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scalascala-compiler

Parse a file to AST with non-interactive scala.tools.nsc.Global

In scala.tools.nsc.interactive.Global, there is a parseTree method. I'd like to get the AST from a file using scala.tools.nsc.Global instead. Looking at parseTree definition, I wrote

val settings = new Settings
settings.embeddedDefaults(getClass.getClassLoader)
settings.usejavacp.value = true
val reporter = new StoreReporter
val compiler: Compiler = new Global(settings, reporter)

val run = new compiler.Run
val tree = compiler.newUnitParser(new compiler.CompilationUnit(source)).parse()

but this produces

[info]   java.lang.AssertionError: assertion failed: <no phase>: <?>
[info]   at scala.reflect.internal.Symbols$TypeHistory.<init>(Symbols.scala:3667)
[info]   at scala.reflect.internal.Symbols$Symbol.info_$eq(Symbols.scala:1509)
[info]   at scala.reflect.internal.Symbols$TypeSymbol.info_$eq(Symbols.scala:3099)
[info]   at scala.reflect.internal.Symbols$Symbol.setInfo(Symbols.scala:1515)
[info]   at scala.reflect.internal.Mirrors$Roots$RootClass.<init>(Mirrors.scala:307)
[info]   at scala.reflect.internal.Mirrors$Roots.RootClass$lzycompute(Mirrors.scala:321)
[info]   at scala.reflect.internal.Mirrors$Roots.RootClass(Mirrors.scala:321)
[info]   at scala.reflect.internal.Mirrors$Roots$EmptyPackageClass.<init>(Mirrors.scala:330)
[info]   at scala.reflect.internal.Mirrors$Roots.EmptyPackageClass$lzycompute(Mirrors.scala:336)
[info]   at scala.reflect.internal.Mirrors$Roots.EmptyPackageClass(Mirrors.scala:336)
[info]   ...

How to initialize the compiler correctly? Scala version 2.11.7.

Solution

  • Answer given by Li Haoyi on scala-users:

    val run = new compiler.Run()
compiler.phase = run.parserPhase
run.cancel()

val tree = compiler.newUnitParser(new compiler.CompilationUnit(source)).parse()