以下是我的ADT。注意主要的是塊可以嵌套(看children
財產。模式匹配和遞歸問題
trait Cda {
def format: String = this match {
case f: Field => f.value
case Block(fields, children) => fields.map(f => f.format).mkString("|") + "|" + children.map(b => b.format).mkString("|")
case Record(keys, blocks) => blocks.map(b => b.format).mkString("|")
}
}
trait Field extends Cda {
val name: String
val value: String
}
case class StringField(name: String, value: String) extends Field
case class DateField(name: String, value: String) extends Field
case class TimeField(name: String, value: String) extends Field
case class MatchKey(keyFields: Seq[Field]) extends Cda
case class Block(fields: Seq[Field], children: Seq[Block] = Seq()) extends Cda
case class Record(key: MatchKey, blocks: Seq[Block]) extends Cda
以下是ADT
//Block - AI
val aiBlockId = StringField("blockId", "AI")
val addlFieldPos = StringField("AdditionalFieldPosition", "addlFieldPos")
val addlFieldName = StringField("AdditionalFieldName", "addlFieldName")
val AI = Block(Seq(aiBlockId, addlFieldPos, addlFieldName))
//Block - RPS
val rpsBlockId = StringField("blockId", "RPS")
val dateOfStatus = DateField("DateOfStatus", "19240811")
val timeOfStatus = TimeField("TimeOfStatus", "023829")
val rpsBlocks = Seq(rpsBlockId, dateOfStatus, timeOfStatus)
val rpsNestedBlocks = Seq(AI)
val RPS = Block(rpsBlocks, rpsNestedBlocks)
我期待的格式返回RPS|19240811|023829|AI|addlFieldPos|addlFieldName
的實例例示,但我得到一個額外的管|在最後:RPS|19240811|023829|AI|addlFieldPos|addlFieldName|
如何改變遞歸函數format
(特別是case Block(fields,children)
)更正此問題?