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|
package commando
class Command(val name: String) {
import Command._
import collection.mutable
private case class Parameter(
var named: Boolean,
var name: String,
var short: Option[Char],
var argName: String,
var acceptsArg: Boolean,
var requiresArg: Boolean,
var required: Boolean,
var repeated: Boolean,
var action: Option[String] => Unit
)
class NamedBuilder(param: Parameter) {
def require() = { param.required = true; this }
def repeat() = { param.repeated = true; this }
def action(fct: () => Unit) = { param.action = opt => fct(); this }
def arg(name: String) = {
param.argName = name; param.acceptsArg = true; param.requiresArg = true;
new NamedArgBuilder(param)
}
def optionalArg(name: String) = {
param.argName = name; param.acceptsArg = true; param.requiresArg = false;
new NamedOptArgBuilder(param)
}
}
class NamedArgBuilder(param: Parameter) {
def require() = { param.required = true; this }
def repeat() = { param.repeated = true; this }
def action(fct: String => Unit) = {
param.action = opt => fct(opt.get); this
}
}
class NamedOptArgBuilder(param: Parameter) {
def require() = { param.required = true; this }
def repeat() = { param.repeated = true; this }
def action(fct: Option[String] => Unit) = { param.action = fct; this }
}
class PositionalBuilder(param: Parameter) {
def optional() = { param.required = false; this }
def repeat() = { param.repeated = true; param.required = false; this }
def action(fct: String => Unit) = {
param.action = opt => fct(opt.get); this
}
}
private val params = mutable.ListBuffer.empty[Parameter]
def named(name: String, short: Char = 0): NamedBuilder = {
val shortName = if (short == 0) None else Some(short)
val param =
Parameter(true, name, shortName, "", false, false, false, false, _ => ())
params += param
new NamedBuilder(param)
}
def positional(name: String): PositionalBuilder = {
val param =
Parameter(false, name, None, "", false, false, true, false, _ => ())
params += param
new PositionalBuilder(param)
}
/** Raise a fatal parse error. This will call parsing to fail with
* the given message.
*/
def error(message: String): Nothing = throw new ParseError(message)
/** Parse this command wrt the given arguments.
*
* Returns 'None' if parsing was successful, or an error message otherwise.
*/
def parse(args: Iterable[String]): Option[String] =
try {
var (named, positional) = params.toList.partition(_.named)
// keeps track of which parameters have already been set
val seen: mutable.Set[Parameter] = mutable.Set.empty[Parameter]
val it = args.iterator
var arg = ""
var done = false
def next() = if (it.hasNext) arg = it.next() else done = true
next()
var escaping = false
def process(param: Parameter, value: Option[String]) = {
param.action(value)
}
def readPositional(arg: String) =
if (positional.isEmpty) {
error("too many arguments")
} else {
process(positional.head, Some(arg))
seen += positional.head
if (!positional.head.repeated) {
positional = positional.tail
}
next()
}
def getNamed(
filter: Parameter => Boolean,
friendlyName: String
): Parameter = named.find(filter) match {
case None => error(s"unknown parameter: '$friendlyName'")
case Some(param) if (!param.repeated && seen.contains(param)) =>
error(
s"parameter '$friendlyName' has already been given and repetitions are not allowed"
)
case Some(param) =>
seen += param
param
}
def getLong(name: String): Parameter =
getNamed(p => p.name == name, s"--$name")
def getShort(name: Char): Parameter =
getNamed(p => p.short == Some(name), s"-$name")
def readNamed(param: Parameter, friendlyName: String) = {
next()
val nextIsArg = !done && (!arg.startsWith("-") || arg == "--")
if (param.requiresArg && nextIsArg) {
process(param, Some(arg))
next()
} else if (param.requiresArg && !nextIsArg) {
error(s"parameter '$friendlyName' requires an argument")
} else if (param.acceptsArg && nextIsArg) {
process(param, Some(arg))
next()
} else {
process(param, None)
}
}
while (!done) {
if (escaping == true) {
readPositional(arg)
} else if (arg == "--") {
escaping = true
next()
} else if (arg.startsWith("--")) {
arg.drop(2).split("=", 2) match {
case Array(name, embeddedValue) =>
val param = getLong(name)
if (param.acceptsArg) {
process(param, Some(embeddedValue))
next()
} else {
error(s"parameter '--$name' does not accept an argument")
}
case Array(name) =>
readNamed(getLong(name), s"--$name")
}
} else if (arg.startsWith("-") && arg != "-") {
val chars = arg.drop(1)
val params = chars.map(c => getShort(c))
if (params.length > 1) {
if (!params.forall(!_.acceptsArg)) {
error(
s"only flags are allowed when multiple short parameters are given: $chars"
)
} else {
params.foreach(p => process(p, None))
next()
}
} else {
readNamed(params.head, s"-${chars.head}")
}
} else {
readPositional(arg)
}
}
for (param <- params) {
if (param.required && !seen.contains(param))
error(s"missing parameter: '${param.name}'")
}
None
} catch {
case ParseError(message) => Some(message)
}
def completion(): String = {
val completions: List[String] = params.toList.filter(_.named).flatMap {
param =>
if (param.requiresArg) {
List(s"--${param.name}=")
} else if (param.acceptsArg) {
List(s"--${param.name}", s"--${param.name}=")
} else {
List(s"--${param.name}")
}
}
s"""|_${name}_complete() {
| local cur_word param_list
| cur_word="$${COMP_WORDS[COMP_CWORD]}"
| param_list="${completions.mkString(" ")}"
| if [[ $${cur_word} == -* ]]; then
| COMPREPLY=( $$(compgen -W "$$param_list" -- $${cur_word}) )
| else
| COMPREPLY=()
| fi
| return 0
|}
|complete -F _${name}_complete ${name}
|""".stripMargin
}
}
object Command {
case class ParseError(message: String) extends RuntimeException(message)
}
|
