Redesigned JsonVariant to leverage converting constructors instead of assignment operators

include/ArduinoJson/JsonVariantBase.hpp

@@ -0,0 +1,148 @@
+// Copyright Benoit Blanchon 2014-2015
+// MIT License
+//
+// Arduino JSON library
+// https://github.com/bblanchon/ArduinoJson
+
+#pragma once
+
+#include "Internals/ForceInline.hpp"
+
+namespace ArduinoJson {
+
+// Forward declarations.
+class JsonArraySubscript;
+class JsonObjectSubscript;
+
+template <typename TImpl>
+class JsonVariantBase {
+ public:
+  // Gets the variant as a boolean value.
+  // Returns false if the variant is not a boolean value.
+  JSON_FORCE_INLINE operator bool() const { return as<bool>(); }
+
+  // Gets the variant as a floating-point value.
+  // Returns 0.0 if the variant is not a floating-point value
+  JSON_FORCE_INLINE operator double() const { return as<double>(); }
+  JSON_FORCE_INLINE operator float() const { return as<float>(); }
+
+  // Gets the variant as an integer value.
+  // Returns 0 if the variant is not an integer value.
+  JSON_FORCE_INLINE operator signed long() const { return as<signed long>(); }
+  JSON_FORCE_INLINE operator signed char() const { return as<signed char>(); }
+  JSON_FORCE_INLINE operator signed int() const { return as<signed int>(); }
+  JSON_FORCE_INLINE operator signed short() const { return as<signed short>(); }
+  JSON_FORCE_INLINE operator unsigned char() const {
+    return as<unsigned char>();
+  }
+  JSON_FORCE_INLINE operator unsigned int() const { return as<unsigned int>(); }
+  JSON_FORCE_INLINE operator unsigned long() const {
+    return as<unsigned long>();
+  }
+  JSON_FORCE_INLINE operator unsigned short() const {
+    return as<unsigned short>();
+  }
+
+  // Gets the variant as a string.
+  // Returns NULL if variant is not a string.
+  JSON_FORCE_INLINE operator const char *() const { return as<const char *>(); }
+  JSON_FORCE_INLINE const char *asString() const { return as<const char *>(); }
+
+  // Gets the variant as an array.
+  // Returns a reference to the JsonArray or JsonArray::invalid() if the
+  // variant
+  // is not an array.
+  JSON_FORCE_INLINE operator JsonArray &() const { return as<JsonArray &>(); }
+  JSON_FORCE_INLINE JsonArray &asArray() const { return as<JsonArray &>(); }
+
+  // Gets the variant as an object.
+  // Returns a reference to the JsonObject or JsonObject::invalid() if the
+  // variant is not an object.
+  JSON_FORCE_INLINE operator JsonObject &() const { return as<JsonObject &>(); }
+  JSON_FORCE_INLINE JsonObject &asObject() const { return as<JsonObject &>(); }
+
+  template <typename T>
+  JSON_FORCE_INLINE const T as() const {
+    return impl()->template as<T>();
+  }
+
+  // Mimics an array or an object.
+  // Returns the size of the array or object if the variant has that type.
+  // Returns 0 if the variant is neither an array nor an object
+  size_t size() const { return asArray().size() + asObject().size(); }
+
+  // Mimics an array.
+  // Returns the element at specified index if the variant is an array.
+  // Returns JsonVariant::invalid() if the variant is not an array.
+  JSON_FORCE_INLINE const JsonArraySubscript operator[](int index) const;
+
+  // Mimics an object.
+  // Returns the value associated with the specified key if the variant is
+  // an object.
+  // Return JsonVariant::invalid() if the variant is not an object.
+  JSON_FORCE_INLINE const JsonObjectSubscript operator[](const char *key) const;
+
+ private:
+  const TImpl *impl() const { return static_cast<const TImpl *>(this); }
+};
+
+template <typename TImpl, typename TComparand>
+inline bool operator==(const JsonVariantBase<TImpl> &left, TComparand right) {
+  return left.template as<TComparand>() == right;
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator==(TComparand left, const JsonVariantBase<TImpl> &right) {
+  return left == right.template as<TComparand>();
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator!=(const JsonVariantBase<TImpl> &left, TComparand right) {
+  return left.template as<TComparand>() != right;
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator!=(TComparand left, const JsonVariantBase<TImpl> &right) {
+  return left != right.template as<TComparand>();
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator<=(const JsonVariantBase<TImpl> &left, TComparand right) {
+  return left.template as<TComparand>() <= right;
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator<=(TComparand left, const JsonVariantBase<TImpl> &right) {
+  return left <= right.template as<TComparand>();
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator>=(const JsonVariantBase<TImpl> &left, TComparand right) {
+  return left.template as<TComparand>() >= right;
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator>=(TComparand left, const JsonVariantBase<TImpl> &right) {
+  return left >= right.template as<TComparand>();
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator<(const JsonVariantBase<TImpl> &left, TComparand right) {
+  return left.template as<TComparand>() < right;
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator<(TComparand left, const JsonVariantBase<TImpl> &right) {
+  return left < right.template as<TComparand>();
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator>(const JsonVariantBase<TImpl> &left, TComparand right) {
+  return left.template as<TComparand>() > right;
+}
+
+template <typename TImpl, typename TComparand>
+inline bool operator>(TComparand left, const JsonVariantBase<TImpl> &right) {
+  return left > right.template as<TComparand>();
+}
+}