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/* NSC -- new Scala compiler
* Copyright 2005-2009 LAMP/EPFL
* @author Martin Odersky
*/
// $Id: NamesDefaults.scala 17081 2009-02-10 17:45:38Z rytz $
package scala.tools.nsc.typechecker
import scala.collection.mutable.ListBuffer
import symtab.Flags._
/**
* @author Lukas Rytz
* @version 1.0
*/
trait NamesDefaults { self: Analyzer =>
import global._
import definitions._
case class NamedApplyInfo(qual: Option[Tree], targs: List[Tree],
vargss: List[List[Tree]], blockTyper: Typer)
val noApplyInfo = NamedApplyInfo(None, Nil, Nil, null)
def nameOf(arg: Tree) = arg match {
case Assign(Ident(name), rhs) => Some(name)
case _ => None
}
def isNamed(arg: Tree) = nameOf(arg).isDefined
/** @param pos maps indicies from old to new */
def reorderArgs[T](args: List[T], pos: Int => Int): List[T] = {
val res = new Array[T](args.length)
// (hopefully) faster than zipWithIndex
(0 /: args) { case (index, arg) => res(pos(index)) = arg; index + 1 }
res.toList
}
/** @param pos maps indicies from new to old (!) */
def reorderArgsInv[T](args: List[T], pos: Int => Int): List[T] = {
val argsArray = args.toArray
val res = new ListBuffer[T]
for (i <- 0 until argsArray.length)
res += argsArray(pos(i))
res.toList
}
/** returns `true' if every element is equal to its index */
def isIdentity(a: Array[Int]) = (0 until a.length).forall(i => a(i) == i)
/**
* Transform a function application into a Block, and assigns typer.context
* .namedApplyBlockInfo to the new block as side-effect. If tree has the form
* Apply(fun, args)
* first the function "fun" (which might be an application itself!) is transformed into a
* block of the form
* {
* val qual$1 = qualifier_of_fun
* val x$1 = arg_1_of_fun
* ...
* val x$n = arg_n_of_fun
* qual$1.fun[targs](x$1, ...)...(..., x$n)
* }
* then for each argument in args, a value is created and entered into the block. finally
* the application expression of the block is updated.
* {
* val qual$1 = ..
* ...
* val x$n = ...
* > val qual$n+1 = arg(1)
* > ...
* > val qual$n+m = arg(m)
* > qual$1.fun[targs](x$1, ...)...(..., x$n)(x$n+1, ..., x$n+m)
* }
*
* @param typer the typer calling this method; this method calls
* typer.doTypedApply
* @param mode the mode to use for calling typer.doTypedApply
* @param pt the expected type for calling typer.doTypedApply
*
* @param tree: the function application tree
* @argPos: a function mapping arguments from their current position to the
* position specified by the method type. example:
* def foo(a: Int, b: String)
* foo(b = "1", a = 2)
* calls
* transformNamedApplication(Apply(foo, List("1", 2), { 0 => 1, 1 => 0 })
*
* @return the transformed application (a Block) together with the NamedApplyInfo.
* if isNamedApplyBlock(tree), returns the existing context.namedApplyBlockInfo
*/
def transformNamedApplication(typer: Typer, mode: Int, pt: Type)
(tree: Tree, argPos: Int => Int): Tree = {
import typer._
import typer.infer._
val context = typer.context
import context.unit
/**
* Transform a function into a block, and assing context.namedApplyBlockInfo to
* the new block as side-effect.
* Fun is transformed in the following way:
* - Ident(f) ==> Block(Nil, Ident(f))
* - Select(qual, f) if (qual is stable) ==> Block(Nil, Select(qual, f))
* - Select(qual, f) otherwise ==> Block(ValDef(qual$1, qual), Select(qual$1, f))
* - TypeApply(fun, targs) ==> Block(Nil or qual$1, TypeApply(fun, targs))
* - Select(New(TypeTree()), <init>) ==> Block(Nil, Select(New(TypeTree()), <init>))
* - Select(New(Select(qual, typeName)), <init>) if (qual is stable)
* ==> Block(Nil, Select(...))
