no recursion depth const generic

CHANGELOG.md

@@ -6,6 +6,39 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased](https://github.com/quartiq/miniconf/compare/v0.16.3...HEAD) - DATE
+
+### Changed
+
+* The "recursion depth" const generic of the `Tree*` traits has been removed in favor of
+  explicit newtypes implementing the traits for leaf values `Leaf<T>` and `StrLeaf<T>`.
+  This reduces code duplication, macro usage and complexity.
+  It enables any recursion depth, does away with most manual tracking of recursion depth
+  in proc macro attributes, and simplifies code and derive macros, at the expense of having
+  to wrap leaves in newtypes and having to pass an indices length to `TreeKey::nodes()`.
+* `TreeKey::nodes` requires the indices length as a const generic.
+* `get`, `get_mut`, `validate` proc macro attributes are now `Expr`
+* `Key::find` and `Keys::finalize` return a `Result`, not an `Option` to reduce code duplication
+* Derive macro lifetime and type param trait bound heuristics have been improved.
+  They should now yield the correct result in mpst cases.
+* Internal nodes must always have at least one leaf. Trait impls for `[T; 0]` and `()`
+  have been removed. The `len` argument to the `traverse_by_key` closure is now a
+  `NonZero<usize>`.
+
+### Added
+
+* `Leaf` to explicitly manage `Serialize/Deserialize` leaf values.
+* `StrLeaf` to manage values via `AsRef<str>`/`TryFrom<&str>` (e.g. Enums via `strum`)
+* `Tree*` impls for heterogeneous inline tuples `(T0, T1, ...)` up to length 8 (also useful
+  for enum variants)
+* `impl Tree* for &{mut,} T where T: Tree*` blanket impls to simplify usage downstream
+* `defer` derive attribute to quickly defer to a downstream field without having to write accessors
+* `Metadata` now also computes maximum `Packed` bits usage
+
+### Removed
+
+* `TreeSerialize`/`TreeDeserialize`/`TreeAny` don't need `TreeKey`
+
 ## [0.16.3](https://github.com/quartiq/miniconf/compare/v0.16.2...v0.16.3) - 2024-10-20
 
 ### Added

miniconf/README.md

@@ -19,58 +19,51 @@ providers are supported.
 
 ```rust
 use serde::{Deserialize, Serialize};
-use miniconf::{Error, json, JsonPath, Traversal, Tree, TreeKey, Path, Packed, Node};
+use miniconf::{Error, json, JsonPath, Traversal, Tree, TreeKey, Path, Packed, Node, Leaf};
 
 #[derive(Deserialize, Serialize, Default, Tree)]
-enum Either {
+pub enum Either {
     #[default]
     Bad,
     Good,
-    A(i32),
-    B(#[tree(depth=1)] Inner),
-    C(#[tree(depth=2)] [Inner; 2]),
+    A(Leaf<i32>),
+    B(Inner),
+    C([Inner; 2]),
 }
 
 #[derive(Deserialize, Serialize, Default, Tree)]
-struct Inner {
-    a: i32,
-    b: i32,
+pub struct Inner {
+    a: Leaf<i32>,
+    b: Leaf<i32>,
 }
 
 #[derive(Tree, Default)]
-struct Settings {
-    foo: bool,
-    enum_: Either,
-    struct_: Inner,
-    array: [i32; 2],
-    option: Option<i32>,
+pub struct Settings {
+    foo: Leaf<bool>,
+    enum_: Leaf<Either>,
+    struct_: Leaf<Inner>,
+    array: Leaf<[i32; 2]>,
+    option: Leaf<Option<i32>>,
 
     #[tree(skip)]
     #[allow(unused)]
     skipped: (),
 
-    #[tree(depth=1)]
     struct_tree: Inner,
-    #[tree(depth=3)]
     enum_tree: Either,
-    #[tree(depth=1)]
