[RFC] Parameterize context type of decorators (#137)

This allows customizing the way by-type parameters can be read: instead of always reading data from a `cask.Request`, this allows a decorator to parameterize the context type and pass it in explicitly from the `wrapFunction` method. Essentially, this makes the context parameter of `ArgReader`s (which are used to translate data from a HTTP request to a scala parameter) customizable for every decorator. ## Motivation The idea behind this proposal is to uniformize the way "named" and "by-type" parameters within the same endpoint are handled. By "named" parameters I mean parameters which are set from the `Map[String, Input]` in the delegate function, and by `by-type` parameters I mean parameters which are computed from an arity zero `ArgReader`, and thus use the `cask.Request` context to compute their value. E.g. ``` @cask.get(/:foo/:bar) def index(foo: String, bar: Int, cookie1: cask.Cookies, req: cask.Request) ``` In this case, `foo` and `bar` and "named" and `cookie1` and `req` are "by-type". Right now, the `wrapFunction` method handles how named parameters are set, and therefore can centrally do arbitrary pre- and post-processing. However, by-type parameters must always use a `cask.Request` to compute any values, which can be problematic if the computation is expensive or if any kind of state is maintained. **This pull request removes this asymmetry, by allowing the `wrapFunction` to compute a custom context which is computed once before being passed to all `InputReader`s** ## Implementation approach - add `InputContext` type parameter to decorators - add a parameter of type `InputContext` to `delegate`. `type Delegate = (InputContext, Map[String, Input)) => ...` - change `Decorator.invoke()` to carry a list of input contexts, one for each parameter list - also change the `Entrypoint` macros to use these input contexts rather than hardcoding `cask.Request`
com-lihaoyi · Nov 3, 2024 · d823a8a · d823a8a
1 parent e7fcba1
commit d823a8a
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diff --git a/build.mill b/build.mill
@@ -105,6 +105,7 @@ def zippedExamples = T {
     build.example.cookies.millSourcePath,
     build.example.decorated.millSourcePath,
     build.example.decorated2.millSourcePath,
+    build.example.decoratedContext.millSourcePath,
     build.example.endpoints.millSourcePath,
     build.example.formJsonPost.millSourcePath,
     build.example.httpMethods.millSourcePath,
@@ -143,6 +144,7 @@ def zippedExamples = T {
         .replaceFirst(
           "object app extends.*\ntrait AppModule extends CrossScalaModule(.*)\\{",
           s"object app extends ScalaModule $$1\\{\n  def scalaVersion = \"${scala213}\"")
+        .replaceAll("build.scala3", s"\"${scala3}\"")
         .replaceFirst(
           "def ivyDeps = Agg\\[Dep\\]\\(",
           "def ivyDeps = Agg(\n    ivy\"com.lihaoyi::cask:" + releaseTag + "\","

diff --git a/cask/src-2/cask/main/Routes.scala b/cask/src-2/cask/main/Routes.scala
@@ -6,7 +6,7 @@ import language.experimental.macros
 
 trait Routes{
 
-  def decorators = Seq.empty[cask.router.Decorator[_, _, _]]
+  def decorators = Seq.empty[cask.router.Decorator[_, _, _, _]]
   private[this] var metadata0: RoutesEndpointsMetadata[this.type] = null
   def caskMetadata =
     if (metadata0 != null) metadata0

