Add Flow<Boolean> operators: not(), inverted(), and toggle()

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## [Unreleased]
 
+### Added
+
+- Add `Flow<Boolean>.not()` operator - Returns a Flow that emits the boolean negation of each value emitted by the source Flow.
+- Add `Flow<Boolean>.inverted()` operator - Alias for `not()`.
+- Add `Flow<Boolean>.toggle()` operator - Alias for `not()`.
+
 ## [1.0.0] - Sep 22, 2024
 
 This is our first stable release! Thanks everyone for using FlowExt, reporting bugs, providing feedback and sending PRs.

README.md

@@ -146,6 +146,9 @@ dependencies {
 
 - Intermediate operators
   - [`bufferCount`](#buffercount--chunked)
+  - [`not`](#not--inverted--toggle) (`Flow<Boolean>`)
+  - [`inverted`](#not--inverted--toggle) (`Flow<Boolean>`)
+  - [`toggle`](#not--inverted--toggle) (`Flow<Boolean>`)
   - [`combine`](#combine)
   - [`cast`](#cast--castnotnull--castnullable--safeCast)
   - [`castNotNull`](#cast--castnotnull--castnullable--safeCast)
@@ -228,6 +231,53 @@ bufferCount: [8, 9]
 
 ----
 
+#### not / inverted / toggle
+
+Returns a `Flow<Boolean>` that emits the boolean negation (opposite) of each value emitted by the source `Flow<Boolean>`.
+
+- `not()` - Returns the negated boolean values 
+- `inverted()` - Alias for `not()`
+- `toggle()` - Alias for `not()`
+
+```kotlin
+flowOf(true, false, true, false)
+  .not()
+  .collect { println("not: $it") }
+
+println("---")
+
+flowOf(true, false, true, false)
+  .inverted()
+  .collect { println("inverted: $it") }
+
+println("---")
+
+flowOf(true, false, true, false)
+  .toggle()
+  .collect { println("toggle: $it") }
+```
+
+Output:
+
+```none
+not: false
+not: true
+not: false
+not: true
+---
+inverted: false
+inverted: true
+inverted: false
+inverted: true
+---
+toggle: false
+toggle: true
+toggle: false
+toggle: true
+```
+
+----
+
 #### concat
 
 - Similar to [RxJS concat](https://rxjs.dev/api/index/function/concat)

api/FlowExt.api

@@ -1,3 +1,9 @@
+public final class com/hoc081098/flowext/BooleanOperatorsKt {
+	public static final fun inverted (Lkotlinx/coroutines/flow/Flow;)Lkotlinx/coroutines/flow/Flow;
+	public static final fun not (Lkotlinx/coroutines/flow/Flow;)Lkotlinx/coroutines/flow/Flow;
+	public static final fun toggle (Lkotlinx/coroutines/flow/Flow;)Lkotlinx/coroutines/flow/Flow;
+}
+
 public final class com/hoc081098/flowext/BufferCountKt {
 	public static final fun bufferCount (Lkotlinx/coroutines/flow/Flow;I)Lkotlinx/coroutines/flow/Flow;
 	public static final fun bufferCount (Lkotlinx/coroutines/flow/Flow;II)Lkotlinx/coroutines/flow/Flow;

src/commonMain/kotlin/com/hoc081098/flowext/booleanOperators.kt

@@ -0,0 +1,54 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2021-2024 Petrus Nguyễn Thái Học
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.hoc081098.flowext
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+
+/**
+ * Returns a [Flow] that emits the boolean negation (opposite) of each value emitted by the source [Flow].
+ *
+ * @return A [Flow] that emits `false` when the source emits `true` and `true` when the source emits `false`.
+ */
+@Suppress("NOTHING_TO_INLINE")
+public inline fun Flow<Boolean>.not(): Flow<Boolean> = map { !it }
+
+/**
+ * Returns a [Flow] that emits the boolean negation (opposite) of each value emitted by the source [Flow].
+ * This is an alias for [not].
+ *
+ * @return A [Flow] that emits `false` when the source emits `true` and `true` when the source emits `false`.
+ */
+@Suppress("NOTHING_TO_INLINE")
+public inline fun Flow<Boolean>.inverted(): Flow<Boolean> = not()
+
+/**
+ * Returns a [Flow] that emits the boolean negation (opposite) of each value emitted by the source [Flow].
+ * This is an alias for [not].
+ *
+ * @return A [Flow] that emits `false` when the source emits `true` and `true` when the source emits `false`.
+ */
+@Suppress("NOTHING_TO_INLINE")
+public inline fun Flow<Boolean>.toggle(): Flow<Boolean> = not()

