diff --git a/src/combinators.rs b/src/combinators.rs
index ce64d75..ea5fd0c 100644
--- a/src/combinators.rs
+++ b/src/combinators.rs
@@ -65,7 +65,7 @@ macro_rules! not {
     ($i:expr, $f:ident( $( $args:tt )* ) ) => {
         not!($i, run!($f($($args)*)))
     };
-    
+
     ($i:expr, $f:ident) => {
         not!($i, run!($f))
     };
@@ -104,7 +104,7 @@ macro_rules! peek {
     ($i:expr, $f:ident( $( $args:tt )* ) ) => {
         peek!($i, run!($f($($args)*)))
     };
-    
+
     ($i:expr, $f:ident) => {
         peek!($i, run!($f))
     };
@@ -160,7 +160,7 @@ macro_rules! must {
     ($i:expr, $f:ident!( $( $args:tt )* ) ) => {
         $crate::combinators::must($f!($i, $($args)*))
     };
-    
+
     ($i:expr, $f:ident) => {
         must!($i, run!($f))
     };
@@ -179,11 +179,11 @@ macro_rules! wrap_err {
             $crate::Result::Abort(e) => $crate::Result::Abort($crate::Error::caused_by($e, Box::new(e), Box::new(_i.clone()))),
         }
     }};
-    
+
     ($i:expr, $f:ident( $( $args:tt )* ), $e:expr ) => {
         wrap_err!($i, run!($f($($args)*)), $e:expr)
     };
-    
+
     ($i:expr, $f:ident, $e:expr) => {
         wrap_err!($i, run!($f), $e)
     };
@@ -225,7 +225,7 @@ macro_rules! trap {
     ($i:expr, $f:ident!( $( $args:tt )* ) ) => {
         $crate::combinators::trap($f!($i, $($args)*))
     };
-    
+
     ($i:expr, $f:ident) => {
         trap!($i, run!($f))
     };
@@ -250,7 +250,7 @@ where
 
 /// Turns `Result::Incomplete` into `Result::Fail`.
 pub fn complete<I, O, S>(result: Result<I, O>, msg: S) -> Result<I, O>
-where 
+where
     I: InputIter,
     S: Into<String>,
 {
@@ -268,7 +268,7 @@ macro_rules! complete {
     ($i:expr, $e:expr, $f:ident!( $( $args:tt )* ) ) => {
         $crate::combinators::complete($f!($i, $($args)*), $e)
     };
-    
+
     ($i:expr, $efn:expr, $f:ident) => {
         complete!($i, $efn, run!($f))
     };
@@ -293,7 +293,7 @@ macro_rules! must_complete {
     ($i:expr, $e:expr, $f:ident!( $( $args:tt )* ) ) => {{
         $crate::combinators::must_complete($f!($i.clone(), $($args)*), $e)
     }};
-    
+
     ($i:expr, $efn:expr, $f:ident) => {
         must_complete!($i, $efn, run!($f))
     };
@@ -354,7 +354,7 @@ macro_rules! do_each {
         // This is a compile failure.
         compile_error!("do_each! must end with a tuple capturing the results")
     };
-    
+
     ($i:expr, $val:ident => $f:ident!($( $args:tt )* ), $($rest:tt)* ) => {
         // If any single one of these matchers fails then all of them are failures.
         match $f!($i, $($args)*) {
@@ -369,7 +369,7 @@ macro_rules! do_each {
             $crate::Result::Abort(e) => Result::Abort(e),
         }
     };
-    
+
     ($i:expr, _ => $f:ident!($( $args:tt )* ), $($rest:tt)* ) => {
         // If any single one of these matchers fails then all of them are failures.
         match $f!($i, $($args)*) {
@@ -383,7 +383,7 @@ macro_rules! do_each {
             $crate::Result::Abort(e) => Result::Abort(e),
         }
     };
-    
+
     ($i:expr, $val:ident => $f:ident, $($rest:tt)* ) => {
         // If any single one of these matchers fails then all of them are failures.
         do_each!($i, $val => run!($f), $( $rest )* )
@@ -612,14 +612,14 @@ macro_rules! repeat {
             None => $crate::Result::Complete(_i, seq),
         }
     }};
-    
+
     ($i:expr, $f:ident) => {
         repeat!($i, run!($f))
     };
 }
 
