1 files changed, 70 insertions, 0 deletions
diff --git a/guide/build.rs b/guide/build.rs
new file mode 100644
index 00000000..3d73a984
--- /dev/null
+++ b/guide/build.rs
@@ -0,0 +1,70 @@
+use std::env;
+use std::io::{self, Write, BufRead};
+use std::fs::{self, DirEntry};
+use std::ffi::OsString;
+use std::path::{Path, PathBuf};
+
+// one possible implementation of walking a directory only visiting files
+fn visit_dirs(dir: &Path, cb: &Fn(&DirEntry) -> io::Result<()>)
+              -> io::Result<()> {
+    if dir.is_dir() {
+        for entry in fs::read_dir(dir)? {
+            let entry = entry?;
+            let path = entry.path();
+            if path.is_dir() {
+                visit_dirs(&path, cb)?;
+            } else {
+                cb(&entry)?;
+            }
+        }
+    }
+    Ok(())
+}
+
+fn manifest_dir() -> PathBuf {
+    PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap())
+}
+
+fn out_dir() -> PathBuf {
+    env::var_os("OUT_DIR").unwrap().into()
+}
+
+fn lib_path() -> PathBuf {
+    out_dir().join("src/lib.rs")
+}
+
+fn translate_path(src: &Path) -> PathBuf {
+    let src = src.to_str().unwrap();
+    format!("{}rs", &src[..src.len() - 2]).into()
+}
+
+fn translate2rs(src: &DirEntry) -> io::Result<()> {
+    let path = src.path();
+    if path.extension() != Some(&OsString::from("md")) {
+        return Ok(());
+    }
+
+    let sink_filename = out_dir().join(
+        translate_path(&path).strip_prefix(&manifest_dir()).unwrap());
+
+    eprintln!("{:?} -> {:?}", path, sink_filename);
+    println!("rerun-if-changed={}", path.to_str().unwrap());
+
+    fs::create_dir_all(sink_filename.parent().unwrap())?;
+    let mut sink = fs::File::create(sink_filename)?;
+
+    for line in io::BufReader::new(fs::File::open(&path)?).lines() {
+        writeln!(&mut sink, "//! {}", line?)?;
+    }
+
+    let mut lib =
+        fs::OpenOptions::new().create(true).append(true).open(&lib_path())?;
+    writeln!(&mut lib, "pub mod {};", path.file_stem().unwrap().to_str().unwrap())?;
+
+    Ok(())
+}
+
+fn main() {
+    let _ = fs::remove_file(&lib_path());
+    visit_dirs(&manifest_dir().join("src"), &translate2rs).unwrap();
+}