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Make ensure's doc comment apply to the cfg(not(doc)) macro too #360

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Apr 10, 2024
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Make ensure's doc comment apply to the cfg(not(doc)) macro too #360

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186 changes: 98 additions & 88 deletions src/macros.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -65,98 +65,108 @@ macro_rules! bail {
};
}

/// Return early with an error if a condition is not satisfied.
///
/// This macro is equivalent to `if !$cond { return
/// Err(`[`anyhow!($args...)`][anyhow!]`); }`.
///
/// The surrounding function's or closure's return value is required to be
/// `Result<_,`[`anyhow::Error`][crate::Error]`>`.
///
/// Analogously to `assert!`, `ensure!` takes a condition and exits the function
/// if the condition fails. Unlike `assert!`, `ensure!` returns an `Error`
/// rather than panicking.
///
/// [anyhow!]: crate::anyhow
///
/// # Example
///
/// ```
/// # use anyhow::{ensure, Result};
/// #
/// # fn main() -> Result<()> {
/// # let user = 0;
/// #
/// ensure!(user == 0, "only user 0 is allowed");
/// # Ok(())
/// # }
/// ```
///
/// ```
/// # use anyhow::{ensure, Result};
/// # use thiserror::Error;
/// #
/// # const MAX_DEPTH: usize = 1;
/// #
/// #[derive(Error, Debug)]
/// enum ScienceError {
/// #[error("recursion limit exceeded")]
/// RecursionLimitExceeded,
/// # #[error("...")]
/// # More = (stringify! {
/// ...
/// # }, 1).1,
/// }
///
/// # fn main() -> Result<()> {
/// # let depth = 0;
/// #
/// ensure!(depth <= MAX_DEPTH, ScienceError::RecursionLimitExceeded);
/// # Ok(())
/// # }
/// ```
#[cfg(doc)]
#[macro_export]
macro_rules! ensure {
($cond:expr $(,)?) => {
if !$cond {
return $crate::__private::Err($crate::Error::msg(
$crate::__private::concat!("Condition failed: `", $crate::__private::stringify!($cond), "`")
));
}
};
($cond:expr, $msg:literal $(,)?) => {
if !$cond {
return $crate::__private::Err($crate::__anyhow!($msg));
}
};
($cond:expr, $err:expr $(,)?) => {
if !$cond {
return $crate::__private::Err($crate::__anyhow!($err));
}
};
($cond:expr, $fmt:expr, $($arg:tt)*) => {
if !$cond {
return $crate::__private::Err($crate::__anyhow!($fmt, $($arg)*));
}
macro_rules! __ensure {
($ensure:item) => {
/// Return early with an error if a condition is not satisfied.
///
/// This macro is equivalent to `if !$cond { return
/// Err(`[`anyhow!($args...)`][anyhow!]`); }`.
///
/// The surrounding function's or closure's return value is required to be
/// `Result<_,`[`anyhow::Error`][crate::Error]`>`.
///
/// Analogously to `assert!`, `ensure!` takes a condition and exits the function
/// if the condition fails. Unlike `assert!`, `ensure!` returns an `Error`
/// rather than panicking.
///
/// [anyhow!]: crate::anyhow
///
/// # Example
///
/// ```
/// # use anyhow::{ensure, Result};
/// #
/// # fn main() -> Result<()> {
/// # let user = 0;
/// #
/// ensure!(user == 0, "only user 0 is allowed");
/// # Ok(())
/// # }
/// ```
///
/// ```
/// # use anyhow::{ensure, Result};
/// # use thiserror::Error;
/// #
/// # const MAX_DEPTH: usize = 1;
/// #
/// #[derive(Error, Debug)]
/// enum ScienceError {
/// #[error("recursion limit exceeded")]
/// RecursionLimitExceeded,
/// # #[error("...")]
/// # More = (stringify! {
/// ...
/// # }, 1).1,
/// }
///
/// # fn main() -> Result<()> {
/// # let depth = 0;
/// #
/// ensure!(depth <= MAX_DEPTH, ScienceError::RecursionLimitExceeded);
/// # Ok(())
/// # }
/// ```
$ensure
};
}

#[cfg(doc)]
__ensure![
#[macro_export]
macro_rules! ensure {
($cond:expr $(,)?) => {
if !$cond {
return $crate::__private::Err($crate::Error::msg(
$crate::__private::concat!("Condition failed: `", $crate::__private::stringify!($cond), "`")
));
}
};
($cond:expr, $msg:literal $(,)?) => {
if !$cond {
return $crate::__private::Err($crate::__anyhow!($msg));
}
};
($cond:expr, $err:expr $(,)?) => {
if !$cond {
return $crate::__private::Err($crate::__anyhow!($err));
}
};
($cond:expr, $fmt:expr, $($arg:tt)*) => {
if !$cond {
return $crate::__private::Err($crate::__anyhow!($fmt, $($arg)*));
}
};
}
];

#[cfg(not(doc))]
#[macro_export]
macro_rules! ensure {
($($tt:tt)*) => {
$crate::__parse_ensure!(
/* state */ 0
/* stack */ ()
/* bail */ ($($tt)*)
/* fuel */ (~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~)
/* parse */ {()}
/* dup */ ($($tt)*)
/* rest */ $($tt)*
)
};
}
__ensure![
#[macro_export]
macro_rules! ensure {
($($tt:tt)*) => {
$crate::__parse_ensure!(
/* state */ 0
/* stack */ ()
/* bail */ ($($tt)*)
/* fuel */ (~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~)
/* parse */ {()}
/* dup */ ($($tt)*)
/* rest */ $($tt)*
)
};
}
];

/// Construct an ad-hoc error from a string or existing non-`anyhow` error
/// value.
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