chore: Stream Gatherers example

Author: sureshg

shared/src/jsMain/kotlin/dev/suresh/http/HttpClient.js.kt

@@ -11,3 +11,5 @@ actual fun httpClient(
     httpLogger: KLogger,
     config: HttpClientConfig<*>.() -> Unit
 ) = HttpClient(Js) { config(this) }
+
+fun getKtorEnvLogLevel(): String? = js("process.env.KTOR_LOG_LEVEL")

shared/src/jvmMain/java/dev/suresh/Gatherers.java

@@ -0,0 +1,49 @@
+package dev.suresh;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Gatherer;
+import java.util.stream.Gatherer.Downstream;
+import java.util.stream.Gatherer.Integrator;
+import java.util.stream.Stream;
+
+public class Gatherers {
+
+    static <T, R> Gatherer<T, ?, R> map(Function<T, R> f) {
+        Integrator<Void, T, R> integrator = (_, e, ds) -> {
+            var ir = f.apply(e);
+            return ds.push(ir);
+        };
+        return Gatherer.of(integrator);
+    }
+
+    static <T> Gatherer<T, List<T>, List<T>> group(int size) {
+        Supplier<List<T>> initializer = ArrayList::new;
+        Integrator<List<T>, T, List<T>> integrator = (list, e, ds) -> {
+            list.add(e);
+            if (list.size() < size) {
+                return true;
+            } else {
+                var group = List.copyOf(list);
+                list.clear();
+                return ds.push(group);
+            }
+        };
+        BiConsumer<List<T>, Downstream<? super List<T>>> finisher = (list, ds) -> {
+            var group = List.copyOf(list);
+            if (!group.isEmpty()) {
+                ds.push(group);
+            }
+        };
+        return Gatherer.ofSequential(initializer, integrator, finisher);
+    }
+
+    public static void main(String[] args) {
+        Stream.of(1, 2, 3, 4, 5).gather(map(e -> e + 1)).gather(group(2)).forEach(System.out::println);
+    }
+}
+
+