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package caseapp.core.argparser
import caseapp.@@
import caseapp.core.{Counter, Error}
/** Parses argument values of type `T`.
*
* @tparam T:
* parsed value type
*/
abstract class ArgParser[T] {
/** Parses a value.
*
* `value` must be consumed. Corresponds to cases like `--foo=bar`.
*
* @param current:
* latest parsed value wrapped in [[scala.Some]] if any, [[scala.None]] else
* @param value:
* [[scala.Predef.String]] to parse
* @return
* in case of success, a `T`, wrapped in [[scala.Right]]; else, and error message, wrapped in
* [[caseapp.core.Error]] and [[scala.Left]]
*/
def apply(current: Option[T], index: Int, span: Int, value: String): Either[Error, T]
/** Parses a value.
*
* Unlike `apply` above, `value` may or may not be consumed. Corresponds to cases like `--foo
* bar`.
*
* Use of `value` or not must be returned via the [[caseapp.core.argparser.Consumed]] value.
*
* @param current:
* latest parsed value wrapped in [[scala.Some]] if any, [[scala.None]] else
* @param value:
* [[scala.Predef.String]] to parse
* @return
* in case of success, whether `value` was consumed and a `T`, wrapped in [[scala.Right]];
* else, and error message, wrapped in [[caseapp.core.Error]] and [[scala.Left]]
*/
def optional(
current: Option[T],
index: Int,
span: Int,
value: String
): (Consumed, Either[Error, T]) =
(Consumed(true), apply(current, index, span, value))
/** Called when the corresponding argument was specified with no value.
*
* Can happen if the option was enabled as very last argument, like `--bar` in `--foo 1 other
* --bar`.
*
* @param current:
* latest parsed value wrapped in [[scala.Some]] if any, [[scala.None]] else
* @return
* a `T` wrapped in [[scala.Right]] in case of success, or an error message wrapped in
* [[caseapp.core.Error]] and [[scala.Left]] else
*/
def apply(current: Option[T], index: Int): Either[Error, T] =
Left(Error.ArgumentMissing)
/** Whether the parsed value corresponds to a flag.
*
* Prevents telling corresponding arguments expect a value in help messages.
*/
def isFlag: Boolean =
false
/** Value description.
*
* Used in help messages.
*/
def description: String
final def xmap[U](from: U => T, to: T => U): ArgParser[U] =
new MapErrorArgParser[T, U](this, from, t => Right(to(t)))
final def xmapError[U](from: U => T, to: T => Either[Error, U]): ArgParser[U] =
new MapErrorArgParser(this, from, to)
}
object ArgParser extends PlatformArgParsers {
/** Look for an implicit `ArgParser[T]` */
def apply[T](implicit parser: ArgParser[T]): ArgParser[T] = parser
implicit def int: ArgParser[Int] =
SimpleArgParser.int
implicit def long: ArgParser[Long] =
SimpleArgParser.long
implicit def double: ArgParser[Double] =
SimpleArgParser.double
implicit def float: ArgParser[Float] =
SimpleArgParser.float
implicit def bigDecimal: ArgParser[BigDecimal] =
SimpleArgParser.bigDecimal
implicit def string: ArgParser[String] =
SimpleArgParser.string
implicit def unit: ArgParser[Unit] =
FlagArgParser.unit
implicit def boolean: ArgParser[Boolean] =
FlagArgParser.boolean
implicit def counter: ArgParser[Int @@ Counter] =
FlagAccumulatorArgParser.counter
implicit def list[T: ArgParser]: ArgParser[List[T]] =
if (ArgParser[T].isFlag)
FlagAccumulatorArgParser.list
else
AccumulatorArgParser.list
implicit def vector[T: ArgParser]: ArgParser[Vector[T]] =
if (ArgParser[T].isFlag)
FlagAccumulatorArgParser.vector
else
AccumulatorArgParser.vector
implicit def option[T: ArgParser]: ArgParser[Option[T]] =
if (ArgParser[T].isFlag)
FlagAccumulatorArgParser.option
else
AccumulatorArgParser.option
implicit def last[T: ArgParser]: ArgParser[Last[T]] =
LastArgParser(implicitly)
}
