1 | // Copyright Benoit Blanchon 2014-2016
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2 | // MIT License
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3 | //
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4 | // Arduino JSON library
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5 | // https://github.com/bblanchon/ArduinoJson
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6 | // If you like this project, please add a star!
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7 |
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8 | #pragma once
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9 |
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10 | #include <stddef.h>
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11 | #include <stdint.h> // for uint8_t
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12 |
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13 | #include "Internals/JsonPrintable.hpp"
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14 | #include "Internals/JsonVariantContent.hpp"
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15 | #include "Internals/JsonVariantType.hpp"
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16 | #include "Internals/Unparsed.hpp"
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17 | #include "JsonVariantBase.hpp"
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18 | #include "TypeTraits/EnableIf.hpp"
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19 | #include "TypeTraits/IsFloatingPoint.hpp"
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20 | #include "TypeTraits/IsIntegral.hpp"
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21 | #include "TypeTraits/IsSame.hpp"
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22 | #include "TypeTraits/RemoveConst.hpp"
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23 | #include "TypeTraits/RemoveReference.hpp"
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24 |
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25 | namespace ArduinoJson {
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26 |
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27 | // Forward declarations.
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28 | class JsonArray;
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29 | class JsonObject;
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30 |
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31 | // A variant that can be a any value serializable to a JSON value.
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32 | //
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33 | // It can be set to:
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34 | // - a boolean
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35 | // - a char, short, int or a long (signed or unsigned)
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36 | // - a string (const char*)
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37 | // - a reference to a JsonArray or JsonObject
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38 | class JsonVariant : public JsonVariantBase<JsonVariant> {
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39 | public:
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40 | template <typename T>
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41 | struct IsConstructibleFrom;
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42 |
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43 | // Creates an uninitialized JsonVariant
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44 | FORCE_INLINE JsonVariant() : _type(Internals::JSON_UNDEFINED) {}
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45 |
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46 | // Create a JsonVariant containing a boolean value.
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47 | // It will be serialized as "true" or "false" in JSON.
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48 | FORCE_INLINE JsonVariant(bool value);
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49 |
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50 | // Create a JsonVariant containing a floating point value.
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51 | // The second argument specifies the number of decimal digits to write in
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52 | // the JSON string.
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53 | // JsonVariant(double value, uint8_t decimals);
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54 | // JsonVariant(float value, uint8_t decimals);
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55 | template <typename T>
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56 | FORCE_INLINE JsonVariant(
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57 | T value, uint8_t decimals = 2,
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58 | typename TypeTraits::EnableIf<TypeTraits::IsFloatingPoint<T>::value>::type
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59 | * = 0) {
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60 | using namespace Internals;
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61 | _type = static_cast<JsonVariantType>(JSON_FLOAT_0_DECIMALS + decimals);
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62 | _content.asFloat = static_cast<JsonFloat>(value);
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63 | }
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64 |
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65 | // Create a JsonVariant containing an integer value.
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66 | // JsonVariant(short)
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67 | // JsonVariant(int)
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68 | // JsonVariant(long)
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69 | template <typename T>
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70 | FORCE_INLINE JsonVariant(
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71 | T value,
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72 | typename TypeTraits::EnableIf<TypeTraits::IsIntegral<T>::value>::type * =
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73 | 0) {
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74 | using namespace Internals;
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75 | _type = JSON_INTEGER;
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76 | _content.asInteger = static_cast<JsonInteger>(value);
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77 | }
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78 |
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79 | // Create a JsonVariant containing a string.
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80 | FORCE_INLINE JsonVariant(const char *value);
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81 |
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82 | // Create a JsonVariant containing an unparsed string
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83 | FORCE_INLINE JsonVariant(Internals::Unparsed value);
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84 |
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85 | // Create a JsonVariant containing a reference to an array.
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86 | FORCE_INLINE JsonVariant(JsonArray &array);
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87 |
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88 | // Create a JsonVariant containing a reference to an object.
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89 | FORCE_INLINE JsonVariant(JsonObject &object);
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90 |
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91 | // Get the variant as the specified type.
