No options for recursive calls

tokiostreamtest/Cargo.lock

@@ -17,6 +17,17 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
 
+[[package]]
+name = "async-recursion"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5fd55a5ba1179988837d24ab4c7cc8ed6efdeff578ede0416b4225a5fca35bd0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "async-stream"
 version = "0.3.5"
@@ -237,6 +248,7 @@ dependencies = [
 name = "tokiostreamtest"
 version = "0.1.0"
 dependencies = [
+ "async-recursion",
  "async-stream",
  "futures-core",
  "futures-util",

tokiostreamtest/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+async-recursion = "1.0.5"
 async-stream = "0.3.5"
 futures-core = "0.3.28"
 futures-util = "0.3.28"

tokiostreamtest/src/main.rs

@@ -4,7 +4,8 @@ use async_stream::stream;
 use futures_core::Stream;
 use futures_util::{StreamExt, pin_mut};
 
-fn filenames(start: &Path) -> impl Stream<Item = PathBuf> + '_ {
+#[async_recursion::async_recursion]
+async fn filenames(start: &Path) -> impl Stream<Item = PathBuf> + '_ {
     stream! {
         let contents = tokio::fs::read_dir(start).await;
         if let Ok(mut reader) = contents {
@@ -12,6 +13,35 @@ fn filenames(start: &Path) -> impl Stream<Item = PathBuf> + '_ {
                 let entry = entry.path();
                 if entry.is_file() {
                     yield entry;
+                } else if entry.is_dir() {
+                    // And this doesn't work 'cause we can't yield its results and we can't return
+                    // it due the return types being different.
+                    let under_dir = filenames(&entry).await;
+                    pin_mut!(under_dir);
+                    while let Some(name) = under_dir.next().await {
+                        yield name
+                    }
+                }
+            }
+        }
+    }
+}
+
+fn sync_filenames(start: &Path) -> impl Stream<Item = PathBuf> + '_ {
+    stream! {
+        let contents = start.read_dir();
+        if let Ok(reader) = contents {
+            for entry in reader {
+                let entry = entry.unwrap().path();
+                if entry.is_file() {
+                    yield entry;
+                } else if entry.is_dir() {
+                    let under_dir = sync_filenames(&entry);
+                    pin_mut!(under_dir);
+
+                    while let Some(name) = under_dir.next().await {
+                        yield name
+                    }
                 }
             }
         }
@@ -20,7 +50,9 @@ fn filenames(start: &Path) -> impl Stream<Item = PathBuf> + '_ {
 
 #[tokio::main(flavor = "current_thread")]
 async fn main() {
-    let name_stream = filenames(Path::new("src"));
+    // let name_stream = filenames(Path::new(".")).await;
+    // pin_mut!(name_stream);
+    let name_stream = sync_filenames(Path::new("."));
     pin_mut!(name_stream);
 
     while let Some(name) = name_stream.next().await {