jaskell.parsec.Ahead.scala Maven / Gradle / Ivy

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package jaskell.parsec

import scala.util.Try

/**
 * Ahead use a parser to parse state, return the result and rollback whatever
 *
 * @author mars
 * @version 1.0.0
 */
class Ahead[E, T](val parser: Parsec[E, T]) extends Parsec[E, T] {

  def apply(s: State[E]): Try[T] = {
    val tran = s.begin()
    val result = parser ? s
    s.rollback(tran)
    result
  }
}

object Ahead {
  def apply[E, T](parser: Parsec[E, T]): Ahead[E, T] = new Ahead[E, T](parser)
}