Working with iter

diritertest/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "diritertest"
+version = "0.1.0"

diritertest/Cargo.toml

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+[package]
+name = "diritertest"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

diritertest/README.md

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+# DirIterTest
+
+An iterator over directories (and subdirectories).

diritertest/src/diriter.rs

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+//! Iterator over directories
+
+use std::collections::VecDeque;
+use std::fs::DirEntry;
+use std::fs::ReadDir;
+use std::path::Path;
+use std::path::PathBuf;
+
+pub struct DirIter {
+    curr_dir: ReadDir,
+    remaining_dirs: VecDeque<PathBuf>,
+}
+
+impl DirIter {
+    pub fn new(start: &Path) -> std::io::Result<Self> {
+        Ok(Self {
+            curr_dir: start.read_dir()?,
+            remaining_dirs: VecDeque::new(),
+        })
+    }
+
+    pub fn advance(&mut self) -> Option<PathBuf> {
+        let next = self.curr_dir.next();
+        match next {
+            Some(Ok(x)) => {
+                if x.path().is_dir() {
+                    self.remaining_dirs.push_back(x.path());
+                    self.advance()
+                } else {
+                    Some(x.path())
+                }
+            }
+            Some(Err(_)) | None => {
+                let next_dir = self.remaining_dirs.pop_front()?;
+                self.curr_dir = std::fs::read_dir(next_dir).ok()?;
+                self.advance()
+            }
+        }
+    }
+}
+
+impl Iterator for DirIter {
+    type Item = PathBuf;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.advance()
+    }
+}

diritertest/src/main.rs

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+use std::path::Path;
+
+use crate::diriter::DirIter;
+
+mod diriter;
+
+fn main() {
+    let mut all_iter = DirIter::new(&Path::new(".")).unwrap();
+    while let Some(path) = all_iter.next() {
+        println!(">> {:?}", path);
+    }
+
+    println!("-----------------------");
+
+    let all_iter = DirIter::new(&Path::new(".")).unwrap();
+    for path in all_iter {
+        println!(">>> {:?}", path);
+    }
+
+    println!("Hello, world!");
+}