derive support for enums with newtype/unit variants

CHANGELOG.md

@@ -8,12 +8,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/quartiq/miniconf/compare/v0.13.0...HEAD) - DATE
 
+### Added
+* Derive support for enums with newtype/unit/skipped variants
+
 ### Removed
 
 * The `KeyLookup::NAMES` associated constant is now an implementation
   detail
 
-
 ## [0.13.0](https://github.com/quartiq/miniconf/compare/v0.12.0...v0.13.0) - 2024-07-10
 
 ### Changed

miniconf/Cargo.toml

@@ -9,7 +9,6 @@ description = "Serialize/deserialize/access reflection for trees"
 repository = "https://github.com/quartiq/miniconf"
 keywords = ["config", "serde", "no_std", "reflection", "graph"]
 categories = ["embedded", "config", "data-structures", "parsing"]
-resolver = "2"
 
 [dependencies]
 serde = { version = "1.0.120", default-features = false }
@@ -23,7 +22,6 @@ default = ["derive"]
 json-core = ["dep:serde-json-core"]
 postcard = ["dep:postcard"]
 derive = ["dep:miniconf_derive", "serde/derive"]
-std = []
 
 [package.metadata.docs.rs]
 all-features = true
@@ -37,6 +35,7 @@ embedded-io-adapters = { version = "0.6.1", features = ["tokio-1"] }
 heapless = "0.8.0"
 yafnv = "3.0.0"
 tokio = { version = "1.38.0", features = ["io-std", "rt", "macros"] }
+strum = { version = "0.26.3", features = ["derive"] }
 
 [[test]]
 name = "arrays"
@@ -74,6 +73,10 @@ required-features = ["derive"]
 name = "structs"
 required-features = ["json-core", "derive"]
 
+[[test]]
+name = "enum"
+required-features = ["json-core", "derive"]
+
 [[test]]
 name = "validate"
 required-features = ["json-core", "derive"]

miniconf/README.md

@@ -107,7 +107,7 @@ let len = settings.get_json("/struct_", &mut buf).unwrap();
 assert_eq!(&buf[..len], br#"{"a":3,"b":3}"#);
 
 // Iterating over all paths
-for path in Settings::nodes::<Path<String, '/'>>() {
+for path in Settings::nodes::<Path<heapless::String<32>, '/'>>() {
     let (path, node) = path.unwrap();
     assert!(node.is_leaf());
     // Serialize each
@@ -168,7 +168,7 @@ Fields/items that form internal nodes (non-leaf) need to implement the respectiv
 Leaf fields/items need to support the respective [`serde`] trait (and the desired `serde::Serializer`/`serde::Deserializer`
 backend).
 
-Structs, arrays, and Options can then be cascaded to construct more complex trees.
+Structs, enums, arrays, and Options can then be cascaded to construct more complex trees.
 When using the derive macro, the behavior and tree recursion depth can be configured for each
 struct field using the `#[tree(depth(Y))]` attribute.
 
@@ -187,10 +187,11 @@ It implements [`Keys`].
 
 ## Limitations
 
-Access to inner fields of some types is not yet supported, e.g. enums
-other than [`Option`]. These are still however usable in their atomic `serde` form as leaf nodes.
+The derive macros don't support enums with record (named fields) variants or tuple (non-newtype) variants.
+These are still however usable in their atomic `serde` form as leaf nodes.
 
-Many `std` smart pointers are not supported or handled in any special way: `Box`, `Rc`, `Arc`.
+The derive macros don't handle `std`/`alloc` smart pointers ( `Box`, `Rc`, `Arc`) in any special way.
+They however still be handled with accessors (`get`, `get_mut`, `validate`).
 
 ## Features
 

miniconf/src/lib.rs

@@ -1,6 +1,5 @@
-#![cfg_attr(not(any(feature = "std", test, doctest)), no_std)]
-#![cfg_attr(feature = "json-core", doc = include_str!("../README.md"))]
-#![cfg_attr(not(feature = "json-core"), doc = "miniconf")]
+#![no_std]
+#![doc = include_str!("../README.md")]
 #![deny(rust_2018_compatibility)]
 #![deny(rust_2018_idioms)]
 #![warn(missing_docs)]

miniconf/src/node.rs

@@ -225,10 +225,12 @@ impl<T: Write + ?Sized, const S: char> Transcode for Path<T, S> {
     {
         M::traverse_by_key(keys.into_keys(), |index, name, _len| {
             self.0
-                .write_char(self.separator())
-                .and_then(|()| match name {
-                    Some(name) => self.0.write_str(name),
-                    None => self.0.write_str(itoa::Buffer::new().format(index)),
+                .write_char(S)
+                .and_then(|()| {
+                    let mut buf = itoa::Buffer::new();
+                    let name = name.unwrap_or_else(|| buf.format(index));
+                    debug_assert!(!name.contains(S));
+                    self.0.write_str(name)
                 })
                 .or(Err(()))
         })
@@ -311,10 +313,10 @@ mod test {
 
