9059514335
This warning prevents using std::move() where it can hurt - on an unnamed temporary or a named automatic variable being returned from a function. In both cases the value could be constructed directly in its final destination, but std::move() prevents it. Fix the handful of cases (all trivial), and enable the warning. Closes #8992
275 lines
8.6 KiB
C++
275 lines
8.6 KiB
C++
/*
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* Copyright (C) 2017-present ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "types.hh"
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#include "types/collection.hh"
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#include "bytes.hh"
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#include <optional>
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#include <variant>
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#include <seastar/util/variant_utils.hh>
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#include "utils/fragmented_temporary_buffer.hh"
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namespace cql3 {
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struct null_value {
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};
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struct unset_value {
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};
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class raw_value;
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/// \brief View to a raw CQL protocol value.
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///
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/// \see raw_value
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class raw_value_view {
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std::variant<fragmented_temporary_buffer::view, managed_bytes_view, null_value, unset_value> _data;
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// Temporary storage is only useful if a raw_value_view needs to be instantiated
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// with a value which lifetime is bounded only to the view itself.
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// This hack is introduced in order to avoid storing temporary storage
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// in an external container, which may cause memory leaking problems.
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// This pointer is disengaged for regular raw_value_view instances.
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// Data is stored in a shared pointer for two reasons:
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// - pointers are cheap to copy
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// - it makes the view keep its semantics - it's safe to copy a view multiple times
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// and all copies still refer to the same underlying data.
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lw_shared_ptr<managed_bytes> _temporary_storage = nullptr;
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raw_value_view(null_value data)
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: _data{std::move(data)}
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{}
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raw_value_view(unset_value data)
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: _data{std::move(data)}
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{}
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raw_value_view(fragmented_temporary_buffer::view data)
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: _data{data}
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{}
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raw_value_view(managed_bytes_view data)
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: _data{data}
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{}
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// This constructor is only used by make_temporary() and it acquires ownership
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// of the given buffer. The view created that way refers to its own temporary storage.
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explicit raw_value_view(managed_bytes&& temporary_storage);
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public:
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static raw_value_view make_null() {
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return raw_value_view{null_value{}};
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}
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static raw_value_view make_unset_value() {
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return raw_value_view{unset_value{}};
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}
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static raw_value_view make_value(fragmented_temporary_buffer::view view) {
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return raw_value_view{view};
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}
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static raw_value_view make_value(managed_bytes_view view) {
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return raw_value_view{view};
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}
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static raw_value_view make_value(bytes_view view) {
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return raw_value_view{managed_bytes_view(view)};
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}
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static raw_value_view make_temporary(raw_value&& value);
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bool is_null() const {
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return std::holds_alternative<null_value>(_data);
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}
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bool is_unset_value() const {
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return std::holds_alternative<unset_value>(_data);
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}
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bool is_value() const {
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return _data.index() <= 1;
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}
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explicit operator bool() const {
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return is_value();
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}
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template <typename Func>
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requires std::invocable<Func, const managed_bytes_view&> && std::invocable<Func, const fragmented_temporary_buffer::view&>
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decltype(auto) with_value(Func f) const {
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switch (_data.index()) {
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case 0: return f(std::get<fragmented_temporary_buffer::view>(_data));
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default: return f(std::get<managed_bytes_view>(_data));
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}
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}
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template <typename Func>
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requires std::invocable<Func, bytes_view>
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decltype(auto) with_linearized(Func f) const {
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return with_value([&] (const FragmentedView auto& v) {
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return ::with_linearized(v, std::forward<Func>(f));
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});
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}
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size_t size_bytes() const {
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return with_value([&] (const FragmentedView auto& v) {
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return v.size_bytes();
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});
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}
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template <typename ValueType>
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ValueType deserialize(const abstract_type& t) const {
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return value_cast<ValueType>(with_value([&] (const FragmentedView auto& v) { return t.deserialize(v); }));
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}
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template <typename ValueType>
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ValueType deserialize(const collection_type_impl& t, cql_serialization_format sf) const {
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return value_cast<ValueType>(with_value([&] (const FragmentedView auto& v) { return t.deserialize(v, sf); }));
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}
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void validate(const abstract_type& t, cql_serialization_format sf) const {
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return with_value([&] (const FragmentedView auto& v) { return t.validate(v, sf); });
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}
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template <typename ValueType>
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ValueType validate_and_deserialize(const collection_type_impl& t, cql_serialization_format sf) const {
