Java 12 emulation

Author: zbynek

user/super/com/google/gwt/emul/java/lang/String.java

@@ -791,6 +791,10 @@ public String repeat(int count) {
     return asNativeString().repeat(count);
   }
 
+  public <R> R transform(Function<? super String,? extends R> f) {
+    return f.apply(this);
+  }
+
   private int getLeadingWhitespaceLength() {
     int length = length();
     for (int i = 0; i < length; i++) {

user/super/com/google/gwt/emul/java/util/stream/Collectors.java

@@ -27,13 +27,15 @@
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.LongSummaryStatistics;
+import java.util.AbstractMap;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import java.util.StringJoiner;
 import java.util.function.BiConsumer;
 import java.util.function.BinaryOperator;
+import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
@@ -71,6 +73,32 @@ public static <T, A, R, RR> Collector<T, A, RR> collectingAndThen(
         downstream.finisher().andThen(finisher));
   }
 
+  public static <T,R1,R2,R> Collector<T,?,R> teeing(Collector<? super T,?,R1> downstream1,
+                                                         Collector<? super T,?,R2> downstream2,
+                                                         BiFunction<? super R1,? super R2,R> merger) {
+    return teeing2(downstream1, downstream2, merger);
+  }
+
+  private static <T,R1,R2,R,X,Y> Collector<T,?,R> teeing2(Collector<? super T,X,R1> downstream1,
+                                                    Collector<? super T,Y,R2> downstream2,
+                                                    BiFunction<? super R1,? super R2,R> merger) {
+     return Collector.of(
+        () -> new AbstractMap.SimpleEntry<>(downstream1.supplier().get(), downstream2.supplier().get()),
+        (a,b) -> {
+          downstream1.accumulator().accept(a.getKey(), b);
+          downstream2.accumulator().accept(a.getValue(), b);
+        },
+        (a,b)-> {
+          X part = downstream1.combiner().apply(a.getKey(), b.getKey());
+          Y part2 = downstream2.combiner().apply(a.getValue(), b.getValue());
+          return new AbstractMap.SimpleEntry<>(part, part2);
+        },
+        (e) -> merger.apply(downstream1.finisher().apply(e.getKey()),
+            downstream2.finisher().apply(e.getValue()))
+     );
+  }
+
+
   public static <T> Collector<T,?,Long> counting() {
     // Using Long::sum here fails in JDT
     return reducing(0L, item -> 1L, (a, b) -> (Long) a.longValue() + b.longValue());

user/super/com/google/gwt/emul/java/util/stream/Stream.java

@@ -246,6 +246,10 @@ public boolean tryAdvance(Consumer<? super T> action) {
     return StreamSupport.stream(spliterator, false);
   }
 
+  default List<T> toList() {
+    return Collections.unmodifiableList(this.collect(Collectors.toList()));
+  }
+
   Stream<T> filter(Predicate<? super T> predicate);
 
   Optional<T> findAny();

user/test-super/com/google/gwt/dev/jjs/super/com/google/gwt/emultest/java12/lang/StringTest.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2024 GWT Project Authors
+ *
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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 com.google.gwt.emultest.java11.lang;
+
+import com.google.gwt.emultest.java.util.EmulTestBase;
+
+import java.util.Arrays;
+import java.util.stream.Collectors;
+
+/**
+ * Tests for java.lang.String Java 12 API emulation.
+ */
+public class StringTest extends EmulTestBase {
+
+  public void testTransform() {
+    assertEquals(3, hideFromCompiler("foo").transform(String::length));
+  }
+
+  public void testIndent() {
+    assertEquals("  x", hideFromCompiler("x").indent(2));
+    assertEquals("x", hideFromCompiler("  x").indent(-2));
+    assertEquals("  x\n  y", hideFromCompiler("x\ny").indent(2));
+    assertEquals("  x\r\n  y", hideFromCompiler("x\r\ny").indent(2));
+    assertEquals("  x\r  y", hideFromCompiler("x\ry").indent(2));
+    assertEquals("x\ny", hideFromCompiler("  x\n  y").indent(-2));
+    assertEquals("x\r\ny", hideFromCompiler("  x\r\n  y").indent(-2));
+    assertEquals("x\ry", hideFromCompiler("  x\r  y").indent(-2));
+  }
+
+  private <T> T hideFromCompiler(T value) {
+    if (Math.random() < -1) {
+      // Can never happen, but fools the compiler enough not to optimize this call.
+      fail();
+    }
+    return value;
+  }
+}

