llvm/include/Support/SetOperations.h

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//===-- Support/SetOperations.h - Generic Set Operations --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines generic set operations that may be used on set's of
// different types, and different element types.
//
//===----------------------------------------------------------------------===//
#ifndef SUPPORT_SETOPERATIONS_H
#define SUPPORT_SETOPERATIONS_H
namespace llvm {
// set_union(A, B) - Compute A := A u B, return whether A changed.
//
template <class S1Ty, class S2Ty>
bool set_union(S1Ty &S1, const S2Ty &S2) {
bool Changed = false;
for (typename S2Ty::const_iterator SI = S2.begin(), SE = S2.end();
SI != SE; ++SI)
if (S1.insert(*SI).second)
Changed = true;
return Changed;
}
// set_intersect(A, B) - Compute A := A ^ B
// Identical to set_intersection, except that it works on set<>'s and
// is nicer to use. Functionally, this iterates through S1, removing
// elements that are not contained in S2.
//
template <template<class S1ElTy> class S1Ty, class ETy, class S2Ty>
void set_intersect(S1Ty<ETy> &S1, const S2Ty &S2) {
for (typename S1Ty<ETy>::iterator I = S1.begin(); I != S1.end();) {
const ETy &E = *I;
++I;
if (!S2.count(E)) S1.erase(E); // Erase element if not in S2
}
}
// set_difference(A, B) - Return A - B
//
template <class S1Ty, class S2Ty>
S1Ty set_difference(const S1Ty &S1, const S2Ty &S2) {
S1Ty Result;
for (typename S1Ty::const_iterator SI = S1.begin(), SE = S1.end();
SI != SE; ++SI)
if (!S2.count(*SI)) // if the element is not in set2
Result.insert(*SI);
return Result;
}
// set_subtract(A, B) - Compute A := A - B
//
template <class S1Ty, class S2Ty>
void set_subtract(S1Ty &S1, const S2Ty &S2) {
for (typename S2Ty::const_iterator SI = S2.begin(), SE = S2.end();
SI != SE; ++SI)
S1.erase(*SI);
}
} // End llvm namespace
#endif