/* NSC -- new Scala compiler * Copyright 2005-2013 LAMP/EPFL * @author Martin Odersky */ package scala.reflect package internal // todo implement in terms of BitSet import scala.collection.{ mutable, immutable } import scala.math.max import util.Statistics /** A base type sequence (BaseTypeSeq) is an ordered sequence spanning all the base types * of a type. It characterized by the following two laws: * * (1) Each element of `tp.baseTypeSeq` is a basetype of `tp` * (2) For each basetype `bt1` of `tp` there is an element `bt` in `tp.baseTypeSeq` such that * * bt.typeSymbol = bt1.typeSymbol * bt <: bt1 * * (3) The type symbols of different elements are different. * * Elements in the sequence are ordered by Symbol.isLess. * @note base type sequences were called closures up to 2.7.1. The name has been changed * to avoid confusion with function closures. */ trait BaseTypeSeqs { this: SymbolTable => import definitions._ import BaseTypeSeqsStats._ protected def newBaseTypeSeq(parents: List[Type], elems: Array[Type]) = new BaseTypeSeq(parents, elems) /** Note: constructor is protected to force everyone to use the factory method newBaseTypeSeq instead. * This is necessary because when run from reflection every base type sequence needs to have a * SynchronizedBaseTypeSeq as mixin. */ class BaseTypeSeq protected[BaseTypeSeqs] (private[BaseTypeSeqs] val parents: List[Type], private[BaseTypeSeqs] val elems: Array[Type]) { self => if (Statistics.canEnable) Statistics.incCounter(baseTypeSeqCount) if (Statistics.canEnable) Statistics.incCounter(baseTypeSeqLenTotal, elems.length) /** The number of types in the sequence */ def length: Int = elems.length // #3676 shows why we can't store NoType in elems to mark cycles // (while NoType is in there to indicate a cycle in this BTS, during the execution of // the mergePrefixAndArgs below, the elems get copied without the pending map, // so that NoType's are seen instead of the original type --> spurious compile error) private val pending = new mutable.BitSet(length) /** The type at i'th position in this sequence; lazy types are returned evaluated. */ def apply(i: Int): Type = if(pending contains i) { pending.clear() throw CyclicInheritance } else elems(i) match { case rtp @ RefinedType(variants, decls) => // can't assert decls.isEmpty; see t0764 //if (!decls.isEmpty) assert(false, "computing closure of "+this+":"+this.isInstanceOf[RefinedType]+"/"+closureCache(j)) //Console.println("compute closure of "+this+" => glb("+variants+")") pending += i try { mergePrefixAndArgs(variants, -1, lubDepth(variants)) match { case Some(tp0) => pending(i) = false elems(i) = tp0 tp0 case None => typeError( "no common type instance of base types "+(variants mkString ", and ")+" exists.") } } catch { case CyclicInheritance => typeError( "computing the common type instance of base types "+(variants mkString ", and ")+" leads to a cycle.") } case tp => tp } def rawElem(i: Int) = elems(i) /** The type symbol of the type at i'th position in this sequence; * no evaluation needed. */ def typeSymbol(i: Int): Symbol = { elems(i) match { case RefinedType(v :: vs, _) => v.typeSymbol case tp => tp.typeSymbol } } /** Return all evaluated types in this sequence as a list */ def toList: List[Type] = elems.toList def copy(head: Type, offset: Int): BaseTypeSeq = { val arr = new Array[Type](elems.length + offset) scala.compat.Platform.arraycopy(elems, 0, arr, offset, elems.length) arr(0) = head newBaseTypeSeq(parents, arr) } /** Compute new base type sequence with `tp` prepended to this sequence */ def prepend(tp: Type): BaseTypeSeq = copy(tp, 1) /** Compute new base type sequence with `tp` replacing the head of this sequence */ def updateHead(tp: Type): BaseTypeSeq = copy(tp, 0) /** Compute new base