add a max-depth option for directory traversal

CR and add integration test

doc/rg.1.md

@@ -136,6 +136,10 @@ the raw speed of grep.
 -L, --follow
 : Follow symlinks.
 
+--maxdepth *NUM*
+: Descend at most NUM directories below the command line arguments.
+  A value of zero searches only the starting-points themselves.
+
 --mmap
 : Search using memory maps when possible. This is enabled by default
   when ripgrep thinks it will be faster. (Note that mmap searching

src/args.rs

@@ -136,6 +136,10 @@ Less common options:
     -L, --follow
         Follow symlinks.
 
+    --maxdepth NUM
+        Descend at most NUM directories below the command line arguments.
+        A value of zero only searches the starting-points themselves.
+
     --mmap
         Search using memory maps when possible. This is enabled by default
         when ripgrep thinks it will be faster. (Note that mmap searching
@@ -222,6 +226,7 @@ pub struct RawArgs {
     flag_invert_match: bool,
     flag_line_number: bool,
     flag_fixed_strings: bool,
+    flag_maxdepth: Option<usize>,
     flag_mmap: bool,
     flag_no_heading: bool,
     flag_no_ignore: bool,
@@ -272,6 +277,7 @@ pub struct Args {
     invert_match: bool,
     line_number: bool,
     line_per_match: bool,
+    maxdepth: Option<usize>,
     mmap: bool,
     no_ignore: bool,
     no_ignore_parent: bool,
@@ -399,6 +405,7 @@ impl RawArgs {
             invert_match: self.flag_invert_match,
             line_number: !self.flag_no_line_number && self.flag_line_number,
             line_per_match: self.flag_vimgrep,
+            maxdepth: self.flag_maxdepth,
             mmap: mmap,
             no_ignore: no_ignore,
             no_ignore_parent:
@@ -681,7 +688,10 @@ impl Args {
 
     /// Create a new recursive directory iterator at the path given.
     pub fn walker(&self, path: &Path) -> Result<walk::Iter> {
-        let wd = WalkDir::new(path).follow_links(self.follow);
+        let mut wd = WalkDir::new(path).follow_links(self.follow);
+        if let Some(maxdepth) = self.maxdepth {
+            wd = wd.max_depth(maxdepth);
+        }
         let mut ig = Ignore::new();
         // Only register ignore rules if this is a directory. If it's a file,
         // then it was explicitly given by the end user, so we always search

tests/tests.rs

@@ -831,6 +831,21 @@ sherlock\x00can extract a clew from a wisp of straw or a flake of cigar ash;
     assert_eq!(lines, expected);
 });
 
+// See: https://github.com/BurntSushi/ripgrep/issues/109
+clean!(max_depth, "far", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_dir("one");
+    wd.create("one/pass", "far");
+    wd.create_dir("one/too");
+    wd.create("one/too/many", "far");
+
+    cmd.arg("--maxdepth").arg("2");
+
+    let lines: String = wd.stdout(&mut cmd);
+    let expected = path("one/pass:far\n");
+
+    assert_eq!(lines, expected);
+});
+
 #[test]
 fn binary_nosearch() {
     let wd = WorkDir::new("binary_nosearch");