src/commonTest/kotlin/com/hoc081098/flowext/BooleanOperatorsTest.kt

@@ -0,0 +1,146 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2021-2024 Petrus Nguyễn Thái Học
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.hoc081098.flowext
+
+import com.hoc081098.flowext.utils.BaseTest
+import com.hoc081098.flowext.utils.TestException
+import com.hoc081098.flowext.utils.test
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.InternalCoroutinesApi
+import kotlinx.coroutines.flow.asFlow
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.flow.toList
+
+@ExperimentalCoroutinesApi
+@InternalCoroutinesApi
+class BooleanOperatorsTest : BaseTest() {
+  @Test
+  fun notBasic() = runTest {
+    val values = flowOf(true, false, true, false).not().toList()
+    assertEquals(listOf(false, true, false, true), values)
+  }
+
+  @Test
+  fun notEmpty() = runTest {
+    val values = flowOf<Boolean>().not().toList()
+    assertEquals(emptyList(), values)
+  }
+
+  @Test
+  fun notSingleTrue() = runTest {
+    val values = flowOf(true).not().toList()
+    assertEquals(listOf(false), values)
+  }
+
+  @Test
+  fun notSingleFalse() = runTest {
+    val values = flowOf(false).not().toList()
+    assertEquals(listOf(true), values)
+  }
+
+  @Test
+  fun notUpstreamError() = runTest {
+    val throwable = TestException()
+
+    flow<Boolean> { throw throwable }
+      .not()
+      .test(listOf(Event.Error(throwable)))
+  }
+
+  @Test
+  fun notSequence() = runTest {
+    listOf(true, false, true, false, true)
+      .asFlow()
+      .not()
+      .test(
+        listOf(
+          Event.Value(false),
+          Event.Value(true),
+          Event.Value(false),
+          Event.Value(true),
+          Event.Value(false),
+          Event.Complete,
+        ),
+      )
+  }
+
+  @Test
+  fun invertedBasic() = runTest {
+    val values = flowOf(true, false, true, false).inverted().toList()
+    assertEquals(listOf(false, true, false, true), values)
+  }
+
+  @Test
+  fun invertedEmpty() = runTest {
+    val values = flowOf<Boolean>().inverted().toList()
+    assertEquals(emptyList(), values)
+  }
+
+  @Test
+  fun invertedUpstreamError() = runTest {
+    val throwable = TestException()
+
+    flow<Boolean> { throw throwable }
+      .inverted()
+      .test(listOf(Event.Error(throwable)))
+  }
+
+  @Test
+  fun toggleBasic() = runTest {
+    val values = flowOf(true, false, true, false).toggle().toList()
+    assertEquals(listOf(false, true, false, true), values)
+  }
+
+  @Test
+  fun toggleEmpty() = runTest {
+    val values = flowOf<Boolean>().toggle().toList()
+    assertEquals(emptyList(), values)
+  }
+
+  @Test
+  fun toggleUpstreamError() = runTest {
+    val throwable = TestException()
+
+    flow<Boolean> { throw throwable }
+      .toggle()
+      .test(listOf(Event.Error(throwable)))
+  }
+
+  @Test
+  fun allVariantsProduceSameResult() = runTest {
+    val input = flowOf(true, false, true, false)
+
+    val notResult = input.not().toList()
+    val invertedResult = input.inverted().toList()
+    val toggleResult = input.toggle().toList()
+
+    assertEquals(notResult, invertedResult)
+    assertEquals(notResult, toggleResult)
+    assertEquals(listOf(false, true, false, true), notResult)
+  }
+}