 /// Parses separated list of items.
-/// 
+///
 /// ```
 /// # #[macro_use] extern crate abortable_parser;
 /// use abortable_parser::iter;
@@ -803,10 +803,16 @@ pub fn ascii_ws<'a, I: InputIter<Item = &'a u8>>(mut i: I) -> Result<I, u8> {
             if (*b as char).is_whitespace() {
                 Result::Complete(i, *b)
             } else {
-                Result::Fail(Error::new("Not whitespace".to_string(), Box::new(i.clone())))
+                Result::Fail(Error::new(
+                    "Not whitespace".to_string(),
+                    Box::new(i.clone()),
+                ))
             }
-        },
-        None => Result::Fail(Error::new("Unexpected End Of Input".to_string(), Box::new(i.clone()))),
+        }
+        None => Result::Fail(Error::new(
+            "Unexpected End Of Input".to_string(),
+            Box::new(i.clone()),
+        )),
     }
 }
 
@@ -815,7 +821,10 @@ pub fn ascii_ws<'a, I: InputIter<Item = &'a u8>>(mut i: I) -> Result<I, u8> {
 pub fn eoi<I: InputIter>(i: I) -> Result<I, ()> {
     let mut _i = i.clone();
     match _i.next() {
-        Some(_) => Result::Fail(Error::new("Expected End Of Input".to_string(), Box::new(i.clone()))),
+        Some(_) => Result::Fail(Error::new(
+            "Expected End Of Input".to_string(),
+            Box::new(i.clone()),
+        )),
         None => Result::Complete(i, ()),
     }
 }
@@ -847,7 +856,7 @@ macro_rules! make_fn {
             $rule!(i, $($body)*)
         }
     };
-    
+
     (pub $name:ident<$i:ty, $o:ty>, $rule:ident!($( $body:tt )* )) => {
         pub fn $name(i: $i) -> $crate::Result<$i, $o> {
             $rule!(i, $($body)*)
@@ -864,7 +873,7 @@ macro_rules! make_fn {
 }
 
 /// Helper macro that returns the input without consuming it.
-/// 
+///
 /// Useful when you need to get the input and use it to retrieve
 /// positional information like offset or line and column.
 #[macro_export]
@@ -881,7 +890,7 @@ macro_rules! input {
 
 /// Consumes the input until the $rule fails and then returns the consumed input as
 /// a slice.
-/// 
+///
 /// ```
 /// # #[macro_use] extern crate abortable_parser;
 /// use abortable_parser::iter;
@@ -932,17 +941,23 @@ macro_rules! consume_all {
 
 /// ascii_digit parses a single ascii alphabetic or digit character from an InputIter of bytes.
 #[inline(always)]
-pub fn ascii_alphanumeric<'a, I: InputIter<Item=&'a u8>>(mut i: I) -> Result<I, u8> {
+pub fn ascii_alphanumeric<'a, I: InputIter<Item = &'a u8>>(mut i: I) -> Result<I, u8> {
     match i.next() {
         Some(b) => {
             let c = *b as char;
             if c.is_ascii_alphabetic() || c.is_ascii_digit() {
                 Result::Complete(i, *b)
             } else {
-                Result::Fail(Error::new("Not an alphanumeric character".to_string(), Box::new(i.clone())))
+                Result::Fail(Error::new(
+                    "Not an alphanumeric character".to_string(),
+                    Box::new(i.clone()),
+                ))
             }
-        },
-        None => Result::Fail(Error::new("Unexpected End Of Input.".to_string(), Box::new(i.clone()))),
+        }
+        None => Result::Fail(Error::new(
+            "Unexpected End Of Input.".to_string(),
+            Box::new(i.clone()),
+        )),
     }
 }
 
