sbt/util/appmacro/TupleNBuilder.scala

52 lines
1.8 KiB
Scala

package sbt
package appmacro
import Types.Id
import scala.tools.nsc.Global
import scala.reflect._
import macros._
/** A builder that uses a TupleN as the tuple representation.
* It is limited to tuples of size 2 to `MaxInputs`. */
object TupleNBuilder extends TupleBuilder
{
/** The largest number of inputs that this builder can handle. */
final val MaxInputs = 11
final val TupleMethodName = "tuple"
def make(c: Context)(mt: c.Type, inputs: Inputs[c.universe.type]): BuilderResult[c.type] = new BuilderResult[c.type]
{
val util = ContextUtil[c.type](c)
import c.universe.{Apply=>ApplyTree,_}
import util._
val global: Global = c.universe.asInstanceOf[Global]
val mTC: Type = mt.asInstanceOf[c.universe.Type]
val ctx: c.type = c
val representationC: PolyType = {
val tcVariable: Symbol = newTCVariable(NoSymbol)
val tupleTypeArgs = inputs.map(in => typeRef(NoPrefix, tcVariable, in.tpe :: Nil).asInstanceOf[global.Type])
val tuple = global.definitions.tupleType(tupleTypeArgs)
PolyType(tcVariable :: Nil, tuple.asInstanceOf[Type] )
}
val resultType = appliedType(representationC, idTC :: Nil)
val input: Tree = mkTuple(inputs.map(_.expr))
val alistInstance: Tree = {
val select = Select(Ident(alist), TupleMethodName + inputs.size.toString)
TypeApply(select, inputs.map(in => TypeTree(in.tpe)))
}
def extract(param: ValDef): List[ValDef] = bindTuple(param, Nil, inputs.map(_.local), 1)
def bindTuple(param: ValDef, revBindings: List[ValDef], params: List[ValDef], i: Int): List[ValDef] =
params match
{
case ValDef(mods, name, tpt, _) :: xs =>
val x = ValDef(mods, name, tpt, Select(Ident(param.name), "_" + i.toString))
bindTuple(param, x :: revBindings, xs, i+1)
case Nil => revBindings.reverse
}
}
}