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/*
* Copyright 2014 Google Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef FRUIT_META_PROOF_TREES_H
#define FRUIT_META_PROOF_TREES_H
#include <fruit/impl/fruit_assert.h>
#include <fruit/impl/injection_debug_errors.h>
#include <fruit/impl/meta/errors.h>
#include <fruit/impl/meta/graph.h>
#include <fruit/impl/meta/set.h>
namespace fruit {
namespace impl {
namespace meta {
// Given a set of formulas Hps=Set<Hp1, ... Hp(n)> and a formula Th, Pair<Th, Hps> represents the
// following proof tree:
//
// Hp1 ... Hp(n)
// -------------
// Th
//
// Hp1, ... Hp(n) must be distinct.
// Formulas are atomic, any type can be used as formula (except None).
//
// A proof forest is a map (i.e. a Set of Pair(s)) from each Th to the corresponding set of Hps.
// Note that a proof forest doesn't need to have any additional property (for example, a proof tree
// might contain the thesis as hypotheses, or there might be a longer loop e.g A=>B, B=>A.
using EmptyProofForest = EmptySet;
#if !FRUIT_NO_LOOP_CHECK
using ProofForestFindHps = GraphFindNeighbors;
// ProofForestFindLoop(F) returns a loop in the given forest as a Vector<Th1, ..., Thk> such that:
// IsInSet(Th1, ProofForestFindHps(Th2)), IsInSet(Th2, ProofForestFindHps(Th3)), ...,
// IsInSet(Th{k-1}, ProofForestFindHps(Thk)), IsInSet(Thk, ProofForestFindHps(Th1))
// if there is no such loop, returns None.
using ProofForestFindLoop = GraphFindLoop;
#else // FRUIT_NO_LOOP_CHECK
struct ProofForestFindLoop {
template <typename F>
struct apply {
using type = None;
};
};
struct AddProofTreeToForest {
template <typename Forest, typename Proof>
struct apply {
using type = Vector<>;
};
};
struct AddProofTreeSetToForest {
template <typename Proofs, typename Forest>
struct apply {
using type = Vector<>;
};
};
#endif // FRUIT_NO_LOOP_CHECK
} // namespace meta
} // namespace impl
} // namespace fruit
#endif // FRUIT_META_PROOF_TREES_H