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package scala.tools.nsc
package typechecker
import symtab.Flags._
import scala.tools.nsc.util._
import scala.reflect.ReflectionUtils
trait Macros { self: Analyzer =>
import global._
import definitions._
def macroMeth(mac: Symbol): Symbol = {
var owner = mac.owner
if (!owner.isModuleClass) owner = owner.companionModule.moduleClass
owner.info.decl(nme.macroMethodName(mac.name))
}
def macroArgs(tree: Tree): (List[List[Tree]]) = tree match {
case Apply(fn, args) =>
macroArgs(fn) :+ args
case TypeApply(fn, args) =>
macroArgs(fn) :+ args
case Select(qual, name) if !isStaticMacro(tree.symbol) =>
List(List(qual))
case _ =>
List(List())
}
private def isStaticMacro(mac: Symbol): Boolean =
mac.owner.isModuleClass
/**
* The definition of the method implementing a macro. Example:
* Say we have in a class C
*
* def macro foo[T](xs: List[T]): T = expr
*
* Then the following macro method is generated for `foo`:
*
* def defmacro$foo(glob: scala.reflect.api.Universe)
* (_this: glob.Tree)
* (T: glob.Type)
* (xs: glob.Tree): glob.Tree = {
* implicit val $glob = glob
* expr
* }
*
* If `foo` is declared in an object, the second parameter list is () instead of (_this: glob.Tree).
*/
def macroMethDef(mdef: DefDef): Tree = {
def paramDef(name: Name, tpt: Tree) = ValDef(Modifiers(PARAM), name, tpt, EmptyTree)
val contextType = TypeTree(ReflectMacroContext.tpe)
val globParamSec = List(paramDef(nme.context, contextType))
def globSelect(name: Name) = Select(Ident(nme.context), name)
def globTree = globSelect(newTypeName("Tree"))
def globType = globSelect(newTypeName("Type"))
val thisParamSec = if (isStaticMacro(mdef.symbol)) List() else List(paramDef(newTermName("_this"), globTree))
def tparamInMacro(tdef: TypeDef) = paramDef(tdef.name.toTermName, globType)
def vparamInMacro(vdef: ValDef): ValDef = paramDef(vdef.name, vdef.tpt match {
case tpt @ AppliedTypeTree(hk, _) if treeInfo.isRepeatedParamType(tpt) => AppliedTypeTree(hk, List(globTree))
case _ => globTree
})
def wrapImplicit(tree: Tree) = atPos(tree.pos) {
// implicit hasn't proven useful so far, so I'm disabling it
//val implicitDecl = ValDef(Modifiers(IMPLICIT), nme.contextImplicit, SingletonTypeTree(Ident(nme.context)), Ident(nme.context))
val importGlob = Import(Ident(nme.context), List(ImportSelector(nme.WILDCARD, -1, null, -1)))
Block(List(importGlob), tree)
}
var formals = (mdef.vparamss map (_ map vparamInMacro))
if (mdef.tparams.nonEmpty) formals = (mdef.tparams map tparamInMacro) :: formals
atPos(mdef.pos) {
new DefDef( // can't call DefDef here; need to find out why
mods = mdef.mods &~ MACRO &~ OVERRIDE,
name = nme.macroMethodName(mdef.name),
tparams = List(),
vparamss = globParamSec :: thisParamSec :: formals,
tpt = globTree,
wrapImplicit(mdef.rhs))
}
}
def addMacroMethods(templ: Template, namer: Namer): Unit = {
for (ddef @ DefDef(mods, _, _, _, _, _) <- templ.body if mods hasFlag MACRO) {
val trace = scala.tools.nsc.util.trace when settings.debug.value
val sym = namer.enterSyntheticSym(trace("macro def: ")(macroMethDef(ddef)))
trace("added to "+namer.context.owner.enclClass+": ")(sym)
}
}
lazy val mirror = new scala.reflect.runtime.Mirror {
lazy val libraryClassLoader = {
val classpath = global.classPath.asURLs
ScalaClassLoader.fromURLs(classpath, self.getClass.getClassLoader)
}
override def defaultReflectiveClassLoader() = libraryClassLoader
}
/** Return optionally address of companion object and implementation method symbol
* of given macro; or None if implementation classfile cannot be loaded or does
* not contain the macro implementation.
*/
def macroImpl(mac: Symbol): Option[(AnyRef, mirror.Symbol)] = {
try {
val mmeth = macroMeth(mac)
if (mmeth == NoSymbol) None
else {
val receiverClass: mirror.Symbol = mirror.classWithName(mmeth.owner.fullName)
val receiverObj = receiverClass.companionModule
if (receiverObj == NoSymbol) None
else {
val receiver = mirror.getCompanionObject(receiverClass)
val rmeth = receiverObj.info.member(mirror.newTermName(mmeth.name.toString))
Some((receiver, rmeth))
}
}
} catch {
case ex: ClassNotFoundException =>
None
}
}
/** Return result of macro expansion.
* Or, if that fails, and the macro overrides a method return
* tree that calls this method instead of the macro.
*/
def macroExpand(tree: Tree, context: Context): Option[Any] = {
val macroDef = tree.symbol
macroImpl(macroDef) match {
case Some((receiver, rmeth)) =>
val argss = List(global) :: macroArgs(tree)
val paramss = macroMeth(macroDef).paramss
val rawArgss = for ((as, ps) <- argss zip paramss) yield {
if (isVarArgsList(ps)) as.take(ps.length - 1) :+ as.drop(ps.length - 1)
else as
}
val rawArgs: Seq[Any] = rawArgss.flatten
try {
Some(mirror.invoke(receiver, rmeth, rawArgs: _*))
} catch {
case ex =>
val realex = ReflectionUtils.unwrapThrowable(ex)
val stacktrace = new java.io.StringWriter()
realex.printStackTrace(new java.io.PrintWriter(stacktrace))
val msg = System.getProperty("line.separator") + stacktrace
context.unit.error(tree.pos, "exception during macro expansion: " + msg)
None
}
case None =>
val trace = scala.tools.nsc.util.trace when settings.debug.value
def notFound() = {
context.unit.error(tree.pos, "macro implementation not found: " + macroDef.name)
None
}
def fallBackToOverridden(tree: Tree): Option[Tree] = {
tree match {
case Select(qual, name) if (macroDef.isMacro) =>
macroDef.allOverriddenSymbols match {
case first :: _ =>
Some(Select(qual, name) setPos tree.pos setSymbol first)
case _ =>
trace("macro is not overridden: ")(tree)
notFound()
}
case Apply(fn, args) =>
fallBackToOverridden(fn) match {
case Some(fn1) => Some(Apply(fn1, args) setPos tree.pos)
case _ => None
}
case TypeApply(fn, args) =>
fallBackToOverridden(fn) match {
case Some(fn1) => Some(TypeApply(fn1, args) setPos tree.pos)
case _ => None
}
case _ =>
trace("unexpected tree in fallback: ")(tree)
notFound()
}
}
fallBackToOverridden(tree) match {
case Some(tree1) =>
trace("falling back to ")(tree1)
currentRun.macroExpansionFailed = true
Some(tree1)
case None =>
None
}
}
}
}
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