109 lines
3.4 KiB
Rust
109 lines
3.4 KiB
Rust
//
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// imag - the personal information management suite for the commandline
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// Copyright (C) 2015-2019 Matthias Beyer <mail@beyermatthias.de> and contributors
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; version
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// 2.1 of the License.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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//
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/// This macro is used to generate extensions for the `Result<T, U>` type which only have
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/// sideeffects.
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///
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/// This macro is then used to generate debug/info/log/warning/etc extensions.
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///
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/// It is exported, so other crates can use it to generate more specific extensions for
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/// `Result<T, U>` types
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///
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/// # Parameters
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///
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/// The documentation for the parameters of the macro follow.
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///
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/// ## `$name`
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///
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/// name of the trait to generate
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///
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/// ## `$map_name`
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///
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/// Name of the function which is generated to call the closure with.
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///
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/// This function gets `&T` from `Result<T, E>` and can now build the argument for
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/// `$closure`. So, this function can, for example, `|e| format!("Look here: {:?}", e)`, the
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/// result gets fed to `$closure`.
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///
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/// ## `$map_str_name`
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///
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/// Name of the function which is generated to call the closure with.
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///
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/// This function gets simply a `&str` which gets fed to the `$closure` later.
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/// So it can be used to `foo().$map_str_name("Something happened")`
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///
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/// ## `$map_err_name`
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///
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/// Same as `$map_name`, but gets `&E` from `Resul<T, E>`.
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///
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/// ## `$map_err_str_name`
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///
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/// Same as `$map_str_name`, but is called for error cases in `Result<T, E>` (though no
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/// argument is passed.
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///
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/// ## `$closure`
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///
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/// The closure which should be called when mapping.
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///
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/// This closure can now do things, but the return value of the closure is discarded.
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/// So, this closure can be used for its sideeffects (logging for example) only.
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///
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/// An example would be: `|element| debug!("Element: {:?}", element)`.
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///
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#[macro_export]
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macro_rules! generate_result_logging_extension {
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{
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$name: ident,
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$map_name: ident,
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$map_str_name: ident,
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$map_err_name: ident,
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$map_err_str_name: ident,
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$closure: expr
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} => {
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pub trait $name<T, E> : Sized {
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fn $map_name<F: FnOnce(&T) -> String>(self, f: F) -> Self;
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fn $map_str_name(self, s: &str) -> Self {
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self.$map_name(|_| format!("{}", s))
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}
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fn $map_err_name<F: FnOnce(&E) -> String>(self, f: F) -> Self;
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fn $map_err_str_name(self, s: &str) -> Self {
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self.$map_err_name(|_| format!("{}", s))
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}
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}
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impl<T, E> $name<T, E> for Result<T, E> {
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fn $map_name<F: FnOnce(&T) -> String>(self, f: F) -> Self {
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self.map(|x| { $closure(f(&x)); x })
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}
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fn $map_err_name<F: FnOnce(&E) -> String>(self, f: F) -> Self {
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self.map_err(|e| { $closure(f(&e)); e })
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}
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}
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}
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}
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