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package commando
import scala.collection.mutable
class ParseException(message: String) extends RuntimeException(message)
object Parser {
private sealed trait TokenKind
private case object SHORT extends TokenKind // -<n>
private case object LONG extends TokenKind // --<n>
private case object POSITIONAL extends TokenKind // <n>
private case object DOUBLE_DASH extends TokenKind // --
private case object EOL extends TokenKind
private case class Token(value: String, kind: TokenKind)
private def lex(input: Seq[String]): Iterator[Token] = new Iterator[Token] {
val args = input.iterator
val shortOptions = new mutable.Queue[Token]
var escaping = false
override def hasNext: Boolean = args.hasNext || shortOptions.nonEmpty
override def next(): Token =
if (shortOptions.nonEmpty) {
shortOptions.dequeue()
} else {
val arg = args.next
if (escaping) {
Token(arg, POSITIONAL)
} else if (arg == "--") {
escaping = true
Token("--", DOUBLE_DASH)
} else if (arg.startsWith("--")) {
Token(arg.drop(2), LONG)
} else if (arg.startsWith("-") && arg != "-") {
arg.drop(1).foreach { char =>
shortOptions.enqueue(Token(char.toString, SHORT))
}
next()
} else {
Token(arg, POSITIONAL)
}
}
}
def parse(args: Seq[String],
command: Command,
onError: (Command, String) => Unit): Unit =
try {
val tokens: Iterator[Token] = lex(args)
var token: Token = Token("end-of-line", EOL)
def readToken(): Unit = {
if (tokens.hasNext) {
token = tokens.next
} else {
token = Token("end-of-line", EOL)
}
}
def accept(): Token = {
val tok = token
readToken()
tok
}
val _parsedArguments = new mutable.HashMap[String, List[String]]
def addArgument(name: String, value: String): Unit =
_parsedArguments.get(name) match {
case None => _parsedArguments(name) = value :: Nil
case Some(values) => _parsedArguments(name) = value :: values
}
def parsedArguments =
_parsedArguments.map {
case (key, values) =>
key -> values.reverse.toSeq
}.toMap
def line(command: Command): Unit = {
val longs: Map[String, Optional] = command.optionals.map {
case opt: Optional => opt.long -> opt
}.toMap
val shorts: Map[String, Optional] = command.optionals.collect {
case opt: Optional if opt.short.isDefined =>
opt.short.get.toString -> opt
}.toMap
val remainingPositionals = command.positionals.collect {
case pos: Positional => pos
}.iterator
val subcommands: Map[String, Command] = command.commands.map { cmd =>
cmd.name -> cmd
}.toMap
def fatal(message: String) = throw new ParseException(message)
def optional(): Unit = {
val tok = accept()
val parts = tok.value.split("=", 2)
val name = parts(0)
val embedded: Option[String] =
if (parts.size > 1) Some(parts(1)) else None
val opt = (tok.kind: @unchecked) match {
case LONG =>
longs.getOrElse(name, fatal(s"option --$name unknown"))
case SHORT =>
shorts.getOrElse(name, fatal(s"option -$name unknown"))
}
if (opt.argumentRequired) {
embedded match {
case Some(value) =>
addArgument(opt.long, value)
case None if token.kind == POSITIONAL =>
addArgument(opt.long, accept().value)
case None =>
fatal(
s"option ${opt.usage} requires an argument but ${token.value} found")
}
} else if (opt.argumentAllowed) {
embedded match {
case Some(value) =>
addArgument(opt.long, value)
case None =>
if (token.kind == POSITIONAL) {
addArgument(opt.long, accept().value)
} else {
addArgument(opt.long, "")
}
}
} else { // no argument allowed
embedded match {
case Some(value) =>
fatal(
s"no argument allowed for option ${opt.usage} (it is set to $value)")
case None => addArgument(opt.long, "")
}
}
}
def positional(): Unit = {
if (remainingPositionals.hasNext) {
addArgument(
remainingPositionals.next.name,
accept().value
)
} else {
fatal(s"too many parameters: '${token.value}'")
}
}
// make sure all required positional parameters have been parsed
def checkPositionals(): Unit = {
val remaining = remainingPositionals.toList
if (!remaining.forall(_.required == false)) {
val missing = remaining.map(p => s"'${p.name}'")
fatal(s"missing parameter(s) ${missing.mkString(", ")}")
}
}
var escaping = false
@annotation.tailrec
def innerLine(): Unit = {
if (token.kind == EOL) {
checkPositionals()
if (subcommands.nonEmpty) {
val missing = command.commands.map(c => s"'${c.name}'")
fatal(
s"command not specified (must be one of ${missing.mkString(", ")})")
}
command.action.get(parsedArguments)
} else if (escaping) {
positional()
innerLine()
} else if (token.kind == DOUBLE_DASH) {
escaping = true
readToken()
innerLine()
} else if (token.kind == POSITIONAL && remainingPositionals.nonEmpty) {
positional()
innerLine()
} else if (token.kind == POSITIONAL) {
if (subcommands.isEmpty) {
fatal(s"too many parameters: '${token.value}'")
} else {
subcommands.get(token.value) match {
case None =>
val cmds = command.commands.map(c => s"'${c.name}'")
fatal(
s"command '${token.value}' not found (must be one of ${cmds
.mkString(", ")})")
case Some(cmd) =>
checkPositionals()
readToken()
line(cmd)
}
}
} else if (token.kind == LONG || token.kind == SHORT) {
optional()
innerLine()
} else {
fatal(s"unknown token $token")
}
}
innerLine()
}
readToken()
line(command)
} catch {
case ex: ParseException => onError(command, ex.getMessage)
}
}
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