llvm-6502/include/llvm/ADT/DeltaAlgorithm.h
David Blaikie 7462aeac16 DeltaAlgorithm: Provide protected default copy ctor for use by test derived class.
Without this, use of this copy ctor is deprecated in C++11 due to the
presence of a user-declared dtor.

Marking the class final is just a little extra security that there are
no further derived classes that may then end up using the intermediate
base class's copy assignment operator and cause slicing to occur.

I didn't bother marking the other (non-test) base class final, since it
has reference members so it won't have any implicit assignment operators
anyway. Open to ideas on that, though.

We probably want a warning about use of a slicing assignment operator,
then I wouldn't worry so much about marking the class as final.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231114 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-03 19:53:04 +00:00

94 lines
3.5 KiB
C++

//===--- DeltaAlgorithm.h - A Set Minimization Algorithm -------*- C++ -*--===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_DELTAALGORITHM_H
#define LLVM_ADT_DELTAALGORITHM_H
#include <set>
#include <vector>
namespace llvm {
/// DeltaAlgorithm - Implements the delta debugging algorithm (A. Zeller '99)
/// for minimizing arbitrary sets using a predicate function.
///
/// The result of the algorithm is a subset of the input change set which is
/// guaranteed to satisfy the predicate, assuming that the input set did. For
/// well formed predicates, the result set is guaranteed to be such that
/// removing any single element would falsify the predicate.
///
/// For best results the predicate function *should* (but need not) satisfy
/// certain properties, in particular:
/// (1) The predicate should return false on an empty set and true on the full
/// set.
/// (2) If the predicate returns true for a set of changes, it should return
/// true for all supersets of that set.
///
/// It is not an error to provide a predicate that does not satisfy these
/// requirements, and the algorithm will generally produce reasonable
/// results. However, it may run substantially more tests than with a good
/// predicate.
class DeltaAlgorithm {
public:
typedef unsigned change_ty;
// FIXME: Use a decent data structure.
typedef std::set<change_ty> changeset_ty;
typedef std::vector<changeset_ty> changesetlist_ty;
private:
/// Cache of failed test results. Successful test results are never cached
/// since we always reduce following a success.
std::set<changeset_ty> FailedTestsCache;
/// GetTestResult - Get the test result for the \p Changes from the
/// cache, executing the test if necessary.
///
/// \param Changes - The change set to test.
/// \return - The test result.
bool GetTestResult(const changeset_ty &Changes);
/// Split - Partition a set of changes \p S into one or two subsets.
void Split(const changeset_ty &S, changesetlist_ty &Res);
/// Delta - Minimize a set of \p Changes which has been partioned into
/// smaller sets, by attempting to remove individual subsets.
changeset_ty Delta(const changeset_ty &Changes,
const changesetlist_ty &Sets);
/// Search - Search for a subset (or subsets) in \p Sets which can be
/// removed from \p Changes while still satisfying the predicate.
///
/// \param Res - On success, a subset of Changes which satisfies the
/// predicate.
/// \return - True on success.
bool Search(const changeset_ty &Changes, const changesetlist_ty &Sets,
changeset_ty &Res);
protected:
/// UpdatedSearchState - Callback used when the search state changes.
virtual void UpdatedSearchState(const changeset_ty &Changes,
const changesetlist_ty &Sets) {}
/// ExecuteOneTest - Execute a single test predicate on the change set \p S.
virtual bool ExecuteOneTest(const changeset_ty &S) = 0;
DeltaAlgorithm& operator=(const DeltaAlgorithm&) = default;
public:
virtual ~DeltaAlgorithm();
/// Run - Minimize the set \p Changes by executing \see ExecuteOneTest() on
/// subsets of changes and returning the smallest set which still satisfies
/// the test predicate.
changeset_ty Run(const changeset_ty &Changes);
};
} // end namespace llvm
#endif