Add support for -d depth flag

Following a user request the option '-d N' allows a user to output N
levels of sub directories.

Fixed bug: so that trailing slashes are now removed.

src/utils/mod.rs

@@ -9,20 +9,35 @@ use std::path::PathBuf;
 mod platform;
 use self::platform::*;
 
-pub fn get_dir_tree(filenames: &Vec<&str>, apparent_size: bool) -> (bool, HashMap<String, u64>) {
+pub fn get_dir_tree(
+    filenames: &Vec<&str>,
+    apparent_size: bool,
+) -> (bool, HashMap<String, u64>, Vec<String>) {
     let mut permissions = 0;
     let mut inodes: HashSet<(u64, u64)> = HashSet::new();
     let mut data: HashMap<String, u64> = HashMap::new();
+    let mut top_level_names = Vec::new();
+
     for b in filenames {
+        let top_level_name = strip_end_slashes(b);
         examine_dir(
-            &Path::new(b).to_path_buf(),
+            &Path::new(&top_level_name).to_path_buf(),
             apparent_size,
             &mut inodes,
             &mut data,
             &mut permissions,
         );
+        top_level_names.push(top_level_name);
     }
-    (permissions == 0, data)
+    (permissions == 0, data, top_level_names)
+}
+
+fn strip_end_slashes(s: &str) -> String {
+    let mut new_name = String::from(s);
+    while new_name.chars().last() == Some('/') && new_name.len() != 1 {
+        new_name.pop();
+    }
+    new_name
 }
 
 fn examine_dir(
@@ -66,11 +81,14 @@ fn examine_dir(
     }
 }
 
-pub fn find_big_ones<'a>(data: HashMap<String, u64>, max_to_show: usize) -> Vec<(String, u64)> {
+pub fn sort<'a>(data: HashMap<String, u64>) -> Vec<(String, u64)> {
     let mut new_l: Vec<(String, u64)> = data.iter().map(|(a, b)| (a.clone(), *b)).collect();
     new_l.sort_by(|a, b| b.1.cmp(&a.1));
+    new_l
+}
 
-    if new_l.len() > max_to_show {
+pub fn find_big_ones<'a>(new_l: Vec<(String, u64)>, max_to_show: usize) -> Vec<(String, u64)> {
+    if max_to_show > 0 && new_l.len() > max_to_show {
         new_l[0..max_to_show + 1].to_vec()
     } else {
         new_l