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package commando
import scala.collection.mutable
import scala.{Option => Maybe}
case class CommandLine(
command: String,
arguments: Map[String, String],
subcommand: Maybe[CommandLine]
)
class ParseException(message: String) extends RuntimeException(message)
object Parser {
private sealed trait TokenKind
private case object SHORT extends TokenKind
private case object LONG extends TokenKind
private case object POSITIONAL extends TokenKind
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]) = new Iterator[Token] {
val args = input.iterator
val shortOptions = new mutable.Queue[Token]
var escaping = false
def hasNext = args.hasNext || !shortOptions.isEmpty
def next(): Token =
if (!shortOptions.isEmpty) {
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(command: Command,
args: Seq[String]): Either[ParseException, CommandLine] =
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
}
def line(command: Command): CommandLine = {
val longs: Map[String, Optional] = command.options.map {
case opt => opt.long -> opt
}.toMap
val shorts: Map[String, Optional] = command.options.collect {
case opt if opt.short.isDefined => opt.short.get.toString -> opt
}.toMap
val subcommands: Map[String, Command] = command.commands.map {
case cmd => cmd.name -> cmd
}.toMap
def fatal(message: String) =
throw new ParseException(s"${command.name}: $message")
def option(): (String, String) = {
val tok = accept()
val parts = tok.value.split("=", 2)
val name = parts(0)
val embedded: Maybe[String] =
if (parts.size > 1) Some(parts(1)) else None
val opt = (tok.kind: @unchecked) match {
case LONG =>
longs.getOrElse(name, fatal(s"option --$name unknown"))
case SHORT =>
shorts.getOrElse(name, fatal(s"option -$name unknown"))
}
if (opt.argumentRequired) {
embedded match {
case Some(value) => opt.long -> value
case None if token.kind == POSITIONAL =>
opt.long -> accept().value
case None =>
fatal(
s"option ${opt} requires an argument but ${token.value} found")
}
} else if (opt.argumentAllowed) {
embedded match {
case Some(value) => opt.long -> value
case None =>
if (token.kind == POSITIONAL) {
opt.long -> accept.value
} else {
opt.long -> ""
}
}
} else { // no argument allowed
embedded match {
case Some(value) =>
fatal(
s"no argument allowed for option $opt (it is set to $value)")
case None => opt.long -> ""
}
}
}
val remainingParameters = command.parameters.iterator
def parameter(): (String, String) = {
if (remainingParameters.hasNext) {
remainingParameters.next.name -> accept().value
} else {
fatal(s"too many parameters: '${token.value}'")
}
}
val parsedOptions = new mutable.HashMap[String, String]
val parsedParameters = new mutable.HashMap[String, String]
var escaping = false
def check(subline: Maybe[CommandLine]): CommandLine = {
val remaining = remainingParameters.toList
if (!remaining.forall(_.required == false)) {
val missing = remaining.toList.map(p => s"'${p.name}'")
fatal(s"missing parameter(s) ${missing.mkString(", ")}")
} else if (!subcommands.isEmpty && subline.isEmpty) {
val missing = command.commands.map(c => s"'${c.name}'")
fatal(
s"command not specified (must be one of ${missing.mkString(", ")})")
} else {
CommandLine(command.name,
parsedOptions.toMap ++ parsedParameters.toMap,
subline)
}
}
@annotation.tailrec
def innerLine(): CommandLine = {
if (token.kind == EOL) {
check(None)
} else if (escaping) {
parsedParameters += parameter()
innerLine()
} else if (token.kind == DOUBLE_DASH) {
escaping = true
readToken()
innerLine()
} else if (token.kind == POSITIONAL && !remainingParameters.isEmpty) {
parsedParameters += parameter()
innerLine()
} else if (token.kind == POSITIONAL) {
if (subcommands.isEmpty) {
fatal(s"too many parameters: '${token.value}'")
} else {
subcommands.get(token.value) match {
case None =>
val cmds = command.commands.map(c => s"'${c.name}'")
fatal(
s"subcommand '${token.value}' not found (must be one of ${cmds
.mkString(", ")})")
case Some(_) =>
val subline = line(subcommands(accept().value))
check(Some(subline))
}
}
} else if (token.kind == LONG || token.kind == SHORT) {
parsedOptions += option()
innerLine()
} else {
fatal(s"unknown token $token")
}
}
innerLine()
}
readToken()
Right(line(command))
} catch {
case ex: ParseException => Left(ex)
}
}
|