-    array_tree: [i32; 2],
-    #[tree(depth=2)]
+    array_tree: [Leaf<i32>; 2],
     array_tree2: [Inner; 2],
 
-    #[tree(depth=1)]
-    option_tree: Option<i32>,
-    #[tree(depth=2)]
+    option_tree: Option<Leaf<i32>>,
     option_tree2: Option<Inner>,
-    #[tree(depth=3)]
     array_option_tree: [Option<Inner>; 2],
 }
 
 let mut settings = Settings::default();
 
 // Atomic updates by field name
 json::set(&mut settings,"/foo", b"true")?;
-assert_eq!(settings.foo, true);
+assert_eq!(*settings.foo, true);
 json::set(&mut settings, "/enum_", br#""Good""#)?;
 json::set(&mut settings, "/struct_", br#"{"a": 3, "b": 3}"#)?;
 json::set(&mut settings, "/array", b"[6, 6]")?;
@@ -96,7 +89,7 @@ json::set_by_key(&mut settings, &JsonPath(".array_tree2[1].b"), b"10")?;
 
 // Hiding paths by setting an Option to `None` at runtime
 assert_eq!(json::set(&mut settings, "/option_tree", b"13"), Err(Traversal::Absent(1).into()));
-settings.option_tree = Some(0);
+settings.option_tree = Some(0.into());
 json::set(&mut settings, "/option_tree", b"13")?;
 // Hiding a path and descending into the inner `Tree`
 settings.option_tree2 = Some(Inner::default());
@@ -112,7 +105,7 @@ let len = json::get(&settings, "/struct_", &mut buf).unwrap();
 assert_eq!(&buf[..len], br#"{"a":3,"b":3}"#);
 
 // Iterating over all paths
-for path in Settings::nodes::<Path<heapless::String<32>, '/'>>() {
+for path in Settings::nodes::<Path<heapless::String<32>, '/'>, 4>() {
     let (path, node) = path.unwrap();
     assert!(node.is_leaf());
     // Serialize each
@@ -173,8 +166,6 @@ Leaf fields/items need to support the respective [`serde`] (and the desired `ser
 backend) or [`core::any`] trait.
 
 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.
 
 See also the [`TreeKey`] trait documentation for details.
 
@@ -191,7 +182,7 @@ It implements [`Keys`].
 
 ## Limitations
 
-* `enum`: The derive macros don't support enums with record (named fields) variants or tuple variants with more than one field. Only unit, newtype and skipped variants are supported. Without the derive macros, these `enums` are still however usable in their atomic `serde` form as leaf nodes.
+* `enum`: The derive macros don't support enums with record (named fields) variants or tuple variants with more than one field. Only unit, newtype and skipped variants are supported. Without the derive macros, these `enums` are still however usable in their atomic `serde` form as leaf nodes. Inline tuple variants are supported.
 * 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`).
 * The derive macros only support flattening in non-ambiguous situations (single field structs and single variant enums, both modulo skipped fields/variants and unit variants).
 

miniconf/examples/cli.rs

@@ -23,7 +23,7 @@ fn main() -> anyhow::Result<()> {
 
     // Dump settings
     let mut buf = vec![0; 1024];
-    for (key, _node) in Settings::nodes::<Path<String, '-'>>().map(Result::unwrap) {
+    for (key, _node) in Settings::nodes::<Path<String, '-'>, 4>().map(Result::unwrap) {
         match json::get_by_key(&settings, &key, &mut buf[..]) {
             Ok(len) => {
                 println!(

miniconf/examples/common.rs

