clean up

- removed m_final member
- parse_internal now takes a reference to a basic_json object to fill
with data
- header is automatically regenerated if re2c file is changed

Makefile

@@ -16,7 +16,9 @@ json_unit: test/unit.cpp src/json.hpp test/catch.hpp
 	$(CXX) -std=c++11 $(CXXFLAGS) $(FLAGS) $(CPPFLAGS) -I src -I test $< $(LDFLAGS) -o $@
 
 # create scanner with re2c
-re2c: src/json.hpp.re2c
+re2c: src/json.hpp
+
+src/json.hpp: src/json.hpp.re2c
 	$(RE2C) -b -s -i --no-generation-date $< | $(SED) '1d' > src/json.hpp
 
 # static analyser

src/json.hpp.re2c

@@ -416,13 +416,12 @@ class basic_json
         // the initializer list could describe an object
         bool is_object = true;
 
-        // check if each element is an array with two elements whose first element
-        // is a string
+        // check if each element is an array with two elements whose first
+        // element is a string
         for (const auto& element : init)
         {
-            if ((element.m_final and element.m_type == value_t::array)
-                    or (element.m_type != value_t::array or element.size() != 2
-                        or element[0].m_type != value_t::string))
+            if ((element.m_type != value_t::array or element.size() != 2
+                    or element[0].m_type != value_t::string))
             {
                 // we found an element that makes it impossible to use the
                 // initializer list as object
@@ -434,9 +433,6 @@ class basic_json
         // adjust type if type deduction is not wanted
         if (not type_deduction)
         {
-            // mark this object's type as final
-            m_final = true;
-
             // if array is wanted, do not create an object though possible
             if (manual_type == value_t::array)
             {
@@ -758,6 +754,12 @@ class basic_json
         return m_type;
     }
 
+    /// return the type of the object (implicit)
+    inline operator value_t() const noexcept
+    {
+        return m_type;
+    }
+
     // return whether value is null
     inline bool is_null() const noexcept
     {
@@ -794,12 +796,6 @@ class basic_json
         return m_type == value_t::string;
     }
 
-    /// return the type of the object (implicit)
-    inline operator value_t() const noexcept
-    {
-        return m_type;
-    }
-
   private:
     //////////////////////
     // value conversion //
@@ -1083,6 +1079,7 @@ class basic_json
             throw std::runtime_error("cannot use [] with " + type_name());
         }
 
+        // fill gaps with null values
         for (size_t i = m_value.array->size(); i <= idx; ++i)
         {
             m_value.array->push_back(basic_json());
@@ -1520,6 +1517,7 @@ class basic_json
         {
             case (value_t::null):
             {
+                // null values are empty
                 return true;
             }
 
@@ -1551,6 +1549,7 @@ class basic_json
         {
             case (value_t::null):
             {
+                // null values are empty
                 return 0;
             }
 
@@ -1582,6 +1581,7 @@ class basic_json
         {
             case (value_t::null):
             {
+                // null values are empty
                 return 0;
             }
 
@@ -2258,9 +2258,6 @@ class basic_json
     /// the type of the current element
     value_t m_type = value_t::null;
 
-    /// whether the type of JSON object may change later
-    bool m_final = false;
-
     /// the value of the current element
     json_value m_value = {};
 
@@ -3850,7 +3847,8 @@ class basic_json
         /// public parser interface
         inline basic_json parse()
         {
-            basic_json result = parse_internal();
+            basic_json result;
+            parse_internal(result);
 
             expect(lexer::token_type::end_of_input);
 
@@ -3859,14 +3857,17 @@ class basic_json
 
       private:
         /// the actual parser
-        inline basic_json parse_internal()
+        inline void parse_internal(basic_json& pos)
         {
             switch (last_token)
             {
                 case (lexer::token_type::begin_object):
                 {
                     // explicitly set result to object to cope with {}
-                    basic_json result(value_t::object);
+                    pos.m_type = value_t::object;
+                    AllocatorType<object_t> alloc;
+                    pos.m_value.object = alloc.allocate(1);
+                    alloc.construct(pos.m_value.object);
 
