autumn-macros 0.1.0

Proc macros for the Autumn web framework
Documentation 
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//! `routes![]` collection macro implementation.
//!
//! Expands `routes![handler_a, handler_b]` into a `Vec<Route>` by calling
//! the companion `__autumn_route_info_{name}()` functions generated by the
//! route attribute macros.

use proc_macro2::TokenStream;
use quote::{format_ident, quote};
use syn::{Path, Token, punctuated::Punctuated};

/// Expand a comma-separated list of handler paths into a `Vec<Route>`.
///
/// Each path's last segment is transformed from `name` to
/// `__autumn_route_info_name`, so module-qualified paths like `users::list`
/// become `users::__autumn_route_info_list`.
pub fn routes_macro(input: TokenStream) -> TokenStream {
    // Handle empty input
    if input.is_empty() {
        return quote! { ::std::vec::Vec::new() };
    }

    // Parse comma-separated list of paths (trailing comma ok)
    let paths: Punctuated<Path, Token![,]> =
        match syn::parse::Parser::parse2(Punctuated::parse_terminated, input) {
            Ok(paths) => paths,
            Err(err) => return err.to_compile_error(),
        };

    // Transform each path's last segment to __autumn_route_info_{name}
    let route_info_calls: Vec<_> = paths
        .iter()
        .map(|path| {
            let mut info_path = path.clone();
            if let Some(last) = info_path.segments.last_mut() {
                let info_name = format_ident!("__autumn_route_info_{}", last.ident);
                last.ident = info_name;
            }
            quote! { #info_path() }
        })
        .collect();

    quote! {
        vec![#(#route_info_calls),*]
    }
}