commit c46afd5ff6b5bf39ff130a9dce6b736cb8253c39 Author: ByteDream Date: Sat Feb 11 15:28:13 2023 +0100 Initial commit diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml new file mode 100644 index 0000000..71396d2 --- /dev/null +++ b/.github/workflows/ci.yml @@ -0,0 +1,31 @@ +name: ci + +on: + push: + pull_request: + workflow_dispatch: + +jobs: + test: + runs-on: ubuntu-latest + + steps: + - name: Checkout + uses: actions/checkout@v3 + + - name: Generate cargo lockfile + run: cargo generate-lockfile + + - name: Cargo cache + uses: actions/cache@v3 + with: + path: | + ~/.cargo/bin/ + ~/.cargo/registry/index/ + ~/.cargo/registry/cache/ + ~/.cargo/git/db/ + target/ + key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }} + + - name: Test + run: cargo test diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml new file mode 100644 index 0000000..7faf21d --- /dev/null +++ b/.github/workflows/publish.yml @@ -0,0 +1,17 @@ +name: publish + +on: + push: + tags: + - v* + +jobs: + publish: + runs-on: ubuntu-latest + + steps: + - name: Checkout + uses: actions/checkout@v3 + + - name: Publish crate + run: cargo publish --token ${{ secrets.CRATES_TOKEN }} diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..4fffb2f --- /dev/null +++ b/.gitignore @@ -0,0 +1,2 @@ +/target +/Cargo.lock diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..5ad65f3 --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,23 @@ +[package] +name = "serde-inline-default" +version = "0.1.0" +authors = ["ByteDream"] +edition = "2021" +description = "Serde default values via inline declaration" +readme = "README.md" +repository = "https://github.com/ByteDream/serde-inline-default" +license = "MIT OR Apache-2.0" +keywords = ["serde", "serialization"] +categories = ["encoding"] + +[lib] +proc-macro = true + +[dependencies] +proc-macro2 = "1.0" +quote = "1.0" +syn = { version = "1.0", features = ["full"] } + +[dev-dependencies] +serde = { version = "1.0", features = ["derive"] } +serde_json = "1.0" diff --git a/LICENSE-APACHE b/LICENSE-APACHE new file mode 100644 index 0000000..4403dad --- /dev/null +++ b/LICENSE-APACHE @@ -0,0 +1,201 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. 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IN NO EVENT +SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY +CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR +IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +DEALINGS IN THE SOFTWARE. diff --git a/README.md b/README.md new file mode 100644 index 0000000..00c3988 --- /dev/null +++ b/README.md @@ -0,0 +1,41 @@ +# 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/crunchyroll-rs/latest/serde-inline-default/) + +Tiny crate to set default values for serde fields via inline attribute declaration. + +## Overview + +This crate is an approach to do what serde-rs/serde#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. +```rust +#[derive(Deserialize)] +struct Test { + #[serde(default = "value_default")] + value: u32 +} + +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. + +```rust +#[serde_inline_default] +#[derive(Deserialize)] +struct Test { + #[serde_inline_default(42)] + value: u32 +} +``` + +Internally, `#[serde_inline_default(...)]` gets expanded to a function which returns the set value and the attribute is replaced with `#[serde(default = "")]`. +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!`. + +## License + +This project is licensed under either of the following licenses, at your option: + +- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0) +- MIT License ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) diff --git a/src/expand.rs b/src/expand.rs new file mode 100644 index 0000000..c530464 --- /dev/null +++ b/src/expand.rs @@ -0,0 +1,54 @@ +use proc_macro2::{Ident, Span, TokenStream}; +use quote::quote; +use syn::{parse_quote, ItemStruct}; + +pub(crate) fn expand_struct(mut item: ItemStruct) -> proc_macro::TokenStream { + let mut inline_fns: Vec<(String, TokenStream, TokenStream)> = 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; + } + + let _default_str = attr.tokens.to_string(); + let default: TokenStream = _default_str[1.._default_str.len() - 1].parse().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 return_type = &field.ty; + + let inline_fn = quote! { + #[doc(hidden)] + 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; + } + } + + let real_inline_fns: Vec = + inline_fns.into_iter().map(|(_, _, func)| func).collect(); + let expanded = quote! { + #( #real_inline_fns )* + + #item + }; + expanded.into() +} diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..facb51f --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,14 @@ +use proc_macro::TokenStream; +use syn::{parse_macro_input, Item}; + +mod expand; + +#[proc_macro_attribute] +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"), + } +} diff --git a/tests/test_serde_inline_default.rs b/tests/test_serde_inline_default.rs new file mode 100644 index 0000000..cfc3f28 --- /dev/null +++ b/tests/test_serde_inline_default.rs @@ -0,0 +1,27 @@ +use serde::Deserialize; +use serde_inline_default::serde_inline_default; +use serde_json::json; + +#[test] +fn test_serde_inline_default() { + fn native_default() -> u32 { + 69 + } + + #[serde_inline_default] + #[derive(Deserialize)] + struct Test { + #[serde(default = "native_default")] + native: u32, + #[serde_inline_default(420)] + inline: u32, + #[serde_inline_default(-1337)] + inline_negative: i32, + } + + let test: Test = serde_json::from_value(json!({})).unwrap(); + + assert_eq!(test.native, 69); + assert_eq!(test.inline, 420); + assert_eq!(test.inline_negative, -1337); +}