通过IMain在scala repl中获取类型信息

Question

意图

我试图添加:kind对scala repl的命令支持.感谢Eugene Burmako,我得到了一个工作原型.虽然它只适用于完全限定名称,但无法解析导入的名称.

我现在正试图用它IMain.exprTyper来完成这项工作,因为它知道导入到repl中的类型.但有一个问题.我尝试的所有东西都返回ClassInfoType如下(显示showRaw):

ClassInfoType(List(TypeRef(TypeRef(TypeRef(TypeRef(NoPrefix(), package <root>, List()), package java, List()), package lang, List()), class Object, List()), TypeRef(TypeRef(TypeRef(NoPrefix(), package <root>, List()), package scala, List()), trait Serializable, List())), Scope{
  def <init>(): Option.type;
  implicit def option2Iterable(xo: Option): Iterable;
  def apply(x: Object): Option;
  def empty(): Option;
  private def readResolve(): Object
}, object Option)

工作实施具体回报Type:

PolyType(List(TypeName("A")), ClassInfoType(List(TypeRef(ThisType(scala), TypeName("AnyRef"), List()), TypeRef(ThisType(scala), scala.Product, List()), TypeRef(ThisType(scala), scala.Serializable, List())), Scope(nme.CONSTRUCTOR, TermName("isEmpty"), TermName("isDefined"), TermName("get"), TermName("getOrElse"), TermName("orNull"), TermName("map"), TermName("fold"), TermName("flatMap"), TermName("flatten"), TermName("filter"), TermName("filterNot"), TermName("nonEmpty"), TermName("withFilter"), TypeName("WithFilter"), TermName("contains"), TermName("exists"), TermName("forall"), TermName("foreach"), TermName("collect"), TermName("orElse"), TermName("iterator"), TermName("toList"), TermName("toRight"), TermName("toLeft")), scala.Option))

题

我觉得我真的很亲密.这是一个游乐场,您可以自己尝试一切:

Welcome to Scala version 2.11.0-20130328-093148-47645c7e7e (OpenJDK 64-Bit Server VM, Java 1.7.0_17).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import scala.reflect.runtime.universe._
import scala.reflect.runtime.universe._

scala> import scala.tools.nsc.interpreter.IMain
import scala.tools.nsc.interpreter.IMain

scala> val mirror = runtimeMirror(getClass.getClassLoader) // Working approach
mirror: reflect.runtime.universe.Mirror = JavaMirror with scala.tools.nsc.interpreter.IMain$TranslatingClassLoader@3d34ec98 of type class scala.tools.nsc.interpreter.IMain$TranslatingClassLoader with classpath [<unknown>] and parent being scala.tools.nsc.util.ScalaClassLoader$URLClassLoader@5d990e8c of type class scala.tools.nsc.util.ScalaClassLoader$URLClassLoader with classpath [file:/usr/lib/jvm/java-7-openjdk/jre/lib/resources.jar,file:/usr/lib/jvm/java-7-openjdk/jre/lib/rt.jar,file:/usr/lib/jvm/java-7-openjdk/jre/lib/jsse.jar,file:/usr/lib/jvm/java-7-openjdk/jre/lib/jce.jar,file:/usr/lib/jvm/java-7-openjdk/jre/lib/charsets.jar,file:/usr/lib/jvm/java-7-openjdk/jre/lib/rhino.jar,file:/home/folone/workspace/scala-myfork/build/pack/lib/jline.jar,file:/home/folone/workspace/scala-myfork...

scala> val typer = new IMain().exprTyper // Not working approach
typer: scala.tools.nsc.interpreter.IMain#exprTyper.type = scala.tools.nsc.interpreter.IMain$exprTyper$@68c181f0

