function reduce toRange added and covered by tests

johnw42 · May 29, 2023 · 6a58dc4 · 6a58dc4
1 parent 638e07f
commit 6a58dc4
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diff --git a/src/async-stream.ts b/src/async-stream.ts
@@ -57,6 +57,7 @@ import {
   toMinAsync,
   toMinMaxAsync,
   toProductAsync,
+  toRangeAsync,
   toSumAsync,
   toValueAsync,
 } from "./reduce";
@@ -851,6 +852,17 @@ export class AsyncStream {
     return await toProductAsync(this as AsyncIterable<number>);
   }
 
+  /**
+   * Reduces given collection to its range.
+   *
+   * Returns 0 if given collection is empty.
+   *
+   * @see reduce.toRangeAsync
+   */
+  async toRange(): Promise<number> {
+    return await toRangeAsync(this as AsyncIterable<number>);
+  }
+
   /**
    * Returns true if all elements of stream match the predicate function.
    *

diff --git a/src/index.ts b/src/index.ts
@@ -87,6 +87,7 @@ import {
   toMin,
   toMinMax,
   toProduct,
+  toRange,
   toSum,
   toValue,
   toFirst,
@@ -101,6 +102,7 @@ import {
   toMinAsync,
   toMinMaxAsync,
   toProductAsync,
+  toRangeAsync,
   toSumAsync,
   toValueAsync,
 } from "./reduce";
@@ -255,6 +257,7 @@ export const reduce = {
   toMin,
   toMinMax,
   toProduct,
+  toRange,
   toSum,
   toValue,
   toAverageAsync,
@@ -266,6 +269,7 @@ export const reduce = {
   toMinAsync,
   toMinMaxAsync,
   toProductAsync,
+  toRangeAsync,
   toSumAsync,
   toValueAsync,
 };

diff --git a/src/reduce.ts b/src/reduce.ts
@@ -307,6 +307,38 @@ export async function toMinMaxAsync<T>(
   )) as [T?, T?];
 }
 
+/**
+ * Reduces given collection to its range.
+ *
+ * Returns 0 if given collection is empty.
+ *
+ * @param numbers
+ */
+export function toRange(numbers: Iterable<number> | Iterator<number>): number {
+  const [min, max] = toMinMax(numbers);
+
+  return (max ?? 0) - (min ?? 0);
+}
+
+/**
+ * Reduces given async collection to its range.
+ *
+ * Returns 0 if given async collection is empty.
+ *
+ * @param numbers
+ */
+export async function toRangeAsync(
+  numbers:
+    | AsyncIterable<number>
+    | AsyncIterator<number>
+    | Iterable<number>
+    | Iterator<number>
+): Promise<number> {
+  const [min, max] = await toMinMaxAsync(numbers);
+
+  return (max ?? 0) - (min ?? 0);
+}
+
 /**
  * Reduces given collection to the sum of its items.
  *

diff --git a/src/stream.ts b/src/stream.ts
@@ -45,6 +45,7 @@ import {
   toMin,
   toMinMax,
   toProduct,
+  toRange,
   toSum,
   toValue,
 } from "./reduce";
@@ -758,6 +759,17 @@ export class Stream {
     return toProduct(this as Iterable<number>);
   }
 
+  /**
+   * Reduces given collection to its range.
+   *
+   * Returns 0 if given collection is empty.
+   *
+   * @see reduce.toRange
+   */
+  toRange(): number {
+    return toRange(this as Iterable<number>);
+  }
+
   /**
    * Returns true if all elements of stream match the predicate function.
    *

diff --git a/tests/async-stream/reduce.test.ts b/tests/async-stream/reduce.test.ts
@@ -212,6 +212,18 @@ function dataProviderForArrays(): Array<unknown> {
         .toAverage(),
       0,
     ],
+    [
+      [],
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      0,
+    ],
+    [
+      [1, -1, 2, -2, 3, -3],
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      6,
+    ],
     [
       [],
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
@@ -657,6 +669,18 @@ function dataProviderForGenerators(): Array<unknown> {
         .toAverage(),
       0,
     ],
+    [
+      createGeneratorFixture([]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      0,
+    ],
+    [
+      createGeneratorFixture([1, -1, 2, -2, 3, -3]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      6,
+    ],
     [
       createGeneratorFixture([]),
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
@@ -1092,6 +1116,18 @@ function dataProviderForIterables(): Array<unknown> {
         .toAverage(),
       0,
     ],
+    [
+      createIterableFixture([]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      0,
+    ],
+    [
+      createIterableFixture([1, -1, 2, -2, 3, -3]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      6,
+    ],
     [
       createIterableFixture([]),
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
@@ -1527,6 +1563,18 @@ function dataProviderForIterators(): Array<unknown> {
         .toAverage(),
       0,
     ],
+    [
+      createIteratorFixture([]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      0,
+    ],
+    [
+      createIteratorFixture([1, -1, 2, -2, 3, -3]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      6,
+    ],
     [
       createIteratorFixture([]),
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
@@ -1929,6 +1977,18 @@ function dataProviderForStrings(): Array<unknown> {
         .toAverage(),
       2,
     ],
+    [
+      '',
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      0,
+    ],
+    [
+      '123',
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      2,
+    ],
     [
       '',
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
@@ -2236,6 +2296,18 @@ function dataProviderForSets(): Array<unknown> {
         .toAverage(),
       0,
     ],
+    [
+      new Set([]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      0,
+    ],
+    [
+      new Set([1, -1, 2, -2, 3, -3]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      6,
+    ],
     [
       new Set([1, 2, 3, 4, 5]),
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
@@ -2693,6 +2765,20 @@ function dataProviderForMaps(): Array<unknown> {
         .toAverage(),
       0,
     ],
+    [
+      createMapFixture([]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .map((item) => (item as [unknown, number])[1])
+        .toRange(),
+      0,
+    ],
+    [
+      createMapFixture([1, -1, 2, -2, 3, -3]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .map((item) => (item as [unknown, number])[1])
+        .toRange(),
+      6,
+    ],
     [
       createMapFixture([]),
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
@@ -3114,6 +3200,18 @@ function dataProviderForAsyncGenerators(): Array<unknown> {
         .toAverage(),
       0,
     ],
+    [
+      createAsyncGeneratorFixture([]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      0,
+    ],
+    [
+      createAsyncGeneratorFixture([1, -1, 2, -2, 3, -3]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      6,
+    ],
     [
       createAsyncGeneratorFixture([]),
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
@@ -3549,6 +3647,18 @@ function dataProviderForAsyncIterables(): Array<unknown> {
         .toAverage(),
       0,
     ],
+    [
+      createAsyncIterableFixture([]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      0,
+    ],
+    [
+      createAsyncIterableFixture([1, -1, 2, -2, 3, -3]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      6,
+    ],
     [
       createAsyncIterableFixture([]),
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
@@ -3984,6 +4094,18 @@ function dataProviderForAsyncIterators(): Array<unknown> {
         .toAverage(),
       0,
     ],
+    [
+      createAsyncIteratorFixture([]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      0,
+    ],
+    [
+      createAsyncIteratorFixture([1, -1, 2, -2, 3, -3]),
+      (iterable: Iterable<unknown>) => AsyncStream.of(iterable)
+        .toRange(),
+      6,
+    ],
     [
       createAsyncIteratorFixture([]),
       (iterable: Iterable<unknown>) => AsyncStream.of(iterable)