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- //
- // imag - the personal information management suite for the commandline
- // Copyright (C) 2015, 2016 Matthias Beyer <mail@beyermatthias.de> and contributors
- //
- // This library is free software; you can redistribute it and/or
- // modify it under the terms of the GNU Lesser General Public
- // License as published by the Free Software Foundation; version
- // 2.1 of the License.
- //
- // This library is distributed in the hope that it will be useful,
- // but WITHOUT ANY WARRANTY; without even the implied warranty of
- // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- // Lesser General Public License for more details.
- //
- // You should have received a copy of the GNU Lesser General Public
- // License along with this library; if not, write to the Free Software
- // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- //
- /// This macro is used to generate extensions for the `Result<T, U>` type which only have
- /// sideeffects.
- ///
- /// This macro is then used to generate debug/info/log/warning/etc extensions.
- ///
- /// It is exported, so other crates can use it to generate more specific extensions for
- /// `Result<T, U>` types
- ///
- /// # Parameters
- ///
- /// The documentation for the parameters of the macro follow.
- ///
- /// ## `$name`
- ///
- /// name of the trait to generate
- ///
- /// ## `$map_name`
- ///
- /// Name of the function which is generated to call the closure with.
- ///
- /// This function gets `&T` from `Result<T, E>` and can now build the argument for
- /// `$closure`. So, this function can, for example, `|e| format!("Look here: {:?}", e)`, the
- /// result gets fed to `$closure`.
- ///
- /// ## `$map_str_name`
- ///
- /// Name of the function which is generated to call the closure with.
- ///
- /// This function gets simply a `&str` which gets fed to the `$closure` later.
- /// So it can be used to `foo().$map_str_name("Something happened")`
- ///
- /// ## `$map_err_name`
- ///
- /// Same as `$map_name`, but gets `&E` from `Resul<T, E>`.
- ///
- /// ## `$map_err_str_name`
- ///
- /// Same as `$map_str_name`, but is called for error cases in `Result<T, E>` (though no
- /// argument is passed.
- ///
- /// ## `$closure`
- ///
- /// The closure which should be called when mapping.
- ///
- /// This closure can now do things, but the return value of the closure is discarded.
- /// So, this closure can be used for its sideeffects (logging for example) only.
- ///
- /// An example would be: `|element| debug!("Element: {:?}", element)`.
- ///
- #[macro_export]
- macro_rules! generate_result_logging_extension {
- {
- $name: ident,
- $map_name: ident,
- $map_str_name: ident,
- $map_err_name: ident,
- $map_err_str_name: ident,
- $closure: expr
- } => {
- pub trait $name<T, E> : Sized {
- fn $map_name<F: FnOnce(&T) -> String>(self, f: F) -> Self;
- fn $map_str_name(self, s: &str) -> Self {
- self.$map_name(|_| format!("{}", s))
- }
- fn $map_err_name<F: FnOnce(&E) -> String>(self, f: F) -> Self;
- fn $map_err_str_name(self, s: &str) -> Self {
- self.$map_err_name(|_| format!("{}", s))
- }
- }
- impl<T, E> $name<T, E> for Result<T, E> {
- fn $map_name<F: FnOnce(&T) -> String>(self, f: F) -> Self {
- self.map(|x| { $closure(f(&x)); x })
- }
- fn $map_err_name<F: FnOnce(&E) -> String>(self, f: F) -> Self {
- self.map_err(|e| { $closure(f(&e)); e })
- }
- }
- }
- }
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