Add comments describing the behavior of filters

googletest/src/gtest.cc

@@ -752,6 +752,7 @@ class Filter {
   std::vector<std::string> patterns_;
 
  public:
+  // Constructs a filter form a string of patterns separated by `:`.
   explicit Filter(const std::string& filter) {
     if (filter.empty()) return;
 
@@ -766,6 +767,8 @@ class Filter {
     }
   }
 
+  // Returns true if and only if name matches at least one of the patterns in
+  // the filter.
   bool MatchesName(const std::string& name) const {
     const auto pattern_matches_name = [&name](const std::string& pattern) {
       return PatternMatchesString(name, pattern.c_str(),
@@ -790,17 +793,24 @@ class PositiveAndNegativeFilter {
               filter.substr(dash_pos + 1)};
     }
   }
-
   PositiveAndNegativeFilter(
       const std::pair<std::string, std::string>& positive_and_negative_filters)
       : positive_filter_(positive_and_negative_filters.first),
         negative_filter_(positive_and_negative_filters.second) {}
 
  public:
+  // Constructs a positive and a negative filter from a string. The string
+  // contains a positive filter optionally followed by a '-' character and a
+  // negative filter. In case only a negative filter is provided the positive
+  // filter will be assumed "*".
+  // A filter is a list of patterns separated by ':'.
   explicit PositiveAndNegativeFilter(const std::string& filter)
       : PositiveAndNegativeFilter(BreakIntoPositiveAndNegativeFilters(filter)) {
   }
 
+  // Returns true if and only if test name (this is generated by appending test
+  // suit name and test name via a '.' character) matches the positive filter
+  // and does not match the negative filter.
   bool MatchesTest(const std::string& test_suite_name,
                    const std::string& test_name) const {
     const std::string& full_name = test_suite_name + "." + test_name.c_str();
@@ -808,6 +818,8 @@ class PositiveAndNegativeFilter {
     return MatchesName(full_name);
   }
 
+  // Returns true if and only if name matches the positive filter and does not
+  // match the negative filter.
   bool MatchesName(const std::string& name) const {
     return positive_filter_.MatchesName(name) &&
            !negative_filter_.MatchesName(name);