Function expand_modules_into_inline_modules

pub fn expand_modules_into_inline_modules<R: Resolver>(
    content: &mut File,
    resolver: &mut R,
) -> Result<(), Error>

Take a syn representation of a Rust source file and turn into similar syn representation, but with mod something; expanded into mod something { ... }.

It is low-level IO-agnostic function: your callback is responsible for reading and parsing the data.

Use read_full_crate_source_code for easy way to just load crate source code.

Example:

let mut ast: syn::File = syn::parse2(quote::quote! {
    mod inner_module;
}).unwrap();
let cfg_evaluator = |_cfg: syn::Meta|Ok(false);
let code_loader = |_module:syn::Path, path:std::path::PathBuf|{
   if path == std::path::Path::new("inner_module/mod.rs") {
       Ok(Some(syn::parse2(quote::quote! {
           trait Foo {
           }
       }).unwrap()))
   } else {
       Ok(None)
   }
};
let mut resolver = syn_file_expand::ResolverHelper(code_loader, cfg_evaluator);
syn_file_expand::expand_modules_into_inline_modules(&mut ast, &mut resolver)?;

let expanded: syn::File = syn::parse2(quote::quote! {
    mod inner_module {
        trait Foo { }
    }
}).unwrap();

assert_eq!(ast, expanded);