Update Collections and Iterables.

Author: gk-brown

README.md

@@ -1006,8 +1006,6 @@ The `Collections` class provides a set of static utility methods for declarative
 public static <E> List<E> listOf(E... elements) { ... }
 public static <E> List<E> immutableListOf(E... elements) { ... }
 public static <E> List<E> emptyListOf(Class<E> elementType) { ... }
-
-public static <E extends Comparable<? super E>> List<E> sortedListOf(E... elements) { ... }
 ```
 
 ```java
@@ -1126,7 +1124,10 @@ public static <T, R> Iterable<R> mapAll(Iterable<T> iterable, Function<? super T
 public static <T> Iterable<T> limit(Iterable<T> iterable, int count) { ... }
 
 public static <T, R> List<R> flatten(Iterable<T> iterable, Function<? super T, ? extends Iterable<? extends R>> transform) { ... }
-public static <T, R extends Comparable<? super R>> SortedSet<R> collect(Iterable<T> iterable, Function<? super T, ? extends Iterable<? extends R>> transform) { ... }
+
+public static <T, V extends Comparable<? super V>> List<T> sortBy(Iterable<T> iterable, Function<? super T, ? extends V> identifier) { ... }
+public static <T, V> List<T> sortBy(Iterable<T> iterable, Function<? super T, ? extends V> identifier, Comparator<? super V> comparator) { ... }
+
 public static <T, K extends Comparable<? super K>> SortedMap<K, List<T>> groupBy(Iterable<T> iterable, Function<? super T, ? extends K> classifier) { ... }
 
 public static <T> boolean exists(Iterable<T> iterable, Predicate<? super T> predicate) { ... }

kilo-client/src/main/java/org/httprpc/kilo/util/Collections.java

@@ -158,47 +158,6 @@ public static <E> List<E> emptyListOf(Class<E> elementType) {
         return java.util.Collections.emptyList();
     }
 
-    /**
-     * Creates a sorted list.
-     *
-     * @param <E>
-     * The element type.
-     *
-     * @param elements
-     * The list elements.
-     *
-     * @return
-     * A sorted list of the provided elements.
-     */
-    @SafeVarargs
-    public static <E extends Comparable<? super E>> List<E> sortedListOf(E... elements) {
-        var list = listOf(elements);
-
-        java.util.Collections.sort(list);
-
-        return list;
-    }
-
-    /**
-     * Creates a sorted list.
-     *
-     * @param <E>
-     * The element type.
-     *
-     * @param elements
-     * The list elements.
-     *
-     * @return
-     * A sorted list of the provided elements.
-     */
-    public static <E extends Comparable<? super E>> List<E> sortedListOf(Iterable<? extends E> elements) {
-        List<E> list = listOf(elements);
-
-        java.util.Collections.sort(list);
-
-        return list;
-    }
-
     /**
      * Creates a map.
      *

kilo-client/src/main/java/org/httprpc/kilo/util/Iterables.java

@@ -21,9 +21,7 @@
 import java.util.List;
 import java.util.NoSuchElementException;
 import java.util.SortedMap;
-import java.util.SortedSet;
 import java.util.TreeMap;
-import java.util.TreeSet;
 import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.ToDoubleFunction;
@@ -235,37 +233,58 @@ public static <T, R> List<R> flatten(Iterable<T> iterable, Function<? super T, ?
     }
 
     /**
-     * Collects iterable contents.
+     * Sorts iterable contents.
      *
      * @param <T>
      * The element type.
      *
-     * @param <R>
-     * The target type.
+     * @param <V>
+     * The value type.
      *
      * @param iterable
-     * The iterable to collect.
+     * The iterable to sort.
      *
-     * @param transform
-     * The transform function.
+     * @param identifier
+     * The identification function.
      *
      * @return
-     * The collected contents.
+     * The sorted contents.
      */
-    public static <T, R extends Comparable<? super R>> SortedSet<R> collect(Iterable<T> iterable, Function<? super T, ? extends Iterable<? extends R>> transform) {
-        if (iterable == null || transform == null) {
-            throw new IllegalArgumentException();
-        }
+    public static <T, V extends Comparable<? super V>> List<T> sortBy(Iterable<T> iterable, Function<? super T, ? extends V> identifier) {
+        return sortBy(iterable, identifier, Comparator.naturalOrder());
+    }
 