diff --git a/cask/src-2/cask/router/Macros.scala b/cask/src-2/cask/router/Macros.scala
@@ -43,7 +43,6 @@ class Macros[C <: blackbox.Context](val c: C) {
   def extractMethod(method: MethodSymbol,
                     curCls: c.universe.Type,
                     convertToResultType: c.Tree,
-                    ctx: c.Tree,
                     argReaders: Seq[c.Tree],
                     annotDeserializeTypes: Seq[c.Tree]): c.universe.Tree = {
     val baseArgSym = TermName(c.freshName())
@@ -64,7 +63,7 @@ class Macros[C <: blackbox.Context](val c: C) {
     val ctxSymbol = q"${c.fresh[TermName](TermName("ctx"))}"
     val argData = for(argListIndex <- method.paramLists.indices) yield{
       val annotDeserializeType = annotDeserializeTypes.lift(argListIndex).getOrElse(tq"scala.Any")
-      val argReader = argReaders.lift(argListIndex).getOrElse(q"cask.router.NoOpParser.instanceAny")
+      val argReader = argReaders.lift(argListIndex).getOrElse(q"cask.router.NoOpParser.instanceAnyRequest")
       val flattenedArgLists = method.paramss(argListIndex)
       def hasDefault(i: Int) = {
         // defaults are numbered globally on a class-level, this means that we
@@ -108,18 +107,18 @@ class Macros[C <: blackbox.Context](val c: C) {
 
         val argSig =
           q"""
-          cask.router.ArgSig[$annotDeserializeType, $curCls, $docUnwrappedType, $ctx](
+          cask.router.ArgSig[$annotDeserializeType, $curCls, $docUnwrappedType, Any](
             ${arg.name.toString},
             ${docUnwrappedType.toString},
             $docTree,
             $defaultOpt
-          )($argReader[$docUnwrappedType])
+          )($argReader[$docUnwrappedType].asInstanceOf[cask.router.ArgReader[$annotDeserializeType, $docUnwrappedType, Any]])
         """
 
         val reader = q"""
           cask.router.Runtime.makeReadCall(
             $argValuesSymbol($argListIndex),
-            $ctxSymbol,
+            $ctxSymbol($argListIndex),
             $default,
             $argSigsSymbol($argListIndex)($i)
           )
@@ -151,7 +150,7 @@ class Macros[C <: blackbox.Context](val c: C) {
     for(argNameCast <- argNameCasts) methodCall = q"$methodCall(..$argNameCast)"
 
     val res = q"""
-    cask.router.EntryPoint[$curCls, $ctx](
+    cask.router.EntryPoint[$curCls, Any](
       ${method.name.toString},
       ${argSigs.toList},
       ${methodDoc match{
@@ -160,9 +159,9 @@ class Macros[C <: blackbox.Context](val c: C) {
       }},
       (
         $baseArgSym: $curCls,
-        $ctxSymbol: $ctx,
+        $ctxSymbol: Seq[_],
         $argValuesSymbol: Seq[Map[String, Any]],
-        $argSigsSymbol: scala.Seq[scala.Seq[cask.router.ArgSig[Any, _, _, $ctx]]]
+        $argSigsSymbol: scala.Seq[scala.Seq[cask.router.ArgSig[Any, _, _, Any]]]
       ) =>
         cask.router.Runtime.validate(Seq(..${readArgs.flatten.toList})).map{
           case Seq(..${argNames.flatten.toList}) => $convertToResultType($methodCall)

diff --git a/cask/src-2/cask/router/RoutesEndpointMetadata.scala b/cask/src-2/cask/router/RoutesEndpointMetadata.scala
@@ -15,15 +15,15 @@ object RoutesEndpointsMetadata{
 
