MicroDexed/third-party/ArduinoJson/CHANGELOG.md

ArduinoJson: change log

v6.18.4 (2021-09-06)

• Fixed error 'dummy' may be used uninitialized on GCC 11
• Fixed error expected unqualified-id before 'const' on GCC 11 (issue #1622)
• Filter: exact match takes precedence over wildcard (issue #1628)
• Fixed deserialization of \u0000 (issue #1646)

v6.18.3 (2021-07-27)

• Changed return type of convertToJson() and Converter<T>::toJson() to void
• Added as<std::string_view>() and is<std::string_view>()

v6.18.2 (2021-07-19)

• Removed a symlink because the Arduino Library Specification forbids it

v6.18.1 (2021-07-03)

• Fixed support for volatile float and volatile double (issue #1557)
• Fixed error [Pe070]: incomplete type is not allowed on IAR (issue #1560)
• Fixed serializeJson(doc, String) when allocation fails (issue #1572)
• Fixed clang-tidy warnings (issue #1574, PR #1577 by @armandas)
• Added fake class InvalidConversion<T1,T2> to easily identify invalid conversions (issue #1585)
• Added support for std::string_view (issue #1578, PR #1554 by @0xFEEDC0DE64)
• Fixed warning definition of implicit copy constructor for 'MsgPackDeserializer' is deprecated because it has a user-declared copy assignment operator
• Added JsonArray::clear() (issue #1597)
• Fixed JsonVariant::as<unsigned>() (issue #1601)
• Added support for ESP-IDF component build (PR #1562 by @qt1, PR #1599 by @andreaskuster)

v6.18.0 (2021-05-05)

• Added support for custom converters (issue #687)
• Added support for Printable (issue #1444)
• Removed support for char values, see below (issue #1498)
• deserializeJson() leaves \uXXXX unchanged instead of returning NotSupported
• deserializeMsgPack() inserts null instead of returning NotSupported
• Removed DeserializationError::NotSupported
• Added JsonVariant::is<JsonArrayConst/JsonObjectConst>() (issue #1412)
• Added JsonVariant::is<JsonVariant/JsonVariantConst>() (issue #1412)
• Changed JsonVariantConst::is<JsonArray/JsonObject>() to return false (issue #1412)
• Simplified JsonVariant::as<T>() to always return T (see below)
• Updated folders list in .mbedignore (PR #1515 by @AGlass0fMilk)
• Fixed member-call-on-null-pointer in getMember() when array is empty
• serializeMsgPack(doc, buffer, size) doesn't add null-terminator anymore (issue #1545)
• serializeJson(doc, buffer, size) adds null-terminator only if there is enough room
• PlatformIO: set build.libArchive to false (PR #1550 by @askreet)

BREAKING CHANGES

Support for char removed

We cannot cast a JsonVariant to a char anymore, so the following will break:

char age = doc["age"];  //  error: no matching function for call to 'variantAs(VariantData*&)'

Instead, you must use another integral type, such as int8_t:

int8_t age = doc["age"];  // OK

Similarly, we cannot assign from a char anymore, so the following will break:

char age;
doc["age"] = age;  // error: no matching function for call to 'VariantRef::set(const char&)'

Instead, you must use another integral type, such as int8_t:

int8_t age;
doc["age"] = age;  // OK

A deprecation warning with the message "Support for char is deprecated, use int8_t or uint8_t instead" was added to allow a smooth transition.

as<T>() always returns T

Previously, JsonVariant::as<T>() could return a type different from T. The most common example is as<char*>() that returned a const char*. While this feature simplified a few use cases, it was confusing and complicated the implementation of custom converters.

Starting from this version, as<T> doesn't try to auto-correct the return type and always return T, which means that you cannot write this anymore:

Serial.println(doc["sensor"].as<char*>());  // error: invalid conversion from 'const char*' to 'char*' [-fpermissive]

Instead, you must write:

Serial.println(doc["sensor"].as<const char*>());  // OK

A deprecation warning with the message "Replace as<char*>() with as<const char*>()" was added to allow a smooth transition.

