make argparse work on c++ 17

include/blt/compatibility.h

@@ -22,10 +22,12 @@
 #if __cplusplus >= 202002L
     #define BLT_CONTAINS(container, value) container.contains(value)
     #define BLT_CPP20_CONSTEXPR constexpr
+    #define BLT_USE_CPP20
 #else
     #include <algorithm>
     #define BLT_CONTAINS(container, value) std::find(container.begin(), container.end(), value) != container.end()
     #define BLT_CPP20_CONSTEXPR
+    #undef BLT_USE_CPP20
 #endif
 
 #define INCLUDE_FS \

include/blt/parse/argparse.h

@@ -13,6 +13,7 @@
 #include <initializer_list>
 #include <optional>
 #include <blt/std/hashmap.h>
+#include <blt/std/string.h>
 #include <variant>
 #include <algorithm>
 #include <type_traits>
@@ -118,7 +119,6 @@ namespace blt
     
     struct arg_properties_t
     {
-        private:
         public:
             arg_vector_t a_flags;
             arg_action_t a_action = arg_action_t::STORE;
@@ -130,6 +130,11 @@ namespace blt
             std::string a_version{};
             std::string a_metavar{};
             bool a_required = true;
+            
+            arg_properties_t() = delete;
+            
+            explicit arg_properties_t(arg_vector_t flags): a_flags(std::move(flags))
+            {}
     };
     
     class arg_builder
@@ -237,13 +242,13 @@ namespace blt
             // returns true if the current arg is a flag
             inline bool isFlag()
             {
-                return args[currentIndex].starts_with('-');
+                return blt::string::starts_with(args[currentIndex], '-');
             }
             
             // returns true if we have next and the next arg is a flag
             inline bool isNextFlag()
             {
-                return hasNext() && args[currentIndex + 1].starts_with('-');
+                return hasNext() && blt::string::starts_with(args[currentIndex + 1], '-');
             }
             
             // advances to the next flag
@@ -306,6 +311,7 @@ namespace blt
                     return static_cast<T>(std::stoll(s));
                 return static_cast<T>(std::stoull(s));
             }
+        
         private:
             struct
             {
@@ -359,9 +365,9 @@ namespace blt
                     
                     inline bool contains(const std::string& key)
                     {
-                        if (key.starts_with("--"))
+                        if (blt::string::starts_with(key, "--"))
                             return data.find(key.substr(2)) != data.end();
-                        if (key.starts_with('-'))
+                        if (blt::string::starts_with(key, '-'))
                             return data.find(key.substr(1)) != data.end();
                         return data.find(key) != data.end();
                     }

include/blt/std/string.h

@@ -63,6 +63,9 @@ namespace blt::string
     
     static inline BLT_CPP20_CONSTEXPR bool starts_with(const std::string& string, const std::string& search)
     {
+#ifdef BLT_USE_CPP20
+        return string.starts_with(search);
+#else
         if (search.length() > string.length())
             return false;
         auto chars = string.c_str();
@@ -73,10 +76,25 @@ namespace blt::string
                 return false;
         }
         return true;
+#endif
+    }
+    
+    static inline BLT_CPP20_CONSTEXPR bool starts_with(const std::string& string, char search)
+    {
+#ifdef BLT_USE_CPP20
+        return string.starts_with(search);
+#else
+        if (string.empty())
+            return false;
+        return string[0] == search;
+#endif
     }
     
     static inline BLT_CPP20_CONSTEXPR bool ends_with(const std::string& string, const std::string& search)
     {
+#ifdef BLT_USE_CPP20
+        return string.ends_with(search);
+#else
         if (search.length() > string.length())
             return false;
         auto chars = string.c_str();
@@ -88,6 +106,18 @@ namespace blt::string
                 return false;
         }
         return true;
+#endif
+    }
+    
+    static inline BLT_CPP20_CONSTEXPR bool ends_with(const std::string& string, char search)
+    {
+#ifdef BLT_USE_CPP20
+        return string.ends_with(search);
+#else
+        if (string.empty())
+            return false;
+        return string[string.size() - 1] == search;
+#endif
     }
     
     static inline BLT_CPP20_CONSTEXPR bool contains(const std::string& string, const char search)
@@ -97,7 +127,8 @@ namespace blt::string
             return c == search;
         });
 #else
-        for (const char c : string){
+        for (const char c : string)
+        {
             if (c == search)
                 return true;
         }
@@ -278,7 +309,8 @@ namespace blt::string
             return std::isdigit(c);
         });
 #else
-        for (const char c : s){
+        for (const char c : s)
+        {
             if (!std::isdigit(c))
                 return false;
         }