|
| 1 | +// Vendored from https://github.com/matklad/always-assert/commit/4cf564eea6fcf18b30c3c3483a611004dc03afbb |
| 2 | +//! Recoverable assertions, inspired by [the use of `assert()` in |
| 3 | +//! SQLite](https://www.sqlite.org/assert.html). |
| 4 | +//! |
| 5 | +//! `never!` and `always!` return the actual value of the condition if |
| 6 | +//! `debug_assertions` are disabled. |
| 7 | +//! |
| 8 | +//! Use them when terminating on assertion failure is worse than continuing. |
| 9 | +//! |
| 10 | +//! One example would be a critical application like a database: |
| 11 | +//! |
| 12 | +//! ```ignore |
| 13 | +//! use stdx::never; |
| 14 | +//! |
| 15 | +//! fn apply_transaction(&mut self, tx: Transaction) -> Result<(), TransactionAborted> { |
| 16 | +//! let delta = self.compute_delta(&tx); |
| 17 | +//! |
| 18 | +//! if never!(!self.check_internal_invariant(&delta)) { |
| 19 | +//! // Ok, something in this transaction messed up our internal state. |
| 20 | +//! // This really shouldn't be happening, and this signifies a bug. |
| 21 | +//! // Luckily, we can recover by just rejecting the transaction. |
| 22 | +//! return abort_transaction(tx); |
| 23 | +//! } |
| 24 | +//! self.commit(delta); |
| 25 | +//! Ok(()) |
| 26 | +//! } |
| 27 | +//! ``` |
| 28 | +//! |
| 29 | +//! Another example is assertions about non-critical functionality in usual apps |
| 30 | +//! |
| 31 | +//! ```ignore |
| 32 | +//! use stdx::never; |
| 33 | +//! |
| 34 | +//! let english_message = "super app installed!" |
| 35 | +//! let mut local_message = localize(english_message); |
| 36 | +//! if never!(local_message.is_empty(), "missing localization for {}", english_message) { |
| 37 | +//! // We localized all the messages but this one slipper through the cracks? |
| 38 | +//! // Better to show the english one then than to fail outright; |
| 39 | +//! local_message = english_message; |
| 40 | +//! } |
| 41 | +//! println!("{}", local_message); |
| 42 | +//! ``` |
| 43 | +
|
| 44 | +/// Asserts that the condition is always true and returns its actual value. |
| 45 | +/// |
| 46 | +/// If the condition is true does nothing and and evaluates to true. |
| 47 | +/// |
| 48 | +/// If the condition is false: |
| 49 | +/// * panics if `force` feature or `debug_assertions` are enabled, |
| 50 | +/// * logs an error if the `tracing` feature is enabled, |
| 51 | +/// * evaluates to false. |
| 52 | +/// |
| 53 | +/// Accepts `format!` style arguments. |
| 54 | +#[macro_export] |
| 55 | +macro_rules! always { |
| 56 | + ($cond:expr) => { |
| 57 | + $crate::always!($cond, "assertion failed: {}", stringify!($cond)) |
| 58 | + }; |
| 59 | + |
| 60 | + ($cond:expr, $fmt:literal $($arg:tt)*) => {{ |
| 61 | + let cond = $cond; |
| 62 | + if cfg!(debug_assertions) || $crate::assert::__FORCE { |
| 63 | + assert!(cond, $fmt $($arg)*); |
| 64 | + } |
| 65 | + if !cond { |
| 66 | + $crate::assert::__tracing_error!($fmt $($arg)*); |
| 67 | + } |
| 68 | + cond |
| 69 | + }}; |
| 70 | +} |
| 71 | + |
| 72 | +/// Asserts that the condition is never true and returns its actual value. |
| 73 | +/// |
| 74 | +/// If the condition is false does nothing and and evaluates to false. |
| 75 | +/// |
| 76 | +/// If the condition is true: |
| 77 | +/// * panics if `force` feature or `debug_assertions` are enabled, |
| 78 | +/// * logs an error if the `tracing` feature is enabled, |
| 79 | +/// * evaluates to true. |
| 80 | +/// |
| 81 | +/// Accepts `format!` style arguments. |
| 82 | +/// |
| 83 | +/// Empty condition is equivalent to false: |
| 84 | +/// |
| 85 | +/// ```ignore |
| 86 | +/// never!("oups") ~= unreachable!("oups") |
| 87 | +/// ``` |
| 88 | +#[macro_export] |
| 89 | +macro_rules! never { |
| 90 | + (true $($tt:tt)*) => { $crate::never!((true) $($tt)*) }; |
| 91 | + (false $($tt:tt)*) => { $crate::never!((false) $($tt)*) }; |
| 92 | + () => { $crate::never!("assertion failed: entered unreachable code") }; |
| 93 | + ($fmt:literal $(, $($arg:tt)*)?) => {{ |
| 94 | + if cfg!(debug_assertions) || $crate::assert::__FORCE { |
| 95 | + unreachable!($fmt $(, $($arg)*)?); |
| 96 | + } |
| 97 | + $crate::assert::__tracing_error!($fmt $(, $($arg)*)?); |
| 98 | + }}; |
| 99 | + |
| 100 | + ($cond:expr) => {{ |
| 101 | + let cond = !$crate::always!(!$cond); |
| 102 | + cond |
| 103 | + }}; |
| 104 | + |
| 105 | + ($cond:expr, $fmt:literal $($arg:tt)*) => {{ |
| 106 | + let cond = !$crate::always!(!$cond, $fmt $($arg)*); |
| 107 | + cond |
| 108 | + }}; |
| 109 | +} |
| 110 | + |
| 111 | +#[doc(hidden)] |
| 112 | +pub use tracing::error as __tracing_error; |
| 113 | + |
| 114 | +#[doc(hidden)] |
| 115 | +pub const __FORCE: bool = cfg!(feature = "force-always-assert"); |
0 commit comments