package dotty.tools.dotc
package core
import annotation.tailrec
import Symbols._
import Contexts._, Names._, Phases._, printing.Texts._, printing.Printer, printing.Showable
import util.Positions.Position, util.SourcePosition
import collection.mutable.ListBuffer
import dotty.tools.dotc.transform.TreeTransforms._
import ast.tpd._
import scala.language.implicitConversions
import printing.Formatting._
/** This object provides useful implicit decorators for types defined elsewhere */
object Decorators {
/** Turns Strings into PreNames, adding toType/TermName methods */
implicit class PreNamedString(val s: String) extends AnyVal with PreName {
def toTypeName: TypeName = typeName(s)
def toTermName: TermName = termName(s)
def toText(printer: Printer): Text = Str(s)
}
implicit class StringDecorator(val s: String) extends AnyVal {
def splitWhere(f: Char => Boolean, doDropIndex: Boolean): Option[(String, String)] = {
def splitAt(idx: Int, doDropIndex: Boolean): Option[(String, String)] =
if (idx == -1) None
else Some((s.take(idx), s.drop(if (doDropIndex) idx + 1 else idx)))
splitAt(s.indexWhere(f), doDropIndex)
}
}
/** Implements a findSymbol method on iterators of Symbols that
* works like find but avoids Option, replacing None with NoSymbol.
*/
implicit class SymbolIteratorDecorator(val it: Iterator[Symbol]) extends AnyVal {
final def findSymbol(p: Symbol => Boolean): Symbol = {
while (it.hasNext) {
val sym = it.next
if (p(sym)) return sym
}
NoSymbol
}
}
final val MaxFilterRecursions = 1000
/** Implements filterConserve, zipWithConserve methods
* on lists that avoid duplication of list nodes where feasible.
*/
implicit class ListDecorator[T](val xs: List[T]) extends AnyVal {
final def mapconserve[U](f: T => U): List[U] = {
@tailrec
def loop(mapped: ListBuffer[U], unchanged: List[U], pending: List[T]): List[U] =
if (pending.isEmpty) {
if (mapped eq null) unchanged
else mapped.prependToList(unchanged)
} else {
val head0 = pending.head
val head1 = f(head0)
if (head1.asInstanceOf[AnyRef] eq head0.asInstanceOf[AnyRef])
loop(mapped, unchanged, pending.tail)
else {
val b = if (mapped eq null) new ListBuffer[U] else mapped
var xc = unchanged
while (xc ne pending) {
b += xc.head
xc = xc.tail
}
b += head1
val tail0 = pending.tail
loop(b, tail0.asInstanceOf[List[U]], tail0)
}
}
loop(null, xs.asInstanceOf[List[U]], xs)
}
/** Like `xs filter p` but returns list `xs` itself - instead of a copy -
* if `p` is true for all elements and `xs` is not longer
* than `MaxFilterRecursions`.
*/
def filterConserve(p: T => Boolean): List[T] = {
def loop(xs: List[T], nrec: Int): List[T] = xs match {
case Nil => xs
case x :: xs1 =>
if (nrec < MaxFilterRecursions) {
val ys1 = loop(xs1, nrec + 1)
if (p(x))
if (ys1 eq xs1) xs else x :: ys1
else
ys1
} else xs filter p
}
loop(xs, 0)
}
/** Like `(xs, ys).zipped.map(f)`, but returns list `xs` itself
* - instead of a copy - if function `f` maps all elements of
* `xs` to themselves. Also, it is required that `ys` is at least
* as long as `xs`.
*/
def zipWithConserve[U](ys: List[U])(f: (T, U) => T): List[T] =
if (xs.isEmpty || ys.isEmpty) Nil
else {
val x1 = f(xs.head, ys.head)
val xs1 = xs.tail.zipWithConserve(ys.tail)(f)
if ((x1.asInstanceOf[AnyRef] eq xs.head.asInstanceOf[AnyRef]) &&
(xs1 eq xs.tail)) xs
else x1 :: xs1
}
def foldRightBN[U](z: => U)(op: (T, => U) => U): U = xs match {
case Nil => z
case x :: xs1 => op(x, xs1.foldRightBN(z)(op))
}
final def hasSameLengthAs[U](ys: List[U]): Boolean = {
@tailrec def loop(xs: List[T], ys: List[U]): Boolean =
if (xs.isEmpty) ys.isEmpty
else ys.nonEmpty && loop(xs.tail, ys.tail)
loop(xs, ys)
}
/** Union on lists seen as sets */
def | (ys: List[T]): List[T] = xs ++ (ys filterNot (xs contains _))
/** Intersection on lists seen as sets */
def & (ys: List[T]): List[T] = xs filter (ys contains _)
}
implicit class ListOfListDecorator[T](val xss: List[List[T]]) extends AnyVal {
def nestedMap[U](f: T => U): List[List[U]] = xss map (_ map f)
def nestedMapconserve[U](f: T => U): List[List[U]] = xss mapconserve (_ mapconserve f)
}
implicit class TextToString(val text: Text) extends AnyVal {
def show(implicit ctx: Context) = text.mkString(ctx.settings.pageWidth.value)
}
/** Test whether a list of strings representing phases contains
* a given phase. See [[config.CompilerCommand#explainAdvanced]] for the
* exact meaning of "contains" here.
*/
implicit class PhaseListDecorator(val names: List[String]) extends AnyVal {
def containsPhase(phase: Phase): Boolean = phase match {
case phase: TreeTransformer => phase.miniPhases.exists(containsPhase)
case _ =>
names exists { name =>
name == "all" || {
val strippedName = name.stripSuffix("+")
val logNextPhase = name ne strippedName
phase.phaseName.startsWith(strippedName) ||
(logNextPhase && phase.prev.phaseName.startsWith(strippedName))
}
}
}
}
implicit def sourcePos(pos: Position)(implicit ctx: Context): SourcePosition = {
def recur(inlinedCalls: List[Tree], pos: Position): SourcePosition = inlinedCalls match {
case inlinedCall :: rest =>
sourceFile(inlinedCall).atPos(pos).withOuter(recur(rest, inlinedCall.pos))
case empty =>
ctx.source.atPos(pos)
}
recur(enclosingInlineds, pos)
}
implicit class StringInterpolators(val sc: StringContext) extends AnyVal {
/** General purpose string formatting */
def i(args: Any*)(implicit ctx: Context): String =
new StringFormatter(sc).assemble(args)
/** Formatting for error messages: Like `i` but suppress follow-on
* error messages after the first one if some of their arguments are "non-sensical".
*/
def em(args: Any*)(implicit ctx: Context): String =
new ErrorMessageFormatter(sc).assemble(args)
/** Formatting with added explanations: Like `em`, but add explanations to
* give more info about type variables and to disambiguate where needed.
*/
def ex(args: Any*)(implicit ctx: Context): String =
explained(implicit ctx => em(args: _*))
/** Formatter that adds syntax highlighting to all interpolated values */
def hl(args: Any*)(implicit ctx: Context): String =
new SyntaxFormatter(sc).assemble(args).stripMargin
}
}
