如何将经toolbox转换的Scala AST传入ScriptEngine？或转回Scala代码？

Great question! Let's break down both parts of your query clearly:

Can you pass a transformed Scala AST directly to a ScriptEngine? #

Short answer: No, not directly. Most ScriptEngine implementations (including the Scala ScriptEngine) are built to accept string-based source code as input, not pre-parsed or transformed AST nodes. ScriptEngines rely on their own parsing step to convert text into an executable form, so they don't have built-in support for consuming ASTs generated via runtimeMirror's toolbox.

How to convert a transformedTree back to Scala source code for ScriptEngine? #

You're in luck—Scala's ToolBox has a built-in method to convert ASTs back to executable, human-readable source code: print(). Here's a practical example of how to use it:

import scala.reflect.runtime.universe._
import scala.tools.reflect.ToolBox

// Initialize your mirror and toolbox (you likely already have this set up)
val mirror = runtimeMirror(getClass.getClassLoader)
val toolbox = mirror.mkToolBox()

// Assume transformedTree is your already modified AST
val generatedSource = toolbox.print(transformedTree)

// Now pass the generated source string to your ScriptEngine
val scriptEngine = new javax.script.ScriptEngineManager().getEngineByName("scala")
scriptEngine.eval(generatedSource)

Pro Tip: Skip the ScriptEngine entirely (if possible) #

If your end goal is just to execute the transformed AST, you don't need to convert it back to source code at all. The ToolBox itself has an eval() method that runs ASTs directly—this is more efficient, as it avoids the round-trip to source text:

val executionResult = toolbox.eval(transformedTree)

Just note that when using toolbox.print(), the generated source code will preserve the exact semantics of your transformed AST, though formatting might differ from hand-written code. For nearly all use cases, this is more than sufficient for passing to a ScriptEngine.

内容的提问来源于stack exchange，提问作者Choppy The Lumberjack