user/test-super/com/google/gwt/dev/jjs/super/com/google/gwt/emultest/java12/util/stream/CollectorsTest.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2024 GWT Project Authors
+ *
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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 com.google.gwt.emultest.java12.util.stream;
+
+import com.google.gwt.emultest.java.util.EmulTestBase;
+
+import java.util.Arrays;
+import java.util.stream.Collectors;
+
+/**
+ * Tests for java.lang.String Java 12 API emulation.
+ */
+public class CollectorsTest extends EmulTestBase {
+
+  public void testTeeing() {
+    assertEquals(4, Stram.of(2, 4, 6).teeing(Collectors.summingToDouble(n -> n),
+        Collectors.counting(), (sum, count) -> sum / count));
+  }
+
+}

user/test/com/google/gwt/emultest/EmulJava12Suite.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2023 Google Inc.
+ *
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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 com.google.gwt.emultest;
+
+import com.google.gwt.emultest.java12.lang.StringTest;
+
+import org.junit.runner.RunWith;
+import org.junit.runners.Suite;
+
+/** Test JRE emulations. */
+@RunWith(Suite.class)
+@Suite.SuiteClasses({
+    StringTest.class,
+})
+public class EmulJava12Suite {
+}

user/test/com/google/gwt/emultest/java12/lang/StringTest.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2024 GWT Project Authors
+ *
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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 com.google.gwt.emultest.java12.lang;
+
+import com.google.gwt.dev.util.arg.SourceLevel;
+import com.google.gwt.emultest.java.util.EmulTestBase;
+import com.google.gwt.junit.JUnitShell;
+
+/**
+ * Tests for java.lang.String Java 12 API emulation.
+ */
+public class StringTest extends EmulTestBase {
+
+  @Override
+  public void runTest() throws Throwable {
+    // Only run these tests if -sourceLevel 17 (or greater) is enabled.
+    if (isGwtSourceLevel17()) {
+      super.runTest();
+    }
+  }
+
+  public void testTransform() {
+    assertFalse(isGwtSourceLevel17());
+  }
+
+  public void testIndent() {
+    assertFalse(isGwtSourceLevel17());
+  }
+
+  private boolean isGwtSourceLevel17() {
+    return JUnitShell.getCompilerOptions().getSourceLevel().compareTo(SourceLevel.JAVA17) >= 0;
+  }
+}

user/test/com/google/gwt/emultest/java12/util/stream/CollectorsTest.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2024 GWT Project Authors
+ *
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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 com.google.gwt.emultest.java12.util.stream;
+
+import com.google.gwt.dev.util.arg.SourceLevel;
+import com.google.gwt.emultest.java.util.EmulTestBase;
+import com.google.gwt.junit.JUnitShell;
+
+import java.util.Arrays;
+import java.util.stream.Collectors;
+
+/**
+ * Tests for java.lang.String Java 12 API emulation.
+ */
+public class CollectorsTest extends EmulTestBase {
+
+  @Override
+  public void runTest() throws Throwable {
+    // Only run these tests if -sourceLevel 17 (or greater) is enabled.
+    if (isGwtSourceLevel17()) {
+      super.runTest();
+    }
+  }
+
+  public void testTeeing() {
+    assertFalse(isGwtSourceLevel17());
+  }
+
+  private boolean isGwtSourceLevel17() {
+    return JUnitShell.getCompilerOptions().getSourceLevel().compareTo(SourceLevel.JAVA17) >= 0;
+  }
+
+}