* - Select(New(Select(qual, typeName)), <init>) otherwise
* ==> Block(ValDef(qual$1, qual), Select(New(Select(qual$1, typeName)), <init>))
*/
def baseFunBlock(baseFun: Tree): Tree = {
val isConstr = baseFun.symbol.isConstructor
val blockTyper = newTyper(context.makeNewScope(tree, context.owner)(BlockScopeKind(context.depth)))
// baseFun1: extract the function from a potential TypeApply
// funTargs: type arguments on baseFun, used to reconstruct TypeApply in blockWith(Out)Qualifier
// defaultTargs: type arguments to be used for calling defaultGetters. If the type arguments are given
// in the source code, re-use them for default getter. Otherwise infer the default getter's t-args.
val (baseFun1, funTargs, defaultTargs) = baseFun match {
case TypeApply(fun, targs) =>
val targsInSource =
if (targs.forall(a => context.undetparams contains a.symbol)) Nil
else targs
(fun, targs, targsInSource)
case Select(New(tpt @ TypeTree()), _) if isConstr =>
val targsInSource = tpt.tpe match {
case TypeRef(pre, sym, args)
if (!args.forall(a => context.undetparams contains a.typeSymbol)) =>
args.map(TypeTree(_))
case _ => Nil
}
(baseFun, Nil, targsInSource)
case _ => (baseFun, Nil, Nil)
}
def blockWithQualifier(qual: Tree, fun: Symbol => Tree, defaultQual: Symbol => Option[Tree]) = {
val sym = blockTyper.context.owner.newValue(baseFun1.pos,
unit.fresh.newName(baseFun1.pos, "qual$"))
.setInfo(qual.tpe)
blockTyper.context.scope.enter(sym)
val vd = atPos(sym.pos) { ValDef(sym, qual).setType(NoType) }
var baseFunTransformed: Tree = fun(sym)
if (!funTargs.isEmpty)
baseFunTransformed = treeCopy.TypeApply(baseFun, baseFunTransformed, funTargs)
val b = atPos(baseFun1.pos) { Block(List(vd), baseFunTransformed)
.setType(baseFunTransformed.tpe) }
context.namedApplyBlockInfo =
Some((b, NamedApplyInfo(defaultQual(sym), defaultTargs, Nil, blockTyper)))
b
}
def blockWithoutQualifier(fun: Tree, defaultQual: Option[Tree]) = {
val fun1 = if (funTargs.isEmpty) fun
else treeCopy.TypeApply(baseFun, fun, funTargs)
val b = atPos(baseFun.pos) { Block(Nil, fun1).setType(fun1.tpe) }
context.namedApplyBlockInfo =
Some((b, NamedApplyInfo(defaultQual, defaultTargs, Nil, blockTyper)))
b
}
baseFun1 match {
// constructor calls
case Select(New(TypeTree()), _) if isConstr =>
blockWithoutQualifier(baseFun1, None)
case Select(New(Ident(_)), _) if isConstr =>
blockWithoutQualifier(baseFun1, None)
case Select(nev @ New(sel @ Select(qual, typeName)), constr) if isConstr =>
// #2057
val module = baseFun.symbol.owner.linkedModuleOfClass
val defaultQual = if (module == NoSymbol) None
else Some(gen.mkAttributedSelect(qual.duplicate, module))
// in `new q.C()', q is always stable
assert(treeInfo.isPureExpr(qual), qual)
blockWithoutQualifier(baseFun1, defaultQual)
// super constructor calls
case Select(Super(_, _), _) if isConstr =>
blockWithoutQualifier(baseFun1, None)
// self constructor calls (in secondary constructors)
case Select(qual, name) if isConstr =>
assert(treeInfo.isPureExpr(qual), qual)
blockWithoutQualifier(baseFun1, None)
// other method calls
case Ident(_) =>
blockWithoutQualifier(baseFun1, None)
case Select(qual, name) =>
if (treeInfo.isPureExpr(qual))
blockWithoutQualifier(baseFun1, Some(qual.duplicate))
else
blockWithQualifier(qual,
sym => treeCopy.Select(baseFun1, gen.mkAttributedRef(sym), name),
sym => Some(gen.mkAttributedRef(sym)))
}
}
/**
* For each argument (arg: T), create a local value
* x$n: T = arg
*
* assumes "args" are typed. owner of the definitions in the block is the owner of
* the block (see typedBlock), but the symbols have to be entered into the block's scope.
