTextSegment("0");
+    else {
+      boolean firstItem = true;
+      if (mySuperclassOverridesEqualEqualAndHashCode) {
+        template.addTextSegment("super.hashCode");
+        firstItem = false;
+      }
+      for (DartComponent component : elementsToProcess) {
+        if (!firstItem) {
+          template.addTextSegment(" ^ ");
+        }
+        template.addTextSegment(component.getName() + ".hashCode");
+        firstItem = false;
+      }
     }
     template.addTextSegment(";\n");
     template.addTextSegment(" "); // trailing space is removed when auto-reformatting, but it helps to enter line break if needed

Dart/testData/generate/EqualsAndHashCode1.txt

@@ -11,6 +11,6 @@ class EqualsAndHashCode1 {
               str == other.str && v == other.v && i == other.i;
 
   @override
-  int get hashCode => str.hashCode ^ v.hashCode ^ i.hashCode;
+  int get hashCode => Object.hash(str, v, i);
 <caret>
 }

Dart/testData/generate/EqualsAndHashCode20.dart

@@ -0,0 +1,23 @@
+// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+class Test {
+  int? a;
+  int? b;
+  int? c;
+  int? d;
+  int? e;
+  int? f;
+  int? g;
+  int? h;
+  int? i;
+  int? j;
+  int? k;
+  int? l;
+  int? m;
+  int? n;
+  int? o;
+  int? p;
+  int? q;
+  int? r;
+  int? s;
+  int? t;<caret>
+}

Dart/testData/generate/EqualsAndHashCode20.txt

@@ -0,0 +1,53 @@
+// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+class Test {
+  int? a;
+  int? b;
+  int? c;
+  int? d;
+  int? e;
+  int? f;
+  int? g;
+  int? h;
+  int? i;
+  int? j;
+  int? k;
+  int? l;
+  int? m;
+  int? n;
+  int? o;
+  int? p;
+  int? q;
+  int? r;
+  int? s;
+  int? t;
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Test &&
+          runtimeType == other.runtimeType &&
+          a == other.a &&
+          b == other.b &&
+          c == other.c &&
+          d == other.d &&
+          e == other.e &&
+          f == other.f &&
+          g == other.g &&
+          h == other.h &&
+          i == other.i &&
+          j == other.j &&
+          k == other.k &&
+          l == other.l &&
+          m == other.m &&
+          n == other.n &&
+          o == other.o &&
+          p == other.p &&
+          q == other.q &&
+          r == other.r &&
+          s == other.s &&
+          t == other.t;
+
+  @override
+  int get hashCode =>
+      Object.hash(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t);<caret>
+}

Dart/testData/generate/EqualsAndHashCode21.dart

@@ -0,0 +1,24 @@
+// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+class Test {
+  int? a;
+  int? b;
+  int? c;
+  int? d;
+  int? e;
+  int? f;
+  int? g;
+  int? h;
+  int? i;
+  int? j;
+  int? k;
+  int? l;
+  int? m;
+  int? n;
+  int? o;
+  int? p;
+  int? q;
+  int? r;
+  int? s;
+  int? t;
+  int? u;<caret>
+}

Dart/testData/generate/EqualsAndHashCode21.txt

@@ -0,0 +1,55 @@
+// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+class Test {
+  int? a;
+  int? b;
+  int? c;
+  int? d;
+  int? e;
+  int? f;
+  int? g;
+  int? h;
+  int? i;
+  int? j;
+  int? k;
+  int? l;
+  int? m;
+  int? n;
+  int? o;
+  int? p;
+  int? q;
+  int? r;
+  int? s;
+  int? t;
+  int? u;
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Test &&
+          runtimeType == other.runtimeType &&
+          a == other.a &&
+          b == other.b &&
+          c == other.c &&
+          d == other.d &&
+          e == other.e &&
+          f == other.f &&
+          g == other.g &&
+          h == other.h &&
+          i == other.i &&
+          j == other.j &&
+          k == other.k &&
+          l == other.l &&
+          m == other.m &&
+          n == other.n &&
+          o == other.o &&
+          p == other.p &&
+          q == other.q &&
+          r == other.r &&
+          s == other.s &&
+          t == other.t &&
+          u == other.u;
+
+  @override
+  int get hashCode => Object.hashAll(
+      [a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u]);<caret>
+}

Dart/testSrc/com/jetbrains/lang/dart/generate/DartGenerateActionTest.java

@@ -45,6 +45,14 @@ public void testEqualsAndHashCode2() {
     doEqualsAndHashcodeTest();
   }
 
+  public void testEqualsAndHashCode20() {
+    doEqualsAndHashcodeTest();
+  }
+
+  public void testEqualsAndHashCode21() {
+    doEqualsAndHashcodeTest();
+  }
+
   public void testImplement1() {
     doImplementTest();
   }