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|
//! This module defines error types and conversions for issue that can
//! occur while dealing with persisted state machines.
use std::result;
use std::fmt::Display;
use uuid::Uuid;
// errors to chain:
use serde_json::Error as JsonError;
use postgres::Error as PgError;
pub type Result<T> = result::Result<T, Error>;
#[derive(Debug)]
pub struct Error {
pub kind: ErrorKind,
pub context: Option<String>,
}
#[derive(Debug)]
pub enum ErrorKind {
/// Errors occuring during JSON serialization of FSM types.
Serialization(String),
/// Errors occuring during communication with the database.
Database(String),
/// State machine could not be found.
FSMNotFound(Uuid),
/// Action could not be found.
ActionNotFound(Uuid),
}
impl <E: Into<ErrorKind>> From<E> for Error {
fn from(err: E) -> Error {
Error {
kind: err.into(),
context: None,
}
}
}
impl From<JsonError> for ErrorKind {
fn from(err: JsonError) -> ErrorKind {
ErrorKind::Serialization(err.to_string())
}
}
impl From<PgError> for ErrorKind {
fn from(err: PgError) -> ErrorKind {
ErrorKind::Database(err.to_string())
}
}
/// Helper trait that makes it possible to supply contextual
/// information with an error.
pub trait ResultExt<T> {
fn context<C: Display>(self, ctx: C) -> Result<T>;
}
impl <T, E: Into<Error>> ResultExt<T> for result::Result<T, E> {
fn context<C: Display>(self, ctx: C) -> Result<T> {
self.map_err(|err| Error {
context: Some(format!("{}", ctx)),
.. err.into()
})
}
}
|