*
* For by-name parameters, create a value
* x$n: () => T = () => arg
*/
def argValDefs(args: List[Tree], paramTypes: List[Type], blockTyper: Typer): List[ValDef] = {
val context = blockTyper.context
val symPs = List.map2(args, paramTypes)((arg, tpe) => {
val byName = tpe.typeSymbol == ByNameParamClass
val s = context.owner.newValue(arg.pos, unit.fresh.newName(arg.pos, "x$"))
val valType = if (byName) functionType(List(), arg.tpe)
else arg.tpe
s.setInfo(valType)
(context.scope.enter(s), byName)
})
List.map2(symPs, args)((symP, arg) => {
val (sym, byName) = symP
val body = if (byName) blockTyper.typed(Function(List(), arg))
else arg
ValDef(sym, body).setType(NoType)
})
}
// begin transform
if (isNamedApplyBlock(tree)) {
context.namedApplyBlockInfo.get._1
} else tree match {
// we know that Apply(Apply(...)) can only be an application of a curried method;
// for functions, it's transformed to applying the .apply() method already.
case Apply(fun, namelessArgs) =>
val transformedFun = transformNamedApplication(typer, mode, pt)(fun, x => x)
if (transformedFun.isErroneous) setError(tree)
else {
assert(isNamedApplyBlock(transformedFun), transformedFun)
val NamedApplyInfo(qual, targs, vargss, blockTyper) =
context.namedApplyBlockInfo.get._2
val existingBlock @ Block(stats, funOnly) = transformedFun
// type the application without names; put the arguments in definition-site order
val typedApp = doTypedApply(tree, funOnly, reorderArgs(namelessArgs, argPos), mode, pt)
if (typedApp.tpe.isError) setError(tree)
else typedApp match {
// Extract the typed arguments, restore the call-site evaluation order (using
// ValDef's in the block), change the arguments to these local values.
case Apply(expr, typedArgs) =>
// typedArgs: definition-site order
val formals = formalTypes(expr.tpe.paramTypes, typedArgs.length, false)
// valDefs: call-site order
val valDefs = argValDefs(reorderArgsInv(typedArgs, argPos),
reorderArgsInv(formals, argPos),
blockTyper)
// refArgs: definition-site order again
val refArgs = List.map2(reorderArgs(valDefs, argPos), formals)((vDef, tpe) => {
val ref = gen.mkAttributedRef(vDef.symbol)
// for by-name parameters, the local value is a nullary function returning the argument
if (tpe.typeSymbol == ByNameParamClass) Apply(ref, List())
else ref
})
// cannot call blockTyper.typedBlock here, because the method expr might be partially applied only
val res = blockTyper.doTypedApply(tree, expr, refArgs, mode, pt)
val block = treeCopy.Block(existingBlock, stats ::: valDefs, res).setType(res.tpe)
context.namedApplyBlockInfo =
Some((block, NamedApplyInfo(qual, targs, vargss ::: List(refArgs), blockTyper)))
block
}
}
// case ApplyDynamic??? case AppliedTypeTree???
case baseFun => // also treats "case TypeApply(fun, targs)" and "case Select(New(..), <init>)"
baseFunBlock(baseFun)
}
}
def missingParams[T](args: List[T], params: List[Symbol], argName: T => Option[Name] = nameOf _): (List[Symbol], Boolean) = {
val namedArgs = args.dropWhile(arg => {
val n = argName(arg)
n.isEmpty || params.forall(p => p.name != n.get)
})
val namedParams = params.drop(args.length - namedArgs.length)
// missing: keep those with a name which doesn't exist in namedArgs
val missingParams = namedParams.filter(p => namedArgs.forall(arg => {
val n = argName(arg)
n.isEmpty || n.get != p.name
}))
val allPositional = missingParams.length == namedParams.length
(missingParams, allPositional)
}
/**
* Extend the argument list `givenArgs' with default arguments. Defaults are added
* as named arguments calling the corresponding default getter.