scala> val expr = "scala.Option"
expr: String = scala.Option

scala> showRaw(mirror.staticClass(expr).toType.typeSymbol.typeSignature) // Correct signature
res6: String = PolyType(List(TypeName("A")), ClassInfoType(List(TypeRef(ThisType(scala), TypeName("AnyRef"), List()), TypeRef(ThisType(scala), scala.Product, List()), TypeRef(ThisType(scala), scala.Serializable, List())), Scope(nme.CONSTRUCTOR, TermName("isEmpty"), TermName("isDefined"), TermName("get"), TermName("getOrElse"), TermName("orNull"), TermName("map"), TermName("fold"), TermName("flatMap"), TermName("flatten"), TermName("filter"), TermName("filterNot"), TermName("nonEmpty"), TermName("withFilter"), TypeName("WithFilter"), TermName("contains"), TermName("exists"), TermName("forall"), TermName("foreach"), TermName("collect"), TermName("orElse"), TermName("iterator"), TermName("toList"), TermName("toRight"), TermName("toLeft")), scala.Option))

scala> showRaw(typer.typeOfExpression(expr).typeSymbol.typeSignature) // Wrong signature
res7: String = 
ClassInfoType(List(TypeRef(TypeRef(TypeRef(TypeRef(NoPrefix(), package <root>, List()), package java, List()), package lang, List()), class Object, List()), TypeRef(TypeRef(TypeRef(NoPrefix(), package <root>, List()), package scala, List()), trait Serializable, List())), Scope{
  def <init>(): Option.type;
  implicit def option2Iterable(xo: Option): Iterable;
  def apply(x: Object): Option;
  def empty(): Option;
  private def readResolve(): Object
}, object Option)

如何转换ClassInfoType为Type包含所需信息的有效信息？另外,我怎么了Type使用IMain摆在首位？

Answer 1

这个怎么样？我正在使用电源模式，它使您可以从当前运行的 REPL 访问全局，这比创建新的IMain.

scala> :power
Already in power mode.

scala> val g = global
g: $r.intp.global.type = <global>

scala> val context = g.analyzer.rootContext(NoCompilationUnit)
context: g.analyzer.Context = Context(<root>@EmptyTree unit=NoCompilationUnit scope=997093283 errors=false, reportErrors=true, throwErrors=false)

// aware imports of scala._, etc.
scala> val sym = context.lookupSymbol("Option": TypeName, _ => true).symbol
sym: g.analyzer.global.Symbol = class Option

scala> sym.tpeHK.typeParams
res21: List[g.analyzer.global.Symbol] = List(type A)

也可以看看：

scala> intp.symbolOfType("Foo")
res26: $r.intp.global.Symbol = class Foo

但我不确定如何获取以前导入的符号：

scala> object Bar { class Bop }
defined object Bar

scala> import Bar.Bop
import Bar.Bop

scala> intp.symbolOfType("Bop")
res27: $r.intp.global.Symbol = <none>

编辑：

OP 之所以取ClassInfoType反，PolyType是因为相位。为了获得与功率模式相同的结果global，必须将相位设置为typer。引用 REPL 中 @retronym 的解释： intp.global vs "global" available in :power mode：

scala> :power
** Power User mode enabled - BEEP WHIR GYVE **
** :phase has been set to 'typer'.          **
    ^
    `----  this part is relevant

符号有一个类型列表（又名info-s），按编译器阶段索引。（又名类型历史）。许多编译器阶段安装InfoTransformers 来改变类型。有关一些文档，请参阅 src/compiler/scala/tools/nsc/transform/InfoTransform.scala。

要检查特定阶段的类型，您可以使用“exitingTyper”等方法。

scala> exitingPostErasure($intp.global.rootMirror.staticClass("scala.Option").typeSignature).getClass
res6: Class[_ <: $intp.global.Type] = class scala.reflect.internal.Types$ClassInfoType

scala> exitingTyper($intp.global.rootMirror.staticClass("scala.Option").typeSignature).getClass
res7: Class[_ <: $intp.global.Type] = class scala.reflect.internal.Types$PolyType

或者，在 :power 模式下更方便一点：

scala> :phase typer
Active phase is now: Typer

scala> global.rootMirror.staticClass("scala.Option").typeSignature.getClass
res16: Class[_ <: $r.global.Type] = class scala.reflect.internal.Types$PolyType

scala> :phase cleanup
Active phase is now: Cleanup

scala> global.rootMirror.staticClass("scala.Option").typeSignature.getClass
res17: Class[_ <: $r.global.Type] = class scala.reflect.internal.Types$ClassInfoType