try-drop 0.2.0

Batteries included error handling mechanisms for drops which can fail
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
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166

pub(crate) mod imports {}

use crate::handlers::common::Handler;
use crate::handlers::UninitializedError;
use parking_lot::{
    MappedRwLockReadGuard, MappedRwLockWriteGuard, RwLock, RwLockReadGuard, RwLockWriteGuard,
};
use std::marker::PhantomData;

pub trait GlobalDefinition: Handler {
    const UNINITIALIZED_ERROR: &'static str;
    type Global: 'static;

    fn global() -> &'static RwLock<Option<Self::Global>>;
}

pub trait DefaultGlobalDefinition: GlobalDefinition {
    fn default() -> Self::Global;
}

pub struct Global<T: GlobalDefinition>(PhantomData<T>);

impl<T: GlobalDefinition> Global<T> {
    pub fn install_dyn(strategy: T::Global) {
        T::global().write().replace(strategy);
    }

    pub fn install(strategy: impl Into<T::Global>) {
        Self::install_dyn(strategy.into())
    }

    pub fn try_read() -> Result<MappedRwLockReadGuard<'static, T::Global>, UninitializedError> {
        let global = T::global().read();

        if global.is_some() {
            Ok(RwLockReadGuard::map(global, |global| {
                global.as_ref().unwrap()
            }))
        } else {
            Err(UninitializedError(()))
        }
    }

    pub fn read() -> MappedRwLockReadGuard<'static, T::Global> {
        Self::try_read().expect(T::UNINITIALIZED_ERROR)
    }

    pub fn try_write() -> Result<MappedRwLockWriteGuard<'static, T::Global>, UninitializedError> {
        let global = T::global().write();

        if global.is_some() {
            Ok(RwLockWriteGuard::map(global, |global| {
                global.as_mut().unwrap()
            }))
        } else {
            Err(UninitializedError(()))
        }
    }

    pub fn write() -> MappedRwLockWriteGuard<'static, T::Global> {
        Self::try_write().expect(T::UNINITIALIZED_ERROR)
    }

    pub fn uninstall() {
        *T::global().write() = None
    }
}

impl<T: DefaultGlobalDefinition> Global<T> {
    pub fn read_or_default() -> MappedRwLockReadGuard<'static, T::Global> {
        drop(Self::write_or_default());
        Self::read()
    }

    pub fn write_or_default() -> MappedRwLockWriteGuard<'static, T::Global> {
        RwLockWriteGuard::map(T::global().write(), |drop_strategy| {
            drop_strategy.get_or_insert_with(T::default)
        })
    }
}

macro_rules! global_methods {
    (
        Global = $global:ident;
        GenericStrategy = $generic_strategy:ident;
        DynStrategy = $dyn_strategy:ident;
        feature = $feature:literal;

        $(#[$($install_dyn_tt:tt)*])*
        install_dyn;

        $(#[$($install_tt:tt)*])*
        install;

        $(#[$($try_read_tt:tt)*])*
        try_read;

        $(#[$($read_tt:tt)*])*
        read;

        $(#[$($try_write_tt:tt)*])*
        try_write;

        $(#[$($write_tt:tt)*])*
        write;

        $(#[$($uninstall_tt:tt)*])*
        uninstall;

        $(#[$($read_or_default_tt:tt)*])*
        read_or_default;

        $(#[$($write_or_default_tt:tt)*])*
        write_or_default;
    ) => {
        #[allow(unused_imports)]
        use $crate::handlers::common::global::imports::*;

        $(#[$($install_dyn_tt)*])*
        pub fn install_dyn(strategy: $dyn_strategy) {
            $global::install_dyn(strategy)
        }

        $(#[$($install_tt)*])*
        pub fn install(strategy: impl $generic_strategy) {
            $global::install(strategy)
        }

        $(#[$($try_read_tt)*])*
        pub fn try_read() -> Result<MappedRwLockReadGuard<'static, $dyn_strategy>, UninitializedError> {
            $global::try_read()
        }

        $(#[$($read_tt)*])*
        pub fn read() -> MappedRwLockReadGuard<'static, $dyn_strategy> {
            $global::read()
        }

        $(#[$($try_write_tt)*])*
        pub fn try_write() -> Result<MappedRwLockWriteGuard<'static, $dyn_strategy>, UninitializedError> {
            $global::try_write()
        }

        $(#[$($write_tt)*])*
        pub fn write() -> MappedRwLockWriteGuard<'static, $dyn_strategy> {
            $global::write()
        }

        $(#[$($uninstall_tt)*])*
        pub fn uninstall() {
            $global::uninstall()
        }

        $(#[$($read_or_default_tt)*])*
        #[cfg(feature = $feature)]
        pub fn read_or_default() -> MappedRwLockReadGuard<'static, $dyn_strategy> {
            $global::read_or_default()
        }

        $(#[$($write_or_default_tt)*])*
        #[cfg(feature = $feature)]
        pub fn write_or_default() -> MappedRwLockWriteGuard<'static, $dyn_strategy> {
            $global::write_or_default()
        }
    };
}