Mutable v3

json11.cpp

@@ -131,27 +131,6 @@ void Json::dump(string &out) const {
     m_ptr->dump(out);
 }
 
-/* * * * * * * * * * * * * * * * * * * *
- * Indexed wrapper to prevent autovivification
- */
-
-JsonIndex::JsonIndex(Json obj, const std::string & key)
-{
-    m_object = obj;
-    m_key = key;
-}
-
-Json & JsonIndex::operator =(const Json & value)
-{
-    auto & obj = m_object.object_items();
-    return obj[m_key] = value;
-}
-
-JsonIndex::operator Json()
-{
-    return m_object[m_key];
-}
-
 /* * * * * * * * * * * * * * * * * * * *
  * Value wrappers
  */
@@ -258,7 +237,7 @@ public:
 
 class JsonArray final : public Value<Json::ARRAY, Json::array> {
     Json::array &array_items() override { return m_value; }
-    Json & operator[](size_t i) override;
+    const Json & operator[](size_t i) const override;
 public:
     explicit JsonArray(const Json::array &value) : Value(value) {}
     explicit JsonArray(Json::array &&value)      : Value(move(value)) {}
@@ -266,7 +245,7 @@ public:
 
 class JsonObject final : public Value<Json::OBJECT, Json::object> {
     Json::object &object_items() override { return m_value; }
-    Json & operator[](const string &key) override;
+    const Json & operator[](const string &key) const override;
 public:
     explicit JsonObject(const Json::object &value) : Value(value) {}
     explicit JsonObject(Json::object &&value)      : Value(move(value)) {}
@@ -347,8 +326,8 @@ string Json::as_string()                          const { return m_ptr->as_strin
 const string & Json::string_value()               const { return m_ptr->string_value(); }
 vector<Json> & Json::array_items()                      { return m_ptr->array_items();  }
 map<string, Json> & Json::object_items()                { return m_ptr->object_items(); }
-Json & Json::operator[] (size_t i)                      { return (*m_ptr)[i];           }
-Json & Json::operator[] (const string &key)             { return (*m_ptr)[key];         }
+const Json & Json::operator[] (size_t i)          const { return (*m_ptr)[i];           }
+const Json & Json::operator[] (const string &key) const { return (*m_ptr)[key];         }
 
 double                    JsonValue::number_value()              const { return 0; }
 int64_                    JsonValue::int64_value()               const { return 0; }
@@ -356,16 +335,16 @@ uint64_                   JsonValue::uint64_value()              const { return
 bool                      JsonValue::bool_value()                const { return false; }
 string                    JsonValue::as_string()                 const { return statics().empty_string; }
 const string &            JsonValue::string_value()              const { return statics().empty_string; }
-vector<Json> &            JsonValue::array_items()                     { return statics().empty_vector; }
-map<string, Json> &       JsonValue::object_items()                    { return statics().empty_map; }
-Json &                    JsonValue::operator[] (size_t)               { return static_null(); }
-Json &                    JsonValue::operator[] (const string &)       { return static_null(); }
+vector<Json> &            JsonValue::array_items()                     { return statics().stub_vector; }
+map<string, Json> &       JsonValue::object_items()                    { return statics().stub_map; }
+const Json &              JsonValue::operator[] (size_t)         const { return static_null(); }
+const Json &              JsonValue::operator[] (const string &) const { return static_null(); }
 
-Json & JsonObject::operator[] (const string &key) {
+const Json & JsonObject::operator[] (const string &key) const {
     auto iter = m_value.find(key);
     return (iter == m_value.end()) ? static_null() : iter->second;
 }
-Json & JsonArray::operator[] (size_t i) {
+const Json & JsonArray::operator[] (size_t i) const {
     if (i >= m_value.size()) return static_null();
     else return m_value[i];
 }

json11.hpp

@@ -163,9 +163,9 @@ public:
     object &object_items();
 
     // Return a reference to arr[i] if this is an array, Json() otherwise.
-    Json & operator[](size_t i);
+    const Json & operator[](size_t i) const;
     // Return a reference to obj[key] if this is an object, Json() otherwise.
-    Json & operator[](const std::string &key);
+    const Json & operator[](const std::string &key) const;
 
     // Serialize.
     void dump(std::string &out) const;
@@ -220,20 +220,9 @@ public:
     bool has_shape(const shape & types, std::string & err) const;
 
 private:
-    friend class JsonIndex;
     std::shared_ptr<JsonValue> m_ptr;
 };
 
-class JsonIndex {
-protected:
-    Json m_object;
-    std::string m_key;
-public:
-    JsonIndex(Json obj, const std::string & key);
-    Json &operator = (const Json & value);
-    operator Json ();
-};
-
 // Internal class hierarchy - JsonValue objects are not exposed to users of this API.
 class JsonValue {
 protected:
@@ -252,9 +241,9 @@ protected:
     virtual const std::string &string_value() const;
     virtual std::string as_string() const;
     virtual Json::array &array_items();
-    virtual Json &operator[](size_t i);
+    virtual const Json &operator[](size_t i) const;
     virtual Json::object &object_items();
-    virtual Json &operator[](const std::string &key);
+    virtual const Json &operator[](const std::string &key) const;
     virtual ~JsonValue() {}
 };