Support top level itemless modules (djmcgill#14)

* add support for toplevel itemless modules

* clippy

README.md

@@ -1,6 +1,6 @@
 # Form
 ![crates.io badge](https://img.shields.io/crates/v/form.svg)
-[![CircleCI](https://circleci.com/gh/djmcgill/form/tree/master.svg?style=svg)](https://circleci.com/gh/djmcgill/form/tree/master)
+[![CircleCI](https://circleci.com/gh/djmcgill/form/tree/main.svg?style=svg)](https://circleci.com/gh/djmcgill/form/tree/main)
 
 A library for splitting apart a large file with multiple modules into the idiomatic rust directory structure, intended for use with svd2rust.
 Creates a lib.rs as well as a subdirectory structure in the target directory. It does NOT create the cargo project or the cargo manifest file.

src/main.rs

@@ -39,5 +39,5 @@ fn run() -> Result<(), Error> {
         create_directory_structure(opts.output_dir, opts.input)?;
         println!("Completed successfully");
     }
-    return Ok(());
+    Ok(())
 }

src/opts.rs

@@ -13,10 +13,10 @@ pub struct FormOpts {
 
 impl FormOpts {
     pub fn from_args() -> Result<Option<Self>, Error> {
-        const SHORT_INPUT: &'static str = "i";
-        const SHORT_OUTDIR: &'static str = "o";
-        const SHORT_HELP: &'static str = "h";
-        const SHORT_VERSION: &'static str = "v";
+        const SHORT_INPUT: &str = "i";
+        const SHORT_OUTDIR: &str = "o";
+        const SHORT_HELP: &str = "h";
+        const SHORT_VERSION: &str = "v";
 
         let args: Vec<String> = env::args().collect();
         let program = args[0].clone();
@@ -42,7 +42,7 @@ impl FormOpts {
         }
         let output_dir = matches
             .opt_str(SHORT_OUTDIR)
-            .ok_or(err_msg("Output directory missing"))?;
+            .ok_or_else(|| err_msg("Output directory missing"))?;
         let input = read_input(matches.opt_str(SHORT_INPUT))?;
 
         Ok(Some(FormOpts { output_dir, input }))

src/util.rs

@@ -31,6 +31,7 @@ pub fn create_directory_structure<P: AsRef<Path>>(
 
     let mut folder = FileIntoMods {
         current_dir: &base_dir,
+        top_level: true,
     };
 
     // Why doesn't syn::Fold::fold handle errors again?
@@ -52,11 +53,13 @@ pub fn create_directory_structure<P: AsRef<Path>>(
 #[derive(Debug)]
 struct FileIntoMods<P: AsRef<Path> + Send + Sync> {
     current_dir: P,
+    top_level: bool,
 }
 impl<P: AsRef<Path> + Send + Sync> FileIntoMods<P> {
     fn sub_mod<Q: AsRef<Path>>(&self, path: Q) -> FileIntoMods<PathBuf> {
         FileIntoMods {
             current_dir: self.current_dir.as_ref().join(path),
+            top_level: false,
         }
     }
 }
@@ -100,7 +103,7 @@ impl<P: AsRef<Path> + Send + Sync> FileIntoMods<P> {
 
 impl<P: AsRef<Path> + Send + Sync> Fold for FileIntoMods<P> {
     fn fold_item(&mut self, mut item: Item) -> Item {
-        for (mod_name, mod_file) in extract_mod(&mut item) {
+        if let Some((mod_name, mod_file)) = extract_mod(&mut item, self.top_level) {
             self.fold_sub_mod(mod_name, mod_file).unwrap();
         }
         fold_item(self, item)
@@ -116,10 +119,16 @@ fn write_mod_file(item_mod: syn::File, file_name: &Path) -> Result<(), Error> {
     write_all_tokens(&item_mod, &mut file)
 }
 
-fn extract_mod<'a>(node: &'a mut Item) -> Option<(Ident, syn::File)> {
+fn extract_mod(node: &mut Item, top_level: bool) -> Option<(Ident, syn::File)> {
     if let Item::Mod(mod_item) = &mut *node {
-        let items = mod_item.content.take().unwrap().1;
-        Some((mod_item.ident.clone(), make_file(items)))
+        if let Some(item_content) = mod_item.content.take() {
+            let items = item_content.1;
+            Some((mod_item.ident.clone(), make_file(items)))
+        } else if top_level {
+            None
+        } else {
+            panic!("Moving nested non-inline `mod` declarations not currently supported.")
+        }
     } else {
         None
     }

tests/resources/after/lib.rs

@@ -13,3 +13,5 @@ pub mod interrupt;
 pub use cortex_m::peripheral::TPIU;
 pub struct AC;
 pub mod ac;
+
+mod foo;

tests/resources/small-lib-before.rs

@@ -23,3 +23,5 @@ pub mod ac {
     }
     pub const AC: AC = AC;
 }
+
+mod foo;