Fix issue with CharIn type of RichTextCodec (zio#1704)

zio-http/src/main/scala/zio/http/api/internal/RichTextCodec.scala

@@ -45,6 +45,9 @@ sealed trait RichTextCodec[A] { self =>
  final def |[B](that: => RichTextCodec[B]): RichTextCodec[Either[A, B]] =
  RichTextCodec.Alt(self, RichTextCodec.defer(that))
 
+ final def as[B](b: => B)(implicit ev: A =:= Unit): RichTextCodec[B] =
+ self.asType[Unit].transform(_ => b, _ => ())
+
  final def asType[B](implicit ev: A =:= B): RichTextCodec[B] =
  self.asInstanceOf[RichTextCodec[B]]
 
@@ -109,7 +112,7 @@ sealed trait RichTextCodec[A] { self =>
 }
 object RichTextCodec {
  private[internal] case object Empty extends RichTextCodec[Unit]
- private[internal] final case class CharIn(set: BitSet) extends RichTextCodec[Unit]
+ private[internal] final case class CharIn(set: BitSet) extends RichTextCodec[Char]
  private[internal] final case class TransformOrFail[A, B](
  codec: RichTextCodec[A],
  to: A => Either[String, B],
@@ -135,12 +138,12 @@ object RichTextCodec {
  /**
  * A codec that describes a single specified character.
  */
- def char(c: Char): RichTextCodec[Unit] = CharIn(BitSet(c.toInt))
+ def char(c: Char): RichTextCodec[Unit] = CharIn(BitSet(c.toInt)).unit(c)
 
  /**
  * A codec that describes a digit character.
  */
- val digit: RichTextCodec[Unit] = filter(_.isDigit)
+ val digit: RichTextCodec[Int] = filter(_.isDigit).transform(_.toInt, _.toChar)
 
  /**
  * A codec that describes nothing at all. Such codecs successfully decode even
@@ -152,21 +155,27 @@ object RichTextCodec {
  * Defines a new codec for a single character based on the specified
  * predicate.
  */
- def filter(pred: Char => Boolean): RichTextCodec[Unit] =
+ def filter(pred: Char => Boolean): RichTextCodec[Char] =
  CharIn(BitSet((Char.MinValue to Char.MaxValue).map(_.toInt): _*))
 
  /**
  * A codec that describes a letter character.
  */
- val letter: RichTextCodec[Unit] = filter(_.isLetter)
+ val letter: RichTextCodec[Char] = filter(_.isLetter)
 
  /**
  * A codec that describes a literal character sequence.
  */
- def literal(lit: CharSequence): RichTextCodec[Unit] =
- lit.toString().foldLeft(empty) { case (acc, c) =>
- acc ~> char(c)
- }
+ def literal(lit: String): RichTextCodec[String] = {
+ def loop(list: List[Char]): RichTextCodec[Unit] =
+ list match {
+ case head :: tail =>
+ char(head) ~> loop(tail)
+ case Nil => empty
+ }
+
+ loop(lit.toString().toList).as(lit)
+ }
 
  /**
  * A codec that describes any number of whitespace characters.
@@ -177,5 +186,5 @@ object RichTextCodec {
  /**
  * A codec that describes a single whitespace character.
  */
- lazy val whitespaceChar: RichTextCodec[Unit] = filter(_.isWhitespace)
+ lazy val whitespaceChar: RichTextCodec[Unit] = filter(_.isWhitespace).unit(' ')
 }