Fix #204.

src/dfa.rs

@@ -1319,7 +1319,19 @@ impl<'a> Fsm<'a> {
         empty_flags: EmptyFlags,
         state_flags: StateFlags,
     ) -> Option<StatePtr> {
-        let flagi = empty_flags.as_index();
+        // Compute an index into our cache of start states based on the set
+        // of empty/state flags set at the current position in the input. We
+        // don't use every flag since not all flags matter. For example, since
+        // matches are delayed by one byte, start states can never be match
+        // states.
+        let flagi = {
+            (((empty_flags.start as u8) << 0) |
+             ((empty_flags.end as u8) << 1) |
+             ((empty_flags.start_line as u8) << 2) |
+             ((empty_flags.end_line as u8) << 3) |
+             ((state_flags.is_word() as u8) << 4))
+            as usize
+        };
         match self.cache.start_states[flagi] {
             STATE_UNKNOWN => {}
             STATE_DEAD => return Some(STATE_DEAD),
@@ -1592,18 +1604,6 @@ impl Transitions {
     }
 }
 
-impl EmptyFlags {
-    fn as_index(&self) -> usize {
-        (((self.start as u8) << 0) |
-         ((self.end as u8) << 1) |
-         ((self.start_line as u8) << 2) |
-         ((self.end_line as u8) << 3) |
-         ((self.word_boundary as u8) << 4) |
-         ((self.not_word_boundary as u8) << 5))
-        as usize
-    }
-}
-
 impl StateFlags {
     fn is_match(&self) -> bool {
         self.0 & 0b0000000_1 > 0

tests/api.rs

@@ -234,3 +234,8 @@ expand!(expand9, r"(?P<a>\w+)\s+(?P<b>\d+)",
         "abc 123", " $b $a ", " 123 abc ");
 expand!(expand10, r"(?P<a>\w+)\s+(?P<b>\d+)",
         "abc 123", "$bz$az", "");
+
+split!(split1, r"\s+", "a b\nc\td\n\t e",
+       &[t!("a"), t!("b"), t!("c"), t!("d"), t!("e")]);
+split!(split2, r"\b", "a b c",
+       &[t!(""), t!("a"), t!(" "), t!("b"), t!(" "), t!("c")]);

tests/macros.rs

@@ -114,3 +114,14 @@ macro_rules! nomatset {
         }
     }
 }
+
+macro_rules! split {
+    ($name:ident, $re:expr, $text:expr, $expected:expr) => {
+        #[test]
+        fn $name() {
+            let re = regex!($re);
+            let splitted: Vec<_> = re.split(t!($text)).collect();
+            assert_eq!($expected, &*splitted);
+        }
+    }
+}

tests/regression.rs

@@ -46,6 +46,14 @@ mat!(uni_case_lower_nocase_flag, u!(r"(?i)\p{Ll}+"), "ΛΘΓΔα", Some((0, 10))
 // See: https://github.com/rust-lang-nursery/regex/issues/191
 mat!(many_alternates, r"1|2|3|4|5|6|7|8|9|10|int", "int", Some((0, 3)));
 
+// burntsushi was bad and didn't create an issue for this bug.
 mat!(anchored_prefix1, r"^a\S", "a ", None);
 mat!(anchored_prefix2, r"^a\S", "foo boo a ", None);
 mat!(anchored_prefix3, r"^-[a-z]", "r-f", None);
+
+// See: https://github.com/rust-lang-nursery/regex/issues/204
+split!(split_on_word_boundary, r"\b", r"Should this (work?)",
+       &[t!(""), t!("Should"), t!(" "), t!("this"),
+         t!(" ("), t!("work"), t!("?)")]);
+matiter!(word_boundary_dfa, r"\b", "a b c",
+         (0, 0), (1, 1), (2, 2), (3, 3), (4, 4), (5, 5));

tests/word_boundary.rs

@@ -40,6 +40,7 @@ matiter!(wb37, r"^^^^^\b.$$$$$", "x", (0, 1));
 matiter!(wb38, r"^^^^^\b$$$$$", "x");
 matiter!(wb39, r"^^^^^\b\b\b.\b\b\b$$$$$", "x", (0, 1));
 matiter!(wb40, r"\b.+\b", "$$abc$$", (2, 5));
+matiter!(wb41, r"\b", "a b c", (0, 0), (1, 1), (2, 2), (3, 3), (4, 4), (5, 5));
 
 matiter!(nb1, r"\Bfoo\B", "n foo xfoox that", (7, 10));
 matiter!(nb2, r"a\B", "faoa x", (1, 2));