@@ -954,10 +969,16 @@ pub fn ascii_digit<'a, I: InputIter<Item = &'a u8>>(mut i: I) -> Result<I, u8> {
             if (*b as char).is_ascii_digit() {
                 Result::Complete(i, *b)
             } else {
-                Result::Fail(Error::new("Not an digit character".to_string(), Box::new(i.clone())))
+                Result::Fail(Error::new(
+                    "Not an digit character".to_string(),
+                    Box::new(i.clone()),
+                ))
             }
-        },
-        None => Result::Fail(Error::new("Unexpected End Of Input.".to_string(), Box::new(i.clone()))),
+        }
+        None => Result::Fail(Error::new(
+            "Unexpected End Of Input.".to_string(),
+            Box::new(i.clone()),
+        )),
     }
 }
 
@@ -969,12 +990,18 @@ pub fn ascii_alpha<'a, I: InputIter<Item = &'a u8>>(mut i: I) -> Result<I, u8> {
             if (*b as char).is_ascii_alphabetic() {
                 Result::Complete(i, *b)
             } else {
-                Result::Fail(Error::new("Not an alpha character".to_string(), Box::new(i.clone())))
+                Result::Fail(Error::new(
+                    "Not an alpha character".to_string(),
+                    Box::new(i.clone()),
+                ))
             }
-        },
-        None => Result::Fail(Error::new("Unexpected End Of Input.".to_string(), Box::new(i.clone()))),
+        }
+        None => Result::Fail(Error::new(
+            "Unexpected End Of Input.".to_string(),
+            Box::new(i.clone()),
+        )),
     }
 }
 
 // TODO(jwall): We need a helper to convert Optional into failures.
-// TODO(jwall): We need a helper to convert std::result::Result into failures.
\ No newline at end of file
+// TODO(jwall): We need a helper to convert std::result::Result into failures.
diff --git a/src/integration_tests.rs b/src/integration_tests.rs
index 9543566..68ec772 100644
--- a/src/integration_tests.rs
+++ b/src/integration_tests.rs
@@ -12,7 +12,7 @@
 //  See the License for the specific language governing permissions and
 //  limitations under the License.
 use super::{ascii_ws, eoi, Result};
-use iter::{StrIter, SliceIter};
+use iter::{SliceIter, StrIter};
 
 make_fn!(proto<StrIter, &str>,
      do_each!(
@@ -33,7 +33,8 @@ make_fn!(path<StrIter, &str>,
       until!(either!(discard!(ascii_ws), eoi))
  );
 
-make_fn!(sliceit<SliceIter<u8>, ()>,
+make_fn!(
+    sliceit<SliceIter<u8>, ()>,
     do_each!(
         _ => input!(),
         end_of_input => eoi,
@@ -41,7 +42,8 @@ make_fn!(sliceit<SliceIter<u8>, ()>,
     )
 );
 
-make_fn!(long_string_path<SliceIter<u8>, ()>,
+make_fn!(
+    long_string_path<SliceIter<u8>, ()>,
     do_each!(
         _ => input!(),
         end_of_input => eoi,
diff --git a/src/iter.rs b/src/iter.rs
index 98def77..bed36fc 100644
--- a/src/iter.rs
+++ b/src/iter.rs
@@ -16,7 +16,7 @@
 use std::fmt::Debug;
 use std::iter::Iterator;
 
-use super::{InputIter, Offsetable, Seekable, Span, SpanRange, TextPositionTracker};
+use super::{InputIter, Offsetable, Positioned, Seekable, Span, SpanRange};
 
 /// Implements `InputIter` for any slice of T.
 #[derive(Debug)]
@@ -55,6 +55,25 @@ impl<'a, T: Debug + 'a> Offsetable for SliceIter<'a, T> {
     }
 }
 
+impl<'a, It> Positioned for SliceIter<'a, It>
+where
+    It: Positioned + Debug,
+{
+    fn line(&self) -> usize {
+        match self.peek_next() {
+            Some(i) => i.line(),
+            None => 0,
+        }
+    }
+
+    fn column(&self) -> usize {
+        match self.peek_next() {
+            Some(i) => i.column(),
+            None => 0,
+        }
+    }
+}
+
 impl<'a, T: Debug + 'a> Clone for SliceIter<'a, T> {
     fn clone(&self) -> Self {
         SliceIter {
@@ -149,7 +168,7 @@ impl<'a> Offsetable for StrIter<'a> {
     }
 }
 