-        var set = new TreeSet<R>();
+    /**
+     * Sorts iterable contents.
+     *
+     * @param <T>
+     * The element type.
+     *
+     * @param <V>
+     * The value type.
+     *
+     * @param iterable
+     * The iterable to sort.
+     *
+     * @param identifier
+     * The identification function.
+     *
+     * @param comparator
+     * The comparator.
+     *
+     * @return
+     * The sorted contents.
+     */
+    public static <T, V> List<T> sortBy(Iterable<T> iterable, Function<? super T, ? extends V> identifier, Comparator<? super V> comparator) {
+        var list = new ArrayList<T>();
 
-        for (var elements : mapAll(iterable, transform)) {
-            for (var element : elements) {
-                set.add(element);
-            }
+        for (var element : iterable) {
+            list.add(element);
         }
 
-        return set;
+        list.sort((t1, t2) -> comparator.compare(identifier.apply(t1), identifier.apply(t2)));
+
+        return list;
     }
 
     /**

kilo-client/src/test/java/org/httprpc/kilo/util/CollectionsTest.java

@@ -75,20 +75,6 @@ public void testEmptyListOf() {
         assertTrue(emptyListOf(Integer.class).isEmpty());
     }
 
-    @Test
-    public void testSortedListOf() {
-        var sortedList = sortedListOf(3, 2, 1);
-
-        assertEquals(listOf(1, 2, 3), sortedList);
-    }
-
-    @Test
-    public void testSortedListOfIterable() {
-        var sortedList = sortedListOf(listOf(3, 2, 1));
-
-        assertEquals(listOf(1, 2, 3), sortedList);
-    }
-
     @Test
     public void testMapOf() {
         var expected = new HashMap<String, Integer>();

kilo-client/src/test/java/org/httprpc/kilo/util/IterablesTest.java

@@ -21,7 +21,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
-import java.util.TreeSet;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
 
@@ -111,19 +110,8 @@ public void testFlatten() {
     }
 
     @Test
-    public void testCollect() {
-        List<Supplier<List<Integer>>> values = listOf(
-            () -> listOf(1),
-            () -> listOf(1, 2),
-            () -> listOf(1, 2, 3)
-        );
-
-        var result = collect(values, Supplier::get); // 1, 2, 3
-
-        assertEquals(sortedSetOf(1, 2, 3), result);
-
-        assertEquals(result, values.stream().flatMap(value -> value.get().stream())
-            .collect(Collectors.toCollection(TreeSet::new)));
+    public void testSortBy() {
+        // TODO
     }
 
     @Test

kilo-server/src/main/java/org/httprpc/kilo/WebService.java

@@ -80,7 +80,7 @@ public abstract class WebService extends HttpServlet {
     /**
      * Describes a service instance.
      */
-    public static class ServiceDescriptor implements Comparable<ServiceDescriptor> {
+    public static class ServiceDescriptor {
         private String path;
         private String description;
 
@@ -144,11 +144,6 @@ public List<EnumerationDescriptor> getEnumerations() {
         public List<StructureDescriptor> getStructures() {
             return new ArrayList<>(structures.values());
         }
-
-        @Override
-        public int compareTo(ServiceDescriptor serviceDescriptor) {
-            return path.compareTo(serviceDescriptor.path);
-        }
     }
 
     /**
@@ -820,7 +815,7 @@ public static synchronized <T extends WebService> T getInstance(Class<T> type) {
      * A list of active service descriptors.
      */
     public static synchronized List<ServiceDescriptor> getServiceDescriptors() {
-        return sortedListOf(mapAll(instances.values(), WebService::getServiceDescriptor));
+        return sortBy(mapAll(instances.values(), WebService::getServiceDescriptor), ServiceDescriptor::getPath);
     }
 
     @Override