literal: fix reverse suffix literal optimization again

BurntSushi · BurntSushi · commit edf45e6f5fa5 · 2019-02-27T17:37:40.000-05:00
The position at which we start searching for the literal should begin
at the given starting position, not 0.
diff --git a/src/exec.rs b/src/exec.rs
@@ -745,13 +745,13 @@ impl<'c> ExecNoSync<'c> {
         debug_assert!(lcs.len() >= 1);
         let mut start = original_start;
         let mut end = start;
-        let mut last_literal_match = 0;
+        let mut last_literal = start;
         while end <= text.len() {
-            last_literal_match += match lcs.find(&text[last_literal_match..]) {
+            last_literal += match lcs.find(&text[last_literal..]) {
                 None => return Some(NoMatch(text.len())),
                 Some(i) => i,
             };
-            end = last_literal_match + lcs.len();
+            end = last_literal + lcs.len();
             match dfa::Fsm::reverse(
                 &self.ro.dfa_reverse,
                 self.cache,
@@ -760,10 +760,10 @@ impl<'c> ExecNoSync<'c> {
                 end - start,
             ) {
                 Match(0) | NoMatch(0) => return None,
-                Match(s) => return Some(Match((s + start, end))),
+                Match(i) => return Some(Match((start + i, end))),
                 NoMatch(i) => {
-                    start = i;
-                    last_literal_match += 1;
+                    start += i;
+                    last_literal += 1;
                     continue;
                 }
                 Quit => return Some(Quit),
diff --git a/tests/regression.rs b/tests/regression.rs
@@ -83,7 +83,9 @@ ismatch!(strange_anchor_non_complete_prefix, r"a^{2}", "", false);
 ismatch!(strange_anchor_non_complete_suffix, r"${2}a", "", false);
 
 // See: https://github.com/BurntSushi/ripgrep/issues/1203
-ismatch!(wat1, r"[0-4][0-4][0-4]000", "153.230000", true);
+ismatch!(reverse_suffix1, r"[0-4][0-4][0-4]000", "153.230000", true);
+ismatch!(reverse_suffix2, r"\d\d\d000", "153.230000\n", true);
+matiter!(reverse_suffix3, r"\d\d\d000", "153.230000\n", (4, 10));
 
 // See: https://github.com/rust-lang/regex/issues/334
 mat!(captures_after_dfa_premature_end, r"a(b*(X|$))?", "abcbX",
