1.0 wip

src/system/iterable.ts

@@ -0,0 +1,55 @@
+'use strict';
+
+export namespace Iterables {
+    export function* filter<T>(source: Iterable<T> | IterableIterator<T>, predicate: (item: T) => boolean): Iterable<T> {
+        for (const item of source) {
+            if (predicate(item)) yield item;
+        }
+    }
+
+    export function* filterMap<T, TMapped>(source: Iterable<T> | IterableIterator<T>, predicateMapper: (item: T) => TMapped | undefined | null): Iterable<TMapped> {
+        for (const item of source) {
+            const mapped = predicateMapper(item);
+            if (mapped) yield mapped;
+        }
+    }
+
+    export function forEach<T>(source: Iterable<T> | IterableIterator<T>, fn: (item: T, index: number) => void): void {
+        let i = 0;
+        for (const item of source) {
+            fn(item, i);
+            i++;
+        }
+    }
+
+    export function find<T>(source: Iterable<T> | IterableIterator<T>, predicate: (item: T) => boolean): T {
+        for (const item of source) {
+            if (predicate(item)) return item;
+        }
+        return null;
+    }
+
+    export function first<T>(source: Iterable<T>): T {
+        return source[Symbol.iterator]().next().value;
+    }
+
+    export function* flatMap<T, TMapped>(source: Iterable<T> | IterableIterator<T>, mapper: (item: T) => Iterable<TMapped>): Iterable<TMapped> {
+        for (const item of source) {
+            yield* mapper(item);
+        }
+    }
+
+    export function isIterable(source: Iterable<any>): boolean {
+        return typeof source[Symbol.iterator] === 'function';
+    }
+
+    export function* map<T, TMapped>(source: Iterable<T> | IterableIterator<T>, mapper: (item: T) => TMapped): Iterable<TMapped> {
+        for (const item of source) {
+            yield mapper(item);
+        }
+    }
+
+    export function next<T>(source: IterableIterator<T>): T {
+        return source.next().value;
+    }
+}