-impl<'a> TextPositionTracker for StrIter<'a> {
+impl<'a> Positioned for StrIter<'a> {
     fn line(&self) -> usize {
         self.line
     }
@@ -194,11 +213,7 @@ impl<'a> Span<&'a str> for StrIter<'a> {
 impl<'a> Seekable for StrIter<'a> {
     fn seek(&mut self, to: usize) -> usize {
         let self_len = self.source.len();
-        let offset = if self_len > to {
-            to
-        } else {
-            self_len
-        };
+        let offset = if self_len > to { to } else { self_len };
         self.offset = offset;
         self.offset
     }
@@ -210,4 +225,4 @@ impl<'a> Peekable<&'a u8> for StrIter<'a> {
     fn peek_next(&self) -> Option<&'a u8> {
         self.source.as_bytes().get(self.offset)
     }
-}
\ No newline at end of file
+}
diff --git a/src/lib.rs b/src/lib.rs
index 85cc679..137a7ec 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -102,7 +102,7 @@
 //! assert!(bad_result.is_abort());
 //! # }
 //! ```
-use std::fmt::{Display,Debug};
+use std::fmt::{Debug, Display};
 use std::iter::Iterator;
 use std::result;
 
@@ -121,8 +121,8 @@ pub trait Seekable {
     fn seek(&mut self, usize) -> usize;
 }
 
-/// Trait for Inputs that can track lines and columns in a text input.
-pub trait TextPositionTracker {
+/// Trait for Inputs that can report current lines and columns in a text input.
+pub trait Positioned {
     fn line(&self) -> usize;
     fn column(&self) -> usize;
 }
@@ -150,20 +150,16 @@ pub trait InputIter: Iterator + Clone + Offsetable {}
 /// The custom error type for use in `Result::{Fail, Abort}`.
 /// Stores a wrapped err that must implement Display as well as an offset and
 /// an optional cause.
-#[derive(Debug,Clone)]
-pub struct Error<C>
-where
-    C: InputIter,
-{
+#[derive(Debug, Clone)]
+pub struct Error<C> {
     msg: String,
     cause: Option<Box<Error<C>>>,
     context: Box<C>,
 }
 
-impl<C: InputIter> Error<C> {
+impl<C> Error<C> {
     /// Constructs a new Error with an offset and no cause.
-    pub fn new<D: Into<String>>(msg: D, ctx: Box<C>) -> Self
-    {
+    pub fn new<D: Into<String>>(msg: D, ctx: Box<C>) -> Self {
         Error {
             msg: msg.into(),
             cause: None,
@@ -172,8 +168,7 @@ impl<C: InputIter> Error<C> {
     }
 
     /// Constructs a new Error with an offset and a cause.
-    pub fn caused_by<'a, D: Into<String>>(msg: D, cause: Box<Self>, ctx: Box<C>) -> Self
-    {
+    pub fn caused_by<'a, D: Into<String>>(msg: D, cause: Box<Self>, ctx: Box<C>) -> Self {
         Error {
             msg: msg.into(),
             cause: Some(cause),
@@ -182,32 +177,31 @@ impl<C: InputIter> Error<C> {
     }
 
     /// Returns the msg.
-    pub fn get_msg<'a>(&'a self) -> String {
-        format!("{}", &self.msg)
+    pub fn get_msg<'a>(&'a self) -> &str {
+        &self.msg
     }
 
     /// Returns `Some(cause)` if there is one, None otherwise.
     pub fn get_cause<'a>(&'a self) -> Option<&'a Error<C>> {
         match self.cause {
             Some(ref e) => Some(e),
-            None => None
+            None => None,
         }
     }
 
