✨ added overload for std::vector<bool> #494

Adds a to_json function for std::vector<bool> to allow implicit
conversion from bit vectors to basic_json.

src/json.hpp

@@ -324,6 +324,19 @@ struct external_constructor<value_t::array>
         j.m_value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
         j.assert_invariant();
     }
+
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j, const std::vector<bool>& arr)
+    {
+        j.m_type = value_t::array;
+        j.m_value = value_t::array;
+        j.m_value.array->reserve(arr.size());
+        for (bool x : arr)
+        {
+            j.m_value.array->push_back(x);
+        }
+        j.assert_invariant();
+    }
 };
 
 template<>
@@ -562,6 +575,12 @@ void to_json(BasicJsonType& j, UnscopedEnumType e) noexcept
     external_constructor<value_t::number_integer>::construct(j, e);
 }
 
+template<typename BasicJsonType>
+void to_json(BasicJsonType& j, std::vector<bool> e) noexcept
+{
+    external_constructor<value_t::array>::construct(j, e);
+}
+
 template <
     typename BasicJsonType, typename CompatibleArrayType,
     enable_if_t <

src/json.hpp.re2c

@@ -324,6 +324,19 @@ struct external_constructor<value_t::array>
         j.m_value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
         j.assert_invariant();
     }
+
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j, const std::vector<bool>& arr)
+    {
+        j.m_type = value_t::array;
+        j.m_value = value_t::array;
+        j.m_value.array->reserve(arr.size());
+        for (bool x : arr)
+        {
+            j.m_value.array->push_back(x);
+        }
+        j.assert_invariant();
+    }
 };
 
 template<>
@@ -562,6 +575,12 @@ void to_json(BasicJsonType& j, UnscopedEnumType e) noexcept
     external_constructor<value_t::number_integer>::construct(j, e);
 }
 
+template<typename BasicJsonType>
+void to_json(BasicJsonType& j, std::vector<bool> e) noexcept
+{
+    external_constructor<value_t::array>::construct(j, e);
+}
+
 template <
     typename BasicJsonType, typename CompatibleArrayType,
     enable_if_t <

test/src/unit-regression.cpp

@@ -795,4 +795,13 @@ TEST_CASE("regression tests")
         std::string s2 = j2.dump();
         CHECK(s1 == s2);
     }
+
+    SECTION("issue #494 - conversion from vector<bool> to json fails to build")
+    {
+        std::vector<bool> boolVector = {false, true, false, false};
+        json j;
+        j["bool_vector"] = boolVector;
+
+        CHECK(j["bool_vector"].dump() == "[false,true,false,false]");
+    }
 }