1 //===--- DeltaAlgorithm.h - A Set Minimization Algorithm -------*- C++ -*--===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //===----------------------------------------------------------------------===//
9 #ifndef LLVM_ADT_DELTAALGORITHM_H
10 #define LLVM_ADT_DELTAALGORITHM_H
17 /// DeltaAlgorithm - Implements the delta debugging algorithm (A. Zeller '99)
18 /// for minimizing arbitrary sets using a predicate function.
20 /// The result of the algorithm is a subset of the input change set which is
21 /// guaranteed to satisfy the predicate, assuming that the input set did. For
22 /// well formed predicates, the result set is guaranteed to be such that
23 /// removing any single element would falsify the predicate.
25 /// For best results the predicate function *should* (but need not) satisfy
26 /// certain properties, in particular:
27 /// (1) The predicate should return false on an empty set and true on the full
29 /// (2) If the predicate returns true for a set of changes, it should return
30 /// true for all supersets of that set.
32 /// It is not an error to provide a predicate that does not satisfy these
33 /// requirements, and the algorithm will generally produce reasonable
34 /// results. However, it may run substantially more tests than with a good
36 class DeltaAlgorithm {
38 typedef unsigned change_ty;
39 // FIXME: Use a decent data structure.
40 typedef std::set<change_ty> changeset_ty;
41 typedef std::vector<changeset_ty> changesetlist_ty;
44 /// Cache of failed test results. Successful test results are never cached
45 /// since we always reduce following a success.
46 std::set<changeset_ty> FailedTestsCache;
48 /// GetTestResult - Get the test result for the \arg Changes from the
49 /// cache, executing the test if necessary.
51 /// \param Changes - The change set to test.
52 /// \return - The test result.
53 bool GetTestResult(const changeset_ty &Changes);
55 /// Split - Partition a set of changes \arg Sinto one or two subsets.
56 void Split(const changeset_ty &S, changesetlist_ty &Res);
58 /// Delta - Minimize a set of \arg Changes which has been partioned into
59 /// smaller sets, by attempting to remove individual subsets.
60 changeset_ty Delta(const changeset_ty &Changes,
61 const changesetlist_ty &Sets);
63 /// Search - Search for a subset (or subsets) in \arg Sets which can be
64 /// removed from \arg Changes while still satisfying the predicate.
66 /// \param Res - On success, a subset of Changes which satisfies the
68 /// \return - True on success.
69 bool Search(const changeset_ty &Changes, const changesetlist_ty &Sets,
73 /// UpdatedSearchState - Callback used when the search state changes.
74 virtual void UpdatedSearchState(const changeset_ty &Changes,
75 const changesetlist_ty &Sets) {}
77 /// ExecuteOneTest - Execute a single test predicate on the change set \arg S.
78 virtual bool ExecuteOneTest(const changeset_ty &S) = 0;
81 virtual ~DeltaAlgorithm();
83 /// Run - Minimize the set \arg Changes by executing \see ExecuteOneTest() on
84 /// subsets of changes and returning the smallest set which still satisfies
85 /// the test predicate.
86 changeset_ty Run(const changeset_ty &Changes);
89 } // end namespace llvm