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// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
#pragma once
#include <algorithm>
#include <string>
#include <vector>
#include "db/dbformat.h"
#include "rocksdb/iterator.h"
#include "rocksdb/slice.h"
#include "table/internal_iterator.h"
namespace ROCKSDB_NAMESPACE {
// Iterator over a vector of keys/values
class VectorIterator : public InternalIterator {
public:
VectorIterator(std::vector<std::string> keys, std::vector<std::string> values,
const InternalKeyComparator* icmp)
: keys_(std::move(keys)),
values_(std::move(values)),
indexed_cmp_(icmp, &keys_),
current_(0) {
assert(keys_.size() == values_.size());
indices_.reserve(keys_.size());
for (size_t i = 0; i < keys_.size(); i++) {
indices_.push_back(i);
}
std::sort(indices_.begin(), indices_.end(), indexed_cmp_);
}
virtual bool Valid() const override {
return !indices_.empty() && current_ < indices_.size();
}
virtual void SeekToFirst() override { current_ = 0; }
virtual void SeekToLast() override { current_ = indices_.size() - 1; }
virtual void Seek(const Slice& target) override {
current_ = std::lower_bound(indices_.begin(), indices_.end(), target,
indexed_cmp_) -
indices_.begin();
}
virtual void SeekForPrev(const Slice& target) override {
current_ = std::lower_bound(indices_.begin(), indices_.end(), target,
indexed_cmp_) -
indices_.begin();
if (!Valid()) {
SeekToLast();
} else {
Prev();
}
}
virtual void Next() override { current_++; }
virtual void Prev() override { current_--; }
virtual Slice key() const override {
return Slice(keys_[indices_[current_]]);
}
virtual Slice value() const override {
return Slice(values_[indices_[current_]]);
}
virtual Status status() const override { return Status::OK(); }
virtual bool IsKeyPinned() const override { return true; }
virtual bool IsValuePinned() const override { return true; }
private:
struct IndexedKeyComparator {
IndexedKeyComparator(const InternalKeyComparator* c,
const std::vector<std::string>* ks)
: cmp(c), keys(ks) {}
bool operator()(size_t a, size_t b) const {
return cmp->Compare((*keys)[a], (*keys)[b]) < 0;
}
bool operator()(size_t a, const Slice& b) const {
return cmp->Compare((*keys)[a], b) < 0;
}
bool operator()(const Slice& a, size_t b) const {
return cmp->Compare(a, (*keys)[b]) < 0;
}
const InternalKeyComparator* cmp;
const std::vector<std::string>* keys;
};
std::vector<std::string> keys_;
std::vector<std::string> values_;
IndexedKeyComparator indexed_cmp_;
std::vector<size_t> indices_;
size_t current_;
};
} // namespace ROCKSDB_NAMESPACE
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