Bill Fisher: This patch fixes a bug where std::regex in ECMAScript mode was ignoring capture groups inside lookahead assertions.

For example, matching /(?=(a))(a)/ to "a" should yield two captures: \1 = "a", \2 = "a"

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@186954 91177308-0d34-0410-b5e6-96231b3b80d8

test/re/re.alg/re.alg.match/lookahead_capture.pass.cpp

@@ -0,0 +1,98 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <regex>
+
+// template <class BidirectionalIterator, class Allocator, class charT, class traits>
+//     bool
+//     regex_match(BidirectionalIterator first, BidirectionalIterator last,
+//                  match_results<BidirectionalIterator, Allocator>& m,
+//                  const basic_regex<charT, traits>& e,
+//                  regex_constants::match_flag_type flags = regex_constants::match_default);
+
+// std::regex in ECMAScript mode should not ignore capture groups inside lookahead assertions. 
+// For example, matching /(?=(a))(a)/ to "a" should yield two captures: \1 = "a", \2 = "a"
+
+#include <regex>
+#include <cassert>
+
+#include "test_iterators.h"
+
+int main()
+{
+    {
+        std::regex re{"^(?=(.))a$"};
+        assert(re.mark_count() == 1);
+
+        std::string s{"a"};
+        std::smatch m;
+        assert(std::regex_match(s, m, re));
+        assert(m.size() == 2);
+        assert(m[0] == "a");
+        assert(m[1] == "a");
+    }
+
+    {
+        std::regex re{"^(a)(?=(.))(b)$"};
+        assert(re.mark_count() == 3);
+
+        std::string s{"ab"};
+        std::smatch m;
+        assert(std::regex_match(s, m, re));
+        assert(m.size() == 4);
+        assert(m[0] == "ab");
+        assert(m[1] == "a");
+        assert(m[2] == "b");
+        assert(m[3] == "b");
+    }
+
+    {
+        std::regex re{"^(.)(?=(.)(?=.(.)))(...)$"};
+        assert(re.mark_count() == 4);
+
+        std::string s{"abcd"};
+        std::smatch m;
+        assert(std::regex_match(s, m, re));
+        assert(m.size() == 5);
+        assert(m[0] == "abcd");
+        assert(m[1] == "a");
+        assert(m[2] == "b");
+        assert(m[3] == "d");
+        assert(m[4] == "bcd");
+    }
+
+    {
+        std::regex re{"^(a)(?!([^b]))(.c)$"};
+        assert(re.mark_count() == 3);
+
+        std::string s{"abc"};
+        std::smatch m;
+        assert(std::regex_match(s, m, re));
+        assert(m.size() == 4);
+        assert(m[0] == "abc");
+        assert(m[1] == "a");
+        assert(m[2] == "");
+        assert(m[3] == "bc");
+    }
+
+    {
+        std::regex re{"^(?!((b)))(?=(.))(?!(abc)).b$"};
+        assert(re.mark_count() == 4);
+
+        std::string s{"ab"};
+        std::smatch m;
+        assert(std::regex_match(s, m, re));
+        assert(m.size() == 5);
+        assert(m[0] == "ab");
+        assert(m[1] == "");
+        assert(m[2] == "");
+        assert(m[3] == "a");
+        assert(m[4] == "");
+    }
+}