-    // Returns the offset at which this Error happened.
-    pub fn get_offset(&self) -> usize {
-        self.context.get_offset()
-    }
-
-    pub fn get_context(&self) -> &C 
-    where
-        C: InputIter,
-    {
+    pub fn get_context(&self) -> &C {
         self.context.as_ref()
     }
 }
 
-impl<C: InputIter> Display for Error<C> {
+impl<C: Offsetable> Offsetable for Error<C> {
+    // Returns the offset at which this Error happened.
+    fn get_offset(&self) -> usize {
+        self.context.get_offset()
+    }
+}
+
+impl<C: Offsetable> Display for Error<C> {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> result::Result<(), std::fmt::Error> {
         try!(write!(f, "{}", self.msg));
         match self.cause {
@@ -217,12 +211,11 @@ impl<C: InputIter> Display for Error<C> {
     }
 }
 
-impl<C: InputIter + Debug> std::error::Error for Error<C> {}
+impl<C: Offsetable + Debug> std::error::Error for Error<C> {}
 
 /// The result of a parsing attempt.
 #[derive(Debug)]
-pub enum Result<I: InputIter, O>
-{
+pub enum Result<I: InputIter, O> {
     /// Complete represents a successful match.
     Complete(I, O),
     /// Incomplete indicates input ended before a match could be completed.
@@ -234,8 +227,7 @@ pub enum Result<I: InputIter, O>
     Abort(Error<I>),
 }
 
-impl<I: InputIter, O> Result<I, O>
-{
+impl<I: InputIter, O> Result<I, O> {
     /// Returns true if the Result is Complete.
     pub fn is_complete(&self) -> bool {
         if let &Result::Complete(_, _) = self {
diff --git a/src/test.rs b/src/test.rs
index 0d49384..391d431 100644
--- a/src/test.rs
+++ b/src/test.rs
@@ -14,7 +14,7 @@
 
 use std::fmt::{Debug, Display};
 
-use super::{InputIter, Offsetable, Result, TextPositionTracker};
+use super::{InputIter, Offsetable, Positioned, Result};
 use combinators::*;
 use iter::{SliceIter, StrIter};
 
@@ -53,7 +53,10 @@ where
     I: InputIter<Item = C>,
     C: Debug + Display,
 {
-    Result::Fail(super::Error::new("AAAAHHH!!!".to_string(), Box::new(i.clone())))
+    Result::Fail(super::Error::new(
+        "AAAAHHH!!!".to_string(),
+        Box::new(i.clone()),
+    ))
 }
 
 fn parse_byte<'a, I>(mut i: I) -> Result<I, u8>
@@ -574,7 +577,7 @@ fn test_ascii_alphanumeric() {
     let iter = StrIter::new(input_str);
     let result = repeat!(iter, ascii_alphanumeric);
     assert!(result.is_complete());
-    if let Result::Complete(i,list) = result {
+    if let Result::Complete(i, list) = result {
         assert_eq!(list.len(), 2);
         assert_eq!(list[0], b'a');
         assert_eq!(list[1], b'1');
@@ -596,7 +599,7 @@ fn test_ascii_digit() {
     let iter = StrIter::new(input_str);
     let result = repeat!(iter, ascii_digit);
     assert!(result.is_complete());
-    if let Result::Complete(i,list) = result {
+    if let Result::Complete(i, list) = result {
         assert_eq!(list.len(), 2);
         assert_eq!(list[0], b'1');
         assert_eq!(list[1], b'2');
@@ -618,7 +621,7 @@ fn test_ascii_alpha() {
     let iter = StrIter::new(input_str);
     let result = repeat!(iter, ascii_alpha);
     assert!(result.is_complete());
-    if let Result::Complete(i,list) = result {
+    if let Result::Complete(i, list) = result {
         assert_eq!(list.len(), 2);
         assert_eq!(list[0], b'a');
         assert_eq!(list[1], b'b');
@@ -645,4 +648,4 @@ fn test_consume_all() {
         assert_eq!(o, "foo");
         assert!(text_token!(i, ";").is_complete());
     }
-}
\ No newline at end of file
+}