DeserializationError::NotSupported removed

On a different topic, DeserializationError::NotSupported has been removed. Instead of returning this error:

• deserializeJson() leaves \uXXXX unchanged (only when ARDUINOJSON_DECODE_UNICODE is 0)
• deserializeMsgPack() replaces unsupported values with nulls

Const-aware is<T>()

Lastly, a very minor change concerns JsonVariantConst::is<T>(). It used to return true for JsonArray and JsonOject, but now it returns false. Instead, you must use JsonArrayConst and JsonObjectConst.

v6.17.3 (2021-02-15)

• Made JsonDocument's destructor protected (issue #1480)
• Added missing calls to client.stop() in JsonHttpClient.ino (issue #1485)
• Fixed error expected ')' before 'char' when isdigit() is a macro (issue #1487)
• Fixed error definition of implicit copy constructor is deprecated on Clang 10
• PlatformIO: set framework compatibility to * (PR #1490 by @maxgerhardt)

v6.17.2 (2020-11-14)

• Fixed invalid conversion error in operator|(JsonVariant, char*) (issue #1432)
• Changed the default value of ARDUINOJSON_ENABLE_PROGMEM (issue #1433). It now checks that the pgm_read_XXX macros are defined before enabling PROGMEM.

v6.17.1 (2020-11-07)

• Fixed error ambiguous overload for 'operator|' (issue #1411)
• Fixed operator|(MemberProxy, JsonObject) (issue #1415)
• Allowed more than 32767 values in non-embedded mode (issue #1414)

v6.17.0 (2020-10-19)

• Added a build failure when nullptr is defined as a macro (issue #1355)
• Added JsonDocument::overflowed() which tells if the memory pool was too small (issue #1358)
• Added DeserializationError::EmptyInput which tells if the input was empty
• Added DeserializationError::f_str() which returns a const __FlashStringHelper* (issue #846)
• Added operator|(JsonVariantConst, JsonVariantConst)
• Added filtering for MessagePack (issue #1298, PR #1394 by Luca Passarella)
• Moved float convertion tables to PROGMEM
• Fixed JsonVariant::set((char*)0) which returned false instead of true (issue #1368)
• Fixed error No such file or directory #include <WString.h> (issue #1381)

v6.16.1 (2020-08-04)

• Fixed deserializeJson() that stopped reading after {} (issue #1335)

v6.16.0 (2020-08-01)

• Added comparisons (>, >=, ==, !=, <, and <=) between JsonVariants
• Added string deduplication (issue #1303)
• Added JsonString::operator!=
• Added wildcard key (*) for filters (issue #1309)
• Set ARDUINOJSON_DECODE_UNICODE to 1 by default
• Fixed copyArray() not working with String, ElementProxy, and MemberProxy
• Fixed error getOrAddElement is not a member of ElementProxy (issue #1311)
• Fixed excessive stack usage when compiled with -Og (issues #1210 and #1314)
• Fixed Warning[Pa093]: implicit conversion from floating point to integer on IAR compiler (PR #1328 by @stawiski)

v6.15.2 (2020-05-15)

• CMake: don't build tests when imported in another project
• CMake: made project arch-independent
• Visual Studio: fixed error C2766 with flag /Zc:__cplusplus (issue #1250)
• Added support for JsonDocument to copyArray() (issue #1255)
• Added support for enums in as<T>() and is<T>() (issue #1256)
• Added JsonVariant as an input type for deserializeXxx()
  For example, you can do: deserializeJson(doc2, doc1["payload"])
• Break the build if using 64-bit integers with ARDUINOJSON_USE_LONG_LONG==0

v6.15.1 (2020-04-08)

• Fixed "maybe-uninitialized" warning (issue #1217)
• Fixed "statement is unreachable" warning on IAR (issue #1233)
• Fixed "pointless integer comparison" warning on IAR (issue #1233)
• Added CMake "install" target (issue #1209)
• Disabled alignment on AVR (issue #1231)

v6.15.0 (2020-03-22)

• Added DeserializationOption::Filter (issue #959)
• Added example JsonFilterExample.ino
• Changed the array subscript operator to automatically add missing elements
• Fixed "deprecated-copy" warning on GCC 9 (fixes #1184)
• Fixed MemberProxy::set(char[]) not duplicating the string (issue #1191)
• Fixed enums serialized as booleans (issue #1197)
• Fixed incorrect string comparison on some platforms (issue #1198)
• Added move-constructor and move-assignment to BasicJsonDocument
• Added BasicJsonDocument::garbageCollect() (issue #1195)
• Added StaticJsonDocument::garbageCollect()
• Changed copy-constructor of BasicJsonDocument to preserve the capacity of the source.
• Removed copy-constructor of JsonDocument (issue #1189)

BREAKING CHANGES

Copy-constructor of BasicJsonDocument

In previous versions, the copy constructor of BasicJsonDocument looked at the source's memoryUsage() to choose its capacity. Now, the copy constructor of BasicJsonDocument uses the same capacity as the source.

