From f96b6beefc08f56218ac68b37a4cecd757cb60ee Mon Sep 17 00:00:00 2001 From: Adriaan Moors Date: Fri, 6 Apr 2007 09:39:53 +0000 Subject: adding test files from tcpoly branch without hi... adding test files from tcpoly branch without history -- much faster this way, sorry --- test/files/pos/tcpoly_seq.scala | 175 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 175 insertions(+) create mode 100644 test/files/pos/tcpoly_seq.scala (limited to 'test/files/pos/tcpoly_seq.scala') diff --git a/test/files/pos/tcpoly_seq.scala b/test/files/pos/tcpoly_seq.scala new file mode 100644 index 0000000000..85563488fd --- /dev/null +++ b/test/files/pos/tcpoly_seq.scala @@ -0,0 +1,175 @@ +package examples.tcpoly.collection; + +trait HOSeq { + // an internal interface that encapsulates the accumulation of elements (of type elT) to produce + // a structure of type coll[elT] -- different kinds of collections should provide different implicit + // values implementing this interface, in order to provide more performant ways of building that structure + trait Accumulator[+coll[x], elT] { + def += (el: elT): Unit + def result: coll[elT] + } + + + // Iterable abstracts over the type of its structure as well as its elements (see PolyP's Bifunctor) + // m[x] is intentionally unbounded: fold can then be defined nicely + // variance: if we write m[+x] instead of +m[+x], x is an invariant position because its enclosing type + // is an invariant position -- should probably rule that out? + trait Iterable[+m[+x], +t] { + //def unit[a](orig: a): m[a] + def elements: Iterator[t] + + // construct an empty accumulator that will produce the same structure as this iterable, with elements of type t + def accumulator[t]: Accumulator[m, t] + + def filter(p: t => Boolean): m[t] = { + val buf = accumulator[t] + val elems = elements + while (elems.hasNext) { val x = elems.next; if (p(x)) buf += x } + buf.result + } + + def map[s](f: t => s): m[s] = { + val buf = accumulator[s] + val elems = elements + while (elems.hasNext) buf += f(elems.next) + buf.result + } + + // flatMap is a more specialized map, it only works if the mapped function produces Iterable values, + // which are then added to the result one by one + // the compiler should be able to find the right accumulator (implicit buf) to build the result + // to get concat, resColl = SingletonIterable, f = unit for SingletonIterable + def flatMap[resColl[+x] <: Iterable[resColl, x], s](f: t => resColl[s])(implicit buf: Accumulator[resColl, s]): resColl[s] = { + // TODO: would a viewbound for resColl[x] be better? + // -- 2nd-order type params are not yet in scope in view bound + val elems = elements + while (elems.hasNext) { + val elemss: Iterator[s] = f(elems.next).elements + while (elemss.hasNext) buf += elemss.next + } + buf.result + } + } + + final class ListBuffer[A] { + private var start: List[A] = Nil + private var last: ::[A] = _ + private var exported: boolean = false + + /** Appends a single element to this buffer. + * + * @param x the element to append. + */ + def += (x: A): unit = { + if (exported) copy + if (start.isEmpty) { + last = new HOSeq.this.:: (x, Nil) + start = last + } else { + val last1 = last + last = new HOSeq.this.:: (x, null) // hack: ::'s tail will actually be last + //last1.tl = last + } + } + + /** Converts this buffer to a list + */ + def toList: List[A] = { + exported = !start.isEmpty + start + } + + /** Clears the buffer contents. + */ + def clear: unit = { + start = Nil + exported = false + } + + /** Copy contents of this buffer */ + private def copy = { + var cursor = start + val limit = last.tail + clear + while (cursor ne limit) { + this += cursor.head + cursor = cursor.tail + } + } + } + + implicit def listAccumulator[elT]: Accumulator[List, elT] = new Accumulator[List, elT] { + private[this] val buff = new ListBuffer[elT] + def += (el: elT): Unit = buff += el + def result: List[elT] = buff.toList + } + + trait List[+t] extends Iterable[List, t] { + def head: t + def tail: List[t] + def isEmpty: Boolean + def elements: Iterator[t] = new Iterator[t] { + var these = List.this + def hasNext: Boolean = !these.isEmpty + def next: t = + if (!hasNext) + throw new NoSuchElementException("next on empty Iterator") + else { + val result = these.head; these = these.tail; result + } + } + // construct an empty accumulator that will produce the same structure as this iterable, with elements of type t + def accumulator[t]: Accumulator[List, t] = listAccumulator[t] + } + + // TODO: the var tl approach does not seem to work because subtyping isn't fully working yet + final case class ::[+b](hd: b, private val tl: List[b]) extends List[b] { + def head = hd + def tail = if(tl==null) this else tl // hack + override def isEmpty: boolean = false + } + + case object Nil extends List[Nothing] { + def isEmpty = true + def head: Nothing = + throw new NoSuchElementException("head of empty list") + def tail: List[Nothing] = + throw new NoSuchElementException("tail of empty list") + } +} + + + +// misc signatures collected from mailing list / library code: + /*override def flatMap[B](f: A => Iterable[B]): Set[B] + final override def flatMap[b](f: Any => Iterable[b]): Array[b] + def flatMap[b](f: a => Parser[b]) = new Parser[b] + override def flatMap[b](f: a => Iterable[b]): List[b] + + + MapResult[K] <: Seq[K] + FilterResult <: Seq[T] + Concat <: Seq[T] + Subseq <: Seq[T] + + + def map[K](f: T=>K): MapResult[K] + def filter(f: T=>Boolean): FilterResult + def subseq(from: int, to: int): Subseq + def flatMap[S <: Seq[K], K](f: T => S): S#Concat // legal? + def concat(others: Seq[T]): Concat + */ + +/*trait Iterator[t] { + // @post hasAdvanced implies hasNext + // model def hasAdvanced: Boolean + + def hasNext: Boolean // pure + + // @pre hasAdvanced + def current: t // pure + + // @pre hasNext + // @post hasAdvanced + def advance: Unit +}*/ \ No newline at end of file -- cgit v1.2.3