result.hpp

#pragma once
 
#include <type_traits>
#include <utility>
 
#include "error.hpp"
 
namespace rerun {
    /// A class for representing either a usable value, or an error.
    ///
    /// In essence a simplified version of rust's Result or arrow's arrow::Result, always using
    /// rerun::Status. For simplicity, the wrapped type must be default constructible.
    template <typename T>
    class [[nodiscard]] Result {
        static_assert(
            std::is_default_constructible<T>::value,
            "Result can only wrap default constructible types."
        );
 
      public:
        /// Don't allow uninitialized results.
        Result() = delete;
 
        /// Construct a result from a value, setting error to ok.
        Result(T _value) : value(std::move(_value)), error() {}
 
        /// Construct a result from an error, default constructing the value.
        Result(rerun::Error _error) : value(), error(std::move(_error)) {}
 
        /// Construct a result from an arrow status, default constructing the value.
        Result(const arrow::Status& status) : value(), error(status) {}
 
        /// Construct a result from an arrow status, default constructing the value.
        Result(arrow::Status&& status) : value(), error(std::move(status)) {}
 
        /// Returns true if error is set to rerun::ErrorCode::Ok, implying that a value is
        /// contained, false otherwise.
        bool is_ok() const {
            return error.is_ok();
        }
 
        /// Returns true if error is not set to rerun::ErrorCode::Ok, implying that no value is
        /// contained, false otherwise.
        bool is_err() const {
            return error.is_err();
        }
 
        /// Returns the value if status is ok, throws otherwise.
        ///
        /// If exceptions are disabled, this will exit the application instead.
        /// @see error::value_or_exit
        const T& value_or_throw() const& {
            error.throw_on_failure();
            return value;
        }
 
        /// Returns the value if status is ok, throws otherwise.
        ///
        /// If exceptions are disabled, this will exit the application instead.
        /// @see error::value_or_exit
        T value_or_throw() && {
            error.throw_on_failure();
            // Do an explicit move in order to guarantee that we give up ownership of `value`.
            return std::move(value);
        }
 
        /// Returns the value if status is ok, exits the application otherwise.
        /// @see error::value_or_throw
        const T& value_or_exit() const& {
            error.exit_on_failure();
            return value;
        }
 
        /// Returns the value if status is ok, exits the application otherwise.
        /// @see error::value_or_throw
        T value_or_exit() && {
            error.exit_on_failure();
            // Do an explicit move in order to guarantee that we give up ownership of `value`.
            return std::move(value);
        }
 
      public:
        T value;
        rerun::Error error;
    };
} // namespace rerun