Add default nullptr value to base parameter of url::parse

Also add url::parse function with `const url& base` parameter.

include/upa/url.h

@@ -171,11 +171,21 @@ class url {
     /// @param[in] base    pointer to base URL, may be nullptr
     /// @return error code (@a validation_errc::ok on success)
     template <class T, enable_if_str_arg_t<T> = 0>
-    validation_errc parse(T&& str_url, const url* base) {
+    validation_errc parse(T&& str_url, const url* base = nullptr) {
         const auto inp = make_str_arg(std::forward<T>(str_url));
         return do_parse(inp.begin(), inp.end(), base);
     }
 
+    /// @brief Parses given URL string against base URL.
+    ///
+    /// @param[in] str_url URL string to parse
+    /// @param[in] base    base URL
+    /// @return error code (@a validation_errc::ok on success)
+    template <class T, enable_if_str_arg_t<T> = 0>
+    validation_errc parse(T&& str_url, const url& base) {
+        return parse(std::forward<T>(str_url), &base);
+    }
+
     /// @brief Checks if a given URL string can be successfully parsed
     ///
     /// If @a pbase is not nullptr, then try to parse against *pbase URL.
@@ -1086,7 +1096,7 @@ inline std::string url::origin() const {
         // Note: this library does not support blob URL store, so it allways assumes
         // URL's blob URL entry is null and retrieves origin from the URL's path.
         url path_url;
-        if (path_url.parse(get_part_view(PATH), nullptr) == validation_errc::ok &&
+        if (path_url.parse(get_part_view(PATH)) == validation_errc::ok &&
             path_url.is_http_scheme())
             return path_url.origin();
     }

test/test-url.cpp

@@ -180,6 +180,22 @@ TEST_CASE("url parsing constructor with base URL string") {
 
 // Parse URL
 
+TEST_CASE("Two url::parse functions") {
+    upa::url url;
+    upa::url url_base;
+
+    // first url::parse function
+    CHECK(url_base.parse("http://example.org") == upa::validation_errc::ok);
+    CHECK(url_base.href() == "http://example.org/");
+
+    CHECK(url.parse("/htap", &url_base) == upa::validation_errc::ok);
+    CHECK(url.href() == "http://example.org/htap");
+
+    // second url::parse function
+    CHECK(url.parse("/path", url_base) == upa::validation_errc::ok);
+    CHECK(url.href() == "http://example.org/path");
+}
+
 TEST_CASE("url::parse must clear old URL data") {
     upa::url url;