Display non-printing default options as string literals

.gitignore

@@ -1,2 +1,3 @@
 .idea
+.java-version
 target

src/main/scala/com/fulcrumgenomics/sopt/cmdline/ClpArgumentDefinitionPrinting.scala

@@ -42,6 +42,15 @@ object ClpArgumentDefinitionPrinting {
   private[cmdline] val ArgumentDefaultValuePrefix: String = "Default:"
   private[cmdline] val ArgumentOptionalValue: String = "Optional"
 
+  /** A collection of non-printing ASCII characters and their string literals. */
+  private[cmdline] val NonPrintingCharacters: Map[String, String] = Map(
+    "\t" -> """\t""",
+    "\b" -> """\b""",
+    "\n" -> """\n""",
+    "\r" -> """\r""",
+    "\f" -> """\f""",
+  )
+
   /**  For formatting argument section of usage message. */
   private val ArgumentColumnWidth: Int = 30
   private val DescriptionColumnWidth: Int = Sopt.TerminalWidth - ArgumentColumnWidth
@@ -115,17 +124,27 @@ object ClpArgumentDefinitionPrinting {
     KGRN(if (vs.isEmpty) s"[[$ArgumentOptionalValue]]." else s"[[$ArgumentDefaultValuePrefix ${vs.mkString(", ")}]].")
   }
 
+  /** Converts all non-printing characters in a string into their string literal form. */
+  private[sopt] def nonPrintingToStringLiteral(string: String): String = {
+    NonPrintingCharacters.foldLeft(string) { (toModify, pair: (String, String)) =>
+      toModify.replaceAllLiterally(pair._1, pair._2)
+    }
+  }
+
   /** Returns the set of default values as a Seq of Strings, one per default value. */
   private [sopt] def defaultValuesAsSeq(value: Option[_]): Seq[String] = value match {
       case None | Some(None) | Some(Nil)  => Seq.empty
       case Some(s) if Set.empty == s      => Seq.empty
-      case Some(c) if c.isInstanceOf[util.Collection[_]] => c.asInstanceOf[util.Collection[_]].iterator.map(_.toString).toSeq
-      case Some(t) if t.isInstanceOf[Iterable[_]]     => t.asInstanceOf[Iterable[_]].toSeq.map(_.toString)
-      case Some(Some(x)) => Seq(x.toString)
-      case Some(x)       => Seq(x.toString)
+      case Some(c) if c.isInstanceOf[util.Collection[_]] => {
+        c.asInstanceOf[util.Collection[_]].map(_.toString).map(nonPrintingToStringLiteral).toSeq
+      }
+      case Some(t) if t.isInstanceOf[Iterable[_]]        => {
+        t.asInstanceOf[Iterable[_]].map(_.toString).map(nonPrintingToStringLiteral).toSeq
+      }
+      case Some(Some(x)) => Seq(nonPrintingToStringLiteral(x.toString))
+      case Some(x)       => Seq(nonPrintingToStringLiteral(x.toString))
     }
 
-
   /** Prints the usage for a given argument given its various elements */
   private[cmdline] def printArgumentUsage(stringBuilder: StringBuilder, name: String, shortName: Option[Char], theType: String,
                                           collectionArityString: Option[String], argumentDescription: String,

src/test/scala/com/fulcrumgenomics/sopt/cmdline/ClpArgumentDefinitionPrintingTest.scala

@@ -83,6 +83,47 @@ class ClpArgumentDefinitionPrintingTest extends UnitSpec with BeforeAndAfterAll
     makeDefaultValueString(Some(List("A", "B", "C"))) shouldBe "[[Default: A, B, C]]."
   }
 
+  it should "print non-printing characters as human readable defaults" in {
+    makeDefaultValueString(Some('\t')) shouldBe """[[Default: \t]]."""
+    makeDefaultValueString(Some('\b')) shouldBe """[[Default: \b]]."""
+    makeDefaultValueString(Some('\n')) shouldBe """[[Default: \n]]."""
+    makeDefaultValueString(Some('\r')) shouldBe """[[Default: \r]]."""
+    makeDefaultValueString(Some('\f')) shouldBe """[[Default: \f]]."""
+  }
+
+  it should "print non-printing strings as human readable defaults" in {
+    makeDefaultValueString(Some("\t\t")) shouldBe """[[Default: \t\t]]."""
+    makeDefaultValueString(Some("\r\n")) shouldBe """[[Default: \r\n]]."""
+  }
+
+  it should "print optional non-printing characters as human readable defaults" in {
+    makeDefaultValueString(Some(Some('\t'))) shouldBe """[[Default: \t]]."""
+    makeDefaultValueString(Some(Some('\n'))) shouldBe """[[Default: \n]]."""
+  }
+
+  it should "print optional non-printing strings as human readable defaults" in {
+    makeDefaultValueString(Some(Some("\t"))) shouldBe """[[Default: \t]]."""
+    makeDefaultValueString(Some(Some("\r\n"))) shouldBe """[[Default: \r\n]]."""
+  }
+
+  it should "print optional non-printing characters in options as human readable defaults" in {
+    makeDefaultValueString(Some(Some(Some('\t')))) shouldBe """[[Default: Some(\t)]]."""
+    makeDefaultValueString(Some(Some(Some('\n')))) shouldBe """[[Default: Some(\n)]]."""
+  }
+
+  it should "print optional non-printing strings in options as human readable defaults" in {
+    makeDefaultValueString(Some(Some(Some("\t")))) shouldBe """[[Default: Some(\t)]]."""
+    makeDefaultValueString(Some(Some(Some("\r\n")))) shouldBe """[[Default: Some(\r\n)]]."""
+  }
+
+  it should "print a collection of non-printing characters as human readable defaults" in {
+    makeDefaultValueString(Some(Seq('\t', '\r', '\b'))) shouldBe """[[Default: \t, \r, \b]]."""
+  }
+
+  it should "print a collection of non-printing strings as human readable defaults" in {
+    makeDefaultValueString(Some(Seq("\t\t", "\r\n", "\b\b"))) shouldBe """[[Default: \t\t, \r\n, \b\b]]."""
+  }
+
   private def printArgumentUsage(name: String, shortName: Option[Char], theType: String,
                                  collectionDescription: Option[String], argumentDescription: String,
                                  optional: Boolean = false): String = {