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Compiler for the Scala Programming Language
/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package interpreter
import Predef.{ println => _, _ }
import util.stringFromWriter
import scala.reflect.internal.util._
import java.net.URL
import scala.sys.BooleanProp
import io.VirtualDirectory
import scala.tools.nsc.io.AbstractFile
import reporters._
import symtab.Flags
import scala.reflect.internal.Names
import scala.tools.util.PathResolver
import scala.tools.nsc.util.ScalaClassLoader
import ScalaClassLoader.URLClassLoader
import scala.tools.nsc.util.Exceptional.unwrap
import scala.collection.{ mutable, immutable }
import scala.util.control.Exception.{ ultimately }
import IMain._
import java.util.concurrent.Future
import typechecker.Analyzer
import scala.language.implicitConversions
import scala.reflect.runtime.{ universe => ru }
import scala.reflect.{ ClassTag, classTag }
import scala.tools.reflect.StdRuntimeTags._
/** directory to save .class files to */
private class ReplVirtualDirectory(out: JPrintWriter) extends VirtualDirectory("(memory)", None) {
private def pp(root: AbstractFile, indentLevel: Int) {
val spaces = " " * indentLevel
out.println(spaces + root.name)
if (root.isDirectory)
root.toList sortBy (_.name) foreach (x => pp(x, indentLevel + 1))
}
// print the contents hierarchically
def show() = pp(this, 0)
}
/** An interpreter for Scala code.
*
* The main public entry points are compile(), interpret(), and bind().
* The compile() method loads a complete Scala file. The interpret() method
* executes one line of Scala code at the request of the user. The bind()
* method binds an object to a variable that can then be used by later
* interpreted code.
*
* The overall approach is based on compiling the requested code and then
* using a Java classloader and Java reflection to run the code
* and access its results.
*
* In more detail, a single compiler instance is used
* to accumulate all successfully compiled or interpreted Scala code. To
* "interpret" a line of code, the compiler generates a fresh object that
* includes the line of code and which has public member(s) to export
* all variables defined by that code. To extract the result of an
* interpreted line to show the user, a second "result object" is created
* which imports the variables exported by the above object and then
* exports members called "$eval" and "$print". To accomodate user expressions
* that read from variables or methods defined in previous statements, "import"
* statements are used.
*
* This interpreter shares the strengths and weaknesses of using the
* full compiler-to-Java. The main strength is that interpreted code
* behaves exactly as does compiled code, including running at full speed.
* The main weakness is that redefining classes and methods is not handled
* properly, because rebinding at the Java level is technically difficult.
*
* @author Moez A. Abdel-Gawad
* @author Lex Spoon
*/
class IMain(initialSettings: Settings, protected val out: JPrintWriter) extends Imports {
imain =>
/** Leading with the eagerly evaluated.
*/
val virtualDirectory: VirtualDirectory = new ReplVirtualDirectory(out) // "directory" for classfiles
private var currentSettings: Settings = initialSettings
private[nsc] var printResults = true // whether to print result lines
private[nsc] var totalSilence = false // whether to print anything
private var _initializeComplete = false // compiler is initialized
private var _isInitialized: Future[Boolean] = null // set up initialization future
private var bindExceptions = true // whether to bind the lastException variable
private var _executionWrapper = "" // code to be wrapped around all lines
/** We're going to go to some trouble to initialize the compiler asynchronously.
* It's critical that nothing call into it until it's been initialized or we will
* run into unrecoverable issues, but the perceived repl startup time goes
* through the roof if we wait for it. So we initialize it with a future and
* use a lazy val to ensure that any attempt to use the compiler object waits
* on the future.
*/
private var _classLoader: AbstractFileClassLoader = null // active classloader
private val _compiler: Global = newCompiler(settings, reporter) // our private compiler
private val nextReqId = {
var counter = 0
() => { counter += 1 ; counter }
}
def compilerClasspath: Seq[URL] = (
if (isInitializeComplete) global.classPath.asURLs
else new PathResolver(settings).result.asURLs // the compiler's classpath
)
def settings = currentSettings
def mostRecentLine = prevRequestList match {
case Nil => ""
case req :: _ => req.originalLine
}
// Run the code body with the given boolean settings flipped to true.
def withoutWarnings[T](body: => T): T = beQuietDuring {
val saved = settings.nowarn.value
if (!saved)
settings.nowarn.value = true
try body
finally if (!saved) settings.nowarn.value = false
}
/** construct an interpreter that reports to Console */
def this(settings: Settings) = this(settings, new NewLinePrintWriter(new ConsoleWriter, true))
def this() = this(new Settings())
lazy val repllog: Logger = new Logger {
val out: JPrintWriter = imain.out
val isInfo: Boolean = BooleanProp keyExists "scala.repl.info"
val isDebug: Boolean = BooleanProp keyExists "scala.repl.debug"
val isTrace: Boolean = BooleanProp keyExists "scala.repl.trace"
}
lazy val formatting: Formatting = new Formatting {
val prompt = Properties.shellPromptString
}
lazy val reporter: ReplReporter = new ReplReporter(this)
import formatting._
import reporter.{ printMessage, withoutTruncating }
// This exists mostly because using the reporter too early leads to deadlock.
