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use std::fmt; use std::sync::Arc; use failure; /// Error type returned by `rlua` methods. #[derive(Debug, Clone)] pub enum Error { /// Syntax error while parsing Lua source code. SyntaxError { /// The error message as returned by Lua. message: String, /// `true` if the error can likely be fixed by appending more input to the source code. /// /// This is useful for implementing REPLs as they can query the user for more input if this /// is set. incomplete_input: bool, }, /// Lua runtime error, aka `LUA_ERRRUN`. /// /// The Lua VM returns this error when a builtin operation is performed on incompatible types. /// Among other things, this includes invoking operators on wrong types (such as calling or /// indexing a `nil` value). RuntimeError(String), /// Lua garbage collector error, aka `LUA_ERRGCMM`. /// /// The Lua VM returns this error when there is an error running a `__gc` metamethod. GarbageCollectorError(String), /// A mutable callback has triggered Lua code that has called the same mutable callback again. /// /// This is an error because a mutable callback can only be borrowed mutably once. RecursiveMutCallback, /// Either a callback or a userdata method has been called, but the callback or userdata has /// been destructed. /// /// This can happen either due to to being destructed in a previous __gc, or due to being /// destructed from exiting a `Lua::scope` call. CallbackDestructed, /// Not enough stack space to place arguments to Lua functions or return values from callbacks. /// /// Due to the way `rlua` works, it should not be directly possible to run out of stack space /// during normal use. The only way that this error can be triggered is if a `Function` is /// called with a huge number of arguments, or a rust callback returns a huge number of return /// values. StackError, /// Too many arguments to `Function::bind` BindError, /// A Rust value could not be converted to a Lua value. ToLuaConversionError { /// Name of the Rust type that could not be converted. from: &'static str, /// Name of the Lua type that could not be created. to: &'static str, /// A message indicating why the conversion failed in more detail. message: Option<String>, }, /// A Lua value could not be converted to the expected Rust type. FromLuaConversionError { /// Name of the Lua type that could not be converted. from: &'static str, /// Name of the Rust type that could not be created. to: &'static str, /// A string containing more detailed error information. message: Option<String>, }, /// [`Thread::resume`] was called on an inactive coroutine. /// /// A coroutine is inactive if its main function has returned or if an error has occured inside /// the coroutine. /// /// [`Thread::status`] can be used to check if the coroutine can be resumed without causing this /// error. /// /// [`Thread::resume`]: struct.Thread.html#method.resume /// [`Thread::status`]: struct.Thread.html#method.status CoroutineInactive, /// An [`AnyUserData`] is not the expected type in a borrow. /// /// This error can only happen when manually using [`AnyUserData`], or when implementing /// metamethods for binary operators. Refer to the documentation of [`UserDataMethods`] for /// details. /// /// [`AnyUserData`]: struct.AnyUserData.html /// [`UserDataMethods`]: struct.UserDataMethods.html UserDataTypeMismatch, /// An [`AnyUserData`] immutable borrow failed because it is already borrowed mutably. /// /// This error can occur when a method on a [`UserData`] type calls back into Lua, which then /// tries to call a method on the same [`UserData`] type. Consider restructuring your API to /// prevent these errors. /// /// [`AnyUserData`]: struct.AnyUserData.html /// [`UserData`]: trait.UserData.html UserDataBorrowError, /// An [`AnyUserData`] mutable borrow failed because it is already borrowed. /// /// This error can occur when a method on a [`UserData`] type calls back into Lua, which then /// tries to call a method on the same [`UserData`] type. Consider restructuring your API to /// prevent these errors. /// /// [`AnyUserData`]: struct.AnyUserData.html /// [`UserData`]: trait.UserData.html UserDataBorrowMutError, /// A `RegistryKey` produced from a different Lua state was used. MismatchedRegistryKey, /// A Rust callback returned `Err`, raising the contained `Error` as a Lua error. CallbackError { /// Lua call stack backtrace. traceback: String, /// Original error returned by the Rust code. cause: Arc<Error>, }, /// A custom error. /// /// This can be used for returning user-defined errors from callbacks. /// /// Returning `Err(ExternalError(...))` from a Rust callback will raise the error as a Lua /// error. The Rust code that originally invoked the Lua code then receives a `CallbackError`, /// from which the original error (and a stack traceback) can be recovered. ExternalError(Arc<failure::Error>), } /// A specialized `Result` type used by `rlua`'s API. pub type Result<T> = ::std::result::Result<T, Error>; impl fmt::Display for Error { fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { match *self { Error::SyntaxError { ref message, .. } => write!(fmt, "syntax error: {}", message), Error::RuntimeError(ref msg) => write!(fmt, "runtime error: {}", msg), Error::GarbageCollectorError(ref msg) => { write!(fmt, "garbage collector error: {}", msg) } Error::RecursiveMutCallback => write!(fmt, "mutable callback called recursively"), Error::CallbackDestructed => write!( fmt, "a destructed callback or destructed userdata method was called" ), Error::StackError => write!( fmt, "out of Lua stack, too many arguments to a Lua function or too many return values from a callback" ), Error::BindError => write!( fmt, "too many arguments to Function::bind" ), Error::ToLuaConversionError { from, to, ref message, } => { write!(fmt, "error converting {} to Lua {}", from, to)?; match *message { None => Ok(()), Some(ref message) => write!(fmt, " ({})", message), } } Error::FromLuaConversionError { from, to, ref message, } => { write!(fmt, "error converting Lua {} to {}", from, to)?; match *message { None => Ok(()), Some(ref message) => write!(fmt, " ({})", message), } } Error::CoroutineInactive => write!(fmt, "cannot resume inactive coroutine"), Error::UserDataTypeMismatch => write!(fmt, "userdata is not expected type"), Error::UserDataBorrowError => write!(fmt, "userdata already mutably borrowed"), Error::UserDataBorrowMutError => write!(fmt, "userdata already borrowed"), Error::MismatchedRegistryKey => { write!(fmt, "RegistryKey used from different Lua state") } Error::CallbackError { ref traceback, .. } => { write!(fmt, "callback error: {}", traceback) } Error::ExternalError(ref err) => err.fmt(fmt), } } } impl failure::Fail for Error { fn cause(&self) -> Option<&failure::Fail> { match *self { Error::CallbackError { ref cause, .. } => Some(cause.as_ref()), Error::ExternalError(ref err) => err.as_fail().cause(), _ => None, } } fn backtrace(&self) -> Option<&failure::Backtrace> { match *self { Error::ExternalError(ref err) => Some(err.backtrace()), _ => None, } } } impl Error { pub fn external<T: Into<failure::Error>>(err: T) -> Error { Error::ExternalError(Arc::new(err.into())) } } pub trait ExternalError { fn to_lua_err(self) -> Error; } impl<E> ExternalError for E where E: Into<failure::Error>, { fn to_lua_err(self) -> Error { Error::external(self) } } pub trait ExternalResult<T> { fn to_lua_err(self) -> Result<T>; } impl<T, E> ExternalResult<T> for ::std::result::Result<T, E> where E: ExternalError, { fn to_lua_err(self) -> Result<T> { self.map_err(|e| e.to_lua_err()) } }