build: update version to 1.0.1

unsupported item

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde-inline-default"
-version = "0.2.2"
+version = "1.0.1"
 authors = ["bytedream"]
 edition = "2021"
 description = "Serde default values via inline declaration"

README.md

@@ -1,12 +1,12 @@
-# serde-inline-default [![ci](https://github.com/ByteDream/serde-inline-default/actions/workflows/ci.yml/badge.svg)](https://github.com/ByteDream/serde-inline-default/actions/workflows/ci.yml) [![crates.io](https://img.shields.io/crates/v/serde-inline-default)](https://crates.io/crates/serde-inline-default) [![docs](https://img.shields.io/docsrs/serde-inline-default)](https://docs.rs/serde-inline-default/latest/serde_inline_default/)
+# serde-inline-default [![ci](https://github.com/ByteDream/serde-inline-default/actions/workflows/ci.yml/badge.svg)](https://github.com/ByteDream/serde-inline-default/actions/workflows/ci.yml) [![crates.io](https://img.shields.io/crates/v/serde-inline-default)](https://crates.io/crates/serde-inline-default) [![crates.io downloads](https://img.shields.io/crates/d/serde-inline-default)](https://crates.io/crates/serde-inline-default) [![docs](https://img.shields.io/docsrs/serde-inline-default)](https://docs.rs/serde-inline-default/latest/serde_inline_default/)
 
-Tiny crate to set default values for serde fields via inline attribute declaration.
+A tiny crate to set default values for serde struct fields via inline attribute declaration.
 
 ## Overview
 
-This crate is an approach to do what [serde-rs/serde#368](https://github.com/serde-rs/serde/issues/368) purposes.
-If you want to set default values in plain [`serde`](https://serde.rs/), you have to create a function and link to it with `#[serde(default = "...")`.
-This may be good if you need to do calculations to get the default value, but often you just want a simple integer or string to be the default value and have to create a whole function to return a hard-coded value.
+This crate is an approach to do what [serde-rs/serde#368](https://github.com/serde-rs/serde/issues/368) purposes: Defining default values for struct fields via inline declaration instead of creating a separate function for it.
+
+So instead of writing something like this, which can get very verbose quickly with many fields:
 ```rust
 #[derive(Deserialize)]
 struct Test {
@@ -16,11 +16,7 @@ struct Test {
 
 fn value_default() -> u32 { 42 }
 ```
-
-That can get quiet messy if you have many fields with many (different) default values.
-This crate tries to solve this issue by providing the `#[serde_inline_default]` proc macro.
-With this macro set at the struct level (_**before `#[derive(Deserialize)]`/`#[derive(Serialize)]`!, otherwise it's not working correctly**_), you can set default values via `#[serde_inline_default(...)]` for your serde fields inline, without creating an extra function.
-
+you can just do this:
 ```rust
 #[serde_inline_default]
 #[derive(Deserialize)]
@@ -30,8 +26,53 @@ struct Test {
 }
 ```
 
+> [!IMPORTANT]
+> **`#[serde_inline_default]` must be set before `#[derive(Deserialize)]`/`#[derive(Serialize)]`!**
+
 Internally, `#[serde_inline_default(...)]` gets expanded to a function which returns the set value and the attribute is replaced with `#[serde(default = "<function name>")]`.
-So this macro is just some syntax sugar for you, but can get quiet handy if you want to keep your code clean or write declarative macros / `macro_rules!`.
+So this macro is just some syntax sugar for you, but can get quite handy if you want to keep your code clean or write declarative macros / `macro_rules!`.
+
+## Alternatives
+
+This crate isn't perfect. Thus, you might be more satisfied with alternatives `serde` provides.
+
+With `#[serde(default)]` + `impl Default` on a struct, `serde` uses the default implementation of the struct to get default values for each field ([docs](https://serde.rs/container-attrs.html#default)):
+```rust
+#[derive(Deserialize)]
+#[serde(default)]
+struct Test {
+    value: u32
+}
+
+impl Default for Test {
+    fn default() -> Self {
+        Self {
+            value: 42
+        }
+    }
+}
+```
+
+If you still need/want `serde-inline-default` features, you also can combine them with `#[serde(default))` and `impl Default`:
+```rust
+#[serde_inline_default]
+#[derive(Deserialize)]
+#[serde(default)]
+struct Test {
+    value: u32,
+    #[serde_inline_default(0)]
+    other_value: u32,
+}
+
+impl Default for Test {
+    fn default() -> Self {
+        Self {
+            value: 42,
+            other_value: 42
+        }
+    }
+}
+```
 
