scala.pickling.util.Externalizables.scala Maven / Gradle / Ivy
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package scala.pickling.util
import scala.language.experimental.macros
import scala.reflect.macros.Context
import java.io.ObjectInput
object Externalizables {
/** Generates a specialized `ObjectInput` instance.
*
* @tparam T a tuple type representing a sequence of types read from the ObjectInput.
* @param args a tuple with the values with which the ObjectInput should be initialized.
*/
def genInput[T](arg: T): ObjectInput = macro genInputImpl[T]
/** Generates a specialized `ArrayObjectOutput` instance.
*
* Note that we do not need a whitebox macro, since the return type does not need
* refinements, thanks to using arrays to store multiple values of the same type.
*
* @tparam T a tuple type representing a sequence of types written to the ArrayObjectOutput.
*/
def genOutput[T]: ArrayObjectOutput = macro genOutputImpl[T]
def genInputImpl[T: c.WeakTypeTag](c: Context)(arg: c.Expr[T]): c.Expr[ObjectInput] = {
import c.universe._
import definitions.{BooleanTpe, ByteTpe, CharTpe, DoubleTpe, FloatTpe, IntTpe, LongTpe, ShortTpe}
val tag = weakTypeTag[T]
// TODO: abort if T not a tuple type
val targs = tag.tpe match {
case TypeRef(_, _, args) => args
}
// extract argument trees of `arg` tuple (to avoid allocating and destructuring a tuple)
// note: passing a tuple created using `->` doesn't work
val q"$path[..$ts](..$args)" = arg.tree
/* Int, Int, Array[Byte], Int, Long, Object
0, 1, 2, 3, 4, 5
def readInt(): Int = {
state += 1
if (state == 0) x0
else if (state == 1) x1
else x3
}
*/
def readTree(is: List[Int]): Tree =
if (is.isEmpty) q"???"
else if (is.size == 1) {
val argName = newTermName("x" + is.head)
q"state += 1; $argName"
} else if (is.size == 2) {
val argName0 = newTermName("x" + is.head)
val argName1 = newTermName("x" + is.tail.head)
q"""
state += 1
if (state == ${is.head}) $argName0
else $argName1
"""
} else if (is.size == 3) {
val argName0 = newTermName("x" + is.head)
val argName1 = newTermName("x" + is.tail.head)
val argName2 = newTermName("x" + is.tail.tail.head)
q"""
state += 1
if (state == ${is.head}) $argName0
else if (state == ${is.tail.head}) $argName1
else $argName2
"""
} else
c.abort(c.enclosingPosition, "more arguments not supported")
// create class parameter list
// (val x0: Int, val x1: Int, val x2: Array[Byte], val x3: Int, val x4: Long, ...)
val params = for ((targ, i) <- targs.zipWithIndex) yield {
val name = newTermName("x" + i)
q"val $name: $targ"
}
// per type a sorted list of indices
val perType = targs.zipWithIndex.groupBy { case (targ, i) => targ }
.map { case (targ, things) => (targ, (things.map { case (_, i) => i }).sorted) }
def finalTree(tpe: Type): Tree =
readTree(perType.getOrElse(tpe, List[Int]()))
// copy contents of `xi` where i is the index of `typeOf[Array[Byte]]` in `perType` map
val readFullyTree: Tree = {
val arrIndices = perType.getOrElse(typeOf[Array[Byte]], List[Int]())
if (arrIndices.isEmpty) { // Array[Byte] unused
q"???"
} else {
val name = newTermName("x" + arrIndices.head)
// TODO: faster array copy using Unsafe?
q"System.arraycopy($name, 0, x, 0, x.length)"
}
}
val dummyName = c.fresh(newTypeName("DummyObjectInput"))
val instance: Tree = q"""
class $dummyName(..$params) extends java.io.ObjectInput {
var state = -1
def readByte(): Byte = ${finalTree(ByteTpe)}
def readBoolean(): Boolean = ${finalTree(BooleanTpe)}
def readChar(): Char = ${finalTree(CharTpe)}
def readDouble(): Double = ???
def readFloat(): Float = ???
def readFully(x1: Array[Byte], x2: Int, x3: Int): Unit = ???
def readFully(x: Array[Byte]): Unit = $readFullyTree
def readInt(): Int = ${finalTree(IntTpe)}
def readLine(): String = ???
def readLong(): Long = ???
def readShort(): Short = ???
def readUTF(): String = ???
def readUnsignedByte(): Int = ???
def readUnsignedShort(): Int = ???
def skipBytes(x1: Int): Int = ???
def available(): Int = ???
def close(): Unit = ???
def read(x1: Array[Byte], x2: Int, x3: Int): Int = ???
def read(x1: Array[Byte]): Int = ???
def read(): Int = ???
def readObject(): Object = ${finalTree(typeOf[AnyRef])}
def skip(x1: Long): Long = ???
