Add ifNotNull and ifNull functions

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Added
 
+- `T?.ifNotNull(block: () -> Unit): T?`
+- `T?.ifNull(block: () -> Unit): T?`
 - `Graph` data structure
 
 ### Changed

kotlin-stdlib/common/main/kotlin/com/javiersc/kotlin/stdlib/T.kt

@@ -0,0 +1,11 @@
+package com.javiersc.kotlin.stdlib
+
+public inline fun <T> T?.ifNotNull(block: () -> Unit): T? {
+    if (this != null) block()
+    return this
+}
+
+public inline fun <T> T?.ifNull(block: () -> Unit): T? {
+    if (this == null) block()
+    return this
+}

kotlin-stdlib/common/test/kotlin/com/javiersc/kotlin/stdlib/TTest.kt

@@ -0,0 +1,50 @@
+package com.javiersc.kotlin.stdlib
+
+import kotlin.test.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+@Suppress("RedundantNullableReturnType")
+class TTest {
+
+    private val a: String? = "a"
+    private val b: String? = null
+    private val one: Int? = 1
+    private val two: Int? = null
+
+    @Test
+    fun ifNotNull() {
+        var isA = false
+        var isB = false
+        var isOne = false
+        var isTwo = false
+
+        a.ifNotNull { isA = true }
+        b.ifNotNull { isB = true }
+        one.ifNotNull { isOne = true }
+        two.ifNotNull { isTwo = true }
+
+        assertTrue { isA }
+        assertFalse { isB }
+        assertTrue { isOne }
+        assertFalse { isTwo }
+    }
+
+    @Test
+    fun ifNull() {
+        var isA = false
+        var isB = false
+        var isOne = false
+        var isTwo = false
+
+        a.ifNull { isA = true }
+        b.ifNull { isB = true }
+        one.ifNull { isOne = true }
+        two.ifNull { isTwo = true }
+
+        assertFalse { isA }
+        assertTrue { isB }
+        assertFalse { isOne }
+        assertTrue { isTwo }
+    }
+}