Add removeDuplicateEmptyLines and endWithNewLine

Author: JavierSegoviaCordoba

CHANGELOG.md

@@ -4,6 +4,10 @@
 
 ### Added
 
+- `List<String>.removeDuplicateEmptyLines`
+- `String.removeDuplicateEmptyLines`
+- `String.endWithNewLine`
+
 ### Changed
 
 - `emptyString()` to `String.Empty`

kotlin-stdlib/api/kotlin-stdlib.api

@@ -150,19 +150,22 @@ public final class com/javiersc/kotlin/stdlib/CollectionsKt {
 	public static final fun getIndexOrNull (Ljava/lang/Iterable;I)Ljava/lang/Object;
 	public static final fun penultimate (Ljava/lang/Iterable;)Ljava/lang/Object;
 	public static final fun penultimateOrNull (Ljava/lang/Iterable;)Ljava/lang/Object;
+	public static final fun removeDuplicateEmptyLines (Ljava/util/List;)Ljava/lang/String;
 	public static final fun second (Ljava/lang/Iterable;)Ljava/lang/Object;
 	public static final fun secondOrNull (Ljava/lang/Iterable;)Ljava/lang/Object;
 	public static final fun third (Ljava/lang/Iterable;)Ljava/lang/Object;
 	public static final fun thirdOrNull (Ljava/lang/Iterable;)Ljava/lang/Object;
 }
 
 public final class com/javiersc/kotlin/stdlib/StringsKt {
+	public static final fun endWithNewLine (Ljava/lang/String;)Ljava/lang/String;
 	public static final fun getEmpty (Lkotlin/jvm/internal/StringCompanionObject;)Ljava/lang/String;
 	public static final fun isNotNullNorBlank (Ljava/lang/CharSequence;)Z
 	public static final fun isNotNullNorBlank (Ljava/lang/String;)Z
 	public static final fun isNotNullNorEmpty (Ljava/lang/CharSequence;)Z
 	public static final fun isNotNullNorEmpty (Ljava/lang/String;)Z
 	public static final fun remove (Ljava/lang/String;Ljava/lang/String;Z)Ljava/lang/String;
 	public static synthetic fun remove$default (Ljava/lang/String;Ljava/lang/String;ZILjava/lang/Object;)Ljava/lang/String;
+	public static final fun removeDuplicateEmptyLines (Ljava/lang/String;)Ljava/lang/String;
 }
 

kotlin-stdlib/commonMain/kotlin/com/javiersc/kotlin/stdlib/Collections.kt

@@ -126,3 +126,11 @@ internal inline fun <T> Iterable<T>.getIndexOrNull(index: Int): T? {
         }
     }
 }
+
+/** Remove all consecutive line breaks in a list of `String` */
+public fun List<String>.removeDuplicateEmptyLines(): String =
+    if (isNotEmpty()) {
+        reduce { acc: String, b: String ->
+            if (acc.lines().lastOrNull().isNullOrBlank() && b.isBlank()) acc else "$acc\n$b"
+        }
+    } else ""

kotlin-stdlib/commonMain/kotlin/com/javiersc/kotlin/stdlib/Strings.kt

@@ -39,3 +39,10 @@ public inline fun String?.isNotNullNorEmpty(): Boolean {
 
 public inline val String.Companion.Empty: String
     get() = ""
+
+/** Remove all consecutive line breaks in a `String` */
+public fun String.removeDuplicateEmptyLines(): String = lines().removeDuplicateEmptyLines()
+
+/** Add an empty line as last item if it is not empty */
+public fun String.endWithNewLine(): String =
+    if (lines().lastOrNull().isNullOrBlank()) this else "$this\n"

kotlin-stdlib/commonTest/kotlin/com/javiersc/kotlin/stdlib/CollectionsTest.kt

@@ -85,4 +85,14 @@ class CollectionsTest {
         shouldThrow<NoSuchElementException> { listOf(1).penultimate() }
         shouldThrow<NoSuchElementException> { listOf(1).asIterable().penultimate() }
     }
+
+    @Test
+    fun remove_duplicate_empty_lines() {
+        listOf("a", "b", "", "", "c", "").removeDuplicateEmptyLines().shouldBe("a\nb\n\nc\n")
+        listOf("a", "b", "", "", "", "c", "").removeDuplicateEmptyLines().shouldBe("a\nb\n\nc\n")
+        listOf("a", "b", "", "", "c", "", "").removeDuplicateEmptyLines().shouldBe("a\nb\n\nc\n")
+        listOf("a", "", "", "", "b", "", "").removeDuplicateEmptyLines().shouldBe("a\n\nb\n")
+        emptyList<String>().removeDuplicateEmptyLines().shouldBe("")
+        listOf("").removeDuplicateEmptyLines().shouldBe("")
+    }
 }

kotlin-stdlib/commonTest/kotlin/com/javiersc/kotlin/stdlib/StringsTest.kt

@@ -35,4 +35,22 @@ class StringsTest {
     fun empty_string() {
         String.Empty.shouldBeEmpty()
     }
+
+    @Test
+    fun remove_duplicate_empty_lines() {
+        "a\nb\n\n\nc\n".removeDuplicateEmptyLines().shouldBe("a\nb\n\nc\n")
+        "a\n\nb\n\n\nc\n".removeDuplicateEmptyLines().shouldBe("a\n\nb\n\nc\n")
+        "a\n\nb\n\n\nc\n\n".removeDuplicateEmptyLines().shouldBe("a\n\nb\n\nc\n")
+        "a\n\n\n\n\nb\n\n".removeDuplicateEmptyLines().shouldBe("a\n\nb\n")
+    }
+
+    @Test
+    fun end_with_new_line() {
+        "a".endWithNewLine().shouldBe("a\n")
+        "a\n".endWithNewLine().shouldBe("a\n")
+        "".endWithNewLine().shouldBe("")
+        "a\nb".endWithNewLine().shouldBe("a\nb\n")
+        "".endWithNewLine().shouldBe("")
+        "\n".endWithNewLine().shouldBe("\n")
+    }
 }