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return with_value([&] (const FragmentedView auto& v) {
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t.validate(v, sf);
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return value_cast<ValueType>(t.deserialize(v, sf));
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});
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}
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template <typename ValueType>
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ValueType validate_and_deserialize(const abstract_type& t, cql_serialization_format sf) const {
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return with_value([&] (const FragmentedView auto& v) {
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t.validate(v, sf);
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return value_cast<ValueType>(t.deserialize(v));
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});
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}
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friend managed_bytes_opt to_managed_bytes_opt(const cql3::raw_value_view& view) {
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if (view.is_value()) {
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return view.with_value([] (const FragmentedView auto& v) { return managed_bytes(v); });
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}
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return managed_bytes_opt();
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}
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friend managed_bytes_opt to_managed_bytes_opt(cql3::raw_value_view&& view) {
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if (view._temporary_storage) {
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return std::move(*view._temporary_storage);
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}
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return to_managed_bytes_opt(view);
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}
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friend std::ostream& operator<<(std::ostream& os, const raw_value_view& value);
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friend class raw_value;
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};
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/// \brief Raw CQL protocol value.
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///
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/// The `raw_value` type represents an uninterpreted value from the CQL wire
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/// protocol. A raw value can hold either a null value, an unset value, or a byte
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/// blob that represents the value.
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class raw_value {
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std::variant<bytes, managed_bytes, null_value, unset_value> _data;
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raw_value(null_value&& data)
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: _data{std::move(data)}
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{}
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raw_value(unset_value&& data)
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: _data{std::move(data)}
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{}
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raw_value(bytes&& data)
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: _data{std::move(data)}
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{}
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raw_value(const bytes& data)
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: _data{data}
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{}
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raw_value(managed_bytes&& data)
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: _data{std::move(data)}
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{}
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raw_value(const managed_bytes& data)
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: _data{data}
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{}
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public:
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static raw_value make_null() {
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return raw_value{null_value{}};
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}
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static raw_value make_unset_value() {
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return raw_value{unset_value{}};
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}
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static raw_value make_value(const raw_value_view& view);
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static raw_value make_value(managed_bytes&& mb) {
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return raw_value{std::move(mb)};
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}
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static raw_value make_value(const managed_bytes& mb) {
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return raw_value{mb};
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}
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static raw_value make_value(const managed_bytes_opt& mbo) {
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if (mbo) {
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return make_value(*mbo);
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}
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return make_null();
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}
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static raw_value make_value(bytes&& bytes) {
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return raw_value{std::move(bytes)};
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}
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static raw_value make_value(const bytes& bytes) {
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return raw_value{bytes};
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}
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static raw_value make_value(const bytes_opt& bytes) {
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if (bytes) {
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return make_value(*bytes);
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}
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return make_null();
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}
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bool is_null() const {
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return std::holds_alternative<null_value>(_data);
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}
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bool is_unset_value() const {
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return std::holds_alternative<unset_value>(_data);
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}
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bool is_value() const {
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return _data.index() <= 1;
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}
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explicit operator bool() const {
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return is_value();
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}
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bytes to_bytes() && {
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switch (_data.index()) {
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case 0: return std::move(std::get<bytes>(_data));
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default: return ::to_bytes(std::get<managed_bytes>(_data));
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}
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}
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raw_value_view to_view() const;
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friend class raw_value_view;
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};
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}
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inline bytes to_bytes(const cql3::raw_value_view& view)
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{
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return view.with_value([] (const FragmentedView auto& v) {
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return linearized(v);
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});
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}
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inline bytes_opt to_bytes_opt(const cql3::raw_value_view& view) {
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if (view.is_value()) {
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return to_bytes(view);
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}
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return bytes_opt();
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}
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inline bytes_opt to_bytes_opt(const cql3::raw_value& value) {
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return to_bytes_opt(value.to_view());
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}
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