improve typing of element finding utils

src/async/impl.ts

@@ -11,7 +11,7 @@ import { AsyncRandomOptions } from "../random/types.js";
 import { selectionSorter } from "../sorting.js";
 import { Sequence } from "../sync/types.js";
 import { MaybeAsyncAnyPredicate, MaybeAsyncConverter, MaybeAsyncBiConverter, MaybeAsyncAccumulator, MaybeAsyncAction, MaybePromiseLike, MaybeAsyncGenerator, MaybePromise, MaybeAsyncIterable, MaybeAsyncTypePredicate } from "../types.js";
-import { asAsyncIterable } from "../utils.js";
+import { asAsyncIterable, FindElementResult } from "../utils.js";
 import { array, empty, wrap } from "./index.js";
 import { AsyncSequence, AsyncSequencePipeline, GroupedAsyncSequence, OrderedAsyncSequence } from "./types.js";
 
@@ -173,14 +173,14 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
     return n >= 0 ? n : Infinity;
   }
 
-  async #tryGetFirst(predicate?: MaybeAsyncAnyPredicate<TElement>) {
+  async #tryGetFirst(predicate?: MaybeAsyncAnyPredicate<TElement>): Promise<FindElementResult<TElement>> {
     if (predicate) {
       for await (const element of this) {
         if (await predicate(element)) {
           return {
             found: true,
             element
-          } as const;
+          };
         }
       }
     } else {
@@ -190,13 +190,13 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
         return {
           found: true,
           element: next.value
-        } as const;
+        };
       }
     }
 
     return {
       found: false
-    } as const;
+    };
   }
 
   async first(predicate?: MaybeAsyncAnyPredicate<TElement>) {
@@ -215,7 +215,7 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
     return result.found ? result.element : def;
   }
 
-  async #tryGetLast(predicate?: MaybeAsyncAnyPredicate<TElement>) {
+  async #tryGetLast(predicate?: MaybeAsyncAnyPredicate<TElement>): Promise<FindElementResult<TElement>> {
     let found = false;
     let result: TElement | undefined = undefined;
 
@@ -236,7 +236,7 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
     return {
       found,
       element: result
-    };
+    } as FindElementResult<TElement>;
   }
 
   async last(predicate?: MaybeAsyncAnyPredicate<TElement>) {
@@ -255,9 +255,9 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
     return result.found ? result.element : def;
   }
 
-  async #tryGetSingle(predicate?: MaybeAsyncAnyPredicate<TElement>) {
+  async #tryGetSingle(predicate?: MaybeAsyncAnyPredicate<TElement>): Promise<FindElementResult<TElement>> {
     if (predicate) {
-      let result: { found: true; element: TElement; } | undefined = undefined;
+      let result: FindElementResult<TElement> | undefined = undefined;
 
       for await (const element of this) {
         if (await predicate(element)) {
@@ -265,13 +265,13 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
             return {
               found: false,
               reason: 2
-            } as const;
+            };
           }
 
           result = {
             found: true,
             element
-          } as const;
+          };
         }
       }
     } else {
@@ -279,10 +279,10 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
       let next = await iterator.next();
 
       if (!next.done) {
-        const result = {
+        const result: FindElementResult<TElement> = {
           found: true,
           element: next.value
-        } as const;
+        };
 
         next = await iterator.next();
 
@@ -293,14 +293,14 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
         return {
           found: false,
           reason: 2
-        } as const;
+        };
       }
     }
 
     return {
       found: false,
       reason: 1
-    } as const;
+    };
   }
 
   async single(predicate?: MaybeAsyncAnyPredicate<TElement>) {
@@ -330,7 +330,7 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
     return result.found ? result.element : def;
   }
 
-  async #tryElementAt(index: number) {
+  async #tryElementAt(index: number): Promise<FindElementResult<TElement>> {
     let i = index;
 
     for await (const element of this) {
@@ -338,7 +338,7 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
         return {
           found: true,
           element
-        } as const;
+        };
       }
 
       i--;
@@ -346,7 +346,7 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
 
     return {
       found: false
-    } as const;
+    };
   }
 
   async elementAt(index: number) {
@@ -693,18 +693,12 @@ export abstract class BaseAsyncSequence<TElement> extends AsyncSequenceMarker im
     return new CacheAsyncSequence<TElement>(this);
   }
 
-  async asArray(): Promise<TElement[]> {
+  async asArray() {
-    return await this.toArray();
+    return await Array.fromAsync(this);
   }
 
   async toArray() {
-    const array: TElement[] = [];
+    return await Array.fromAsync(this);
-
-    for await (const element of this) {
-      array.push(element);
-    }
-
-    return array;
   }
 
   toMap<TKey>(keySelector: MaybeAsyncConverter<TElement, TKey>): Promise<Map<TKey, TElement>>;
@@ -1137,13 +1131,9 @@ abstract class BaseOrderedAsyncSequence<TElement> extends BaseAsyncSequence<TEle
   }
 
   override async *iterator() {
-    const arr: TElement[] = [];
+    const arr = await Array.fromAsync(this.#sequence);
 