     val routeParts = for{
       m <- c.weakTypeOf[T].members
-      annotations = m.annotations.filter(_.tree.tpe <:< c.weakTypeOf[Decorator[_, _, _]])
+      annotations = m.annotations.filter(_.tree.tpe <:< c.weakTypeOf[Decorator[_, _, _, _]])
       if annotations.nonEmpty
     } yield {
-      if(!(annotations.last.tree.tpe <:< weakTypeOf[Endpoint[_, _, _]])) c.abort(
+      if(!(annotations.last.tree.tpe <:< weakTypeOf[Endpoint[_, _, _, _]])) c.abort(
         annotations.head.tree.pos,
         s"Last annotation applied to a function must be an instance of Endpoint, " +
           s"not ${annotations.last.tree.tpe}"
       )
-      val allEndpoints = annotations.filter(_.tree.tpe <:< weakTypeOf[Endpoint[_, _, _]])
+      val allEndpoints = annotations.filter(_.tree.tpe <:< weakTypeOf[Endpoint[_, _, _, _]])
       if(allEndpoints.length > 1) c.abort(
         annotations.last.tree.pos,
         s"You can only apply one Endpoint annotation to a function, not " +
@@ -49,7 +49,6 @@ object RoutesEndpointsMetadata{
         m.asInstanceOf[MethodSymbol],
         weakTypeOf[T],
         q"${annotObjectSyms.last}.convertToResultType",
-        tq"cask.Request",
         annotObjectSyms.reverse.map(annotObjectSym => q"$annotObjectSym.getParamParser"),
         annotObjectSyms.reverse.map(annotObjectSym => tq"$annotObjectSym.InputTypeAlias")
       )

diff --git a/cask/src-3/cask/main/Routes.scala b/cask/src-3/cask/main/Routes.scala
@@ -6,7 +6,7 @@ import language.experimental.macros
 
 trait Routes{
 
-  def decorators = Seq.empty[cask.router.Decorator[_, _, _]]
+  def decorators = Seq.empty[cask.router.Decorator[_, _, _, _]]
   private[this] var metadata0: RoutesEndpointsMetadata[this.type] = null
   def caskMetadata =
     if (metadata0 != null) metadata0

diff --git a/cask/src-3/cask/router/Macros.scala b/cask/src-3/cask/router/Macros.scala
@@ -9,21 +9,21 @@ object Macros {
     * This replicates EndpointMetadata.seqify, but in a macro where error
     * positions can be controlled.
     */
-  def checkDecorators(using Quotes)(decorators: List[Expr[Decorator[_, _, _]]]): Boolean = {
+  def checkDecorators(using Quotes)(decorators: List[Expr[Decorator[_, _, _, _]]]): Boolean = {
     import quotes.reflect._
 
     var hasErrors = false
 
-    def check(prevOuter: TypeRepr, decorators: List[Expr[Decorator[_, _, _]]]): Unit =
+    def check(prevOuter: TypeRepr, decorators: List[Expr[Decorator[_, _, _, _]]]): Unit =
       decorators match {
         case Nil =>
-        case '{ $d: Decorator[outer, inner, _] } :: tail =>
+        case '{ $d: Decorator[outer, inner, _, _] } :: tail =>
           if (TypeRepr.of[inner] <:< prevOuter) {
             check(TypeRepr.of[outer], tail)
           } else {
             hasErrors = true
             report.error(
-              s"required: cask.router.Decorator[_, ${prevOuter.show}, _]",
+              s"required: cask.router.Decorator[_, ${prevOuter.show}, _, _]",
               d
             )
           }
@@ -56,7 +56,7 @@ object Macros {
 
   /** Summon the reader for a parameter. */
   def summonReader(using Quotes)(
-    decorator: Expr[Decorator[_,_,_]],
+    decorator: Expr[Decorator[_,_,_,_]],
     param: quotes.reflect.Symbol
   ): Expr[ArgReader[_, _, _]] = {
     import quotes.reflect._
@@ -143,13 +143,13 @@ object Macros {
     */
   def convertToResponse(using Quotes)(
     method: quotes.reflect.Symbol,
-    endpoint: Expr[Endpoint[_, _, _]],
+    endpoint: Expr[Endpoint[_, _, _, _]],
     result: Expr[Any]
   ): Expr[Any] = {
     import quotes.reflect._
 
     val innerReturnedTpt = endpoint.asTerm.tpe.asType match {
-      case '[Endpoint[_, innerReturned, _]] => TypeRepr.of[innerReturned]
+      case '[Endpoint[_, innerReturned, _, _]] => TypeRepr.of[innerReturned]
       case _ => ???
     }
 
