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97 lines
3.2 KiB
C++
97 lines
3.2 KiB
C++
//===-- Support/EquivalenceClasses.h ----------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Generic implementation of equivalence classes and implementation of
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// union-find algorithms A not-so-fancy implementation: 2 level tree i.e root
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// and one more level Overhead of a union = size of the equivalence class being
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// attached Overhead of a find = 1.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SUPPORT_EQUIVALENCECLASSES_H
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#define SUPPORT_EQUIVALENCECLASSES_H
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#include <map>
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#include <vector>
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namespace llvm {
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template <class ElemTy>
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class EquivalenceClasses {
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// Maps each element to the element that is the leader of its
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// equivalence class.
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std::map<ElemTy, ElemTy> Elem2ECLeaderMap;
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// Make Element2 the leader of the union of classes Element1 and Element2
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// Element1 and Element2 are presumed to be leaders of their respective
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// equivalence classes.
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void attach(ElemTy Element1, ElemTy Element2) {
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for (typename std::map<ElemTy, ElemTy>::iterator ElemI =
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Elem2ECLeaderMap.begin(), ElemE = Elem2ECLeaderMap.end();
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ElemI != ElemE; ++ElemI) {
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if (ElemI->second == Element1)
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Elem2ECLeaderMap[ElemI->first] = Element2;
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}
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}
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public:
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void addElement (ElemTy NewElement) {
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if (Elem2ECLeaderMap.find(NewElement) == Elem2ECLeaderMap.end())
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Elem2ECLeaderMap[NewElement] = NewElement;
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}
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ElemTy findClass(ElemTy Element) {
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if (Elem2ECLeaderMap.find(Element) == Elem2ECLeaderMap.end())
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return 0;
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else
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return Elem2ECLeaderMap[Element];
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}
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/// Attach the set with Element1 to the set with Element2 adding Element1 and
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/// Element2 to the set of equivalence classes if they are not there already.
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/// Implication: Make Element1 the element in the smaller set.
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void unionSetsWith(ElemTy Element1, ElemTy Element2) {
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// If either Element1 or Element2 does not already exist, include it
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if (Elem2ECLeaderMap.find(Element1) == Elem2ECLeaderMap.end())
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Elem2ECLeaderMap[Element1] = Element1;
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if (Elem2ECLeaderMap.find(Element2) == Elem2ECLeaderMap.end())
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Elem2ECLeaderMap[Element2] = Element2;
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attach(Elem2ECLeaderMap[Element1], Elem2ECLeaderMap[Element2]);
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}
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// Returns a vector containing all the elements in the equivalent class
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// including Element1
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std::vector<ElemTy> getEqClass(ElemTy Element1) {
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std::vector<ElemTy> EqClass;
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if (Elem2ECLeaderMap.find(EqClass) == Elem2ECLeaderMap.end())
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return EqClass;
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ElemTy classLeader = Elem2ECLeaderMap[Element1];
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for (typename std::map<ElemTy, ElemTy>::iterator ElemI =
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Elem2ECLeaderMap.begin(), ElemE = Elem2ECLeaderMap.end();
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ElemI != ElemE; ++ElemI) {
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if (ElemI->second == classLeader)
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EqClass.push_back(ElemI->first);
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}
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return EqClass;
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}
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std::map<ElemTy, ElemTy>& getLeaderMap() {
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return Elem2ECLeaderMap ;
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}
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};
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} // End llvm namespace
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#endif
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