                     // read next token
                     get_token();
@@ -3875,7 +3876,7 @@ class basic_json
                     if (last_token == lexer::token_type::end_object)
                     {
                         get_token();
-                        return result;
+                        return;
                     }
 
                     // otherwise: parse key-value pairs
@@ -3897,21 +3898,25 @@ class basic_json
 
                         // parse and add value
                         get_token();
-                        result.m_value.object->emplace(key, parse_internal());
+                        auto it = pos.m_value.object->emplace(key, nullptr);
+                        parse_internal(it.first->second);
                     }
                     while (last_token == lexer::token_type::value_separator);
 
                     // closing }
                     expect(lexer::token_type::end_object);
-                    get_token();
 
-                    return result;
+                    get_token();
+                    return;
                 }
 
                 case (lexer::token_type::begin_array):
                 {
                     // explicitly set result to object to cope with []
-                    basic_json result(value_t::array);
+                    pos.m_type = value_t::array;
+                    AllocatorType<array_t> alloc;
+                    pos.m_value.array = alloc.allocate(1);
+                    alloc.construct(pos.m_value.array);
 
                     // read next token
                     get_token();
@@ -3920,7 +3925,7 @@ class basic_json
                     if (last_token == lexer::token_type::end_array)
                     {
                         get_token();
-                        return result;
+                        return;
                     }
 
                     // otherwise: parse values
@@ -3933,40 +3938,51 @@ class basic_json
                         }
 
                         // parse and add value
-                        result.m_value.array->emplace_back(parse_internal());
+                        auto it = pos.m_value.array->insert(pos.m_value.array->end(), nullptr);
+                        parse_internal(*it);
                     }
                     while (last_token == lexer::token_type::value_separator);
 
                     // closing ]
                     expect(lexer::token_type::end_array);
-                    get_token();
 
-                    return result;
+                    get_token();
+                    return;
                 }
 
                 case (lexer::token_type::literal_null):
                 {
                     get_token();
-                    return basic_json(nullptr);
+                    return;
                 }
 
                 case (lexer::token_type::value_string):
                 {
-                    const auto s = m_lexer.get_string();
+                    pos.m_type = value_t::string;
+                    AllocatorType<string_t> alloc;
+                    pos.m_value.string = alloc.allocate(1);
+                    alloc.construct(pos.m_value.string, m_lexer.get_string());
+
                     get_token();
-                    return basic_json(s);
+                    return;
                 }
 
                 case (lexer::token_type::literal_true):
                 {
+                    pos.m_type = value_t::boolean;
+                    pos.m_value.boolean = true;
+
                     get_token();
-                    return basic_json(true);
+                    return;
                 }
 
                 case (lexer::token_type::literal_false):
                 {
+                    pos.m_type = value_t::boolean;
+                    pos.m_value.boolean = false;
+
                     get_token();
-                    return basic_json(false);
+                    return;
                 }
 
                 case (lexer::token_type::value_number):
@@ -3981,20 +3997,23 @@ class basic_json
                                                     m_lexer.get_token() + " is not a number");
                     }
 
-                    get_token();
-
                     // check if conversion loses precision
                     const auto int_val = static_cast<number_integer_t>(float_val);
                     if (approx(float_val, static_cast<number_float_t>(int_val)))
                     {
                         // we basic_json not lose precision -> return int
-                        return basic_json(int_val);
+                        pos.m_type = value_t::number_integer;
+                        pos.m_value.number_integer = int_val;
                     }
                     else
                     {
                         // we would lose precision -> returnfloat
-                        return basic_json(float_val);
+                        pos.m_type = value_t::number_float;
+                        pos.m_value.number_float = float_val;
                     }
+
+                    get_token();
+                    return;
                 }
 
                 default: