1 files changed, 8 insertions, 56 deletions

diff --git a/src/rope.rs b/src/rope.rs
index ea37e6c..c5e9aa1 100644
--- a/src/rope.rs
+++ b/src/rope.rs
@@ -1,6 +1,7 @@
 use std::fs::File;
 use std::io::{ErrorKind, Read, Write};
 use std::path::Path;
+use std::error::Error;
 use std::rc::Rc;
 
 // Set to a small value to help identify bugs in the implementation.
@@ -167,13 +168,8 @@ impl Rope {
         }
     }
 
-    pub fn open(path: &Path) -> Result<Rope, String> {
-        let mut f = match File::open(path) {
-            Ok(f) => f,
-            Err(err) => {
-                return Err(format!("open file {}: {}", path.display(), err));
-            }
-        };
+    pub fn open(path: &Path) -> Result<Rope, Box<dyn Error>> {
+        let mut f = File::open(path).map_err(|err| format!("open file {}: {}", path.display(), err))?;
         let mut rope = Rope::leaf(Vec::new());
         loop {
             let mut buf = vec![0; MAX_NODE_SIZE];
@@ -183,7 +179,7 @@ impl Rope {
                     if err.kind() == ErrorKind::Interrupted {
                         continue;
                     }
-                    return Err(format!("read file {}: {}", path.display(), err));
+                    return Err(Box::from(format!("read file {}: {}", path.display(), err)));
                 }
             };
             if n == 0 {
@@ -196,19 +192,10 @@ impl Rope {
         return Ok(rope);
     }
 
-    pub fn save(&self, path: &Path) -> Result<(), String> {
-        let mut f = match File::create(path) {
-            Ok(f) => f,
-            Err(err) => {
-                return Err(format!("save: create file {}: {}", path.display(), err));
-            }
-        };
-        if let Err(err) = self.print(&mut f) {
-            return Err(format!("save: write file {}: {}", path.display(), err));
-        }
-        if let Err(err) = f.sync_all() {
-            return Err(format!("save: write file {}: {}", path.display(), err));
-        }
+    pub fn save(&self, path: &Path) -> Result<(), Box<dyn Error>> {
+        let mut f = File::create(path).map_err(|err| format!("save: create file {}: {}", path.display(), err))?;
+        self.print(&mut f).map_err(|err| format!("save: write file {}: {}", path.display(), err))?;
+        f.sync_all().map_err(|err| format!("save: write file {}: {}", path.display(), err))?;
         return Ok(());
     }
 
@@ -260,41 +247,6 @@ impl Rope {
         return self.slice(start, end-1);
     }
 
-    pub fn char(&self, n: usize) -> Result<usize, usize> {
-        match self {
-            Rope(Node::Leaf(l)) => {
-                let mut count = 0;
-                for (i, &b) in l.bytes().iter().enumerate() {
-                    if b & 0xc0 == 0x80 {
-                        continue;
-                    }
-                    if count == n {
-                        return Ok(i);
-                    }
-                    count += 1;
-                }
-                return Err(count);
-            }
-            Rope(Node::Branch(b)) => {
-                match b.left.char(n) {
-                    Ok(i) => {
-                        return Ok(i);
-                    }
-                    Err(len) => {
-                        match b.right.char(n - len) {
-                            Ok(i) => {
-                                return Ok(b.left.len() + i);
-                            }
-                            Err(right_len) => {
-                                return Err(len + right_len);
-                            }
-                        }
-                    }
-                }
-            }
-        }
-    }
-
     fn is_char_boundary(&self, index: usize) -> bool {
         match self {
             Rope(Node::Leaf(l)) => {