error.hpp

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#pragma once
 
 
#include <cstdint>
#include <expected>
#include <stdexcept>
#include <string>
#include <string_view>
#include <utility>
 
namespace prom {
 
enum class ErrorCode : std::uint8_t {
    InvalidMetricName,   
    InvalidLabelName,    
    EmptyHelp,           
    InvalidBuckets,      
    InvalidQuantiles,    
    EmptyStateSet,       
    RegistrationFailed,  
};
 
[[nodiscard]] constexpr std::string_view to_string(const ErrorCode code) noexcept {
    switch (code) {
    case ErrorCode::InvalidMetricName:
        return "invalid metric name";
    case ErrorCode::InvalidLabelName:
        return "invalid label name";
    case ErrorCode::EmptyHelp:
        return "empty help text";
    case ErrorCode::InvalidBuckets:
        return "invalid histogram buckets";
    case ErrorCode::InvalidQuantiles:
        return "invalid summary quantiles";
    case ErrorCode::EmptyStateSet:
        return "empty state set";
    case ErrorCode::RegistrationFailed:
        return "metric registration failed";
    }
    return "unknown error";
}
 
struct Error {
    ErrorCode code;       
    std::string message;  
 
    bool operator==(const Error&) const = default;
};
 
template <class T>
using expected = std::expected<T, Error>;
 
class Exception : public std::runtime_error {
public:
    explicit Exception(Error error)
        : std::runtime_error(std::string(to_string(error.code)) + ": " + error.message),
          error_(std::move(error)) {}
 
    [[nodiscard]] const Error& error() const noexcept {
        return error_;
    }
 
private:
    Error error_;
};
 
}  // namespace prom