/* NSC -- new Scala compiler * Copyright 2005-2009 LAMP/EPFL * @author Martin Odersky */ package scala.tools.nsc package symtab // todo implement in terms of BitSet import scala.collection.mutable.ListBuffer import scala.collection.immutable.Map import Math.max /** 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._ class BaseTypeSeq(parents: List[Type], elems: Array[Type]) { /** The number of types in the sequence */ def length: Int = elems.length var pending: Map[Int, Type] = Map() /** The type at i'th position in this sequence; lazy types are returned evaluated. */ def apply(i: Int): Type = elems(i) match { case NoType => pending = Map() elems(i) = AnyClass.tpe throw CyclicInheritance 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 -> rtp) elems(i) = NoType try { mergePrefixAndArgs(variants, -1, lubDepth(variants)) match { case Some(tp0) => pending -= i 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 = { def tsym(tp: Type) = tp match { case RefinedType(v :: vs, _) => v.typeSymbol case _ => tp.typeSymbol } elems(i) match { case NoType => pending get i match { case Some(tp) => tsym(tp) case _ => NoType.typeSymbol } case tp => tsym(tp) } } /** Return all evaluated types in this sequence as a list */ def toList: List[Type] = elems.toList private def copy(head: Type, offset: Int): BaseTypeSeq = { val arr = new Array[Type](elems.length + offset) compat.Platform.arraycopy(elems, 0, arr, offset, elems.length) arr(0) = head new BaseTypeSeq(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 } new BaseTypeSeq(parents, arr) } def exists(p: Type => Boolean): Boolean = elems exists p // (0 until length) exists (i => p(this(i))) def normalize(parents: List[Type]) {} /* var j = 0 while (j < elems.length) { elems(j) match { case 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+")") elems(j) = mergePrefixAndArgs(variants, -1, maxBaseTypeSeqDepth(variants) + LubGlbMargin) match { case Some(tp0) => tp0 case None => throw new TypeError( "the type intersection "+(parents mkString " with ")+" is malformed"+ "\n --- because ---"+ "\n no common type instance of base types "+(variants mkString ", and ")+" exists.") } case _ => } j += 1 } } */ lazy val maxDepth: Int = { var d = 0 for (i <- 0 until length) d = Math.max(d, maxDpth(elems(i))) d } /** The maximum depth of type `tp' */ private def maxDpth(tp: Type): Int = tp match { case TypeRef(pre, sym, args) => max(maxDpth(pre), maxDpth(args) + 1) case RefinedType(parents, decls) => max(maxDpth(parents), maxDpth(decls.toList.map(_.info)) + 1) case TypeBounds(lo, hi) => max(maxDpth(lo), maxDpth(hi)) case MethodType(paramtypes, result) => maxDpth(result) case PolyType(tparams, result) => max(maxDpth(result), maxDpth(tparams map (_.info)) + 1) case ExistentialType(tparams, result) => max(maxDpth(result), maxDpth(tparams map (_.info)) + 1) case _ => 1 } /** The maximum depth of all types `tps' */ private def maxDpth(tps: Seq[Type]): Int = { var d = 0 for (tp <- tps) d = max(d, maxDpth(tp)) 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 = new BaseTypeSeq(List(), Array()) /** Create a base type sequence consisting of a single type */ def baseTypeSingletonSeq(tp: Type): BaseTypeSeq = new BaseTypeSeq(List(), Array(tp)) /** Create the base type sequence of a compound type wuth given tp.parents */ def compoundBaseTypeSeq(tp: Type/*tsym: Symbol, parents: List[Type]*/): BaseTypeSeq = { val tsym = tp.typeSymbol val parents = tp.parents // Console.println("computing baseTypeSeq of " + tsym.tpe + " " + parents)//DEBUG val buf = new ListBuffer[Type] buf += tsym.tpe var btsSize = 1 val nparents = parents.length if (nparents != 0) { 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 new BaseTypeSeq(parents, elems) } val CyclicInheritance = new Throwable }