ocelot-base 0.1.2

Shared base utilities for the ocelot project
Documentation 
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
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140

use crate::error::OcelotError;
use crate::shared_string::SharedString;
use std::error::Error as StdError;
use std::panic::Location;

pub type OcelotResult<T> = Result<T, OcelotError>;

pub trait ResultExt<T> {
    #[track_caller]
    fn context(self, context: impl Into<SharedString>) -> OcelotResult<T>;

    #[track_caller]
    fn with_context<C, S>(self, context: C) -> OcelotResult<T>
    where
        C: FnOnce() -> S,
        S: Into<SharedString>;
}

pub trait OptionExt<T> {
    #[track_caller]
    fn context(self, context: impl Into<SharedString>) -> OcelotResult<T>;

    #[track_caller]
    fn with_context<C, S>(self, context: C) -> OcelotResult<T>
    where
        C: FnOnce() -> S,
        S: Into<SharedString>;
}

impl<T, E> ResultExt<T> for Result<T, E>
where
    E: StdError + Send + Sync + 'static,
{
    #[track_caller]
    fn context(self, context: impl Into<SharedString>) -> OcelotResult<T> {
        let caller = Location::caller();
        self.map_err(|error| {
            OcelotError::message_at_location(context.into(), caller)
                .with_std_source_at_location(error, caller)
        })
    }

    #[track_caller]
    fn with_context<C, S>(self, context: C) -> OcelotResult<T>
    where
        C: FnOnce() -> S,
        S: Into<SharedString>,
    {
        let caller = Location::caller();
        self.map_err(|error| {
            OcelotError::message_at_location(context(), caller)
                .with_std_source_at_location(error, caller)
        })
    }
}

impl<T> ResultExt<T> for Result<T, OcelotError> {
    #[track_caller]
    fn context(self, context: impl Into<SharedString>) -> OcelotResult<T> {
        let caller = Location::caller();
        self.map_err(|error| {
            OcelotError::message_at_location(context.into(), caller).with_source(error)
        })
    }

    #[track_caller]
    fn with_context<C, S>(self, context: C) -> OcelotResult<T>
    where
        C: FnOnce() -> S,
        S: Into<SharedString>,
    {
        let caller = Location::caller();
        self.map_err(|error| OcelotError::message_at_location(context(), caller).with_source(error))
    }
}

impl<T> OptionExt<T> for Option<T> {
    #[track_caller]
    fn context(self, context: impl Into<SharedString>) -> OcelotResult<T> {
        let caller = Location::caller();
        self.ok_or_else(|| OcelotError::message_at_location(context.into(), caller))
    }

    #[track_caller]
    fn with_context<C, S>(self, context: C) -> OcelotResult<T>
    where
        C: FnOnce() -> S,
        S: Into<SharedString>,
    {
        let caller = Location::caller();
        self.ok_or_else(|| OcelotError::message_at_location(context(), caller))
    }
}

#[cfg(test)]
mod tests {
    use crate::result::{OptionExt, ResultExt};
    use std::io;

    #[test]
    fn test_with_context_is_lazy_for_ok_results() {
        use std::cell::Cell;

        let context_called = Cell::new(false);
        let result: Result<i32, io::Error> = Ok(123);
        let value = result
            .with_context(|| {
                context_called.set(true);
                "should not be used"
            })
            .unwrap();
        assert_eq!(value, 123);
        assert!(!context_called.get());
    }

    #[test]
    fn test_option_with_context_is_lazy_for_some_results() {
        use std::cell::Cell;

        let context_called = Cell::new(false);
        let value = Some(123)
            .with_context(|| {
                context_called.set(true);
                "should not be used"
            })
            .unwrap();
        assert_eq!(value, 123);
        assert!(!context_called.get());
    }

    #[test]
    fn test_with_context_wraps_existing_error_results() {
        let result: crate::result::OcelotResult<i32> = Err(crate::err!("root cause"));
        let error = result.with_context(|| "outer context").unwrap_err();
        let rendered = error.to_test_string();

        assert!(rendered.contains("outer context"));
        assert!(rendered.contains("root cause"));
    }
}