-    for await (const obj of this.#sequence) {
+    await selectionSorter.sort(arr, this.#descending, this.#sorter);
-      arr.push(obj);
-    }
-
-    await selectionSorter.sort(arr, this.#descending, this.#sorter.comparison());
 
     yield* arr;
   }

src/sync/impl.ts

@@ -11,6 +11,7 @@ import { createQueue } from "../queue.js";
 import { getRandomElement } from "../random/index.js";
 import { RandomOptions } from "../random/types.js";
 import { AnyPredicate, Converter, TypePredicate, BiConverter, Accumulator, Action } from "../types.js";
+import { FindElementResult } from "../utils.js";
 import { array, empty, wrap } from "./index.js";
 import { Sequence, GroupedSequence, OrderedSequence, SequencePipeline } from "./types.js";
 
@@ -181,7 +182,7 @@ export abstract class BaseSequence<TElement> extends SequenceMarker implements S
     return n >= 0 ? n : Infinity;
   }
 
-  #tryGetFirst(predicate?: AnyPredicate<TElement>): { found: boolean, element?: TElement | undefined; } {
+  #tryGetFirst(predicate?: AnyPredicate<TElement>): FindElementResult<TElement> {
     if (predicate) {
       for (const element of this) {
         if (predicate(element)) {
@@ -223,7 +224,7 @@ export abstract class BaseSequence<TElement> extends SequenceMarker implements S
     return result.found ? result.element : def;
   }
 
-  #tryGetLast(predicate?: AnyPredicate<TElement>): { found: boolean, element?: TElement; } {
+  #tryGetLast(predicate?: AnyPredicate<TElement>): FindElementResult<TElement> {
     let found = false;
     let result: TElement | undefined = undefined;
 
@@ -244,7 +245,7 @@ export abstract class BaseSequence<TElement> extends SequenceMarker implements S
     return {
       found,
       element: result
-    };
+    } as FindElementResult<TElement>;
   }
 
   last(predicate?: AnyPredicate<TElement>) {
@@ -263,9 +264,9 @@ export abstract class BaseSequence<TElement> extends SequenceMarker implements S
     return result.found ? result.element : def;
   }
 
-  #tryGetSingle(predicate?: AnyPredicate<TElement>): { found: boolean, element?: TElement, reason?: number; } {
+  #tryGetSingle(predicate?: AnyPredicate<TElement>): FindElementResult<TElement> {
     if (predicate) {
-      let result: { found: boolean; element: TElement; } | undefined = undefined;
+      let result: FindElementResult<TElement> | undefined = undefined;
 
       for (const element of this) {
         if (predicate(element)) {
@@ -287,7 +288,7 @@ export abstract class BaseSequence<TElement> extends SequenceMarker implements S
       let next = iterator.next();
 
       if (!next.done) {
-        const result = {
+        const result: FindElementResult<TElement> = {
           found: true,
           element: next.value
         };
@@ -319,7 +320,7 @@ export abstract class BaseSequence<TElement> extends SequenceMarker implements S
     }
 
     let reason: string;
-    switch (result.reason!) {
+    switch (result.reason) {
       case 1:
         reason = "No element was found.";
         break;
@@ -338,7 +339,7 @@ export abstract class BaseSequence<TElement> extends SequenceMarker implements S
     return result.found ? result.element : def;
   }
 
-  #tryElementAt(index: number) {
+  #tryElementAt(index: number): FindElementResult<TElement> {
     let i = index;
 
     for (const element of this) {
@@ -346,7 +347,7 @@ export abstract class BaseSequence<TElement> extends SequenceMarker implements S
         return {
           found: true,
           element
-        } as const;
+        };
       }
 
       i--;
@@ -354,7 +355,7 @@ export abstract class BaseSequence<TElement> extends SequenceMarker implements S
 
     return {
       found: false
-    } as const;
+    };
   }
 
   elementAt(index: number) {
@@ -1164,11 +1165,7 @@ export abstract class BaseOrderedSequence<TElement> extends BaseSequence<TElemen
   }
 
   override *iterator() {
-    const arr: TElement[] = [];
+    const arr = Array.from(this.#sequence);
-
-    for (const obj of this.#sequence) {
-      arr.push(obj);
-    }
 
     if (this.#sorter) {
       arr.sort((this.#descending ? this.#sorter.reverse() : this.#sorter).comparison());

src/utils.ts

@@ -49,3 +49,14 @@ const _emptyIterableIterator = new class EmptyIterableIterator implements Iterab
 export function emptyIterableIterator<T>(): IterableIterator<T> {
   return _emptyIterableIterator;
 }
+
+type FindElementSuccess<T> = {
+  found: true;
+  element: T;
+};
+type FindElementFail = {
+  found: false;
+  element?: never;
+  reason?: number;
+};
+export type FindElementResult<T> = FindElementSuccess<T> | FindElementFail;