@@ -186,9 +186,9 @@ object Macros {
 
   def extractMethod[Cls: Type](using q: Quotes)(
     method: quotes.reflect.Symbol,
-    decorators: List[Expr[Decorator[_, _, _]]], // these must also include the endpoint
-    endpoint: Expr[Endpoint[_, _, _]]
-  ): Expr[EntryPoint[Cls, cask.Request]] = {
+    decorators: List[Expr[Decorator[_, _, _, _]]], // these must also include the endpoint
+    endpoint: Expr[Endpoint[_, _, _, _]]
+  ): Expr[EntryPoint[Cls, Any]] = {
     import quotes.reflect._
 
     val defaults = getDefaultParams(method)
@@ -198,7 +198,7 @@ object Macros {
 
       // sometimes we have more params than annotated decorators, for example if
       // there are global decorators
-      val decorator: Option[Expr[Decorator[_, _, _]]] = decorators.lift(idx)
+      val decorator: Option[Expr[Decorator[_, _, _, _]]] = decorators.lift(idx)
 
       val exprs1 = for (param <- params) yield {
         val paramTree = param.tree.asInstanceOf[ValDef]
@@ -231,35 +231,35 @@ object Macros {
           case Some(deco) => summonReader(deco, param)
           case None =>
             decoTpe match
-              case '[t] => '{ NoOpParser.instanceAny[t] }
+              case '[t] => '{ NoOpParser.instanceAnyRequest[t] } // TODO
         }
 
         '{
-          ArgSig[Any, Cls, Any, cask.Request](
+          ArgSig[Any, Cls, Any, Any](
             ${Expr(param.name)},
             ${Expr(paramTpeName)},
             doc = None, // TODO
             default = ${defaultGetter}
-          )(using ${reader}.asInstanceOf[ArgReader[Any, Any, cask.Request]])
+          )(using ${reader}.asInstanceOf[ArgReader[Any, Any, Any]])
         }
       }
       Expr.ofList(exprs1)
     }
     val sigExprs = Expr.ofList(exprs0)
 
     '{
-      EntryPoint[Cls, cask.Request](
+      EntryPoint[Cls, Any](
         name = ${Expr(method.name)},
         argSignatures = $sigExprs,
         doc = None, // TODO
         invoke0 = (
           clazz: Cls,
-          ctx: cask.Request,
+          ctxs: Seq[Any],
           argss: Seq[Map[String, Any]],
-          sigss: Seq[Seq[ArgSig[Any, _, _, cask.Request]]]
+          sigss: Seq[Seq[ArgSig[Any, _, _, Any]]]
         ) => {
           val parsedArgss: Seq[Seq[Either[Seq[cask.router.Result.ParamError], Any]]] =
-            sigss.zip(argss).map{ case (sigs, args) =>
+            (sigss, argss, ctxs).zipped.map { case (sigs, args, ctx) =>
               sigs.map{ case sig =>
                 Runtime.makeReadCall(
                   args,

diff --git a/cask/src-3/cask/router/RoutesEndpointMetadata.scala b/cask/src-3/cask/router/RoutesEndpointMetadata.scala
@@ -20,18 +20,18 @@ object RoutesEndpointsMetadata{
 
     val routeParts: List[Expr[EndpointMetadata[T]]] = for {
       m <- TypeRepr.of[T].typeSymbol.memberMethods
-      annotations = m.annotations.filter(_.tpe <:< TypeRepr.of[Decorator[_, _, _]])
+      annotations = m.annotations.filter(_.tpe <:< TypeRepr.of[Decorator[_, _, _, _]])
       if (annotations.nonEmpty)
     } yield {
 
