repo: move all source code in crates directory

The top-level listing was just getting a bit too long for my taste. So
put all of the code in one directory and shrink the large top-level mess
to a small top-level mess.

NOTE: This commit only contains renames. The subsequent commit will
actually make ripgrep build again. We do it this way with the naive hope
that this will make it easier for git history to track the renames.
Sigh.

crates/ignore/examples/walk.rs

@@ -0,0 +1,84 @@
+extern crate crossbeam_channel as channel;
+extern crate ignore;
+extern crate walkdir;
+
+use std::env;
+use std::io::{self, Write};
+use std::path::Path;
+use std::thread;
+
+use ignore::WalkBuilder;
+use walkdir::WalkDir;
+
+fn main() {
+    let mut path = env::args().nth(1).unwrap();
+    let mut parallel = false;
+    let mut simple = false;
+    let (tx, rx) = channel::bounded::<DirEntry>(100);
+    if path == "parallel" {
+        path = env::args().nth(2).unwrap();
+        parallel = true;
+    } else if path == "walkdir" {
+        path = env::args().nth(2).unwrap();
+        simple = true;
+    }
+
+    let stdout_thread = thread::spawn(move || {
+        let mut stdout = io::BufWriter::new(io::stdout());
+        for dent in rx {
+            write_path(&mut stdout, dent.path());
+        }
+    });
+
+    if parallel {
+        let walker = WalkBuilder::new(path).threads(6).build_parallel();
+        walker.run(|| {
+            let tx = tx.clone();
+            Box::new(move |result| {
+                use ignore::WalkState::*;
+
+                tx.send(DirEntry::Y(result.unwrap())).unwrap();
+                Continue
+            })
+        });
+    } else if simple {
+        let walker = WalkDir::new(path);
+        for result in walker {
+            tx.send(DirEntry::X(result.unwrap())).unwrap();
+        }
+    } else {
+        let walker = WalkBuilder::new(path).build();
+        for result in walker {
+            tx.send(DirEntry::Y(result.unwrap())).unwrap();
+        }
+    }
+    drop(tx);
+    stdout_thread.join().unwrap();
+}
+
+enum DirEntry {
+    X(walkdir::DirEntry),
+    Y(ignore::DirEntry),
+}
+
+impl DirEntry {
+    fn path(&self) -> &Path {
+        match *self {
+            DirEntry::X(ref x) => x.path(),
+            DirEntry::Y(ref y) => y.path(),
+        }
+    }
+}
+
+#[cfg(unix)]
+fn write_path<W: Write>(mut wtr: W, path: &Path) {
+    use std::os::unix::ffi::OsStrExt;
+    wtr.write(path.as_os_str().as_bytes()).unwrap();
+    wtr.write(b"\n").unwrap();
+}
+
+#[cfg(not(unix))]
+fn write_path<W: Write>(mut wtr: W, path: &Path) {
+    wtr.write(path.to_string_lossy().as_bytes()).unwrap();
+    wtr.write(b"\n").unwrap();
+}