diff --git a/src/lexer.rs b/src/lexer.rs
index d8e536e..8865328 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -85,6 +85,7 @@ pub enum Buffer {
 }
 
 /// The type of `Buffer` you want in each `Token`
+#[derive(Debug, PartialEq, Clone)]
 pub enum BufferType {
     /// Use a `Buffer::MultiByte` were appropriate. Initialize it with the 
     /// given capcity (to obtain higher performance when pushing charcters)
@@ -257,8 +258,9 @@ impl<I> Iterator for Lexer<I>
                             state = Mode::String(false);
                             if let Some(ref mut v) = buf {
                                 v.push(c);
+                            } else {
+                                set_cursor(self.cursor);
                             }
-                            set_cursor(self.cursor);
                         },
                         b'n' => {
                             state = Mode::Null([c, b'x', b'x', b'x'], 1);
@@ -267,11 +269,12 @@ impl<I> Iterator for Lexer<I>
                          b'0' ... b'9'
                         |b'-'
                         |b'.'=> {
+                            state = Mode::Number;
                             if let Some(ref mut v) = buf {
                                 v.push(c);
+                            } else {
+                                set_cursor(self.cursor);
                             }
-                            state = Mode::Number;
-                            set_cursor(self.cursor);
                         },
                         b't' => {
                             state = Mode::True([c, b'x', b'x', b'x'], 1);
diff --git a/src/lib.rs b/src/lib.rs
index fa41a92..39d8ee7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,7 @@
 mod lexer;
 mod key_value_filter;
+mod reader;
 
 pub use lexer::{Lexer, Token, TokenType, Span, BufferType, Buffer};
 pub use key_value_filter::{FilterTypedKeyValuePairs};
+pub use reader::{TokenReader};
diff --git a/src/reader.rs b/src/reader.rs
new file mode 100644
index 0000000..e1df060
--- /dev/null
+++ b/src/reader.rs
@@ -0,0 +1,23 @@
+use std::io::{Read, Result, self};
+
+use super::{Token, TokenType};
+
+pub struct TokenReader<'a, I: Iterator<Item=Token>> {
+    iter: I,
+    src: Option<&'a str>,
+}
+
+impl<'a, I: Iterator<Item=Token>> TokenReader<'a, I> {
+    pub fn new(iter: I, source: Option<&'a str>) -> TokenReader<'a, I> {
+        TokenReader {
+            iter: iter,
+            src: source,
+        }
+    }
+}
+
+impl<'a, I: Iterator<Item=Token>> Read for TokenReader<'a, I> {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
+        Err(io::Error::last_os_error())
+    }
+}
\ No newline at end of file
diff --git a/tests/filters.rs b/tests/filters.rs
index f1b618f..eae3ef3 100644
--- a/tests/filters.rs
+++ b/tests/filters.rs
@@ -1,19 +1,46 @@
 extern crate json_tools;
 
-use json_tools::{Lexer, FilterTypedKeyValuePairs, BufferType, TokenType};
+use std::io::Read;
+
+use json_tools::{Lexer, FilterTypedKeyValuePairs, BufferType, TokenType, TokenReader};
 
 #[test]
 fn filter_null_values() {
-    for &(src, count, fcount) in &[(r#"{"s":null, "s":true, "s":null }"#, 13, 5),
-                                   (r#"{"s":null, "s":null, "s":null }"#, 13, 2),
-                                   (r#"{"s":true, "s":null, "s":null }"#, 13, 5),
-                                   (r#"{"s":true, "s":null "s":null }"#, 12, 5), // invalid is fine
-                                   (r#"{"s":true,,,, "s":null, "s":null }"#, 16, 8),
-                                   (r#"{"s":null, "s":null, "s":true }"#, 13, 5),
-                                   (r#"{"s":true, "s":null, "s":true }"#, 13, 9),
-                                   (r#"{"s":true, "s":null "s":true }"#, 12, 8),] {
+    for &(src, want, count, fcount) in 
+                                  &[(r#"{  "s":null, "s":true, "s":null }"#,
+                                    r#"{"s":true}"#, 13, 5),
+                                   (r#"{"s " : null, "s":null, "s":null }"#,
+                                    r#"{}"#, 13, 2),
+                                   (r#"{"s":true, "s":null, "s":null }"#,
+                                    r#"{"s":true}"#, 13, 5),
+                                   (r#"{"s":true, "s":null "s":null }"#, 
+                                    r#"{"s":true}"#, 12, 5), // invalid is fine
+                                   (r#"{"s":true,,,, "s":null, "s":null }"#,
+                                    r#"{"s":true,,,}"#, 16, 8),
+                                   (r#"{"s":null, "s":null, "s":true }"#,
+                                    r#"{"s":true}"#, 13, 5),
+                                   (r#"{"s":true, "s":null, "s":true }"#,
+                                    r#"{"s":true,"s":true}"#, 13, 9),
+                                   (r#"{"s":true, "s":null "s":true }"#,
+                                    r#"{"s":true"s":true}"#, 12, 8),] {
         assert_eq!(Lexer::new(src.bytes(), BufferType::Span).count(), count);
-        assert_eq!(FilterTypedKeyValuePairs::new(Lexer::new(src.bytes(), BufferType::Span),
-                                                 TokenType::Null).count(), fcount);    
+        let new_filter = |bt| {
+            FilterTypedKeyValuePairs::new(Lexer::new(src.bytes(), bt), TokenType::Null)
+        };
+        assert_eq!(new_filter(BufferType::Span).count(), fcount);
+
+        for bt in &[BufferType::Bytes(128), BufferType::Span] {
+            let mut buf: Vec<u8> = Vec::new();
+            let mut byte = [0u8];
+            let mut r = TokenReader::new(new_filter(bt.clone()), Some(src));
+
+            while let Ok(l) = r.read(&mut byte) {
+                if l == 0 {
+                    break
+                }
+                buf.push(byte[0]);
+            }
+            assert_eq!(&String::from_utf8(buf).unwrap(), want);
+        }
     }
 }
\ No newline at end of file