content_type.hpp

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#pragma once
 
/// @file userver/http/content_type.hpp
/// @brief @copybrief http::ContentType
 
#include <iosfwd>
#include <stdexcept>
#include <string>
#include <string_view>
 
#include <fmt/core.h>
 
#include <userver/logging/fwd.hpp>
#include <userver/utils/str_icase.hpp>
 
USERVER_NAMESPACE_BEGIN
 
/// @brief HTTP primitives: status codes, URLs, headers, and parsing helpers.
namespace http {
 
/// @brief Content-Type parsing error
class MalformedContentType : public std::runtime_error {
public:
    using std::runtime_error::runtime_error;
 
    MalformedContentType(const MalformedContentType&) = default;
    MalformedContentType(MalformedContentType&&) = default;
    MalformedContentType& operator=(const MalformedContentType&) = default;
    MalformedContentType& operator=(MalformedContentType&&) = default;
 
    ~MalformedContentType() override;
};
 
/// @ingroup userver_universal userver_containers
///
/// @brief Content-Type representation
class ContentType {
public:
    /// Constructor from a single content-type/media-range header value
    /// as per RFC7231.
    /// @{
    /* implicit */ ContentType(std::string_view);
    /* implicit */ ContentType(const std::string&);
    /* implicit */ ContentType(const char*);
    /// @}
 
    /// Media type (application/json).
    std::string MediaType() const;
 
    /// "type" token of media type (application).
    const std::string& TypeToken() const;
 
    /// "subtype" token of media type (json).
    const std::string& SubtypeToken() const;
 
    /// Whether the "charset" option was explicitly specified.
    bool HasExplicitCharset() const;
 
    /// Charset (utf-8).
    const std::string& Charset() const;
 
    /// Value of "q" parameter in range 0--1000.
    int Quality() const;
 
    /// Whether this media range accepts specified content type.
    /// Differs from equality comparison in wildcard support.
    bool DoesAccept(const ContentType&) const;
 
    /// Value of "boundary" parameter.
    const std::string& Boundary() const;
 
    /// Builds a string representation of content-type/media-range
    std::string ToString() const;
 
private:
    friend logging::LogHelper& operator<<(logging::LogHelper&, const ContentType&);
    friend std::ostream& operator<<(std::ostream&, const ContentType&);
 
    void BuildStringRepresentation();
 
    std::string type_;
    std::string subtype_;
    std::string charset_;
    std::string boundary_;
    int quality_;
 
    std::string string_representation_;
};
 
bool operator==(const ContentType&, const ContentType&);
 
/// Weak ordering for Accept media-ranges checking.
/// Positions less specific types before more specific, so that the most
/// specific type can be matched first.
bool operator<(const ContentType&, const ContentType&);
 
class ContentTypeHash {
public:
    size_t operator()(const ContentType&) const;
 
private:
    utils::StrIcaseHash str_hasher_;
};
 
/// @brief MIME content type helpers.
namespace content_type {
 
extern const ContentType kApplicationOctetStream;
extern const ContentType kApplicationJson;
extern const ContentType kTextPlain;
 
}  // namespace content_type
}  // namespace http
 
USERVER_NAMESPACE_END
 
template <>
struct fmt::formatter<USERVER_NAMESPACE::http::ContentType> {
    constexpr static auto parse(format_parse_context& ctx) { return ctx.begin(); }
 
    template <typename FormatContext>
    auto format(const USERVER_NAMESPACE::http::ContentType& value, FormatContext& ctx) const -> decltype(ctx.out()) {
        return fmt::format_to(ctx.out(), "{}", value.ToString());
    }
};