Consolidate preceded! and do_parse! macros

Author: dtolnay

src/fallback.rs

@@ -983,10 +983,11 @@ named!(literal_nocapture -> (), alt!(
 named!(string -> (), alt!(
     quoted_string
     |
-    preceded!(
-        punct!("r"),
-        raw_string
-    ) => { |_| () }
+    do_parse!(
+        punct!("r") >>
+        raw_string >>
+        (())
+    )
 ));
 
 named!(quoted_string -> (), do_parse!(
@@ -1049,10 +1050,11 @@ named!(byte_string -> (), alt!(
         (())
     )
     |
-    preceded!(
-        punct!("br"),
-        raw_string
-    ) => { |_| () }
+    do_parse!(
+        punct!("br") >>
+        raw_string >>
+        (())
+    )
 ));
 
 fn cooked_byte_string(mut input: Cursor) -> PResult<()> {

src/strnom.rs

@@ -355,19 +355,6 @@ pub(crate) fn punct<'a>(input: Cursor<'a>, token: &'static str) -> PResult<'a, &
     }
 }
 
-macro_rules! preceded {
-    ($i:expr, $submac:ident!( $($args:tt)* ), $submac2:ident!( $($args2:tt)* )) => {
-        match tuple!($i, $submac!($($args)*), $submac2!($($args2)*)) {
-            Ok((remaining, (_, o))) => Ok((remaining, o)),
-            Err(LexError) => Err(LexError),
-        }
-    };
-
-    ($i:expr, $submac:ident!( $($args:tt)* ), $g:expr) => {
-        preceded!($i, $submac!($($args)*), call!($g))
-    };
-}
-
 macro_rules! map {
     ($i:expr, $submac:ident!( $($args:tt)* ), $g:expr) => {
         match $submac!($i, $($args)*) {