你显然正在建造一些东西，所以你可能想尝试......一个建造者！
和 Jürgen 一样，我的第一个想法是弃牌，你正在累积一个结果。
mutable.Builder 可变地进行累积，使用 collection.generic.CanBuildFrom 指示构建器用于从源集合生成目标集合。您将可变事物保留足够长的时间以获得结果。这就是我的本地化可变性插件。以免假设从 List[String] 到 List[Project] 的路径是不可变的。
对于其他好的答案（具有非负评价评级的答案），我要补充一点，功能风格意味着功能分解，通常是小功能。
如果您不使用正则表达式解析器，请不要忽略模式匹配中的正则表达式。
并尽量避免点。事实上，我相信明天是 Spare the Dots Day，建议对点敏感的人留在室内。
case class Project(user: String, name: String, description: String)
trait Sample {
val sample = """
|User=Hans
|Project=Blow up the moon
|The slugs are going to eat the mustard. // multiline possible!
|They are sneaky bastards, those slugs.
|
|User=Bob
|I haven't thought up a project name yet.
|
|User=Greta
|Project=Burn the witch
|It's necessary to escape from the witch before
|we blow up the moon. I hope Hans sees it my way.
|Once we burn the bitch, I mean witch, we can
|wreak whatever havoc pleases us.
|""".stripMargin
}
object Test extends App with Sample {
val kv = "(.*?)=(.*)".r
def nonnully(s: String) = if (s == null) "" else s + " "
val empty = Project(null, null, null)
val (res, dummy) = ((List.empty[Project], empty) /: sample.lines) { (acc, line) =>
val (sofar, cur) = acc
line match {
case kv("User", u) => (sofar, cur copy (user = u))
case kv("Project", n) => (sofar, cur copy (name = n))
case kv(k, _) => sys error s"Bad keyword $k"
case x if x.nonEmpty => (sofar, cur copy (description = s"${nonnully(cur.description)}$x"))
case _ if cur != empty => (cur :: sofar, empty)
case _ => (sofar, empty)
}
}
val ps = if (dummy == empty) res.reverse else (dummy :: res).reverse
Console println ps
}
比赛也可以这样捣碎：
val (res, dummy) = ((List.empty[Project], empty) /: sample.lines) {
case ((sofar, cur), kv("User", u)) => (sofar, cur copy (user = u))
case ((sofar, cur), kv("Project", n)) => (sofar, cur copy (name = n))
case ((sofar, cur), kv(k, _)) => sys error s"Bad keyword $k"
case ((sofar, cur), x) if x.nonEmpty => (sofar, cur copy (description = s"${nonnully(cur.description)}$x"))
case ((sofar, cur), _) if cur != empty => (cur :: sofar, empty)
case ((sofar, cur), _) => (sofar, empty)
}
在折叠之前，先做段落似乎更简单。这是必然的想法吗？
object Test0 extends App with Sample {
def grafs(ss: Iterator[String]): List[List[String]] = {
val (g, rest) = ss dropWhile (_.isEmpty) span (_.nonEmpty)
val others = if (rest.nonEmpty) grafs(rest) else Nil
g.toList :: others
}
def toProject(ss: List[String]): Project = {
var p = Project("", "", "")
for (line <- ss; parts = line split '=') parts match {
case Array("User", u) => p = p.copy(user = u)
case Array("Project", n) => p = p.copy(name = n)
case Array(k, _) => sys error s"Bad keyword $k"
case Array(text) => p = p.copy(description = s"${p.description} $text")
}
p
}
val ps = grafs(sample.lines) map toProject
Console println ps
}