@@ -1,4 +1,4 @@
-use miniconf::Tree;
+use miniconf::{Leaf, Tree};
 use serde::{Deserialize, Serialize};
 
 // Either/Inner/Settings are straight from README.md
@@ -8,50 +8,43 @@ pub enum Either {
     #[default]
     Bad,
     Good,
-    A(i32),
-    B(#[tree(depth = 1)] Inner),
-    C(#[tree(depth = 2)] [Inner; 2]),
+    A(Leaf<i32>),
+    B(Inner),
+    C([Inner; 2]),
 }
 
 #[derive(Deserialize, Serialize, Default, Tree)]
 pub struct Inner {
-    a: i32,
-    b: i32,
+    a: Leaf<i32>,
+    b: Leaf<i32>,
 }
 
 #[derive(Tree, Default)]
 pub struct Settings {
-    foo: bool,
-    enum_: Either,
-    struct_: Inner,
-    array: [i32; 2],
-    option: Option<i32>,
+    foo: Leaf<bool>,
+    enum_: Leaf<Either>,
+    struct_: Leaf<Inner>,
+    array: Leaf<[i32; 2]>,
+    option: Leaf<Option<i32>>,
 
     #[tree(skip)]
     #[allow(unused)]
     skipped: (),
 
-    #[tree(depth = 1)]
     struct_tree: Inner,
-    #[tree(depth = 3)]
     enum_tree: Either,
-    #[tree(depth = 1)]
-    array_tree: [i32; 2],
-    #[tree(depth = 2)]
+    array_tree: [Leaf<i32>; 2],
     array_tree2: [Inner; 2],
 
-    #[tree(depth = 1)]
-    option_tree: Option<i32>,
-    #[tree(depth = 2)]
+    option_tree: Option<Leaf<i32>>,
     option_tree2: Option<Inner>,
-    #[tree(depth = 3)]
     array_option_tree: [Option<Inner>; 2],
 }
 
 impl Settings {
     /// Fill some of the Options
     pub fn enable(&mut self) {
-        self.option_tree = Some(8);
+        self.option_tree = Some(8.into());
         self.enum_tree = Either::B(Default::default());
         self.option_tree2 = Some(Default::default());
         self.array_option_tree[1] = Some(Default::default());

miniconf/examples/menu.rs

@@ -61,23 +61,23 @@ impl<I> From<usize> for Error<I> {
 pub const SEPARATOR: char = '/';
 
 #[derive(Debug, PartialEq, PartialOrd)]
-pub struct Menu<M, const Y: usize, const D: usize = Y> {
+pub struct Menu<M, const D: usize> {
     key: Packed,
     _m: PhantomData<M>,
 }
 
-impl<M, const Y: usize> Default for Menu<M, Y>
+impl<M, const D: usize> Default for Menu<M, D>
 where
-    M: TreeKey<Y> + TreeSerialize<Y> + TreeDeserializeOwned<Y> + Default,
+    M: TreeKey + TreeSerialize + TreeDeserializeOwned + Default,
 {
     fn default() -> Self {
         Self::new(Packed::default())
     }
 }
 
-impl<M, const Y: usize> Menu<M, Y>
+impl<M, const D: usize> Menu<M, D>
 where
-    M: TreeKey<Y> + TreeSerialize<Y> + TreeDeserializeOwned<Y> + Default,
+    M: TreeKey + TreeSerialize + TreeDeserializeOwned + Default,
 {
     pub fn new(key: Packed) -> Self {
         Self {
@@ -92,7 +92,7 @@ where
     }
 
     fn pop(&self, levels: usize) -> Result<(Self, Node), Traversal> {
-        let (idx, node): (Indices<[_; Y]>, _) = M::transcode(self.key)?;
+        let (idx, node): (Indices<[_; D]>, _) = M::transcode(self.key)?;
         if let Some(idx) = idx.get(
             ..node
                 .depth()
@@ -121,7 +121,7 @@ where
     pub fn list<S: core::fmt::Write + Default>(
         &self,
     ) -> Result<impl Iterator<Item = Result<S, usize>>, Traversal> {
-        Ok(M::nodes::<Path<S, SEPARATOR>>()
+        Ok(M::nodes::<Path<S, SEPARATOR>, D>()
             .root(self.key)?
