fix(token): Be consistent on take_until("")

We aren't consistent on empty buffers between `simd` and not.

Fixes #489

src/stream/mod.rs

@@ -3479,6 +3479,7 @@ fn memchr3(token: (u8, u8, u8), slice: &[u8]) -> Option<usize> {
 #[inline(always)]
 fn memmem(slice: &[u8], literal: &[u8]) -> Option<crate::lib::std::ops::Range<usize>> {
     match literal.len() {
+        0 => Some(0..0),
         1 => memchr(literal[0], slice).map(|i| i..i + 1),
         _ => memmem_(slice, literal),
     }
@@ -3487,6 +3488,7 @@ fn memmem(slice: &[u8], literal: &[u8]) -> Option<crate::lib::std::ops::Range<us
 #[inline(always)]
 fn memmem2(slice: &[u8], literal: (&[u8], &[u8])) -> Option<crate::lib::std::ops::Range<usize>> {
     match (literal.0.len(), literal.1.len()) {
+        (0, _) | (_, 0) => Some(0..0),
         (1, 1) => memchr2((literal.0[0], literal.1[0]), slice).map(|i| i..i + 1),
         _ => memmem2_(slice, literal),
     }
@@ -3498,6 +3500,7 @@ fn memmem3(
     literal: (&[u8], &[u8], &[u8]),
 ) -> Option<crate::lib::std::ops::Range<usize>> {
     match (literal.0.len(), literal.1.len(), literal.2.len()) {
+        (0, _, _) | (_, 0, _) | (_, _, 0) => Some(0..0),
         (1, 1, 1) => memchr3((literal.0[0], literal.1[0], literal.2[0]), slice).map(|i| i..i + 1),
         _ => memmem3_(slice, literal),
     }

src/token/tests.rs

@@ -102,12 +102,6 @@ fn complete_take_until_empty() {
     fn take_until_empty(i: &str) -> IResult<&str, &str> {
         take_until(0, "").parse_peek(i)
     }
-    #[cfg(not(feature = "simd"))]
-    assert_eq!(
-        take_until_empty(""),
-        Err(ErrMode::Backtrack(error_position!(&"", ErrorKind::Slice)))
-    );
-    #[cfg(feature = "simd")]
     assert_eq!(take_until_empty(""), Ok(("", "")));
     assert_eq!(take_until_empty("end"), Ok(("end", "")));
 }