working hmap class

examples/hmap_example.cpp

@@ -182,23 +182,8 @@ int main()
 
     std::print("push element with key '{}' and value {}\t...", k2, s1);
     ok = hm.push(
-        k2, s1,
-        [](auto const& v) -> decltype(hm)::hmap_expected_t<const char*> {
-            return v.c_str();
-            // if (v) {
-            //     return v.c_str();
-            // } else {
-            //     return std::unexpected(v.error());
-            // }
-        },
-        [](auto const& v) -> decltype(hm)::hmap_expected_t<std::string> {
-            return std::string(v.value());
-            // if (v) {
-            //     return std::string(v.value());
-            // } else {
-            //     return std::unexpected(v.error());
-            // }
-        });
+        k2, s1, [](auto const& v) -> hmap_expected_t<const char*> { return v.c_str(); },
+        [](auto const& v) -> hmap_expected_t<std::string> { return std::string(v); });
     if (!ok) {
         std::println("cannot insert the value {}", s1);
     } else {
@@ -213,6 +198,8 @@ int main()
         std::println("OK");
     }
 
+    std::println("in total {} elelents were pushed", hm.size());
+
     std::println("\n");
 
     std::print("get '{}'-element as double: ", k1);
@@ -223,5 +210,15 @@ int main()
         std::println("FAIL");
     }
 
+    std::println("\n");
+
+    std::print("get '{}'-element as const char*: ", k2);
+    auto sp2 = hm.get<const char*>(k2);
+    if (sp2) {
+        std::println("{}", sp2.value());
+    } else {
+        std::println("FAIL");
+    }
+
     return 0;
 }

include/snipplib/containers/snplib_hmap.h

@@ -116,6 +116,7 @@ public:
         return does_contain;
     }
 
+
     void clear()
     {
         for (auto& func : _clearFunc) {
@@ -413,15 +414,17 @@ inline std::error_code make_error_code(hmap_error_e ec)
 }
 
 
+typedef std::error_code hmap_error_t;
+
+template <typename VT>
+using hmap_expected_t = std::expected<VT, hmap_error_t>;
+
+
+
 template <snplib_hashable_c KeyT>
 class hmap
 {
 public:
-    typedef std::error_code error_t;
-
-    template <typename VT>
-    using hmap_expected_t = std::expected<VT, hmap::error_t>;
-
     template <typename VT, typename UT>
     using hmap_user_conv_from_t = std::function<hmap_expected_t<UT>(hmap_expected_t<VT> const&)>;
 
@@ -439,7 +442,7 @@ protected:
 
     template <typename UT>
     inline static std::unordered_map<const hmap*,
-                                     std::unordered_map<KeyT, std::function<hmap::error_t(UT const&, const hmap*)>>>
+                                     std::unordered_map<KeyT, std::function<hmap_error_t(UT const&, const hmap*)>>>
         _setter{};
 
 
@@ -555,6 +558,16 @@ public:
         return does_contain;
     }
 
+    bool erase(KeyT const& key)
+    {
+        bool ok = false;
+        for (auto& func : _eraseFunc) {
+            ok |= func(key, this);
+        }
+
+        return ok;
+    }
+
     void clear()
     {
         for (auto& func : _clearFunc) {
@@ -574,6 +587,7 @@ public:
         return N;
     }
 
+
     template <typename VT>
     bool push(KeyT const& key, VT&& value)
     {
@@ -632,7 +646,9 @@ public:
         // NOTE: do not use here iterator since after insertion
         //       an rehashing may occur and all iterators will be invalidated!
 
-        _getter<v_t>[this].emplace(key, [key](const hmap* obj) { return _values<v_t>[obj][key]; });
+        _getter<v_t>[this].emplace(key,
+                                   [key](const hmap* obj) -> hmap_expected_t<v_t> { return _values<v_t>[obj][key]; });
+
         _setter<v_t>[this].emplace(key, [key](const v_t& v, const hmap* obj) {
             _values<v_t>[obj][key] = v;
             return hmap_error_e::ERROR_OK;
@@ -643,8 +659,8 @@ public:
 
 
     // FTs - conversional functions:
-    //     convert-from: std::function<hmap_expected_t<UT>(hmap_expected_t<VT> const&)> (from inner type to user)
-    //     convert-to:   std::function<hmap_expected_t<VT>(hmap_expected_t<UT> const&)> (from user type to inner)
+    //     convert-from: std::function<hmap_expected_t<UT>(VT const&)> (from inner type to user)
+    //     convert-to:   std::function<hmap_expected_t<VT>(UT const&)> (from user type to inner)
     //
     template <typename VT, typename... FTs>
         requires(sizeof...(FTs) > 1)
@@ -669,14 +685,14 @@ public:
 
             _getter<u_t>[this].emplace(
                 kk,
-                [kk, from_cnv_func_arg =
-                         std::forward<decltype(from_cnv_func)>(from_cnv_func)](const hmap* obj) mutable -> u_t {
+                [kk, from_cnv_func_arg = std::forward<decltype(from_cnv_func)>(from_cnv_func)](
+                    const hmap* obj) mutable -> hmap_expected_t<u_t> {
                     return std::forward<decltype(from_cnv_func_arg)>(from_cnv_func_arg)(_values<v_t>[obj][kk]);
                 });
 
             _setter<u_t>[this].emplace(kk,
                                        [kk, to_cnv_func_arg = std::forward<decltype(to_cnv_func)>(to_cnv_func)](
-                                           const u_t& v, const hmap* obj) mutable -> hmap::error_t {
+                                           const u_t& v, const hmap* obj) mutable -> hmap_error_t {
                                            auto val = std::forward<decltype(to_cnv_func_arg)>(to_cnv_func_arg)(v);
                                            if (val) {
                                                _values<v_t>[obj][kk] = val.value();
@@ -708,6 +724,9 @@ public:
         return ok;
     }
 
+    //
+    // overloaded method with trivial conversion functions constructed from
+    // element types of the input std::tuple
     template <typename VT, typename... Ts>
         requires(sizeof...(Ts) > 0)
     auto push(KeyT const& key, VT&& value, std::tuple<Ts...>)
@@ -735,7 +754,7 @@ public:
     }
 
     template <typename UT>
-    hmap::error_t set(KeyT const& key, UT&& value)
+    hmap_error_t set(KeyT const& key, UT&& value)
     {
         using u_t = std::decay_t<UT>;