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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_ZUCCHINI_ENCODED_VIEW_H_
#define COMPONENTS_ZUCCHINI_ENCODED_VIEW_H_
#include <stddef.h>
#include <stdint.h>
#include <iterator>
#include <vector>
#include "components/zucchini/image_index.h"
#include "components/zucchini/image_utils.h"
namespace zucchini {
// Zucchini-gen performs semantics-aware matching:
// - Same-typed reference target in "old" and "new" can be associated.
// Associated targets are assigned an identifier called "label" (and for
// unassociated targets, label = 0).
// - EncodedView maps each offset in "old" and "new" images to a "projected
// value", which can be:
// - Raw byte value (0-255) for non-references.
// - Reference "projected value" (> 256) that depends on target {type, label}
// at each reference's location (byte 0).
// - Reference padding value (256) at the body of each reference (bytes 1+).
// - The projected values for "old" and "new" are used to build the equivalence
// map.
constexpr size_t kReferencePaddingProjection = 256;
constexpr size_t kBaseReferenceProjection = 257;
// A Range (providing begin and end iterators) that adapts ImageIndex to make
// image data appear as an Encoded Image, that is encoded data under a higher
// level of abstraction than raw bytes. In particular:
// - First byte of each reference become a projection of its type and label.
// - Subsequent bytes of each reference becomes |kReferencePaddingProjection|.
// - Non-reference raw bytes remain as raw bytes.
class EncodedView {
public:
// RandomAccessIterator whose values are the results of Projection().
class Iterator {
public:
using iterator_category = std::random_access_iterator_tag;
using value_type = size_t;
using difference_type = ptrdiff_t;
using reference = size_t;
using pointer = size_t*;
Iterator(const EncodedView* encoded_view, difference_type pos)
: encoded_view_(encoded_view), pos_(pos) {}
Iterator(const Iterator&) = default;
Iterator& operator=(const Iterator&) = default;
value_type operator*() const {
return encoded_view_->Projection(static_cast<offset_t>(pos_));
}
value_type operator[](difference_type n) const {
return encoded_view_->Projection(static_cast<offset_t>(pos_ + n));
}
Iterator& operator++() {
++pos_;
return *this;
}
Iterator operator++(int) {
Iterator tmp = *this;
++pos_;
return tmp;
}
Iterator& operator--() {
--pos_;
return *this;
}
Iterator operator--(int) {
Iterator tmp = *this;
--pos_;
return tmp;
}
Iterator& operator+=(difference_type n) {
pos_ += n;
return *this;
}
Iterator& operator-=(difference_type n) {
pos_ -= n;
return *this;
}
friend bool operator==(Iterator a, Iterator b) { return a.pos_ == b.pos_; }
friend bool operator!=(Iterator a, Iterator b) { return !(a == b); }
friend bool operator<(Iterator a, Iterator b) { return a.pos_ < b.pos_; }
friend bool operator>(Iterator a, Iterator b) { return b < a; }
friend bool operator<=(Iterator a, Iterator b) { return !(b < a); }
friend bool operator>=(Iterator a, Iterator b) { return !(a < b); }
friend difference_type operator-(Iterator a, Iterator b) {
return a.pos_ - b.pos_;
}
friend Iterator operator+(Iterator it, difference_type n) {
it += n;
return it;
}
friend Iterator operator-(Iterator it, difference_type n) {
it -= n;
return it;
}
private:
const EncodedView* encoded_view_;
difference_type pos_;
};
using value_type = size_t;
using size_type = offset_t;
using difference_type = ptrdiff_t;
using const_iterator = Iterator;
// |image_index| is the annotated image being adapted, and is required to
// remain valid for the lifetime of the object.
explicit EncodedView(const ImageIndex& image_index);
EncodedView(const EncodedView&) = delete;
const EncodedView& operator=(const EncodedView&) = delete;
~EncodedView();
// Projects |location| to a scalar value that describes the content at a
// higher level of abstraction.
value_type Projection(offset_t location) const;
bool IsToken(offset_t location) const {
return image_index_.IsToken(location);
}
// Returns the cardinality of the projection, i.e., the upper bound on
// values returned by Projection().
value_type Cardinality() const;
// Associates |labels| to targets for a given |pool|, replacing previous
// association. Values in |labels| must be smaller than |bound|.
void SetLabels(PoolTag pool, std::vector<uint32_t>&& labels, size_t bound);
const ImageIndex& image_index() const { return image_index_; }
// Range functions.
size_type size() const { return size_type(image_index_.size()); }
const_iterator begin() const {
return const_iterator{this, difference_type(0)};
}
const_iterator end() const {
return const_iterator{this, difference_type(size())};
}
private:
struct PoolInfo {
PoolInfo();
PoolInfo(PoolInfo&&);
~PoolInfo();
// |labels| translates IndirectReference target_key to label.
std::vector<uint32_t> labels;
size_t bound = 0;
};
const ImageIndex& image_index_;
std::vector<PoolInfo> pool_infos_;
};
} // namespace zucchini
#endif // COMPONENTS_ZUCCHINI_ENCODED_VIEW_H_
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