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Diffstat (limited to 'main/core/src/util/Router.scala')
-rw-r--r-- | main/core/src/util/Router.scala | 451 |
1 files changed, 451 insertions, 0 deletions
diff --git a/main/core/src/util/Router.scala b/main/core/src/util/Router.scala new file mode 100644 index 00000000..5dd3c947 --- /dev/null +++ b/main/core/src/util/Router.scala @@ -0,0 +1,451 @@ +package mill.util + +import ammonite.main.Compat +import language.experimental.macros + +import scala.annotation.StaticAnnotation +import scala.collection.mutable +import scala.reflect.macros.blackbox.Context + +/** + * More or less a minimal version of Autowire's Server that lets you generate + * a set of "routes" from the methods defined in an object, and call them + * using passing in name/args/kwargs via Java reflection, without having to + * generate/compile code or use Scala reflection. This saves us spinning up + * the Scala compiler and greatly reduces the startup time of cached scripts. + */ +object Router{ + /** + * Allows you to query how many things are overriden by the enclosing owner. + */ + case class Overrides(value: Int) + object Overrides{ + def apply()(implicit c: Overrides) = c.value + implicit def generate: Overrides = macro impl + def impl(c: Context): c.Tree = { + import c.universe._ + q"new _root_.mill.util.Router.Overrides(${c.internal.enclosingOwner.overrides.length})" + } + } + + class doc(s: String) extends StaticAnnotation + class main extends StaticAnnotation + def generateRoutes[T]: Seq[Router.EntryPoint[T]] = macro generateRoutesImpl[T] + def generateRoutesImpl[T: c.WeakTypeTag](c: Context): c.Expr[Seq[EntryPoint[T]]] = { + import c.universe._ + val r = new Router(c) + val allRoutes = r.getAllRoutesForClass( + weakTypeOf[T].asInstanceOf[r.c.Type] + ).asInstanceOf[Iterable[c.Tree]] + + c.Expr[Seq[EntryPoint[T]]](q"_root_.scala.Seq(..$allRoutes)") + } + + /** + * Models what is known by the router about a single argument: that it has + * a [[name]], a human-readable [[typeString]] describing what the type is + * (just for logging and reading, not a replacement for a `TypeTag`) and + * possible a function that can compute its default value + */ + case class ArgSig[T, V](name: String, + typeString: String, + doc: Option[String], + default: Option[T => V]) + (implicit val reads: scopt.Read[V]) + + def stripDashes(s: String) = { + if (s.startsWith("--")) s.drop(2) + else if (s.startsWith("-")) s.drop(1) + else s + } + /** + * What is known about a single endpoint for our routes. It has a [[name]], + * [[argSignatures]] for each argument, and a macro-generated [[invoke0]] + * that performs all the necessary argument parsing and de-serialization. + * + * Realistically, you will probably spend most of your time calling [[invoke]] + * instead, which provides a nicer API to call it that mimmicks the API of + * calling a Scala method. + */ + case class EntryPoint[T](name: String, + argSignatures: Seq[ArgSig[T, _]], + doc: Option[String], + varargs: Boolean, + invoke0: (T, Map[String, String], Seq[String], Seq[ArgSig[T, _]]) => Result[Any], + overrides: Int){ + def invoke(target: T, groupedArgs: Seq[(String, Option[String])]): Result[Any] = { + var remainingArgSignatures = argSignatures.toList.filter(_.reads.arity > 0) + + val accumulatedKeywords = mutable.Map.empty[ArgSig[T, _], mutable.Buffer[String]] + val