private def echo(msg: String) { Console println msg }
private def _initSources = List(new BatchSourceFile("", "class $repl_$init { }"))
private def _initialize() = {
try {
// todo. if this crashes, REPL will hang
new _compiler.Run() compileSources _initSources
_initializeComplete = true
true
}
catch AbstractOrMissingHandler()
}
private def tquoted(s: String) = "\"\"\"" + s + "\"\"\""
// argument is a thunk to execute after init is done
def initialize(postInitSignal: => Unit) {
synchronized {
if (_isInitialized == null) {
_isInitialized = io.spawn {
try _initialize()
finally postInitSignal
}
}
}
}
def initializeSynchronous(): Unit = {
if (!isInitializeComplete) {
_initialize()
assert(global != null, global)
}
}
def isInitializeComplete = _initializeComplete
/** the public, go through the future compiler */
lazy val global: Global = {
if (isInitializeComplete) _compiler
else {
// If init hasn't been called yet you're on your own.
if (_isInitialized == null) {
repldbg("Warning: compiler accessed before init set up. Assuming no postInit code.")
initialize(())
}
// blocks until it is ; false means catastrophic failure
if (_isInitialized.get()) _compiler
else null
}
}
@deprecated("Use `global` for access to the compiler instance.", "2.9.0")
lazy val compiler: global.type = global
import global._
import definitions.{ScalaPackage, JavaLangPackage, termMember, typeMember}
import rootMirror.{RootClass, getClassIfDefined, getModuleIfDefined, getRequiredModule, getRequiredClass}
implicit class ReplTypeOps(tp: Type) {
def orElse(other: => Type): Type = if (tp ne NoType) tp else other
def andAlso(fn: Type => Type): Type = if (tp eq NoType) tp else fn(tp)
}
// TODO: If we try to make naming a lazy val, we run into big time
// scalac unhappiness with what look like cycles. It has not been easy to
// reduce, but name resolution clearly takes different paths.
object naming extends {
val global: imain.global.type = imain.global
} with Naming {
// make sure we don't overwrite their unwisely named res3 etc.
def freshUserTermName(): TermName = {
val name = newTermName(freshUserVarName())
if (definedNameMap contains name) freshUserTermName()
else name
}
def isUserTermName(name: Name) = isUserVarName("" + name)
def isInternalTermName(name: Name) = isInternalVarName("" + name)
}
import naming._
object deconstruct extends {
val global: imain.global.type = imain.global
} with StructuredTypeStrings
lazy val memberHandlers = new {
val intp: imain.type = imain
} with MemberHandlers
import memberHandlers._
/** Temporarily be quiet */
def beQuietDuring[T](body: => T): T = {
val saved = printResults
printResults = false
try body
finally printResults = saved
}
def beSilentDuring[T](operation: => T): T = {
val saved = totalSilence
totalSilence = true
try operation
finally totalSilence = saved
}
def quietRun[T](code: String) = beQuietDuring(interpret(code))
/** takes AnyRef because it may be binding a Throwable or an Exceptional */
private def withLastExceptionLock[T](body: => T, alt: => T): T = {
assert(bindExceptions, "withLastExceptionLock called incorrectly.")
bindExceptions = false
try beQuietDuring(body)
catch logAndDiscard("withLastExceptionLock", alt)
finally bindExceptions = true
}
def executionWrapper = _executionWrapper
def setExecutionWrapper(code: String) = _executionWrapper = code
def clearExecutionWrapper() = _executionWrapper = ""
/** interpreter settings */
lazy val isettings = new ISettings(this)
/** Instantiate a compiler. Overridable. */
protected def newCompiler(settings: Settings, reporter: Reporter): ReplGlobal = {
settings.outputDirs setSingleOutput virtualDirectory
settings.exposeEmptyPackage.value = true
new Global(settings, reporter) with ReplGlobal
}
/** Parent classloader. Overridable. */
protected def parentClassLoader: ClassLoader =
settings.explicitParentLoader.getOrElse( this.getClass.getClassLoader() )
/* A single class loader is used for all commands interpreted by this Interpreter.
It would also be possible to create a new class loader for each command
to interpret. The advantages of the current approach are:
- Expressions are only evaluated one time. This is especially
significant for I/O, e.g. "val x = Console.readLine"
The main disadvantage is:
- Objects, classes, and methods cannot be rebound. Instead, definitions
shadow the old ones, and old code objects refer to the old
definitions.
*/
def resetClassLoader() = {
repldbg("Setting new classloader: was " + _classLoader)
_classLoader = null
ensureClassLoader()
}
final def ensureClassLoader() {
if (_classLoader == null)
_classLoader = makeClassLoader()
}
def classLoader: AbstractFileClassLoader = {
ensureClassLoader()
_classLoader
}
private class TranslatingClassLoader(parent: ClassLoader) extends AbstractFileClassLoader(virtualDirectory, parent) {
/** Overridden here to try translating a simple name to the generated
* class name if the original attempt fails. This method is used by
* getResourceAsStream as well as findClass.
