[pbs-devel] [RFC backup 1/2] implement an api_string_type helper macro

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
---
 src/tools.rs                 |   3 +
 src/tools/api_string_type.rs | 105 +++++++++++++++++++++++++++++++++++
 2 files changed, 108 insertions(+)
 create mode 100644 src/tools/api_string_type.rs

diff --git a/src/tools.rs b/src/tools.rs
index c58569a6..98597c29 100644
--- a/src/tools.rs
+++ b/src/tools.rs
@@ -18,6 +18,9 @@ use percent_encoding::{utf8_percent_encode, AsciiSet};
 pub use proxmox::tools::fd::Fd;
 use proxmox::tools::fs::{create_path, CreateOptions};
 
+#[macro_use]
+pub mod api_string_type;
+
 pub mod acl;
 pub mod apt;
 pub mod async_io;
diff --git a/src/tools/api_string_type.rs b/src/tools/api_string_type.rs
new file mode 100644
index 00000000..122fcbed
--- /dev/null
+++ b/src/tools/api_string_type.rs
@@ -0,0 +1,105 @@
+/// Helper macro to generate a simple string type wrapper.
+///
+/// This is meant to be used with an API-type tuple struct containing a single `String` like this:
+///
+/// ```ignore
+/// api_string_type! {
+///     #[api(format: &PROXMOX_SAFE_ID_FORMAT)]
+///     /// ACME account name.
+///     #[derive(Clone, Eq, PartialEq, Hash, Deserialize, Serialize)]
+///     #[serde(transparent)]
+///     pub struct AccountName(String);
+/// }
+/// ```
+///
+/// This will automatically implements:
+/// * `Display` as a pass-through to `String`'s `Display`
+/// * `Debug` as a pass-through to `String`'s `Debug`
+/// * `Deref`
+/// * `DerefMut`
+/// * `AsRef<str>`
+/// * `fn into_string(self) -> String`
+/// * `fn as_str(&self) -> &str`
+/// * `fn from_string(inner: String) -> Result<Self, anyhow::Error>` using
+///   `StringSchema::check_constraints`.
+/// * `unsafe fn from_string_unchecked(inner: String) -> Self`
+macro_rules! api_string_type {
+    (
+        $(#[$doc:meta])*
+        $vis:vis struct $name:ident(String);
+    ) => (
+        $(#[$doc])*
+        $vis struct $name(String);
+
+        impl ::std::ops::Deref for $name {
+            type Target = str;
+
+            #[inline]
+            fn deref(&self) -> &str {
+                &self.0
+            }
+        }
+
+        impl ::std::ops::DerefMut for $name {
+            #[inline]
+            fn deref_mut(&mut self) -> &mut str {
+                &mut self.0
+            }
+        }
+
+        impl AsRef<str> for $name {
+            #[inline]
+            fn as_ref(&self) -> &str {
+                self.0.as_ref()
+            }
+        }
+
+        impl $name {
+            /// Get the contained string.
+            pub fn into_string(self) -> String {
+                self.0
+            }
+
+            /// Get the string as slice.
+            pub fn as_str(&self) -> &str {
+                self.0.as_str()
+            }
+
+            /// Create an instance directly from a `String`.
+            ///
+            /// # Safety
+            ///
+            /// It is the caller's job to have validated the contents.
+            /// While there are no memory safety issues, a wrong string can cause API calls to
+            /// fail parameter validation.
+            pub unsafe fn from_string_unchecked(name: String) -> Self {
+                Self(name)
+            }
+
+            /// Create an instance directly from a `String`, validating it using the API schema's
+            /// [`check_constraints`](::proxmox::api::schema::StringSchema::check_constraints())
+            /// method.
+            pub fn from_string(inner: String) -> Result<Self, ::anyhow::Error> {
+                match &Self::API_SCHEMA {
+                    ::proxmox::api::schema::Schema::String(s) => s.check_constraints(&inner)?,
+                    _ => unreachable!(),
+                }
+                Ok(Self(inner))
+            }
+        }
+
+        impl ::std::fmt::Debug for $name {
+            #[inline]
+            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                ::std::fmt::Debug::fmt(&self.0, f)
+            }
+        }
+
+        impl ::std::fmt::Display for $name {
+            #[inline]
+            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                ::std::fmt::Display::fmt(&self.0, f)
+            }
+        }
+    );
+}
-- 
2.20.1