no_debug 3.0.0

Helper types to omit debug info for select values.
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
141

#![doc = include_str!("../README.md")]

use std::fmt::Debug;
use std::ops::{Deref, DerefMut};

/// [Msg] is a trait for defining custom formatters for [NoDebug] values.
pub trait Msg<T> {
    /// Prints a custom message to the given formatter without necessarily revealing the values
    /// information.
    ///
    /// Takes a reference to the value being debugged to allow some introspection.
    fn fmt(value: &T, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error>;
}

#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone)]
pub struct WithTypeInfo;

impl<T> Msg<T> for WithTypeInfo {
    fn fmt(_value: &T, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
        write!(f, "<no debug: {}>", std::any::type_name::<T>())
    }
}

#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone)]
pub struct Ellipses;

impl<T> Msg<T> for Ellipses {
    fn fmt(_value: &T, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
        write!(f, "...")
    }
}

/// Wraps a type `T` and provides a [Debug] impl that does not rely on `T` being [Debug].
#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone)]
pub struct NoDebug<T, M: Msg<T> = WithTypeInfo>(T, std::marker::PhantomData<M>);

impl<T, M: Msg<T>> NoDebug<T, M> {
    pub fn take(self) -> T {
        self.0
    }
}

impl<T> NoDebug<T, WithTypeInfo> {
    pub fn new(value: T) -> Self {
        value.into()
    }
}

impl<T, M: Msg<T>> From<T> for NoDebug<T, M> {
    fn from(value: T) -> Self {
        Self(value, std::marker::PhantomData::default())
    }
}

impl<T, M: Msg<T>> Debug for NoDebug<T, M> {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
        M::fmt(&self.0, f)
    }
}

impl<T, M: Msg<T>> Deref for NoDebug<T, M> {
    type Target = T;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl<T, M: Msg<T>> DerefMut for NoDebug<T, M> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn cannot_debug_nodebug() {
        let value = NoDebug::new(3);
        assert_eq!(format!("{:?}", value), "<no debug: i32>")
    }

    #[test]
    fn cannot_debug_nodebug_via_into() {
        let value: NoDebug<i32> = 3.into();
        assert_eq!(format!("{:?}", value), "<no debug: i32>")
    }

    #[test]
    fn can_show_type_info() {
        let value: NoDebug<i32, WithTypeInfo> = 3.into();
        assert_eq!(format!("{:?}", value), "<no debug: i32>")
    }

    #[test]
    fn can_show_custom_message() {
        let value: NoDebug<i32, Ellipses> = 3.into();
        assert_eq!(format!("{:?}", value), "...")
    }

    #[test]
    fn dereferences_nodebug() {
        let value = NoDebug::new(3);
        assert_eq!(format!("{:?}", value), "<no debug: i32>");
        assert_eq!(format!("{:?}", *value), "3");
    }

    #[test]
    fn mut_dereferences_nodebug() {
        let mut value = NoDebug::new(3);
        *value = 4;
        assert_eq!(format!("{:?}", value), "<no debug: i32>");
        assert_eq!(format!("{:?}", *value), "4");
    }

    #[test]
    fn take_gets_value_from_nodebug() {
        let value = NoDebug::new(3);
        assert_eq!(value.take(), 3);
    }

    #[test]
    fn has_eq_with_inner() {
        let value = NoDebug::new(3);
        assert_eq!(*value, 3);
    }

    #[test]
    fn has_eq_with_raw_value_into_no_debug() {
        let value = NoDebug::new(3);
        assert_eq!(value, 3.into());
    }

    #[test]
    fn has_eq_with_another_no_debug() {
        let value = NoDebug::new(3);
        let other = NoDebug::new(3);
        assert_eq!(value, other);
    }
}