}
new $dummyName(..$args)
"""
c.Expr[ObjectInput](instance)
}
def genOutputImpl[T: c.WeakTypeTag](c: Context): c.Expr[ArrayObjectOutput] = {
import c.universe._
import definitions.{BooleanTpe, ByteTpe, CharTpe, DoubleTpe, FloatTpe, IntTpe, LongTpe, ShortTpe}
val tag = weakTypeTag[T]
// TODO: abort if T not a tuple type
val targs = tag.tpe match {
case TypeRef(_, _, args) => args
}
/* see java.io.DataOutput:
writeBoolean(boolean v)
writeByte(int v)
writeChar(int v)
...
*/
val storage = Map(BooleanTpe -> BooleanTpe, ByteTpe -> IntTpe, CharTpe -> IntTpe, DoubleTpe -> DoubleTpe,
FloatTpe -> FloatTpe, IntTpe -> IntTpe, LongTpe -> LongTpe, ShortTpe -> IntTpe,
typeOf[AnyRef] -> typeOf[Any])
/* Byte, Byte, Array[Byte], Byte, Long, Object
0, 1, 2, 3, 4, 5
val byteArr: Array[Int] = _ // Arr: Array[]
val longArr: Array[Long] = _
val arrByteArr: Array[Array[Byte]] = _
def writeByte(x: Int): Unit = {
state += 1
if (state == 0) bytes(0) = x
else if (state == 1) bytes(1) = x
else bytes(2) = x // note that the index is 2, not 3, since the array should not be bigger than necessary
}
*/
// we assume the methods corresponding to the "writeTree" bodies are called in the right order
def writeTree(is: List[Int], tpeName: String): Tree = {
val fldName = newTermName(tpeName + "Arr")
if (is.isEmpty) q"???"
else if (is.size == 1) {
q"{ state += 1; $fldName(0) = x }"
} else if (is.size == 2) {
q"""
state += 1
if (state == ${is.head}) $fldName(0) = x
else $fldName(1) = x
"""
} else if (is.size == 3) {
q"""
state += 1
if (state == ${is.head}) $fldName(0) = x
else if (state == ${is.tail.head}) $fldName(1) = x
else $fldName(2) = x
"""
} else
c.abort(c.enclosingPosition, "more arguments not supported")
}
// per type a sorted list of indices
val perType = targs.zipWithIndex
.groupBy { case (targ, i) => targ }
.map { case (targ, things) => (targ, (things.map { case (_, i) => i }).sorted) }
// create array-valued fields
// val byteArr: Array[Int] = Array.ofDim[Int](3)
// ...
val fields = (for (targ <- storage.keys) yield {
val TypeRef(_, classSym, _) = targ
val tpestr = classSym.name.toString.toLowerCase
val name = newTermName(tpestr + "Arr")
val storageTpe = storage(targ)
val size = perType.getOrElse(targ, List[Int]()).size
q"val $name: Array[$storageTpe] = Array.ofDim[$storageTpe]($size)"
}) ++ Seq(
// implementation restriction: only store a single array
q"val arrByteArr: Array[Array[Byte]] = Array.ofDim[Array[Byte]](1)", {
val storageTpe = storage(typeOf[AnyRef])
q"val anyRefArr: Array[$storageTpe] = Array.ofDim[$storageTpe](${perType.getOrElse(typeOf[AnyRef], List[Int]()).size})"
}
)
def finalTree(tpe: Type, tpeName: String): Tree =
writeTree(perType.getOrElse(tpe, List[Int]()), tpeName)
val dummyName = c.fresh(newTypeName("DummyObjectOutput"))
val instance: Tree = q"""
class $dummyName extends scala.pickling.util.ArrayObjectOutput {
var state = -1
..$fields
// Members declared in java.io.DataOutput
def writeBoolean(x: Boolean): Unit = ${finalTree(BooleanTpe, "boolean")}
def writeByte(x: Int): Unit = ${finalTree(ByteTpe, "byte")}
def writeBytes(x: String): Unit = ???
def writeChar(x: Int): Unit = ${finalTree(CharTpe, "char")}
def writeChars(x: String): Unit = ???
def writeDouble(x: Double): Unit = ???
def writeFloat(x: Float): Unit = ???
def writeInt(x: Int): Unit = ${finalTree(IntTpe, "int")}
def writeLong(x: Long): Unit = ???
def writeShort(x: Int): Unit = ???
def writeUTF(x: String): Unit = ???
// Members declared in java.io.ObjectOutput
def close(): Unit = ???
def flush(): Unit = ???
def write(x1: Array[Byte],x2: Int,x3: Int): Unit = ???
def write(x: Array[Byte]): Unit = ${finalTree(typeOf[Array[Byte]], "arrByte")}
def write(x: Int): Unit = ???
def writeObject(x: Any): Unit = ${finalTree(typeOf[AnyRef], "anyRef")}
}
new $dummyName
"""
c.Expr[ArrayObjectOutput](instance)
}
}
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