-      if(!(annotations.head.tpe <:< TypeRepr.of[Endpoint[_, _, _]])) {
+      if(!(annotations.head.tpe <:< TypeRepr.of[Endpoint[_, _, _, _]])) {
         report.error(s"Last annotation applied to a function must be an instance of Endpoint, " +
           s"not ${annotations.head.tpe.show}",
           annotations.head.pos
         )
         return '{???} // in this case, we can't continue expansion of this macro
       }
-      val allEndpoints = annotations.filter(_.tpe <:< TypeRepr.of[Endpoint[_, _, _]])
+      val allEndpoints = annotations.filter(_.tpe <:< TypeRepr.of[Endpoint[_, _, _, _]])
       if(allEndpoints.length > 1) {
         report.error(
           s"You can only apply one Endpoint annotation to a function, not " +
@@ -41,16 +41,16 @@ object RoutesEndpointsMetadata{
         return '{???}
       }
 
-      val decorators = annotations.map(_.asExprOf[Decorator[_, _, _]])
+      val decorators = annotations.map(_.asExprOf[Decorator[_, _, _, _]])
 
       if (!Macros.checkDecorators(decorators))
         return '{???} // there was a type mismatch in the decorator chain
 
-      val endpointExpr = decorators.head.asExprOf[Endpoint[_, _, _]]
+      val endpointExpr = decorators.head.asExprOf[Endpoint[_, _, _, _]]
       val entrypointExpr = Macros.extractMethod[T](m, decorators, endpointExpr)
 
       '{
-        val entrypoint: EntryPoint[T, cask.Request] = ${entrypointExpr}
+        val entrypoint: EntryPoint[T, Any] = ${entrypointExpr}
 
         EndpointMetadata[T](
           // the Scala 2 version and non-macro code expects decorators to be reversed

diff --git a/cask/src/cask/decorators/compress.scala b/cask/src/cask/decorators/compress.scala
@@ -11,7 +11,7 @@ class compress extends cask.RawDecorator{
       .toSeq
       .flatMap(_.asScala)
       .flatMap(_.split(", "))
-    val finalResult = delegate(Map()).transform{ case v: cask.Response.Raw  =>
+    val finalResult = delegate(ctx, Map()).transform{ case v: cask.Response.Raw  =>
       val (newData, newHeaders) = if (acceptEncodings.exists(_.toLowerCase == "gzip")) {
         new Response.Data {
           def write(out: OutputStream): Unit = {

diff --git a/cask/src/cask/endpoints/FormEndpoint.scala b/cask/src/cask/endpoints/FormEndpoint.scala
@@ -60,6 +60,7 @@ class postForm(val path: String, override val subpath: Boolean = false)
         .createParser(ctx.exchange)
         .parseBlocking()
       delegate(
+        ctx,
         formData
           .iterator()
           .asScala

diff --git a/cask/src/cask/endpoints/JsonEndpoint.scala b/cask/src/cask/endpoints/JsonEndpoint.scala
@@ -66,7 +66,7 @@ abstract class postJsonBase(val path: String, override val subpath: Boolean = fa
     } yield obj.toMap
     obj match{
       case Left(r) => Result.Success(r.map(Response.Data.WritableData(_)))
-      case Right(params) => delegate(params)
+      case Right(params) => delegate(ctx, params)
     }
   }
   def wrapPathSegment(s: String): ujson.Value = ujson.Str(s)
@@ -78,7 +78,7 @@ class getJson(val path: String, override val subpath: Boolean = false)
   type InputParser[T] = QueryParamReader[T]
 