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92 | // short as<short>() const;
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93 | // int as<int>() const;
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94 | // long as<long>() const;
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95 | template <typename T>
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96 | const typename TypeTraits::EnableIf<TypeTraits::IsIntegral<T>::value, T>::type
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97 | as() const {
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98 | return static_cast<T>(asInteger());
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99 | }
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100 | // double as<double>() const;
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101 | // float as<float>() const;
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102 | template <typename T>
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103 | const typename TypeTraits::EnableIf<TypeTraits::IsFloatingPoint<T>::value,
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104 | T>::type
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105 | as() const {
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106 | return static_cast<T>(asFloat());
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107 | }
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108 | // const String as<String>() const;
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109 | template <typename T>
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110 | const typename TypeTraits::EnableIf<TypeTraits::IsSame<T, String>::value,
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111 | T>::type
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112 | as() const {
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113 | return toString();
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114 | }
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115 | // const char* as<const char*>() const;
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116 | // const char* as<char*>() const;
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117 | template <typename T>
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118 | typename TypeTraits::EnableIf<TypeTraits::IsSame<T, const char *>::value,
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119 | const char *>::type
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120 | as() const {
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121 | return asString();
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122 | }
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123 | // const bool as<bool>() const
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124 | template <typename T>
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125 | const typename TypeTraits::EnableIf<TypeTraits::IsSame<T, bool>::value,
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126 | T>::type
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127 | as() const {
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128 | return asInteger() != 0;
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129 | }
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130 | // JsonArray& as<JsonArray> const;
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131 | // JsonArray& as<JsonArray&> const;
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132 | // JsonArray& as<const JsonArray&> const;
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133 | template <typename T>
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134 | typename TypeTraits::EnableIf<
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135 | TypeTraits::IsSame<
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136 | typename TypeTraits::RemoveConst<
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137 | typename TypeTraits::RemoveReference<T>::type>::type,
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138 | JsonArray>::value,
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139 | JsonArray &>::type
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140 | as() const {
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141 | return asArray();
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142 | }
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143 | // JsonObject& as<JsonObject> const;
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144 | // JsonObject& as<JsonObject&> const;
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145 | // JsonObject& as<const JsonObject&> const;
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146 | template <typename T>
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147 | typename TypeTraits::EnableIf<
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148 | TypeTraits::IsSame<
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149 | typename TypeTraits::RemoveConst<
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150 | typename TypeTraits::RemoveReference<T>::type>::type,
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151 | JsonObject>::value,
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152 | JsonObject &>::type
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153 | as() const {
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154 | return asObject();
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155 | }
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156 |
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157 | // Tells weither the variant has the specified type.
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158 | // Returns true if the variant has type type T, false otherwise.
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159 | template <typename T>
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160 | bool is() const;
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161 |
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162 | // Serialize the variant to a JsonWriter
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163 | void writeTo(Internals::JsonWriter &writer) const;
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164 |
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165 | // TODO: rename
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166 | template <typename T>
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167 | static T invalid();
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168 |
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169 | const char *asString() const;
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170 | JsonArray &asArray() const;
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171 | JsonObject &asObject() const;
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172 |
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173 | private:
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174 | String toString() const;
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175 | Internals::JsonFloat asFloat() const;
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176 | Internals::JsonInteger asInteger() const;
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177 |
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178 | // The current type of the variant
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179 | Internals::JsonVariantType _type;
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180 |
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181 | // The various alternatives for the value of the variant.
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182 | Internals::JsonVariantContent _content;
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183 | };
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184 |
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185 | inline JsonVariant float_with_n_digits(float value, uint8_t digits) {
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186 | return JsonVariant(value, digits);
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187 | }
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188 |
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189 | inline JsonVariant double_with_n_digits(double value, uint8_t digits) {
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190 | return JsonVariant(value, digits);
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191 | }
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192 |
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193 | template <typename T>
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194 | struct JsonVariant::IsConstructibleFrom {
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195 | static const bool value =
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196 | TypeTraits::IsIntegral<T>::value ||
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197 | TypeTraits::IsFloatingPoint<T>::value ||
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198 | TypeTraits::IsSame<T, bool>::value ||
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199 | TypeTraits::IsSame<T, char *>::value ||
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200 | TypeTraits::IsSame<T, const char *>::value ||
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201 | TypeTraits::IsSame<T, JsonArray &>::value ||
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202 | TypeTraits::IsSame<T, const JsonArray &>::value ||
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203 | TypeTraits::IsSame<T, JsonArraySubscript &>::value ||
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204 | TypeTraits::IsSame<T, const JsonArraySubscript &>::value ||
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205 | TypeTraits::IsSame<T, JsonObject &>::value ||
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206 | TypeTraits::IsSame<T, const JsonObject &>::value ||
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207 | TypeTraits::IsSame<T, JsonObjectSubscript<const char *> &>::value ||
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208 | TypeTraits::IsSame<T, const JsonObjectSubscript<const char *> &>::value ||
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209 | TypeTraits::IsSame<T, JsonObjectSubscript<String> &>::value ||
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210 | TypeTraits::IsSame<T, const JsonObjectSubscript<String> &>::value ||
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211 | TypeTraits::IsSame<T, JsonVariant &>::value ||
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212 | TypeTraits::IsSame<T, const JsonVariant &>::value;
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213 | };
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214 | }
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215 |
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216 | // Include inline implementations
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217 | #include "JsonVariant.ipp"
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