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#include "MultigroupCodec.h"
#include "Merkle.h"
#include <map>
namespace nt::MultigroupCodec {
// A relation with zero tuples reports an empty merkle_root externally.
// The merkle tree's payload type is fixed-width Hash32, so the codec
// maps "" ↔ the all-zero hash. The collision probability with a real
// SHA256 hitting all-zero (2^-256) is treated as unreachable.
static nt::Hash32 encode_payload(const std::string& hex) {
if (hex.empty())
return nt::Hash32{};
return nt::hex_to_bin(hex);
}
static std::string decode_payload(const nt::Hash32& bin) {
static const nt::Hash32 zero{};
if (bin == zero)
return "";
return nt::bin_to_hex(bin);
}
std::string Build(IStorageBackend& store, const std::vector<RelationEntry>& relations) {
std::map<std::string, std::string> canonical;
for (const auto& [name, root_hex] : relations)
canonical[name] = root_hex;
std::string root;
for (const auto& [name, root_hex] : canonical)
root = nt::Merkle<std::string>::Insert(store, root, name, encode_payload(root_hex));
return root;
}
std::vector<RelationEntry> List(IStorageBackend& store, const std::string& root_hex) {
std::vector<RelationEntry> out;
constexpr size_t kPageSize = 1024;
size_t offset = 0;
while (true) {
auto page = nt::Merkle<std::string>::Page(store, root_hex, offset, kPageSize);
if (page.empty())
break;
for (auto& entry : page)
out.emplace_back(std::move(entry.key), decode_payload(entry.payload));
if (page.size() < kPageSize)
break;
offset += page.size();
}
return out;
}
std::string InsertOne(IStorageBackend& store, const std::string& root_hex,
const std::string& relation_name, const std::string& relation_root_hex) {
return nt::Merkle<std::string>::Insert(store, root_hex, relation_name,
encode_payload(relation_root_hex));
}
std::string RemoveOne(IStorageBackend& store, const std::string& root_hex,
const std::string& relation_name) {
return nt::Merkle<std::string>::Remove(store, root_hex, relation_name);
}
std::string Lookup(IStorageBackend& store, const std::string& root_hex,
const std::string& relation_name) {
auto found = nt::Merkle<std::string>::Get(store, root_hex, relation_name);
if (!found)
return "";
return decode_payload(*found);
}
} // namespace nt::MultigroupCodec
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