Added variant of trim that operates on nulls

sksamuel · Dec 30, 2023 · fefb12f · fefb12f
1 parent 0996104
commit fefb12f
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diff --git a/tribune-core/src/main/kotlin/com/sksamuel/tribune/core/strings/strings.kt b/tribune-core/src/main/kotlin/com/sksamuel/tribune/core/strings/strings.kt
@@ -7,6 +7,7 @@ import com.sksamuel.tribune.core.Parser
 import com.sksamuel.tribune.core.filter
 import com.sksamuel.tribune.core.flatMap
 import com.sksamuel.tribune.core.map
+import com.sksamuel.tribune.core.mapIfNotNull
 
 /**
  * Modifies the output of a String producing [Parser] by trimming the output string
@@ -16,6 +17,15 @@ import com.sksamuel.tribune.core.map
  */
 fun <I, E> Parser<I, String, E>.trim(): Parser<I, String, E> = map { it.trim() }
 
+/**
+ * Modifies the output of a nullable String producing [Parser] by trimming the output string
+ * to remove prefix and suffix whitespace.
+ *
+ * @return the output of the underlying parser with whitespace trimmed.
+ */
+@JvmName("trimOnNullableString")
+fun <I, E> Parser<I, String?, E>.trim(): Parser<I, String?, E> = mapIfNotNull { it.trim() }
+
 /**
  * Modifies the output of a String producing [Parser] to strip the given [chars].
  */

diff --git a/tribune-core/src/test/kotlin/com/sksamuel/tribune/core/strings.kt b/tribune-core/src/test/kotlin/com/sksamuel/tribune/core/strings.kt
@@ -71,6 +71,13 @@ class StringTest : FunSpec() {
          p.parse("abc    ") shouldBe Foo("abc").right()
       }
 
+      test("trim on nullable") {
+         val p = Parser<String?>().trim()
+         p.parse(" abcd ") shouldBe "abcd".right()
+         p.parse("abc    ") shouldBe "abc".right()
+         p.parse(null) shouldBe null.right()
+      }
+
       test("uppercase") {
          val p = Parser<String>().toUppercase().map { Foo(it) }
          p.parse("abcd") shouldBe Foo("ABCD").right()