             .map(|pn| pn.map(|(p, _n)| p.into_inner())))
     }
@@ -148,7 +148,7 @@ where
         buf: &mut [u8],
     ) -> Result<(), miniconf::Error<::postcard::Error>> {
         let def = M::default();
-        for keys in M::nodes::<Packed>().root(self.key)? {
+        for keys in M::nodes::<Packed, D>().root(self.key)? {
             // Slight abuse of TooLong for "keys to long for packed"
             let (keys, node) = keys.map_err(|depth| Traversal::TooLong(depth))?;
             debug_assert!(node.is_leaf());
@@ -180,11 +180,11 @@ where
         let def = M::default();
         let bl = buf.len();
         let mut sl = &mut buf[..];
-        Path::<_, SEPARATOR>::from(WriteWrap(&mut sl)).transcode::<M, Y, _>(self.key)?;
+        Path::<_, SEPARATOR>::from(WriteWrap(&mut sl)).transcode::<M, _>(self.key)?;
         let root_len = bl - sl.len();
         awrite(&mut write, &buf[..root_len]).await?;
         awrite(&mut write, ">\n".as_bytes()).await?;
-        for keys in M::nodes::<Packed>().root(self.key)? {
+        for keys in M::nodes::<Packed, D>().root(self.key)? {
             let (keys, node) = keys?;
             let (val, rest) = match json::get_by_key(instance, keys, &mut buf[..]) {
                 Err(miniconf::Error::Traversal(Traversal::TooShort(_))) => {
@@ -204,7 +204,7 @@ where
             awrite(&mut write, "  ".as_bytes()).await?;
             let rl = rest.len();
             let mut sl = &mut rest[..];
-            Path::<_, SEPARATOR>::from(WriteWrap(&mut sl)).transcode::<M, Y, _>(keys)?;
+            Path::<_, SEPARATOR>::from(WriteWrap(&mut sl)).transcode::<M, _>(keys)?;
             let path_len = rl - sl.len();
             awrite(&mut write, &rest[root_len..path_len]).await?;
             awrite(&mut write, ": ".as_bytes()).await?;
@@ -279,7 +279,7 @@ async fn main() -> Result<()> {
 
     let mut stdout = embedded_io_adapters::tokio_1::FromTokio::new(tokio::io::stdout());
     let mut stdin = tokio::io::BufReader::new(tokio::io::stdin()).lines();
-    let mut menu = Menu::default();
+    let mut menu = Menu::<_, 4>::default();
 
     while let Some(line) = stdin.next_line().await? {
         let ret = menu

miniconf/examples/scpi.rs

@@ -1,7 +1,7 @@
 use core::str;
 
 use miniconf::{
-    json, IntoKeys, Key, KeyLookup, Keys, PathIter, TreeDeserializeOwned, TreeSerialize,
+    json, IntoKeys, Key, KeyLookup, Keys, PathIter, Traversal, TreeDeserializeOwned, TreeSerialize,
 };
 
 mod common;
@@ -19,7 +19,7 @@ use common::Settings;
 struct ScpiKey<T: ?Sized>(T);
 
 impl<T: AsRef<str> + ?Sized> Key for ScpiKey<T> {
-    fn find(&self, lookup: &KeyLookup) -> Option<usize> {
+    fn find(&self, lookup: &KeyLookup) -> Result<usize, Traversal> {
         let s = self.0.as_ref();
         if let Some(names) = lookup.names {
             let mut truncated = None;
@@ -35,7 +35,7 @@ impl<T: AsRef<str> + ?Sized> Key for ScpiKey<T> {
                 }
                 if name.len() == s.len() {
                     // Exact match: return immediately
-                    return Some(i);
+                    return Ok(i);
                 }
                 if truncated.is_some() {
                     // Multiple truncated matches: ambiguous unless there is an additional exact match
@@ -53,6 +53,7 @@ impl<T: AsRef<str> + ?Sized> Key for ScpiKey<T> {
         } else {
             s.parse().ok()
         }
+        .ok_or(Traversal::NotFound(1))
     }
 }
 
@@ -89,9 +90,9 @@ enum Error {
     Utf8(#[from] core::str::Utf8Error),
 }
 
-struct ScpiCtrl<M, const Y: usize>(M);
+struct ScpiCtrl<M>(M);
 
-impl<M: TreeSerialize<Y> + TreeDeserializeOwned<Y>, const Y: usize> ScpiCtrl<M, Y> {
+impl<M: TreeSerialize + TreeDeserializeOwned> ScpiCtrl<M> {
     fn new(settings: M) -> Self {
         Self(settings)
     }