*/
override protected def findAbstractFile(name: String): AbstractFile = {
super.findAbstractFile(name) match {
// deadlocks on startup if we try to translate names too early
case null if isInitializeComplete =>
generatedName(name) map (x => super.findAbstractFile(x)) orNull
case file =>
file
}
}
}
private def makeClassLoader(): AbstractFileClassLoader =
new TranslatingClassLoader(parentClassLoader match {
case null => ScalaClassLoader fromURLs compilerClasspath
case p => new URLClassLoader(compilerClasspath, p)
})
def getInterpreterClassLoader() = classLoader
// Set the current Java "context" class loader to this interpreter's class loader
def setContextClassLoader() = classLoader.setAsContext()
/** Given a simple repl-defined name, returns the real name of
* the class representing it, e.g. for "Bippy" it may return
* {{{
* $line19.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$Bippy
* }}}
*/
def generatedName(simpleName: String): Option[String] = {
if (simpleName endsWith nme.MODULE_SUFFIX_STRING) optFlatName(simpleName.init) map (_ + nme.MODULE_SUFFIX_STRING)
else optFlatName(simpleName)
}
def flatName(id: String) = optFlatName(id) getOrElse id
def optFlatName(id: String) = requestForIdent(id) map (_ fullFlatName id)
def allDefinedNames = definedNameMap.keys.toList.sorted
def pathToType(id: String): String = pathToName(newTypeName(id))
def pathToTerm(id: String): String = pathToName(newTermName(id))
def pathToName(name: Name): String = {
if (definedNameMap contains name)
definedNameMap(name) fullPath name
else name.toString
}
/** Most recent tree handled which wasn't wholly synthetic. */
private def mostRecentlyHandledTree: Option[Tree] = {
prevRequests.reverse foreach { req =>
req.handlers.reverse foreach {
case x: MemberDefHandler if x.definesValue && !isInternalTermName(x.name) => return Some(x.member)
case _ => ()
}
}
None
}
/** Stubs for work in progress. */
def handleTypeRedefinition(name: TypeName, old: Request, req: Request) = {
for (t1 <- old.simpleNameOfType(name) ; t2 <- req.simpleNameOfType(name)) {
repldbg("Redefining type '%s'\n %s -> %s".format(name, t1, t2))
}
}
def handleTermRedefinition(name: TermName, old: Request, req: Request) = {
for (t1 <- old.compilerTypeOf get name ; t2 <- req.compilerTypeOf get name) {
// Printing the types here has a tendency to cause assertion errors, like
// assertion failed: fatal: has owner value x, but a class owner is required
// so DBG is by-name now to keep it in the family. (It also traps the assertion error,
// but we don't want to unnecessarily risk hosing the compiler's internal state.)
repldbg("Redefining term '%s'\n %s -> %s".format(name, t1, t2))
}
}
def recordRequest(req: Request) {
if (req == null || referencedNameMap == null)
return
prevRequests += req
req.referencedNames foreach (x => referencedNameMap(x) = req)
// warning about serially defining companions. It'd be easy
// enough to just redefine them together but that may not always
// be what people want so I'm waiting until I can do it better.
for {
name <- req.definedNames filterNot (x => req.definedNames contains x.companionName)
oldReq <- definedNameMap get name.companionName
newSym <- req.definedSymbols get name
oldSym <- oldReq.definedSymbols get name.companionName
} {
afterTyper(replwarn(s"warning: previously defined $oldSym is not a companion to $newSym."))
replwarn("Companions must be defined together; you may wish to use :paste mode for this.")
}
// Updating the defined name map
req.definedNames foreach { name =>
if (definedNameMap contains name) {
if (name.isTypeName) handleTypeRedefinition(name.toTypeName, definedNameMap(name), req)
else handleTermRedefinition(name.toTermName, definedNameMap(name), req)
}
definedNameMap(name) = req
}
}
private[nsc] def replwarn(msg: => String) {
if (!settings.nowarnings.value)
printMessage(msg)
}
def isParseable(line: String): Boolean = {
beSilentDuring {
try parse(line) match {
case Some(xs) => xs.nonEmpty // parses as-is
case None => true // incomplete
}
catch { case x: Exception => // crashed the compiler
replwarn("Exception in isParseable(\"" + line + "\"): " + x)
false
}
}
}
def compileSourcesKeepingRun(sources: SourceFile*) = {
val run = new Run()
reporter.reset()
run compileSources sources.toList
(!reporter.hasErrors, run)
}
/** Compile an nsc SourceFile. Returns true if there are
* no compilation errors, or false otherwise.
*/
def compileSources(sources: SourceFile*): Boolean =
compileSourcesKeepingRun(sources: _*)._1
/** Compile a string. Returns true if there are no
* compilation errors, or false otherwise.
*/
def compileString(code: String): Boolean =
compileSources(new BatchSourceFile("