*
* Example: given
* def foo(x: Int = 2, y: String = "def")
* foo(1)
* the argument list (y = "lt") is transformed to (y = "lt", x = foo$default$1())
*/
def addDefaults(givenArgs: List[Tree], qual: Option[Tree], targs: List[Tree],
previousArgss: List[List[Tree]], params: List[Symbol], pos: util.Position): (List[Tree], List[Symbol]) = {
if (givenArgs.length < params.length) {
val (missing, positional) = missingParams(givenArgs, params)
if (missing forall (_.hasFlag(DEFAULTPARAM))) {
val defaultArgs = missing map (p => {
var default1 = qual match {
case Some(q) => gen.mkAttributedSelect(q.duplicate, p.defaultGetter)
case None => gen.mkAttributedRef(p.defaultGetter)
}
default1 = if (targs.isEmpty) default1
else TypeApply(default1, targs.map(_.duplicate)).setPos(pos)
val default2 = (default1 /: previousArgss)((tree, args) =>
Apply(tree, args.map(_.duplicate)).setPos(pos))
if (positional) default2
else Assign(Ident(p.name), default2)
})
(givenArgs ::: defaultArgs, Nil)
} else (givenArgs, missing filter (! _.hasFlag(DEFAULTPARAM)))
} else (givenArgs, Nil)
}
/**
* Removes name assignments from args. Additionally, returns an array mapping
* argument indicies from call-site-order to definition-site-order.
*
* Verifies that names are not specified twice, positional args don't appear
* after named ones.
*/
def removeNames(typer: Typer)(args: List[Tree], params: List[Symbol]): (List[Tree], Array[Int]) = {
import typer.infer.errorTree
// maps indicies from (order written by user) to (order of definition)
val argPos = (new Array[Int](args.length)) map (x => -1)
var positionalAllowed = true
val namelessArgs = for ((arg, index) <- (args.zipWithIndex)) yield arg match {
case Assign(Ident(name), rhs) =>
val pos = params.indexWhere(p => p.name == name && !p.hasFlag(SYNTHETIC))
if (pos == -1) {
if (positionalAllowed) {
argPos(index) = index
// prevent isNamed from being true when calling doTypedApply recursively,
// treat the arg as an assignment of type Unit
Block(List(), arg)
} else {
errorTree(arg, "unknown parameter name: "+ name)
}
} else if (argPos contains pos) {
errorTree(arg, "parameter specified twice: "+ name)
} else {
// for named arguments, check wether the assignment expression would
// typecheck. if it does, report an ambiguous error.
val param = params(pos)
val paramtpe = params(pos).tpe.cloneInfo(param)
// replace type parameters by wildcard. in the below example we need to
// typecheck (x = 1) with wildcard (not T) so that it succeeds.
// def f[T](x: T) = x
// var x = 0
// f(x = 1) << "x = 1" typechecks with expected type WildcardType
val udp = typer.context.extractUndetparams()
val subst = new SubstTypeMap(udp, udp map (_ => WildcardType))
val res = typer.silent(_.typed(arg, subst(paramtpe))) match {
case _: TypeError =>
positionalAllowed = false
argPos(index) = pos
// if `rhs' has the form `x = ...`, wrap it into a block, prevent
// treating it as named argument again.
if (isNamed(rhs)) Block(List(), rhs)
else rhs
case t: Tree =>
errorTree(arg, "reference to "+ name +" is ambiguous; it is both, a parameter\n"+
"name of the method and the name of a variable currently in scope.")
}
typer.context.undetparams = udp
res
}
case _ =>
argPos(index) = index
if (positionalAllowed) arg
else errorTree(arg, "positional after named argument.")
}
(namelessArgs, argPos)
}
}
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