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//! This library is inspired in the `ensure` and `bail` macros from `anyhow`. The difference is that it is not tied to anyhow's types. //! Many libraries have their own error types and using the anyhow's `ensure` macro doesn't work because it returns an anyhow error. This library intends to work with any type. //! This library also provides the `assure` macro, that does the same but evaluates to a `Result` instead of returning. This is useful for using inside `try` blocks. /// Ensures the condition is met. This evaluates to a `Result<(), ERROR>` /// This macro is equivalent to `if !cond { Err(error) } else { Ok(()) }`. /// Example: /// ``` /// use bail_out::*; /// fn test_err() -> Result<(), &'static str> { /// assure!(false, "error") /// } /// assert_eq!(test_err(), Err("error")); /// /// fn test_ok() -> Result<(), &'static str> { /// assure!(true, "error") /// } /// assert!(test_ok().is_ok()); /// ``` #[macro_export] macro_rules! assure { ($cond:expr, $error:expr) => { if !$cond { Err($error) } else { Ok(()) } }; } /// Ensures the condition is met or returns the value. This evaluates to a `Result<VALUE, ERROR>` /// This macro is equivalent to `if !cond { Err(error) } else { Ok(value) }`. /// Example: /// ``` /// use bail_out::*; /// fn test_err() -> Result<&'static str, &'static str> { /// assure_or!(false, "ok", "error") /// } /// assert_eq!(test_err(), Err("error")); /// /// fn test_ok() -> Result<&'static str, &'static str> { /// assure_or!(true, "ok", "error") /// } /// assert_eq!(test_ok(), Ok("ok")); /// ``` #[macro_export] macro_rules! assure_or { ($cond:expr, $ok: expr, $error:expr) => { if !$cond { Err($error) } else { Ok($ok) } }; } /// Ensures the condition is not met. This evaluates to a `Result<(), ERROR>` /// This macro is equivalent to `if cond { Err(error) } else { Ok(()) }`. /// Example: /// ``` /// use bail_out::*; /// fn test_err() -> Result<(), &'static str> { /// assure_not!(true, "error") /// } /// assert_eq!(test_err(), Err("error")); /// /// fn test_ok() -> Result<(), &'static str> { /// assure_not!(false, "error") /// } /// assert!(test_ok().is_ok()); /// ``` #[macro_export] macro_rules! assure_not { ($cond:expr, $error:expr) => { if $cond { Err($error) } else { Ok(()) } }; } /// Ensures the condition is not met or returns the value. This evaluates to a `Result<VALUE, ERROR>` /// This macro is equivalent to `if cond { Err(error) } else { Ok(value) }`. /// Example: /// ``` /// use bail_out::*; /// fn test_err() -> Result<&'static str, &'static str> { /// assure_not_or!(true, "ok", "error") /// } /// assert_eq!(test_err(), Err("error")); /// /// fn test_ok() -> Result<&'static str, &'static str> { /// assure_not_or!(false, "ok", "error") /// } /// assert_eq!(test_ok(), Ok("ok")); /// ``` #[macro_export] macro_rules! assure_not_or { ($cond:expr, $ok:expr, $error:expr) => { if $cond { Err($error) } else { Ok($ok) } }; } /// Return early with an error if the condition is false. This ensures the condition is met. /// This macro is equivalent to `if !cond { return Err(error) }`. /// Example: /// ``` /// use bail_out::*; /// fn test_err() -> Result<(), &'static str> { /// ensure!(false, "error"); /// Ok(()) /// } /// assert_eq!(test_err(), Err("error")); /// /// fn test_ok() -> Result<(), &'static str> { /// ensure!(true, "ok"); /// Ok(()) /// } /// assert_eq!(test_ok(), Ok(())); /// ``` #[macro_export] macro_rules! ensure { ($cond:expr, $error:expr) => { if !$cond { $crate::bail!($error); } }; } /// Return early with an error if the condition is true. This ensures the condition is not met. /// This macro is equivalent to `if cond { return Err(error) }`. /// Example: /// ``` /// use bail_out::*; /// fn test_err() -> Result<(), &'static str> { /// ensure_not!(true, "error"); /// Ok(()) /// } /// assert_eq!(test_err(), Err("error")); /// /// fn test_ok() -> Result<(), &'static str> { /// ensure_not!(false, "ok"); /// Ok(()) /// } /// assert_eq!(test_ok(), Ok(())); /// ``` #[macro_export] macro_rules! ensure_not { ($cond:expr, $error:expr) => { if $cond { $crate::bail!($error); } }; } /// Return early with an error. /// This macro is equivalent to `return Err(error)`. /// Example: /// ``` /// use bail_out::*; /// fn bail_test() -> Result<(), &'static str> { /// bail!("error"); /// Ok(()) /// } /// assert_eq!(bail_test(), Err("error")); /// ``` #[macro_export] macro_rules! bail { ($error:expr) => { return Err($error); }; } #[cfg(test)] mod tests;