keywordableArgs = if (varargs) argSignatures.dropRight(1) else argSignatures + + for(arg <- keywordableArgs) accumulatedKeywords(arg) = mutable.Buffer.empty + + val leftoverArgs = mutable.Buffer.empty[String] + + val lookupArgSig = Map(argSignatures.map(x => (x.name, x)):_*) + + var incomplete: Option[ArgSig[T, _]] = None + + for(group <- groupedArgs){ + + group match{ + case (value, None) => + if (value(0) == '-' && !varargs){ + lookupArgSig.get(stripDashes(value)) match{ + case None => leftoverArgs.append(value) + case Some(sig) => incomplete = Some(sig) + } + + } else remainingArgSignatures match { + case Nil => leftoverArgs.append(value) + case last :: Nil if varargs => leftoverArgs.append(value) + case next :: rest => + accumulatedKeywords(next).append(value) + remainingArgSignatures = rest + } + case (rawKey, Some(value)) => + val key = stripDashes(rawKey) + lookupArgSig.get(key) match{ + case Some(x) if accumulatedKeywords.contains(x) => + if (accumulatedKeywords(x).nonEmpty && varargs){ + leftoverArgs.append(rawKey, value) + }else{ + accumulatedKeywords(x).append(value) + remainingArgSignatures = remainingArgSignatures.filter(_.name != key) + } + case _ => + leftoverArgs.append(rawKey, value) + } + } + } + + val missing0 = remainingArgSignatures + .filter(_.default.isEmpty) + + val missing = if(varargs) { + missing0.filter(_ != argSignatures.last) + } else { + missing0.filter(x => incomplete != Some(x)) + } + val duplicates = accumulatedKeywords.toSeq.filter(_._2.length > 1) + + if ( + incomplete.nonEmpty || + missing.nonEmpty || + duplicates.nonEmpty || + (leftoverArgs.nonEmpty && !varargs) + ){ + Result.Error.MismatchedArguments( + missing = missing, + unknown = leftoverArgs, + duplicate = duplicates, + incomplete = incomplete + + ) + } else { + val mapping = accumulatedKeywords + .iterator + .collect{case (k, Seq(single)) => (k.name, single)} + .toMap + + try invoke0(target, mapping, leftoverArgs, argSignatures) + catch{case e: Throwable => + Result.Error.Exception(e) + } + } + } + } + + def tryEither[T](t: => T, error: Throwable => Result.ParamError) = { + try Right(t) + catch{ case e: Throwable => Left(error(e))} + } + def readVarargs(arg: ArgSig[_, _], + values: Seq[String], + thunk: String => Any) = { + val attempts = + for(item <- values) + yield tryEither(thunk(item), Result.ParamError.Invalid(arg, item, _)) + + + val bad = attempts.collect{ case Left(x) => x} + if (bad.nonEmpty) Left(bad) + else Right(attempts.collect{case Right(x) => x}) + } + def read(dict: Map[String, String], + default: => Option[Any], + arg: ArgSig[_, _], + thunk: String => Any): FailMaybe = { + arg.reads.arity match{ + case 0 => + tryEither(thunk(null), Result.ParamError.DefaultFailed(arg, _)).left.map(Seq(_)) + case 1 => + dict.get(arg.name) match{ + case None => + tryEither(default.get, Result.ParamError.DefaultFailed(arg, _)).left.map(Seq(_)) + + case Some(x) => + tryEither(thunk(x), Result.ParamError.Invalid(arg, x, _)).left.map(Seq(_)) + } + } + + } + + /** + * Represents what comes out of an attempt to invoke an [[EntryPoint]]. + * Could succeed with a value, but could fail in many different ways. + */ + sealed trait Result[+T] + object Result{ + + /** + * Invoking the [[EntryPoint]] was totally successful, and returned a + * result + */ + case class Success[T](value: T) extends Result[T] + + /** + * Invoking the [[EntryPoint]] was not successful + */ + sealed trait Error extends Result[Nothing] + object Error{ + + /** + * Invoking the [[EntryPoint]] failed with an exception while executing + * code within it. + */ + case class Exception(t: Throwable) extends Error + + /** + * Invoking the [[EntryPoint]] failed because the arguments provided + * did not line up with the arguments expected + */ + case class MismatchedArguments(missing: Seq[ArgSig[_, _]], + unknown: Seq[String], + duplicate: Seq[(ArgSig[_, _], Seq[String])], + incomplete: Option[ArgSig[_, _]]) extends Error + /** + * Invoking the [[EntryPoint]] failed because there were problems + * deserializing/parsing individual arguments + */ + case class InvalidArguments(values: Seq[ParamError]) extends Error + } + + sealed trait ParamError + object ParamError{ + /** + * Something went wrong trying to de-serialize the input parameter; + * the thrown exception is stored in [[ex]] + */ + case class Invalid(arg: ArgSig[_, _], value: String, ex: Throwable) extends ParamError + /** + * Something went wrong trying to evaluate the default value + * for this input parameter + */ + case class DefaultFailed(arg: ArgSig[_, _], ex: Throwable) extends ParamError + } + } + + + type FailMaybe = Either[Seq[Result.ParamError], Any] + type FailAll = Either[Seq[Result.ParamError], Seq[Any]] + + def validate(args: Seq[FailMaybe]): Result[Seq[Any]] = { + val lefts = args.collect{case Left(x) => x}.flatten + + if (lefts.nonEmpty) Result.Error.InvalidArguments(lefts) + else { + val rights = args.collect{case Right(x) => x} + Result.Success(rights) + } + } + + def makeReadCall(dict: Map[String, String], + default: => Option[Any], + arg: ArgSig[_, _]) = { + read(dict, default, arg, arg.reads.reads(_)) + } + def makeReadVarargsCall(arg: ArgSig[_, _], values: Seq[String]) = { + readVarargs(arg, values, arg.reads.reads(_)) + } +} + + +class Router [C <: Context](val c: C) { + import c.universe._ + def getValsOrMeths(curCls: Type): Iterable[MethodSymbol] = { + def isAMemberOfAnyRef(member: Symbol) = { + // AnyRef is an alias symbol, we go to the real "owner" of these methods + val anyRefSym = c.mirror.universe.definitions.ObjectClass + member.owner == anyRefSym + } + val extractableMembers = for { + member <- curCls.members.toList.reverse + if !isAMemberOfAnyRef(member) + if !member.isSynthetic + if member.isPublic + if member.isTerm + memTerm = member.asTerm + if memTerm.isMethod + if !memTerm.isModule + } yield memTerm.asMethod + + extractableMembers flatMap { case memTerm => + if (memTerm.isSetter || memTerm.isConstructor || memTerm.isGetter) Nil + else Seq(memTerm) + + } + } + + + + def extractMethod(meth: MethodSymbol, curCls: c.universe.Type): c.universe.Tree = { + val baseArgSym = TermName(c.freshName()) + val flattenedArgLists = meth.paramss.flatten + def hasDefault(i: Int) = { + val defaultName = s"${meth.name}$$default$$${i + 1}" + if (curCls.members.exists(_.name.toString == defaultName)) Some(defaultName) + else None + } + val argListSymbol = q"${c.fresh[TermName]("argsList")}" + val extrasSymbol = q"${c.fresh[TermName]("extras")}" + val defaults = for ((arg, i) <- flattenedArgLists.zipWithIndex) yield { + val arg = TermName(c.freshName()) + hasDefault(i).map(defaultName => q"($arg: $curCls) => $arg.