     #[test]
     fn strsplit() {
+        use heapless::Vec;
         for p in ["/d/1", "/a/bccc//d/e/", "", "/", "a/b", "a"] {
-            let a: Vec<_> = PathIter::<'_, '/'>::new(p).collect();
-            println!("{p} {:?}", a);
-            let b: Vec<_> = p.split('/').skip(1).collect();
+            let a: Vec<_, 10> = PathIter::<'_, '/'>::new(p).collect();
+            let b: Vec<_, 10> = p.split('/').skip(1).collect();
             assert_eq!(a, b);
         }
     }

miniconf/tests/enum.rs

@@ -0,0 +1,69 @@
+use miniconf::{JsonCoreSlash, Path, Tree, TreeDeserialize, TreeKey, TreeSerialize};
+use strum::{AsRefStr, EnumString};
+
+#[derive(Tree, Default, PartialEq, Debug)]
+struct Inner {
+    a: i32,
+}
+
+#[derive(Tree, Default, EnumString, AsRefStr, PartialEq, Debug)]
+enum Enum {
+    #[default]
+    None,
+    #[strum(serialize = "foo")]
+    #[tree(rename = "foo")]
+    A(i32),
+    B(#[tree(depth = 1)] Inner),
+}
+
+#[derive(TreeKey, TreeSerialize, TreeDeserialize, Default)]
+struct Settings {
+    #[tree(typ = "&str", get = Self::get_tag, validate = Self::set_tag)]
+    tag: (),
+    #[tree(depth = 2)]
+    en: Enum,
+}
+
+impl Settings {
+    fn get_tag(&self) -> Result<&str, &'static str> {
+        Ok(self.en.as_ref())
+    }
+
+    fn set_tag(&mut self, tag: &str) -> Result<(), &'static str> {
+        self.en = Enum::try_from(tag).or(Err("invalid tag"))?;
+        Ok(())
+    }
+}
+
+#[test]
+fn enum_switch() {
+    let mut s = Settings::default();
+    assert_eq!(s.en, Enum::None);
+    s.set_json("/tag", b"\"foo\"").unwrap();
+    assert_eq!(
+        s.set_json("/tag", b"\"bar\""),
+        Err(miniconf::Traversal::Invalid(1, "invalid tag").into())
+    );
+    assert_eq!(s.en, Enum::A(0));
+    s.set_json("/en/foo", b"99").unwrap();
+    assert_eq!(s.en, Enum::A(99));
+    assert_eq!(
+        s.set_json("/en/B/a", b"99"),
+        Err(miniconf::Traversal::Absent(2).into())
+    );
+    s.set_json("/tag", b"\"B\"").unwrap();
+    s.set_json("/en/B/a", b"8").unwrap();
+    assert_eq!(s.en, Enum::B(Inner { a: 8 }));
+
+    assert_eq!(
+        Settings::nodes::<Path<String, '/'>>()
+            .exact_size()
+            .map(|pn| {
+                let (p, n) = pn.unwrap();
+                assert!(n.is_leaf());
+                p.into_inner()
+            })
+            .collect::<Vec<_>>(),
+        vec!["/tag", "/en/foo", "/en/B/a"]
+    );
+}

miniconf/tests/index.rs

@@ -1,3 +1,5 @@
+// This follows arrays.rs, just with indices.
+
 use miniconf::{Deserialize, JsonCoreSlash, Serialize, Traversal, Tree};
 
 #[derive(Debug, Copy, Clone, Default, Tree, Deserialize, Serialize)]

miniconf/tests/iter.rs

@@ -29,20 +29,23 @@ fn struct_iter() {
 
 #[test]
 fn struct_iter_indices() {
-    let mut paths = [
+    let paths = [
         ([0, 0, 0], 2),
         ([0, 1, 0], 2),
         ([1, 0, 0], 2),
         ([2, 0, 0], 3),
         ([3, 0, 0], 1),
-    ]
-    .into_iter();
-    for (have, expect) in Settings::nodes::<Indices<_>>().exact_size().zip(&mut paths) {
-        let (idx, node) = have.unwrap();
-        assert_eq!((idx.into_inner(), node.depth()), expect);
-    }
-    // Ensure that all fields were iterated.
-    assert_eq!(paths.next(), None);
+    ];
+    assert_eq!(
+        Settings::nodes::<Indices<[usize; 3]>>()
+            .exact_size()
+            .map(|have| {
+                let (idx, node) = have.unwrap();
+                (idx.into_inner(), node.depth())
+            })
+            .collect::<Vec<_>>(),
+        paths
+    );
 }
 