Example:

DynamicJsonDocument doc1(64);
doc1.set(String("example"));

DynamicJsonDocument doc2 = doc1;
Serial.print(doc2.capacity());  // 8 with ArduinoJson 6.14
                                // 64 with ArduinoJson 6.15

I made this change to get consistent results between copy-constructor and move-constructor, and whether RVO applies or not.

If you use the copy-constructor to optimize your documents, you can use garbageCollect() or shrinkToFit() instead.

Copy-constructor of JsonDocument

In previous versions, it was possible to create a function that take a JsonDocument by value.

void myFunction(JsonDocument doc) {}

This function gives the wrong clues because it doesn't receive a copy of the JsonDocument, only a sliced version. It worked because the copy constructor copied the internal pointers, but it was an accident.

From now, if you need to pass a JsonDocument to a function, you must use a reference:

void myFunction(JsonDocument& doc) {}

v6.14.1 (2020-01-27)

• Fixed regression in UTF16 decoding (issue #1173)
• Fixed containsKey() on JsonVariantConst
• Added getElement() and getMember() to JsonVariantConst

v6.14.0 (2020-01-16)

• Added BasicJsonDocument::shrinkToFit()
• Added support of uint8_t for serializeJson(), serializeJsonPretty(), and serializeMsgPack() (issue #1142)
• Added ARDUINOJSON_ENABLE_COMMENTS to enable support for comments (defaults to 0)
• Auto enable support for std::string and std::stream on modern compilers (issue #1156) (No need to define ARDUINOJSON_ENABLE_STD_STRING and ARDUINOJSON_ENABLE_STD_STREAM anymore)
• Improved decoding of UTF-16 surrogate pairs (PR #1157 by @kaysievers) (ArduinoJson now produces standard UTF-8 instead of CESU-8)
• Added measureJson, measureJsonPretty, and measureMsgPack to keywords.txt (This file is used for syntax highlighting in the Arduino IDE)
• Fixed variant.is<nullptr_t>()
• Fixed value returned by serializeJson(), serializeJsonPretty(), and serializeMsgPack() when writing to a String
• Improved speed of serializeJson(), serializeJsonPretty(), and serializeMsgPack() when writing to a String

BREAKING CHANGES

Comments

Support for comments in input is now optional and disabled by default.

If you need support for comments, you must defined ARDUINOJSON_ENABLE_COMMENTS to 1; otherwise, you'll receive InvalidInput errors.

#define ARDUINOJSON_ENABLE_COMMENTS 1
#include <ArduinoJson.h>

v6.13.0 (2019-11-01)

• Added support for custom writer/reader classes (issue #1088)
• Added conversion from JsonArray and JsonObject to bool, to be consistent with JsonVariant
• Fixed deserializeJson() when input contains duplicate keys (issue #1095)
• Improved deserializeMsgPack() speed by reading several bytes at once
• Added detection of Atmel AVR8/GNU C Compiler (issue #1112)
• Fixed deserializer that stopped reading at the first 0xFF (PR #1118 by @mikee47)
• Fixed dangling reference in copies of MemberProxy and ElementProxy (issue #1120)

v6.12.0 (2019-09-05)

• Use absolute instead of relative includes (issue #1072)
• Changed JsonVariant::as<bool>() to return true for any non-null value (issue #1005)
• Moved ancillary files to extras/ (issue #1011)

v6.11.5 (2019-08-23)

• Added fallback implementations of strlen_P(), strncmp_P(), strcmp_P(), and memcpy_P() (issue #1073)

v6.11.4 (2019-08-12)

• Added measureJson() to the ArduinoJson namespace (PR #1069 by @nomis)
• Added support for basic_string<char, traits, allocator> (issue #1045)
• Fixed example JsonConfigFile.ino for ESP8266
• Include Arduino.h if ARDUINO is defined (PR #1071 by @nomis)

v6.11.3 (2019-07-22)

• Added operators == and != for JsonDocument, ElementProxy, and MemberProxy
• Fixed comparison of JsonVariant when one contains a linked string and the other contains an owned string (issue #1051)

v6.11.2 (2019-07-08)

