schema.hpp

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#pragma once
 
/// @file userver/yaml_config/schema.hpp
/// @brief @copybrief yaml_config::Schema
 
#include <memory>
#include <optional>
#include <string>
#include <string_view>
#include <unordered_map>
#include <unordered_set>
#include <variant>
#include <vector>
 
#include <userver/formats/yaml_fwd.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace yaml_config {
 
struct Schema;
 
enum class FieldType {
    kBool,
    kInteger,
    kNumber,
    kString,
    kArray,
    kObject,
};
 
std::string ToString(FieldType type);
 
class SchemaPtr final {
public:
    explicit SchemaPtr(Schema&& schema);
 
    SchemaPtr(SchemaPtr&&) noexcept = default;
    SchemaPtr& operator=(SchemaPtr&&) noexcept = default;
    SchemaPtr(const SchemaPtr&);
    SchemaPtr& operator=(const SchemaPtr&);
 
    const Schema& operator*() const;
    Schema& operator*();
    const Schema* operator->() const { return &**this; }
    Schema* operator->() { return &**this; }
 
    bool operator==(const SchemaPtr&) const;
 
private:
    std::unique_ptr<Schema> schema_;
};
 
formats::yaml::Value Serialize(const SchemaPtr& schema, formats::serialize::To<formats::yaml::Value>);
 
/// Helper class for Schema that hides `path` from operator== in Schema.
/// `path` is ignored, because it serves a purely diagnostic purpose.
struct PathSupplementary {
    bool operator==(const PathSupplementary&) const noexcept;
 
    std::string path;
};
 
/// @ingroup userver_universal
///
/// @brief JSON Schema-like type definition
///
/// @see https://json-schema.org/specification
/// @see @ref static-configs-validation "Static configs validation"
struct Schema final : public PathSupplementary {
    void UpdateDescription(std::string new_description);
 
    static Schema EmptyObject();
 
    bool operator==(const Schema&) const noexcept;
 
    FieldType type{};
    std::string description;
    std::optional<std::string> default_description;
    std::optional<std::variant<bool, SchemaPtr>> additional_properties;
    std::optional<std::unordered_map<std::string, SchemaPtr>> properties;
    std::optional<SchemaPtr> items;
    std::optional<std::unordered_set<std::string>> enum_values;
    std::optional<double> minimum;
    std::optional<double> maximum;
    std::optional<std::size_t> min_items;
    std::optional<std::size_t> max_items;
    std::optional<std::unordered_set<std::string>> required;
};
 
Schema Parse(const formats::yaml::Value& schema, formats::parse::To<Schema>);
 
formats::yaml::Value Serialize(const Schema& schema, formats::serialize::To<formats::yaml::Value>);
 
namespace impl {
 
Schema SchemaFromString(const std::string& yaml_string);
Schema SchemaFromResource(std::string_view resource_name);
 
}  // namespace impl
 
}  // namespace yaml_config
 
USERVER_NAMESPACE_END