1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
//! This module defines error types and conversions for issue that can
//! occur while dealing with persisted state machines.
use std::result;
use std::fmt;
use uuid::Uuid;
use std::error::Error as StdError;
// 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 fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use ErrorKind::*;
let msg = match &self.kind {
Serialization(err) =>
format!("JSON serialization error: {}", err),
Database(err) =>
format!("PostgreSQL error: {}", err),
FSMNotFound(id) =>
format!("FSM with ID {} not found", id),
ActionNotFound(id) =>
format!("Action with ID {} not found", id),
};
match &self.context {
None => write!(f, "{}", msg),
Some(ctx) => write!(f, "{}: {}", ctx, msg),
}
}
}
impl StdError for Error {}
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: fmt::Display>(self, ctx: C) -> Result<T>;
}
impl <T, E: Into<Error>> ResultExt<T> for result::Result<T, E> {
fn context<C: fmt::Display>(self, ctx: C) -> Result<T> {
self.map_err(|err| Error {
context: Some(format!("{}", ctx)),
.. err.into()
})
}
}
|
