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Fast and elegant PEG parsing in Scala - lightweight, easy-to-use, powerful

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/*
 * Copyright 2009-2019 Mathias Doenitz
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.parboiled2

import org.parboiled2.support.hlist.HList

/** An application needs to implement this interface to receive the result
  * of a dynamic parsing run.
  * Often times this interface is directly implemented by the Parser class itself
  * (even though this is not a requirement).
  */
trait DynamicRuleHandler[P <: Parser, L <: HList] extends Parser.DeliveryScheme[L] {
  def parser: P
  def ruleNotFound(ruleName: String): Result
}

/** Runs one of the rules of a parser instance of type `P` given the rules name.
  * The rule must have type `RuleN[L]`.
  */
trait DynamicRuleDispatch[P <: Parser, L <: HList] {
  def apply(handler: DynamicRuleHandler[P, L], ruleName: String): handler.Result =
    lookup(ruleName).map(_(handler)).getOrElse(handler.ruleNotFound(ruleName))

  def lookup(ruleName: String): Option[RuleRunner[P, L]]
}

trait RuleRunner[P <: Parser, L <: HList] {
  def apply(handler: DynamicRuleHandler[P, L]): handler.Result
}

object DynamicRuleDispatch extends DynamicRuleDispatchMacro