 ## License
 

src/expand.rs

@@ -1,58 +1,70 @@
-use crate::utils::type_lifetimes_to_static;
-use proc_macro2::{Ident, Span, TokenStream};
 use quote::quote;
-use syn::{parse_quote, ItemStruct};
+use syn::{spanned::Spanned, Error, Fields, ItemEnum, ItemStruct};
+
+use crate::utils::{check_field_for_default_expr, ATTR_NAME, DEFAULT_FN_PREFIX};
 
 pub(crate) fn expand_struct(mut item: ItemStruct) -> proc_macro::TokenStream {
-    let mut inline_fns: Vec<(String, TokenStream, TokenStream)> = vec![];
+    let mut default_fns = vec![];
 
     for (i, field) in item.fields.iter_mut().enumerate() {
-        for (j, attr) in field.attrs.iter_mut().enumerate() {
-            if !attr.path().is_ident("serde_inline_default") {
-                continue;
+        default_fns.extend(check_field_for_default_expr(field, || {
+            format!("{}_{}_Field{}", DEFAULT_FN_PREFIX, item.ident, i)
+        }));
+    }
+
+    quote! {
+        #( #default_fns )*
+
+        #item
+    }
+    .into()
+}
+
+pub(crate) fn expand_enum(mut item: ItemEnum) -> proc_macro::TokenStream {
+    let mut default_fns = vec![];
+
+    for (i, variant) in item.variants.iter_mut().enumerate() {
+        if variant.attrs.iter().any(|a| a.path().is_ident(ATTR_NAME)) {
+            return Error::new(
+                variant.span(),
+                format!(
+                    "#[{}] can only be used on named enum variant fields",
+                    ATTR_NAME
+                ),
+            )
+            .to_compile_error()
+            .into();
+        }
+
+        let fields = match &mut variant.fields {
+            Fields::Named(fields) => fields,
+            _ => {
+                return Error::new(
+                    variant.span(),
+                    format!(
+                        "#[{}] can only be used on named enum variant fields",
+                        ATTR_NAME
+                    ),
+                )
+                .to_compile_error()
+                .into()
             }
+        };
 
-            let default: TokenStream = attr.parse_args().unwrap();
-
-            // we check here if a function with the exact same return value already exists. if so,
-            // this function gets used.
-            let fn_name_lit = if let Some((fn_name_lit, _, _)) = inline_fns
-                .iter()
-                .find(|(_, def, _)| def.to_string() == default.to_string())
-            {
-                fn_name_lit.clone()
-            } else {
-                let fn_name_lit = format!("__serde_inline_default_{}_{}", item.ident, i);
-                let fn_name_ident = Ident::new(&fn_name_lit, Span::call_site());
-                let mut return_type = field.ty.clone();
-
-                // replaces most lifetimes with 'static
-                type_lifetimes_to_static(&mut return_type);
-
-                let inline_fn = quote! {
-                    #[doc(hidden)]
-                    #[allow(non_snake_case)]
-                    fn #fn_name_ident () -> #return_type {
-                        #default
-                    }
-                };
-                inline_fns.push((fn_name_lit.clone(), default, inline_fn));
-                fn_name_lit
-            };
-            field.attrs.remove(j);
-            field
-                .attrs
-                .insert(j, parse_quote!( #[serde(default = #fn_name_lit)] ));
-            break;
+        for (j, field) in fields.named.iter_mut().enumerate() {
+            default_fns.extend(check_field_for_default_expr(field, || {
+                format!(
+                    "{}_{}_Variant{}_Field{}",
+                    DEFAULT_FN_PREFIX, item.ident, i, j
+                )
+            }));
         }
     }
 
-    let real_inline_fns: Vec<TokenStream> =
-        inline_fns.into_iter().map(|(_, _, func)| func).collect();
-    let expanded = quote! {
-        #( #real_inline_fns )*
+    quote! {
+        #( #default_fns )*
 
         #item
-    };
-    expanded.into()
+    }
+    .into()
 }

src/lib.rs

@@ -1,19 +1,22 @@
 #![doc = include_str!("../README.md")]
 
 use proc_macro::TokenStream;
-use syn::{parse_macro_input, Item};
+use syn::{parse_macro_input, spanned::Spanned, Error, Item};
 
 mod expand;
 mod utils;
 
 /// The main macro of this crate.
 /// Use it to define default values of fields in structs you [`Serialize`] or [`Deserialize`].
-/// You do not need to create a extra function to provide the default value, as it is the case in serdes' implementation of default (`#[serde(default = "...")]`).
+/// You do not need to create an extra function to provide the default value, as it is the case in
+/// serdes' implementation of default (`#[serde(default = "...")]`).
 ///
-/// Set this macro on a struct where you use [`Serialize`] or [`Deserialize`] and use `#[serde_inline_default(...)]` on the field you want to have a inline default value.
-/// Replace the `...` with the value you want and it will be set as default if serde needs it.
+/// Set this macro on a struct where you use [`Serialize`] or [`Deserialize`] and use
+/// `#[serde_inline_default(...)]` on the field you want to have an inline default value.
+/// Replace the `...` with the value you want, and it will be set as default if serde needs it.
 ///
-/// Note that you must set this macro _before_ `#[derive(Serialize)]` / `#[derive(Deserialize)]` as it wouldn't work properly if set after the derive.
+/// Note that you must set this macro _before_ `#[derive(Serialize)]` / `#[derive(Deserialize)]` as
+/// it won't work properly if it's set after the derive.
 ///
 /// # Examples
 ///
@@ -29,11 +32,17 @@ mod utils;
 /// [`Serialize`]: https://docs.rs/serde/*/serde/trait.Serialize.html
 /// [`Deserialize`]: https://docs.rs/serde/*/serde/trait.Deserialize.html
 #[proc_macro_attribute]
-pub fn serde_inline_default(_attr: TokenStream, input: TokenStream) -> TokenStream {
+pub fn serde_inline_default(attr: TokenStream, input: TokenStream) -> TokenStream {
     let item = parse_macro_input!(input as Item);
 
