diff --git a/syntex_syntax/src/util/lev_distance.rs b/syntex_syntax/src/util/lev_distance.rs
new file mode 100644
index 00000000..9bf96311
--- /dev/null
+++ b/syntex_syntax/src/util/lev_distance.rs
@@ -0,0 +1,71 @@
+// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::cmp;
+
+pub fn lev_distance(me: &str, t: &str) -> usize {
+    if me.is_empty() { return t.chars().count(); }
+    if t.is_empty() { return me.chars().count(); }
+
+    let mut dcol: Vec<_> = (0..t.len() + 1).collect();
+    let mut t_last = 0;
+
+    for (i, sc) in me.chars().enumerate() {
+
+        let mut current = i;
+        dcol[0] = current + 1;
+
+        for (j, tc) in t.chars().enumerate() {
+
+            let next = dcol[j + 1];
+
+            if sc == tc {
+                dcol[j + 1] = current;
+            } else {
+                dcol[j + 1] = cmp::min(current, next);
+                dcol[j + 1] = cmp::min(dcol[j + 1], dcol[j]) + 1;
+            }
+
+            current = next;
+            t_last = j;
+        }
+    }
+
+    dcol[t_last + 1]
+}
+
+pub fn max_suggestion_distance(name: &str) -> usize {
+    use std::cmp::max;
+    // As a loose rule to avoid obviously incorrect suggestions, clamp the
+    // maximum edit distance we will accept for a suggestion to one third of
+    // the typo'd name's length.
+    max(name.len(), 3) / 3
+}
+
+#[test]
+fn test_lev_distance() {
+    use std::char::{ from_u32, MAX };
+    // Test bytelength agnosticity
+    for c in (0..MAX as u32)
+             .filter_map(|i| from_u32(i))
+             .map(|i| i.to_string()) {
+        assert_eq!(lev_distance(&c[..], &c[..]), 0);
+    }
+
+    let a = "\nMäry häd ä little lämb\n\nLittle lämb\n";
+    let b = "\nMary häd ä little lämb\n\nLittle lämb\n";
+    let c = "Mary häd ä little lämb\n\nLittle lämb\n";
+    assert_eq!(lev_distance(a, b), 1);
+    assert_eq!(lev_distance(b, a), 1);
+    assert_eq!(lev_distance(a, c), 2);
+    assert_eq!(lev_distance(c, a), 2);
+    assert_eq!(lev_distance(b, c), 1);
+    assert_eq!(lev_distance(c, b), 1);
+}
diff --git a/syntex_syntax/src/util/move_map.rs b/syntex_syntax/src/util/move_map.rs
new file mode 100644
index 00000000..95c24c66
--- /dev/null
+++ b/syntex_syntax/src/util/move_map.rs
@@ -0,0 +1,79 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use owned_slice::OwnedSlice;
+
+use std::ptr;
+
+pub trait MoveMap<T>: Sized {
+    fn move_map<F>(self, mut f: F) -> Self where F: FnMut(T) -> T {
+        self.move_flat_map(|e| Some(f(e)))
+    }
+
+    fn move_flat_map<F, I>(self, f: F) -> Self
+        where F: FnMut(T) -> I,
+              I: IntoIterator<Item=T>;
+}
+
+impl<T> MoveMap<T> for Vec<T> {
+    fn move_flat_map<F, I>(mut self, mut f: F) -> Self
+        where F: FnMut(T) -> I,
+              I: IntoIterator<Item=T>
+    {
+        let mut read_i = 0;
+        let mut write_i = 0;
+        unsafe {
+            let mut old_len = self.len();
+            self.set_len(0); // make sure we just leak elements in case of panic
+
+            while read_i < old_len {
+                // move the read_i'th item out of the vector and map it
+                // to an iterator
+                let e = ptr::read(self.get_unchecked(read_i));
+                let mut iter = f(e).into_iter();
+                read_i += 1;
+
+                while let Some(e) = iter.next() {
+                    if write_i < read_i {
+                        ptr::write(self.get_unchecked_mut(write_i), e);
+                        write_i += 1;
+                    } else {
+                        // If this is reached we ran out of space
+                        // in the middle of the vector.
+                        // However, the vector is in a valid state here,
+                        // so we just do a somewhat inefficient insert.
+                        self.set_len(old_len);
+                        self.insert(write_i, e);
+
+                        old_len = self.len();
+                        self.set_len(0);
+
+                        read_i += 1;
+                        write_i += 1;
+                    }
+                }
+            }
+
+            // write_i tracks the number of actually written new items.
+            self.set_len(write_i);
+        }
+
+        self
+    }
+}
+
+impl<T> MoveMap<T> for OwnedSlice<T> {
+    fn move_flat_map<F, I>(self, f: F) -> Self
+        where F: FnMut(T) -> I,
+              I: IntoIterator<Item=T>
+    {
+        OwnedSlice::from_vec(self.into_vec().move_flat_map(f))
+    }
+}