75 lines
2.9 KiB
C++
75 lines
2.9 KiB
C++
// Copyright 2017 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef COMPONENTS_ZUCCHINI_TARGETS_AFFINITY_H_
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#define COMPONENTS_ZUCCHINI_TARGETS_AFFINITY_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <deque>
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#include <vector>
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#include "components/zucchini/image_utils.h"
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namespace zucchini {
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class EquivalenceMap;
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// Computes and stores affinity between old and new targets for a single target
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// pool. This is only used during patch generation.
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class TargetsAffinity {
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public:
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TargetsAffinity();
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TargetsAffinity(const TargetsAffinity&) = delete;
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const TargetsAffinity& operator=(const TargetsAffinity&) = delete;
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~TargetsAffinity();
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// Infers affinity between |old_targets| and |new_targets| using similarities
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// described by |equivalence_map|, and updates internal state for retrieval of
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// affinity scores. Both |old_targets| and |new_targets| are targets in the
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// same pool and are sorted in ascending order.
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void InferFromSimilarities(const EquivalenceMap& equivalence_map,
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const std::deque<offset_t>& old_targets,
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const std::deque<offset_t>& new_targets);
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// Assigns labels to targets based on associations previously inferred, using
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// |min_affinity| to reject associations with weak |affinity|. Label 0 is
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// assigned to unassociated targets. Labels for old targets are written to
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// |old_labels| and labels for new targets are written to |new_labels|.
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// Returns the upper bound on assigned labels (>= 1 since 0 is used).
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uint32_t AssignLabels(double min_affinity,
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std::vector<uint32_t>* old_labels,
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std::vector<uint32_t>* new_labels);
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// Returns the affinity score between targets identified by |old_key| and
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// |new_keys|. Affinity > 0 means an association is likely, < 0 means
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// incompatible association, and 0 means neither targets have been associated.
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double AffinityBetween(key_t old_key, key_t new_key) const;
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private:
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struct Association {
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key_t other = 0;
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double affinity = 0.0;
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};
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// Forward and backward associations between old and new targets. For each
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// Association element, if |affinity == 0.0| then no association is defined
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// (and |other| is meaningless|. Otherwise |affinity > 0.0|, and the
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// association between |old_labels[old_key]| and |new_labels[new_key]| is
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// represented by:
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// forward_association_[old_key].other == new_key;
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// backward_association_[new_key].other == old_key;
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// forward_association_[old_key].affinity ==
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// backward_association_[new_key].affinity;
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// The two lists contain the same information, but having both enables quick
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// lookup, given |old_key| or |new_key|.
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std::vector<Association> forward_association_;
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std::vector<Association> backward_association_;
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};
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} // namespace zucchini
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#endif // COMPONENTS_ZUCCHINI_TARGETS_AFFINITY_H_
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