 #[test]

miniconf/tests/option.rs

@@ -11,6 +11,21 @@ struct Settings {
     value: Option<Inner>,
 }
 
+fn nodes<M: miniconf::TreeKey<Y>, const Y: usize>(want: &[&str]) {
+    assert_eq!(
+        M::nodes::<Path<String, '/'>>()
+            .exact_size()
+            .map(|pn| {
+                let (p, n) = pn.unwrap();
+                assert!(n.is_leaf());
+                assert_eq!(p.chars().filter(|c| *c == p.separator()).count(), n.depth());
+                p.into_inner()
+            })
+            .collect::<Vec<_>>(),
+        want
+    );
+}
+
 #[test]
 fn just_option() {
     let mut it = Option::<u32>::nodes::<Path<String, '/'>>().exact_size();
@@ -33,6 +48,7 @@ fn option_get_set_none() {
         settings.get_json("/value", &mut data),
         Err(Traversal::Absent(1).into())
     );
+    // The Absent field indicates at which depth the variant was absent
     assert_eq!(
         settings.set_json("/value/data", b"5"),
         Err(Traversal::Absent(1).into())
@@ -56,21 +72,7 @@ fn option_get_set_some() {
 
 #[test]
 fn option_iterate_some_none() {
-    let mut settings = Settings::default();
-
-    // When the value is None, it will still be iterated over as a topic but may not exist at runtime.
-    settings.value.take();
-    let mut iterator = Settings::nodes::<Path<String, '/'>>().exact_size();
-    let (path, _node) = iterator.next().unwrap().unwrap();
-    assert_eq!(path.as_str(), "/value/data");
-    assert!(iterator.next().is_none());
-
-    // When the value is Some, it should be iterated over.
-    settings.value.replace(Inner { data: 5 });
-    let mut iterator = Settings::nodes::<Path<String, '/'>>().exact_size();
-    let (path, _node) = iterator.next().unwrap().unwrap();
-    assert_eq!(path.as_str(), "/value/data");
-    assert_eq!(iterator.next(), None);
+    nodes::<Settings, 3>(&["/value/data"]);
 }
 
 #[test]
@@ -79,23 +81,14 @@ fn option_test_normal_option() {
     struct S {
         data: Option<u32>,
     }
+    nodes::<S, 1>(&["/data"]);
 
     let mut s = S::default();
     assert!(s.data.is_none());
 
-    let mut iterator = S::nodes::<Path<String, '/'>>().exact_size();
-    let (path, _node) = iterator.next().unwrap().unwrap();
-    assert_eq!(path.as_str(), "/data");
-    assert!(iterator.next().is_none());
-
     s.set_json("/data", b"7").unwrap();
     assert_eq!(s.data, Some(7));
 
-    let mut iterator = S::nodes::<Path<String, '/'>>().exact_size();
-    let (path, _node) = iterator.next().unwrap().unwrap();
-    assert_eq!(path.as_str(), "/data");
-    assert!(iterator.next().is_none());
-
     s.set_json("/data", b"null").unwrap();
     assert!(s.data.is_none());
 }
@@ -107,25 +100,16 @@ fn option_test_defer_option() {
         #[tree(depth = 1)]
         data: Option<u32>,
     }
+    nodes::<S, 2>(&["/data"]);
 
     let mut s = S::default();
     assert!(s.data.is_none());
 
-    let mut iterator = S::nodes::<Path<String, '/'>>().exact_size();
-    let (path, _node) = iterator.next().unwrap().unwrap();
-    assert_eq!(path.as_str(), "/data");
-    assert!(iterator.next().is_none());
-
     assert!(s.set_json("/data", b"7").is_err());
     s.data = Some(0);
     s.set_json("/data", b"7").unwrap();
     assert_eq!(s.data, Some(7));
 
-    let mut iterator = S::nodes::<Path<String, '/'>>().exact_size();
-    let (path, _node) = iterator.next().unwrap().unwrap();
-    assert_eq!(path.as_str(), "/data");
-    assert!(iterator.next().is_none());
-
     assert!(s.set_json("/data", b"null").is_err());
 }
 

miniconf/tests/packed.rs

@@ -136,7 +136,7 @@ fn size() {
     // Bit-hungriest type is [T;0] but that doesn't have any keys so won't recurse/consume with any Transcode/Keys
     // Then [T; 1] which takes one bit per level (not 0 bits, to distinguish empty packed)
     // Worst case for a 32 bit usize we need 31 array levels (marker bit) but TreeKey is only implemented to 16
-    // Easiest is to take 15 length-3 (2 bit) levels and one length-1 (1 bit) level to fill it, needing (3**15 ~ 14 M) storage.
+    // Easiest way to get to 32 bit is to take 15 length-3 (2 bit) levels and one length-1 (1 bit) level to fill it, needing (3**15 ~ 14 M) storage.
     // With the unit as type, we need 0 storage but can't do much.
     type A16 = [[[[[[[[[[[[[[[[(); 3]; 3]; 3]; 3]; 3]; 3]; 3]; 3]; 3]; 3]; 3]; 3]; 3]; 3]; 3]; 1];
     assert_eq!(core::mem::size_of::<A16>(), 0);