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== `sqlite/error.hpp`
=== `sqlite_category`
The sqlite_category is a `boost::system::error_category` to be used with sqlite errors.
=== `error_info`
The `error_info` class hold additional information about error conditions stored in an sqlite-allocate string.
Contains an error message describing what happened. Not all error conditions are able to generate this extended information - those that
can't will have an empty error message.
The `error_info` allocates memory from the sqlite pool and holds it.
[source,cpp]
----
struct error_info
{
// Default constructor.
error_info() = default;
// Initialization constructor. Copies the message into a newly create buffer.
error_info(core::string_view msg) noexcept;
// set the message by copy
void set_message(core::string_view msg);
// Reset the buffer. If `c` is not null, its ownership is transferred into the error_info object.
void reset(char * c = nullptr);
// Format a message into a newly allocated buffer.
cstring_ref format(cstring_ref fmt, ...);
// Format a message into the existing buffer.
cstring_ref snformat(cstring_ref fmt, ...);
/// reserve data in the buffer i.e. allocate
void reserve(std::size_t sz);
// Get the allocated memory
std::size_t capacity() const;
// Gets the error message.
cstring_ref message() const noexcept;
// Release the underlying memory. It must be freed using `sqlite_free` later.
char * release();
// Restores the message to its initial state. Does not release memory.
void clear() noexcept;
};
----
=== `error`
The `error` class holds `error_info` and a `code` and can be used with https://www.boost.org/doc/libs/master/libs/system/doc/html/system.html#ref_boostsystemresult_hpp[`boost::system::result`].
[source,cpp]
----
/**
* \brief An error containing both a code & optional message.
* \ingroup reference
* \details Contains an error .
*/
struct error
{
// The code of the error.
int code;
// The additional information of the error
error_info info;
// Create an error with code & message
error(int code, error_info info) ;
error(int code, core::string_view info);
error(system::error_code code, error_info info) // <1>
// Create an error with only a code.
explicit error(int code);
error(system::error_code code);
// Create an empty error;
error() = default;
error(error && ) noexcept = default;
};
// For compatability with system::result;
void throw_exception_from_error( error const & e, boost::source_location const & loc );
template<typename T = void>
using result = system::result<T, error>;
----
<1> If code.category() is not `sqlite_category`, the code will be set to `SQLITE_FAIL`.
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