${newTermName(defaultName)}") + } + + def getDocAnnotation(annotations: List[Annotation]) = { + val (docTrees, remaining) = annotations.partition(_.tpe =:= typeOf[Router.doc]) + val docValues = for { + doc <- docTrees + if doc.scalaArgs.head.isInstanceOf[Literal] + l = doc.scalaArgs.head.asInstanceOf[Literal] + if l.value.value.isInstanceOf[String] + } yield l.value.value.asInstanceOf[String] + (remaining, docValues.headOption) + } + + def unwrapVarargType(arg: Symbol) = { + val vararg = arg.typeSignature.typeSymbol == definitions.RepeatedParamClass + val unwrappedType = + if (!vararg) arg.typeSignature + else arg.typeSignature.asInstanceOf[TypeRef].args(0) + + (vararg, unwrappedType) + } + + val argSigSymbol = q"${c.fresh[TermName]("argSigs")}" + + val (_, methodDoc) = getDocAnnotation(meth.annotations) + val readArgSigs = for( + ((arg, defaultOpt), i) <- flattenedArgLists.zip(defaults).zipWithIndex + ) yield { + + val (vararg, varargUnwrappedType) = unwrapVarargType(arg) + + val default = + if (vararg) q"scala.Some(scala.Nil)" + else defaultOpt match { + case Some(defaultExpr) => q"scala.Some($defaultExpr($baseArgSym))" + case None => q"scala.None" + } + + val (docUnwrappedType, docOpt) = varargUnwrappedType match{ + case t: AnnotatedType => + + val (remaining, docValue) = getDocAnnotation(t.annotations) + if (remaining.isEmpty) (t.underlying, docValue) + else (Compat.copyAnnotatedType(c)(t, remaining), docValue) + + case t => (t, None) + } + + val docTree = docOpt match{ + case None => q"scala.None" + case Some(s) => q"scala.Some($s)" + } + + + val argSig = q""" + mill.util.Router.ArgSig[$curCls, $docUnwrappedType]( + ${arg.name.toString}, + ${docUnwrappedType.toString + (if(vararg) "*" else "")}, + $docTree, + $defaultOpt + ) + """ + + val reader = + if(vararg) q""" + mill.util.Router.makeReadVarargsCall( + $argSigSymbol($i), + $extrasSymbol + ) + """ else q""" + mill.util.Router.makeReadCall( + $argListSymbol, + $default, + $argSigSymbol($i) + ) + """ + c.internal.setPos(reader, meth.pos) + (reader, argSig, vararg) + } + + val readArgs = readArgSigs.map(_._1) + val argSigs = readArgSigs.map(_._2) + val varargs = readArgSigs.map(_._3) + val (argNames, argNameCasts) = flattenedArgLists.map { arg => + val (vararg, unwrappedType) = unwrapVarargType(arg) + ( + pq"${arg.name.toTermName}", + if (!vararg) q"${arg.name.toTermName}.asInstanceOf[$unwrappedType]" + else q"${arg.name.toTermName}.asInstanceOf[Seq[$unwrappedType]]: _*" + + ) + }.unzip + + + val res = q""" + mill.util.Router.EntryPoint[$curCls]( + ${meth.name.toString}, + scala.Seq(..$argSigs), + ${methodDoc match{ + case None => q"scala.None" + case Some(s) => q"scala.Some($s)" + }}, + ${varargs.contains(true)}, + ( + $baseArgSym: $curCls, + $argListSymbol: Map[String, String], + $extrasSymbol: Seq[String], + $argSigSymbol: Seq[mill.util.Router.ArgSig[$curCls, _]] + ) => + mill.util.Router.validate(Seq(..$readArgs)) match{ + case mill.util.Router.Result.Success(List(..$argNames)) => + mill.util.Router.Result.Success( + $baseArgSym.${meth.name.toTermName}(..$argNameCasts) + ) + case x: mill.util.Router.Result.Error => x + }, + ammonite.main.Router.Overrides() + ) + """ + res + } + + def hasMainAnnotation(t: MethodSymbol) = { + t.annotations.exists(_.tpe =:= typeOf[Router.main]) + } + def getAllRoutesForClass(curCls: Type, + pred: MethodSymbol => Boolean = hasMainAnnotation) + : Iterable[c.universe.Tree] = { + for{ + t <- getValsOrMeths(curCls) + if pred(t) + } yield { + extractMethod(t, curCls) + } + } +} |