Switch from chain to do_parse
diff --git a/src/do_parse.rs b/src/do_parse.rs
new file mode 100644
index 0000000..d56461c
--- /dev/null
+++ b/src/do_parse.rs
@@ -0,0 +1,101 @@
+// Copied from nom master:
+// https://github.com/Geal/nom/blob/a38188f333c29d00c32a3082bec5491d2eefa33f/src/sequence.rs#L591-L687
+// Will be released in nom 2.0.
+
+#[macro_export]
+macro_rules! do_parse (
+  ($i:expr, $($rest:tt)*) => (
+    {
+      do_parse_impl!($i, 0usize, $($rest)*)
+    }
+  );
+);
+
+/// Internal parser, do not use directly
+#[doc(hidden)]
+#[macro_export]
+macro_rules! do_parse_impl (
+
+  ($i:expr, $consumed:expr, ( $($rest:expr),* )) => (
+    ::nom::IResult::Done($i, ( $($rest),* ))
+  );
+
+  ($i:expr, $consumed:expr, $e:ident >> $($rest:tt)*) => (
+    do_parse_impl!($i, $consumed, call!($e) >> $($rest)*);
+  );
+  ($i:expr, $consumed:expr, $submac:ident!( $($args:tt)* ) >> $($rest:tt)*) => (
+    {
+      match $submac!($i, $($args)*) {
+        ::nom::IResult::Error(e)      => ::nom::IResult::Error(e),
+        ::nom::IResult::Incomplete(::nom::Needed::Unknown) =>
+          ::nom::IResult::Incomplete(::nom::Needed::Unknown),
+        ::nom::IResult::Incomplete(::nom::Needed::Size(i)) =>
+          ::nom::IResult::Incomplete(::nom::Needed::Size($consumed + i)),
+        ::nom::IResult::Done(i,_)     => {
+          do_parse_impl!(i,
+            $consumed + (::nom::InputLength::input_len(&($i)) -
+                         ::nom::InputLength::input_len(&i)), $($rest)*)
+        },
+      }
+    }
+  );
+
+  ($i:expr, $consumed:expr, $field:ident : $e:ident >> $($rest:tt)*) => (
+    do_parse_impl!($i, $consumed, $field: call!($e) >> $($rest)*);
+  );
+
+  ($i:expr, $consumed:expr, $field:ident : $submac:ident!( $($args:tt)* ) >> $($rest:tt)*) => (
+    {
+      match  $submac!($i, $($args)*) {
+        ::nom::IResult::Error(e)      => ::nom::IResult::Error(e),
+        ::nom::IResult::Incomplete(::nom::Needed::Unknown) =>
+          ::nom::IResult::Incomplete(::nom::Needed::Unknown),
+        ::nom::IResult::Incomplete(::nom::Needed::Size(i)) =>
+          ::nom::IResult::Incomplete(::nom::Needed::Size($consumed + i)),
+        ::nom::IResult::Done(i,o)     => {
+          let $field = o;
+          do_parse_impl!(i,
+            $consumed + (::nom::InputLength::input_len(&($i)) -
+                         ::nom::InputLength::input_len(&i)), $($rest)*)
+        },
+      }
+    }
+  );
+
+  // ending the chain
+  ($i:expr, $consumed:expr, $e:ident >> ( $($rest:tt)* )) => (
+    do_parse_impl!($i, $consumed, call!($e) >> ( $($rest)* ));
+  );
+
+  ($i:expr, $consumed:expr, $submac:ident!( $($args:tt)* ) >> ( $($rest:tt)* )) => (
+    match $submac!($i, $($args)*) {
+      ::nom::IResult::Error(e)      => ::nom::IResult::Error(e),
+      ::nom::IResult::Incomplete(::nom::Needed::Unknown) =>
+        ::nom::IResult::Incomplete(::nom::Needed::Unknown),
+      ::nom::IResult::Incomplete(::nom::Needed::Size(i)) =>
+        ::nom::IResult::Incomplete(::nom::Needed::Size($consumed + i)),
+      ::nom::IResult::Done(i,_)     => {
+        ::nom::IResult::Done(i, ( $($rest)* ))
+      },
+    }
+  );
+
+  ($i:expr, $consumed:expr, $field:ident : $e:ident >> ( $($rest:tt)* )) => (
+    do_parse_impl!($i, $consumed, $field: call!($e) >> ( $($rest)* ) );
+  );
+
+  ($i:expr, $consumed:expr, $field:ident : $submac:ident!( $($args:tt)* ) >> ( $($rest:tt)* )) => (
+    match $submac!($i, $($args)*) {
+      ::nom::IResult::Error(e)      => ::nom::IResult::Error(e),
+      ::nom::IResult::Incomplete(::nom::Needed::Unknown) =>
+        ::nom::IResult::Incomplete(::nom::Needed::Unknown),
+      ::nom::IResult::Incomplete(::nom::Needed::Size(i)) =>
+        ::nom::IResult::Incomplete(::nom::Needed::Size($consumed + i)),
+      ::nom::IResult::Done(i,o)     => {
+        let $field = o;
+        ::nom::IResult::Done(i, ( $($rest)* ))
+      },
+    }
+  );
+
+);