     match item {
         Item::Struct(s) => expand::expand_struct(s),
-        _ => panic!("can only be used on structs"),
+        Item::Enum(e) => expand::expand_enum(e),
+        _ => Error::new(
+            proc_macro2::TokenStream::from(attr).span(),
+            "can only be used on structs and enums",
+        )
+        .to_compile_error()
+        .into(),
     }
 }

src/utils.rs

@@ -1,4 +1,9 @@
-use syn::{parse_quote, GenericArgument, PathArguments, Type};
+use proc_macro2::{Span, TokenStream};
+use quote::quote;
+use syn::{parse_quote, Field, GenericArgument, Ident, PathArguments, Type};
+
+pub(crate) const ATTR_NAME: &str = "serde_inline_default";
+pub(crate) const DEFAULT_FN_PREFIX: &str = "__serde_inline_default";
 
 pub(crate) fn type_lifetimes_to_static(ty: &mut Type) {
     match ty {
@@ -38,3 +43,45 @@ pub(crate) fn type_lifetimes_to_static(ty: &mut Type) {
         _ => (),
     }
 }
+
+pub(crate) fn check_field_for_default_expr(
+    field: &mut Field,
+    identifier_fn: impl FnOnce() -> String,
+) -> Option<TokenStream> {
+    for (i, attr) in field.attrs.iter_mut().enumerate() {
+        if !attr.path().is_ident(ATTR_NAME) {
+            continue;
+        }
+
+        let default_expr: TokenStream = attr.parse_args().unwrap();
+
+        // copy all the same #[cfg] conditional compilations flags for the field onto our built
+        // default function.
+        // otherwise, it's possible to create a constructor for a type that may be filtered by
+        // the same #[cfg]'s, breaking compilation
+        let cfg_attrs = field.attrs.iter().filter(|a| a.path().is_ident("cfg"));
+
+        let default_fn_lit = identifier_fn();
+        let default_fn_ident = Ident::new(&default_fn_lit, Span::call_site());
+        let mut return_type = field.ty.clone();
+
+        // replace lifetimes with 'static.
+        // the built default function / default values in general can only be static as they're
+        // generated without reference to the parent struct
+        type_lifetimes_to_static(&mut return_type);
+
+        let default_fn_expr = quote! {
+            #[doc(hidden)]
+            #[allow(non_snake_case)]
+            #( #cfg_attrs )*
+            fn #default_fn_ident () -> #return_type {
+                #default_expr
+            }
+        };
+
+        field.attrs[i] = parse_quote!( #[serde(default = #default_fn_lit)] );
+        return Some(default_fn_expr);
+    }
+
+    None
+}

tests/enum.rs

@@ -0,0 +1,20 @@
+use serde::Deserialize;
+use serde_inline_default::serde_inline_default;
+use serde_json::json;
+
+#[test]
+fn enum_default() {
+    #[serde_inline_default]
+    #[derive(Debug, PartialEq, Eq, Deserialize)]
+    #[serde(untagged)]
+    enum Test {
+        VariantWithFields {
+            #[serde_inline_default(255)]
+            test_int: u8,
+        },
+    }
+
+    let enum_test: Test = serde_json::from_value(json!({"VariantWithFields": {}})).unwrap();
+
+    assert_eq!(enum_test, Test::VariantWithFields { test_int: 255 })
+}

tests/struct.rs

@@ -1,10 +1,11 @@
+use std::borrow::Cow;
+
 use serde::Deserialize;
 use serde_inline_default::serde_inline_default;
 use serde_json::json;
-use std::borrow::Cow;
 
 #[test]
-fn test_serde_inline_default() {
+fn struct_normal() {
     fn native_default() -> u32 {
         69
     }
@@ -31,7 +32,7 @@ fn test_serde_inline_default() {
 }
 
 #[test]
-fn test_lifetime() {
+fn lifetime() {
     #[serde_inline_default]
     #[derive(Deserialize)]
     struct LifetimeTest<'a> {
@@ -43,3 +44,26 @@ fn test_lifetime() {
 
     assert_eq!(lifetime_test.test_str, "test");
 }
+
+#[test]
+#[allow(dead_code)]
+fn conditional_compilation() {
+    #[cfg(debug_assertions)]
+    #[derive(Deserialize)]
+    struct TypeA(u8);
+
+    #[cfg(not(debug_assertions))]
+    #[derive(Deserialize)]
+    struct TypeB(u8);
+
+    #[serde_inline_default]
+    #[derive(Deserialize)]
+    struct Test {
+        #[cfg(debug_assertions)]
+        #[serde_inline_default(TypeA(1))]
+        val_a: TypeA,
+        #[cfg(not(debug_assertions))]
+        #[serde_inline_default(TypeB(1))]
+        val_b: TypeB,
+    }
+}