visible/lib.rs
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//! Attributes to override the visibility of items.
//!
//! ## Example
//!
//! ```Rust
//! #[visible::StructFields(pub(crate))]
//! pub struct Test {
//! pub a: i32,
//! pub b: i64,
//! }
//! ```
//!
//! The struct `Test` will be rewritten as below:
//!
//! ```Rust
//! pub struct Test {
//! pub(crate) a: i32,
//! pub(crate) b: i64,
//! }
//! ```
use proc_macro::TokenStream;
use quote::ToTokens;
use syn::{parse_macro_input, Fields, Item, ItemStruct, Visibility};
/// **Override**s the visibility of the annotated struct fields with the one given to
/// this attribute:
///
/// ## Example
///
/// ```rust
/// #[visible::StructFields(pub(crate))]
/// pub struct Test {
/// pub a: i32,
/// pub b: i64,
/// }
/// ```
#[allow(non_snake_case)]
#[proc_macro_attribute]
pub fn StructFields(attrs: TokenStream, input: TokenStream) -> TokenStream {
let visibility: Visibility = parse_macro_input!(attrs);
let mut input: Item = parse_macro_input!(input);
if let Item::Struct(ItemStruct { ref mut fields, .. }) = input {
match fields {
Fields::Named(fields) => {
for field in &mut fields.named {
field.vis = visibility.clone();
}
}
Fields::Unnamed(fields) => {
for field in &mut fields.unnamed {
field.vis = visibility.clone();
}
}
Fields::Unit => {}
}
}
input.into_token_stream().into()
}