type sequence where every element is mapped * with function `f`. Lazy types are mapped but not evaluated */ def map(f: Type => Type): BaseTypeSeq = { // inlined `elems map f` for performance val len = length var arr = new Array[Type](len) var i = 0 while (i < len) { arr(i) = f(elems(i)) i += 1 } newBaseTypeSeq(parents, arr) } def lateMap(f: Type => Type): BaseTypeSeq = new MappedBaseTypeSeq(this, f) def exists(p: Type => Boolean): Boolean = elems exists p lazy val maxDepth = maxDepthOfElems protected def maxDepthOfElems: Int = { var d = 0 for (i <- 1 until length) d = max(d, typeDepth(elems(i))) d } override def toString = elems.mkString("BTS(", ",", ")") private def typeError(msg: String): Nothing = throw new TypeError( "the type intersection "+(parents mkString " with ")+" is malformed"+ "\n --- because ---\n"+msg) } /** A merker object for a base type sequence that's no yet computed. * used to catch inheritance cycles */ val undetBaseTypeSeq: BaseTypeSeq = newBaseTypeSeq(List(), Array()) /** Create a base type sequence consisting of a single type */ def baseTypeSingletonSeq(tp: Type): BaseTypeSeq = newBaseTypeSeq(List(), Array(tp)) /** Create the base type sequence of a compound type wuth given tp.parents */ def compoundBaseTypeSeq(tp: Type): BaseTypeSeq = { val tsym = tp.typeSymbol val parents = tp.parents // Console.println("computing baseTypeSeq of " + tsym.tpe + " " + parents)//DEBUG val buf = new mutable.ListBuffer[Type] buf += tsym.tpe var btsSize = 1 if (parents.nonEmpty) { val nparents = parents.length val pbtss = new Array[BaseTypeSeq](nparents) val index = new Array[Int](nparents) var i = 0 for (p <- parents) { pbtss(i) = if (p.baseTypeSeq eq undetBaseTypeSeq) AnyClass.info.baseTypeSeq else p.baseTypeSeq index(i) = 0 i += 1 } def nextTypeSymbol(i: Int): Symbol = { val j = index(i) val pbts = pbtss(i) if (j < pbts.length) pbts.typeSymbol(j) else AnyClass } def nextRawElem(i: Int): Type = { val j = index(i) val pbts = pbtss(i) if (j < pbts.length) pbts.rawElem(j) else AnyClass.tpe } var minSym: Symbol = NoSymbol while (minSym != AnyClass) { minSym = nextTypeSymbol(0) i = 1 while (i < nparents) { val nextSym = nextTypeSymbol(i) if (nextSym isLess minSym) minSym = nextSym i += 1 } var minTypes: List[Type] = List() i = 0 while (i < nparents) { if (nextTypeSymbol(i) == minSym) { nextRawElem(i) match { case RefinedType(variants, decls) => for (tp <- variants) if (!(minTypes exists (tp =:= _))) minTypes = tp :: minTypes case tp => if (!(minTypes exists (tp =:= _))) minTypes = tp :: minTypes } index(i) = index(i) + 1 } i += 1 } buf += intersectionType(minTypes) btsSize += 1 } } val elems = new Array[Type](btsSize) buf.copyToArray(elems, 0) // Console.println("computed baseTypeSeq of " + tsym.tpe + " " + parents + ": "+elems.toString)//DEBUG newBaseTypeSeq(parents, elems) } class MappedBaseTypeSeq(orig: BaseTypeSeq, f: Type => Type) extends BaseTypeSeq(orig.parents map f, orig.elems) { override def apply(i: Int) = f(orig.apply(i)) override def rawElem(i: Int) = f(orig.rawElem(i)) override def typeSymbol(i: Int) = orig.typeSymbol(i) override def toList = orig.toList map f override def copy(head: Type, offset: Int) = (orig map f).copy(head, offset) override def map(g: Type => Type) = lateMap(g) override def lateMap(g: Type => Type) = orig.lateMap(x => g(f(x))) override def exists(p: Type => Boolean) = elems exists (x => p(f(x))) override protected def maxDepthOfElems: Int = elems.map(x => typeDepth(f(x))).max override def toString = elems.mkString("MBTS(", ",", ")") } val CyclicInheritance = new Throwable } object BaseTypeSeqsStats { val baseTypeSeqCount = Statistics.newCounter("#base type seqs") val baseTypeSeqLenTotal = Statistics.newRelCounter("avg base type seq length", baseTypeSeqCount) }