Don't union inner literals of repetitions.

If we do, this results in extracting `foofoofoo` from `(\wfoo){3}`,
which is wrong. This does prevent us from extracting `foofoofoo` from
`foo{3}`, which is unfortunate, but we miss plenty of other stuff too.
Literal extracting needs a good rethink (all the way down into the regex
engine).

Fixes BurntSushi#93

grep/src/literals.rs

@@ -8,7 +8,6 @@ Note that this implementation is incredibly suspicious. We need something more
 principled.
 */
 use std::cmp;
-use std::iter;
 
 use regex::bytes::Regex;
 use syntax::{
@@ -181,17 +180,19 @@ fn repeat_range_literals<F: FnMut(&Expr, &mut Literals)>(
     lits: &mut Literals,
     mut f: F,
 ) {
-    use syntax::Expr::*;
-
     if min == 0 {
         // This is a bit conservative. If `max` is set, then we could
         // treat this as a finite set of alternations. For now, we
         // just treat it as `e*`.
         lits.cut();
     } else {
         let n = cmp::min(lits.limit_size(), min as usize);
-        let es = iter::repeat(e.clone()).take(n).collect();
-        f(&Concat(es), lits);
+        // We only extract literals from a single repetition, even though
+        // we could do more. e.g., `a{3}` will have `a` extracted instead of
+        // `aaa`. The reason is that inner literal extraction can't be unioned
+        // across repetitions. e.g., extracting `foofoofoo` from `(\w+foo){3}`
+        // is wrong.
+        f(e, lits);
         if n < min as usize {
             lits.cut();
         }

tests/tests.rs

@@ -703,6 +703,15 @@ clean!(regression_90, "test", ".", |wd: WorkDir, mut cmd: Command| {
     assert_eq!(lines, ".foo:test\n");
 });
 
+// See: https://github.com/BurntSushi/ripgrep/issues/93
+clean!(regression_93, r"(\d{1,3}\.){3}\d{1,3}", ".",
+|wd: WorkDir, mut cmd: Command| {
+    wd.create("foo", "192.168.1.1");
+
+    let lines: String = wd.stdout(&mut cmd);
+    assert_eq!(lines, "foo:192.168.1.1\n");
+});
+
 // See: https://github.com/BurntSushi/ripgrep/issues/20
 sherlock!(feature_20, "Sherlock", ".", |wd: WorkDir, mut cmd: Command| {
     cmd.arg("--no-filename");