Add ImmutableEnumSet

utils/src/main/java/org/opentripplanner/utils/collection/ImmutableEnumSet.java

@@ -0,0 +1,68 @@
+package org.opentripplanner.utils.collection;
+
+import java.util.HashSet;
+import java.util.Set;
+import org.opentripplanner.utils.lang.BitSetUtils;
+
+public final class ImmutableEnumSet<T extends Enum<T>> {
+
+  private final int bitset;
+  private final Class<T> clazz;
+
+  private ImmutableEnumSet(Class<T> clazz, int bitset) {
+    this.bitset = bitset;
+    this.clazz = clazz;
+  }
+
+  @SafeVarargs
+  public static <E extends Enum<E>> ImmutableEnumSet<E> of(Class<E> clazz, E... elements)  {
+    checkClass(clazz);
+
+    int bitset = 0;
+    for(E e : elements) {
+      bitset = BitSetUtils.set(bitset, e.ordinal(), true);
+    }
+    return new ImmutableEnumSet<>(clazz, bitset);
+  }
+  public static <E extends Enum<E>> ImmutableEnumSet<E> allOff(Class<E> clazz) {
+    return of(clazz, clazz.getEnumConstants());
+  }
+
+  private static <E extends Enum<E>> void checkClass(Class<E> clazz) {
+    if(!clazz.isEnum()) {
+      throw new IllegalArgumentException(String.format("Class %s is not an enum", clazz.getName()));
+    }
+  }
+
+  public boolean isEmpty() {
+    return bitset == 0;
+  }
+
+  public boolean contains(T value) {
+    return BitSetUtils.get(bitset, value.ordinal());
+  }
+
+  public Set<T> values() {
+    var set = new HashSet<T>();
+    for(var e: clazz.getEnumConstants()){
+      if(BitSetUtils.get(bitset, e.ordinal())) {
+        set.add(e);
+      }
+    }
+    return set;
+  }
+
+  @Override
+  public String toString() {
+    var builder = new StringBuilder();
+    builder.append("[");
+    for(var e: clazz.getEnumConstants()){
+      if(BitSetUtils.get(bitset, e.ordinal())) {
+        builder.append(e.name());
+        builder.append(",");
+      }
+    }
+    builder.append("]");
+    return builder.toString();
+  }
+}

utils/src/test/java/org/opentripplanner/utils/collection/ImmutableEnumSetTest.java

@@ -0,0 +1,63 @@
+package org.opentripplanner.utils.collection;
+
+import static java.time.DayOfWeek.FRIDAY;
+import static java.time.DayOfWeek.MONDAY;
+import static java.time.DayOfWeek.SATURDAY;
+import static java.time.DayOfWeek.SUNDAY;
+import static java.time.DayOfWeek.THURSDAY;
+import static java.time.DayOfWeek.TUESDAY;
+import static java.time.DayOfWeek.WEDNESDAY;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.time.DayOfWeek;
+import java.util.Set;
+import org.junit.jupiter.api.Test;
+
+class ImmutableEnumSetTest {
+
+  @Test
+  void contains(){
+    var set = ImmutableEnumSet.of(DayOfWeek.class, MONDAY, WEDNESDAY);
+    assertFalse(set.isEmpty());
+    assertTrue(set.contains(MONDAY));
+    assertFalse(set.contains(TUESDAY));
+    assertTrue(set.contains(WEDNESDAY));
+    assertFalse(set.contains(THURSDAY));
+    assertFalse(set.contains(FRIDAY));
+    assertFalse(set.contains(SATURDAY));
+    assertFalse(set.contains(SUNDAY));
+  }
+
+  @Test
+  void allOf(){
+    var set = ImmutableEnumSet.allOff(DayOfWeek.class);
+    assertFalse(set.isEmpty());
+    assertTrue(set.contains(MONDAY));
+    assertTrue(set.contains(TUESDAY));
+    assertTrue(set.contains(WEDNESDAY));
+    assertTrue(set.contains(THURSDAY));
+    assertTrue(set.contains(FRIDAY));
+    assertTrue(set.contains(SATURDAY));
+    assertTrue(set.contains(SUNDAY));
+  }
+
+  @Test
+  void empty(){
+    assertFalse(ImmutableEnumSet.of(DayOfWeek.class, SUNDAY).isEmpty());
+    assertTrue(ImmutableEnumSet.of(DayOfWeek.class).isEmpty());
+  }
+
+  @Test
+  void string(){
+    var set = ImmutableEnumSet.of(DayOfWeek.class, SUNDAY, MONDAY, THURSDAY);
+    assertEquals("[MONDAY,THURSDAY,SUNDAY,]", set.toString());
+  }
+
+  @Test
+  void values(){
+    var set = ImmutableEnumSet.of(DayOfWeek.class, SUNDAY, THURSDAY, MONDAY).values();
+    assertEquals(Set.of(SUNDAY, MONDAY, THURSDAY), set);
+  }
+}