Merge #221 'Fix handling of optional regex captures'

Author: muggenhor

CHANGELOG.md

@@ -11,6 +11,7 @@ Please see [CONTRIBUTING.md](https://github.com/cucumber/cucumber/blob/master/CO
 * Statically linking `boost_system` ([#197](https://github.com/cucumber/cucumber-cpp/pull/197) Matthieu Longo)
 * Unable to `add_subdirectory(cucumber-cpp)` ([#211](https://github.com/cucumber/cucumber-cpp/pull/211) Sergey Bon)
 * Warning C4265 on Visual Studio ([#195](https://github.com/cucumber/cucumber-cpp/pull/195) Matthieu Longo)
+* Fix handling of optional regex captures ([#221](https://github.com/cucumber/cucumber-cpp/pull/221) Alain Martin)
 
 ## [0.5](https://github.com/cucumber/cucumber-cpp/compare/v0.4...v0.5) (2 July 2018)
 

src/Regex.cpp

@@ -37,6 +37,8 @@ FindRegexMatch::FindRegexMatch(const boost::regex &regexImpl, const std::string
             if (i->matched) {
                 RegexSubmatch s = {*i, i->first - expression.begin()};
                 submatches.push_back(s);
+            } else {
+                submatches.push_back(RegexSubmatch());
             }
         }
     }

tests/unit/RegexTest.cpp

@@ -46,6 +46,22 @@ TEST(RegexTest, matchesRegexWithSubmatches) {
     EXPECT_EQ("69", match->getSubmatches()[1].value);
 }
 
+TEST(RegexTest, matchesRegexWithOptionalSubmatches) {
+    Regex sum("^(\\d+)\\+(\\d+)(?:\\+(\\d+))?=(\\d+)$");
+
+    shared_ptr<RegexMatch> match(sum.find("1+2+3=6"));
+    EXPECT_TRUE(match->matches());
+    ASSERT_EQ(4, match->getSubmatches().size());
+
+    match = shared_ptr<RegexMatch>(sum.find("42+27=69"));
+    EXPECT_TRUE(match->matches());
+    ASSERT_EQ(4, match->getSubmatches().size());
+    EXPECT_EQ("42", match->getSubmatches()[0].value);
+    EXPECT_EQ("27", match->getSubmatches()[1].value);
+    EXPECT_EQ("", match->getSubmatches()[2].value);
+    EXPECT_EQ("69", match->getSubmatches()[3].value);
+}
+
 TEST(RegexTest, findAllDoesNotMatchIfNoTokens) {
     Regex sum("([^,]+)(?:,|$)");
     shared_ptr<RegexMatch> match(sum.findAll(""));