add 'constnamemap' macro

to be able to define constant values but still have some mapping to
the name of it

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

proxmox/src/tools/constnamemap.rs

@@ -0,0 +1,81 @@
+/// A macro to generate a list of pub const variabales and
+/// an accompaning static array of a given name + value
+/// (with doc comments)
+///
+/// Example:
+/// ```
+/// # use proxmox::constnamemap;
+///
+/// constnamemap! {
+///     /// A list of privileges
+///     PRIVS: u64 => {
+///         /// Some comment for Priv1
+///         PRIV1("Priv1") = 1;
+///         PRIV2("Priv2") = 2;
+///     }
+/// }
+/// ```
+///
+/// this will generate the following variables:
+/// ```
+/// /// Some comment for Priv1
+/// pub const PRIV1: u64 = 1;
+/// pub const PRIV2: u64 = 2;
+///
+/// /// A list of privileges
+/// pub const PRIVS: &[(&str, u64)] = &[
+///     ("Priv1", 1),
+///     ("Priv2", 2),
+/// ];
+/// ```
+#[macro_export(local_inner_macros)]
+macro_rules! constnamemap {
+    (
+        $(#[$outer:meta])*
+        $name:ident : $type:ty => {
+            $($content:tt)+
+        }
+    ) => {
+        __constnamemap_consts! {
+            $type => $($content)+
+        }
+
+        $(#[$outer])*
+        pub const $name: &[(&str, $type)] =
+        __constnamemap_entries! {
+            $($content)+
+        };
+    }
+}
+
+#[doc(hidden)]
+#[macro_export(local_inner_macros)]
+macro_rules! __constnamemap_consts {
+    (
+        $type:ty =>
+        $(
+            $(#[$outer:meta])*
+            $name:ident($text:expr) = $value:expr;
+        )+
+    ) => {
+        $(
+            $(#[$outer])*
+            pub const $name: $type = $value;
+        )+
+    }
+}
+
+#[doc(hidden)]
+#[macro_export(local_inner_macros)]
+macro_rules! __constnamemap_entries {
+    (
+        $(
+            $(#[$outer:meta])*
+            $name:ident($text:expr) = $value:expr;
+        )*
+    ) => {
+        &[
+            $(($text,$value),)*
+        ]
+    }
+}

proxmox/src/tools/mod.rs

@@ -14,6 +14,7 @@ pub mod serde;
 pub mod uuid;
 pub mod vec;
 pub mod time;
+pub mod constnamemap;
 
 #[doc(inline)]
 pub use uuid::Uuid;