Add Option extensions for logging optional values

This patch adds the same extensions that we already have for
Result<T, E> also for Option<T>.

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

4 files changed, 147 insertions, 0 deletions

diff --git a/lib/etc/libimagutil/src/debug_option.rs b/lib/etc/libimagutil/src/debug_option.rs
new file mode 100644
index 00000000..b8ae47fc
--- /dev/null
+++ b/lib/etc/libimagutil/src/debug_option.rs
@@ -0,0 +1,28 @@
+//
+// imag - the personal information management suite for the commandline
+// Copyright (C) 2015-2018 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
+//
+
+// Generates a extension for the `Option<T>`, named `DebugOption` which has functionality to
+// print `T` via `debug!()`.
+generate_option_logging_extension!(
+    DebugOption,
+    map_dbg,
+    map_dbg_str,
+    |s| { debug!("{}", s); }
+);
+
diff --git a/lib/etc/libimagutil/src/info_option.rs b/lib/etc/libimagutil/src/info_option.rs
new file mode 100644
index 00000000..03800af0
--- /dev/null
+++ b/lib/etc/libimagutil/src/info_option.rs
@@ -0,0 +1,28 @@
+//
+// imag - the personal information management suite for the commandline
+// Copyright (C) 2015-2018 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
+//
+
+// Generates a extension for the `Option<T>`, named `DebugOption` which has functionality to
+// print `T` via `info!()`.
+generate_option_logging_extension!(
+    InfoResult,
+    map_info,
+    map_info_str,
+    |s| { info!("{}", s); }
+);
+
diff --git a/lib/etc/libimagutil/src/lib.rs b/lib/etc/libimagutil/src/lib.rs
index d9b33040..19bc795a 100644
--- a/lib/etc/libimagutil/src/lib.rs
+++ b/lib/etc/libimagutil/src/lib.rs
@@ -42,11 +42,14 @@ extern crate tempfile;
 extern crate chrono;
 
 #[macro_use] mod log_result;
+#[macro_use] mod log_option;
 pub mod cli_validators;
 pub mod date;
 pub mod debug_result;
+pub mod debug_option;
 pub mod edit;
 pub mod info_result;
+pub mod info_option;
 pub mod key_value_split;
 pub mod variants;
 pub mod warn_exit;
diff --git a/lib/etc/libimagutil/src/log_option.rs b/lib/etc/libimagutil/src/log_option.rs
new file mode 100644
index 00000000..813eeefc
--- /dev/null
+++ b/lib/etc/libimagutil/src/log_option.rs
@@ -0,0 +1,88 @@
+//
+// imag - the personal information management suite for the commandline
+// Copyright (C) 2015-2018 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 `Option<T>` 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
+/// `Option<T>` 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 `Option<T>` and can now build the argument for
+/// `$closure`. So, this function can, for example, `|e| format!("Look here: {:?}", e)`, the
+/// Option gets fed to `$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().$map_str_name("Something happened")`
+///
+/// ## `$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_option_logging_extension {
+    {
+        $name: ident,
+        $map_name: ident,
+        $map_str_name: ident,
+        $closure: expr
+    } => {
+        pub trait $name<T> : 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))
+            }
+
+        }
+
+        impl<T> $name<T> for Option<T> {
+
+            fn $map_name<F: FnOnce(&T) -> String>(self, f: F) -> Self {
+                self.map(|x| { $closure(f(&x)); x })
+            }
+
+        }
+
+    }
+}
+