   def wrapFunction(ctx: Request, delegate: Delegate): Result[Response.Raw] = {
-    delegate(WebEndpoint.buildMapFromQueryParams(ctx))
+    delegate(ctx, WebEndpoint.buildMapFromQueryParams(ctx))
   }
   def wrapPathSegment(s: String) = Seq(s)
 }
diff --git a/cask/src/cask/endpoints/StaticEndpoints.scala b/cask/src/cask/endpoints/StaticEndpoints.scala
@@ -19,7 +19,7 @@ class staticFiles(val path: String, headers: Seq[(String, String)] = Nil) extend
   type InputParser[T] = QueryParamReader[T]
   override def subpath = true
   def wrapFunction(ctx: Request, delegate: Delegate) = {
-    delegate(Map()).map{t =>
+    delegate(ctx, Map()).map{t =>
       val (path, contentTypeOpt) = StaticUtil.makePathAndContentType(t, ctx)
       cask.model.StaticFile(path, headers ++ contentTypeOpt.map("Content-Type" -> _))
     }
@@ -36,7 +36,7 @@ class staticResources(val path: String,
   type InputParser[T] = QueryParamReader[T]
   override def subpath = true
   def wrapFunction(ctx: Request, delegate: Delegate) = {
-    delegate(Map()).map { t =>
+    delegate(ctx, Map()).map { t =>
       val (path, contentTypeOpt) = StaticUtil.makePathAndContentType(t, ctx)
       cask.model.StaticResource(path, resourceRoot, headers ++ contentTypeOpt.map("Content-Type" -> _))
     }

diff --git a/cask/src/cask/endpoints/WebEndpoints.scala b/cask/src/cask/endpoints/WebEndpoints.scala
@@ -11,7 +11,7 @@ trait WebEndpoint extends HttpEndpoint[Response.Raw, Seq[String]]{
   type InputParser[T] = QueryParamReader[T]
   def wrapFunction(ctx: Request,
                        delegate: Delegate): Result[Response.Raw] = {
-    delegate(WebEndpoint.buildMapFromQueryParams(ctx))
+    delegate(ctx, WebEndpoint.buildMapFromQueryParams(ctx))
   }
   def wrapPathSegment(s: String) = Seq(s)
 }

diff --git a/cask/src/cask/endpoints/WebSocketEndpoint.scala b/cask/src/cask/endpoints/WebSocketEndpoint.scala
@@ -21,12 +21,12 @@ object WebsocketResult{
 }
 
 class websocket(val path: String, override val subpath: Boolean = false)
-  extends cask.router.Endpoint[WebsocketResult, WebsocketResult, Seq[String]]{
+  extends cask.router.Endpoint[WebsocketResult, WebsocketResult, Seq[String], Request]{
   val methods = Seq("websocket")
   type InputParser[T] = QueryParamReader[T]
   type OuterReturned = Result[WebsocketResult]
   def wrapFunction(ctx: Request, delegate: Delegate) = {
-    delegate(WebEndpoint.buildMapFromQueryParams(ctx))
+    delegate(ctx, WebEndpoint.buildMapFromQueryParams(ctx))
   }
 
   def wrapPathSegment(s: String): Seq[String] = Seq(s)

diff --git a/cask/src/cask/main/Main.scala b/cask/src/cask/main/Main.scala
@@ -29,7 +29,7 @@ class MainRoutes extends Main with Routes{
   * application-wide properties.
   */
 abstract class Main{
-  def mainDecorators: Seq[Decorator[_, _, _]] = Nil
+  def mainDecorators: Seq[Decorator[_, _, _, _]] = Nil
   def allRoutes: Seq[Routes]
   def port: Int = 8080
   def host: String = "localhost"
@@ -74,7 +74,7 @@ abstract class Main{
 
 object Main{
   class DefaultHandler(dispatchTrie: DispatchTrie[Map[String, (Routes, EndpointMetadata[_])]],
-                       mainDecorators: Seq[Decorator[_, _, _]],
+                       mainDecorators: Seq[Decorator[_, _, _, _]],
                        debugMode: Boolean,
                        handleNotFound: Request => Response.Raw,
                        handleMethodNotAllowed: Request => Response.Raw,
@@ -120,6 +120,7 @@ object Main{
                 routes,
                 routeBindings,
                 (mainDecorators ++ routes.decorators ++ metadata.decorators).toList,
+                Nil,
                 Nil
               ) match {
                 case Result.Success(res) => runner(res)