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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <vespa/vespalib/stllike/allocator.h>
#include <cstdint>
#include <vector>
namespace vespalib {
class SharedStringRepo;
/**
* A typed integer value representing the identity of a string stored
* in the global SharedStringRepo. This class is a simple wrapper with
* no lifetime management of the mapping between string value and
* string id. For a string_id to be valid, it needs to be owned by at
* least one SharedStringRepo::Handle or SharedStringRepo::Handles
* object. This is similar to how std::enable_shared_from_this works;
* the string_id acts like a reference to a mapping from a string to a
* numerical value (without ownership) and Handle/Handles act like
* shared pointers to the same mapping (with shared ownership).
**/
class string_id {
friend class ::vespalib::SharedStringRepo;
private:
uint32_t _id;
explicit constexpr string_id(uint32_t value_in) noexcept : _id(value_in) {}
public:
constexpr string_id() noexcept : _id(0) {}
constexpr string_id(const string_id &) noexcept = default;
constexpr string_id(string_id &&) noexcept = default;
constexpr string_id &operator=(const string_id &) noexcept = default;
constexpr string_id &operator=(string_id &&) noexcept = default;
constexpr uint32_t hash() const noexcept { return _id; }
constexpr uint32_t value() const noexcept { return _id; }
// NB: not lexical sorting order, but can be used in maps
constexpr bool operator<(const string_id &rhs) const noexcept { return (_id < rhs._id); }
constexpr bool operator==(const string_id &rhs) const noexcept { return (_id == rhs._id); }
constexpr bool operator!=(const string_id &rhs) const noexcept { return (_id != rhs._id); }
};
using StringIdVector = std::vector<string_id, vespalib::allocator_large<string_id>>;
}
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