Modifying grammar to check start fo regex quickly to speed-up attribute parsing

Author: CharlesC87

CMakeLists.txt

@@ -18,12 +18,16 @@ set(
 	src/grammar.cpp
 	src/parser.cpp
 	src/writer.cpp
+	src/matcher.cpp
 )
 
 set(
 	HEADER_FILES
 	include/sdptransform.hpp
 	include/json.hpp
+	include/string_view.hpp
+	include/string_view_lite.hpp
+	include/matcher.hpp
 )
 
 add_library(sdptransform STATIC ${SOURCE_FILES} ${HEADER_FILES})

include/matcher.hpp

@@ -0,0 +1,49 @@
+#pragma once
+
+#include "string_view.hpp"
+#include <vector>
+#include <regex>
+#include <memory>
+
+namespace sdptransform
+{
+    namespace matcher
+    {
+        class Interface {
+        public:
+            virtual bool doMatch(const std::string& content) const = 0;
+            using Results=std::vector<string_view>;
+            virtual Results getMatches(const std::string& content) const = 0;
+        };
+        using Ptr=std::shared_ptr<Interface>;
+
+        class Regex final : public Interface {
+        public:
+            Regex(std::string&& regex) : regex_(std::move(regex)) {}
+            Regex(const char* prefix, std::string&& regex) : regex_(std::move(regex)), prefix_(prefix) {}
+            bool doMatch(const std::string& content) const override;
+            Results getMatches(const std::string& content) const override;
+        private:
+            std::pair<std::string::const_iterator,std::string::const_iterator> getIteratorAfterPrefixMatch(const std::string& content) const;
+            std::regex  regex_;
+            std::string prefix_={};
+        };
+
+        template<typename... T>
+        inline std::shared_ptr<Regex> createRegex(T&&... vals) {
+            return std::make_shared<Regex>(std::forward<T>(vals)...);
+        }
+
+        class WholeMatcher final : public Interface {
+        public:
+            bool doMatch(const std::string&) const override { return true; }
+            Results getMatches(const std::string& content) const override { return {string_view(content)}; }
+        };
+
+        inline std::shared_ptr<WholeMatcher> createWholeMatcher() {
+            return std::make_shared<WholeMatcher>();
+        }
+        
+    } // namespace matcher
+    
+} // namespace sdptransform

include/sdptransform.hpp

@@ -5,8 +5,8 @@
 #include <string>
 #include <vector>
 #include <map>
-#include <regex>
 #include <functional>
+#include "matcher.hpp"
 
 using json = nlohmann::json;
 
@@ -18,7 +18,7 @@ namespace sdptransform
 		{
 			std::string name;
 			std::string push;
-			std::regex reg;
+			matcher::Ptr reg;
 			std::vector<std::string> names;
 			std::vector<char> types;
 			std::string format;

include/string_view.hpp

@@ -6,7 +6,8 @@
 #include <string_view>
 namespace sdptransform {
     using string_view=std::string_view;
-    string_view convertMatchToView(const std::ssub_match& match) {
+    inline string_view convertMatchToView(const std::ssub_match& match)
+    {
         #if __cplusplus >= 202002L && __cpp_lib_concepts
         return string_view(match.first, match.second);
         #else
@@ -18,7 +19,8 @@ namespace sdptransform {
 #include <string_view_lite.hpp>
 namespace sdptransform {
     using string_view=string_view_lite;
-    string_view convertMatchToView(const std::ssub_match& match) {
+    inline string_view convertMatchToView(const std::ssub_match& match)
+    {
         return string_view(match.first, match.second);
     }
 }

include/string_view_lite.hpp

@@ -38,7 +38,7 @@ namespace sdptransform
             }
         }
         string_view_lite(std::string::const_iterator begin, std::string::const_iterator end) : data_(&(*begin)), size_(end - begin) {}
-        string_view_lite(const std::string &s) : data_(s.data()), size_(s.size()) {}
+        explicit string_view_lite(const std::string &s) : data_(s.data()), size_(s.size()) {}
 
         // iterator support
         constexpr const_iterator begin() const noexcept { return data_; }
@@ -176,7 +176,7 @@ namespace sdptransform
         size_type size_ = 0U;     // exposition only
     };
 
-    std::basic_ostream<string_view_lite::value_type, string_view_lite::Traits_type> &
+    inline std::basic_ostream<string_view_lite::value_type, string_view_lite::Traits_type> &
     operator<<(std::basic_ostream<string_view_lite::value_type, string_view_lite::Traits_type> &os,
                string_view_lite str)
     {