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Diffstat (limited to 'examples/src/main/scala/decode.scala')
-rw-r--r-- | examples/src/main/scala/decode.scala | 79 |
1 files changed, 0 insertions, 79 deletions
diff --git a/examples/src/main/scala/decode.scala b/examples/src/main/scala/decode.scala deleted file mode 100644 index 5b083bd..0000000 --- a/examples/src/main/scala/decode.scala +++ /dev/null @@ -1,79 +0,0 @@ -package magnolia.examples - -import magnolia._ -import scala.language.experimental.macros - -/** very basic decoder for converting strings to other types */ -trait Decoder[T] { def decode(str: String): T } - -/** derivation object (and companion object) for [[Decoder]] instances */ -object Decoder { - - /** decodes strings */ - implicit val string: Decoder[String] = new Decoder[String] { - def decode(str: String): String = str - } - - /** decodes ints */ - implicit val int: Decoder[Int] = new Decoder[Int] { def decode(str: String): Int = str.toInt } - - /** binds the Magnolia macro to this derivation object */ - implicit def gen[T]: Decoder[T] = macro Magnolia.gen[T] - - /** type constructor for new instances of the typeclass */ - type Typeclass[T] = Decoder[T] - - /** defines how new [[Decoder]]s for case classes should be constructed */ - def combine[T](ctx: CaseClass[Decoder, T]): Decoder[T] = new Decoder[T] { - def decode(value: String) = { - val (name, values) = parse(value) - ctx.construct { param => - param.typeclass.decode(values(param.label)) - } - } - } - - /** defines how to choose which subtype of the sealed trait to use for decoding */ - def dispatch[T](ctx: SealedTrait[Decoder, T]): Decoder[T] = new Decoder[T] { - def decode(param: String) = { - val (name, values) = parse(param) - val subtype = ctx.subtypes.find(_.label == name).get - subtype.typeclass.decode(param) - } - } - - /** very simple extractor for grabbing an entire parameter value, assuming matching parentheses */ - private def parse(value: String): (String, Map[String, String]) = { - val end = value.indexOf('(') - val name = value.substring(0, end) - - def parts(value: String, - idx: Int = 0, - depth: Int = 0, - collected: List[String] = List("")): List[String] = { - def plus(char: Char): List[String] = collected.head + char :: collected.tail - - if (idx == value.length) collected - else - value(idx) match { - case '(' => - parts(value, idx + 1, depth + 1, plus('(')) - case ')' => - if (depth == 1) plus(')') - else parts(value, idx + 1, depth - 1, plus(')')) - case ',' => - if (depth == 0) parts(value, idx + 1, depth, "" :: collected) - else parts(value, idx + 1, depth, plus(',')) - case char => - parts(value, idx + 1, depth, plus(char)) - } - } - - def keyValue(str: String): (String, String) = { - val List(label, value) = str.split("=", 2).to[List] - (label, value) - } - - (name, parts(value.substring(end + 1, value.length - 1)).map(keyValue).toMap) - } -} |