• Fixed assignment of JsonDocument to JsonVariant (issue #1023)
• Fix invalid conversion error on Particle Argon (issue #1035)

v6.11.1 (2019-06-21)

• Fixed serialized() not working with Flash strings (issue #1030)

v6.11.0 (2019-05-26)

• Fixed deserializeJson() silently accepting a Stream* (issue #978)
• Fixed invalid result from operator| (issue #981)
• Made deserializeJson() more picky about trailing characters (issue #980)
• Added ARDUINOJSON_ENABLE_NAN (default=0) to enable NaN in JSON (issue #973)
• Added ARDUINOJSON_ENABLE_INFINITY (default=0) to enable Infinity in JSON
• Removed implicit conversion in comparison operators (issue #998)
• Added lexicographical comparison for JsonVariant
• Added support for nullptr (issue #998)

BREAKING CHANGES

NaN and Infinity

The JSON specification allows neither NaN not Infinity, but previous versions of ArduinoJson supported it. Now, ArduinoJson behaves like most other libraries: a NaN or and Infinity in the JsonDocument, becomes a null in the output JSON. Also, deserializeJson() returns InvalidInput if the JSON document contains NaN or Infinity.

This version still supports NaN and Infinity in JSON documents, but it's disabled by default to be compatible with other JSON parsers. If you need the old behavior back, define ARDUINOJSON_ENABLE_NAN and ARDUINOJSON_ENABLE_INFINITY to 1;:

#define ARDUINOJSON_ENABLE_NAN 1
#define ARDUINOJSON_ENABLE_INFINITY 1
#include <ArduinoJson.h>

The "or" operator

This version slightly changes the behavior of the | operator when the variant contains a float and the user requests an integer.

Older versions returned the floating point value truncated. Now, it returns the default value.

// suppose variant contains 1.2
int value = variant | 3;

// old behavior:
value == 1

// new behavior
value == 3

If you need the old behavior, you must add if (variant.is<float>()).

v6.10.1 (2019-04-23)

• Fixed error "attributes are not allowed on a function-definition"
• Fixed deserializeJson() not being picky enough (issue #969)
• Fixed error "no matching function for call to write(uint8_t)" (issue #972)

v6.10.0 (2019-03-22)

• Fixed an integer overflow in the JSON deserializer
• Added overflow handling in JsonVariant::as<T>() and JsonVariant::is<T>().
  • as<T>() returns 0 if the integer T overflows
  • is<T>() returns false if the integer T overflows
• Added BasicJsonDocument to support custom allocator (issue #876)
• Added JsonDocument::containsKey() (issue #938)
• Added JsonVariant::containsKey()

v6.9.1 (2019-03-01)

• Fixed warning "unused variable" with GCC 4.4 (issue #912)
• Fixed warning "cast increases required alignment" (issue #914)
• Fixed warning "conversion may alter value" (issue #914)
• Fixed naming conflict with "CAPACITY" (issue #839)
• Muted warning "will change in GCC 7.1" (issue #914)
• Added a clear error message for StaticJsonBuffer and DynamicJsonBuffer
• Marked ArduinoJson.h as a "system header"

v6.9.0 (2019-02-26)

• Decode escaped Unicode characters like \u00DE (issue #304, PR #791) Many thanks to Daniel Schulte (aka @trilader) who implemented this feature.
• Added option ARDUINOJSON_DECODE_UNICODE to enable it
• Converted JsonArray::copyFrom()/copyTo() to free functions copyArray()
• Renamed JsonArray::copyFrom() and JsonObject::copyFrom() to set()
• Renamed JsonArray::get() to getElement()
• Renamed JsonArray::add() (without arg) to addElement()
• Renamed JsonObject::get() to getMember()
• Renamed JsonObject::getOrCreate() to getOrAddMember()
• Fixed JsonVariant::isNull() not returning true after set((char*)0)
• Fixed segfault after variant.set(serialized((char*)0))
• Detect IncompleteInput in false, true, and null
• Added JsonDocument::size()
• Added JsonDocument::remove()
• Added JsonVariant::clear()
• Added JsonVariant::remove()

v6.8.0-beta (2019-01-30)

• Import functions in the ArduinoJson namespace to get clearer errors
• Improved syntax highlighting in Arduino IDE
• Removed default capacity of DynamicJsonDocument
• JsonArray::copyFrom() accepts JsonArrayConst
• JsonVariant::set() accepts JsonArrayConst and JsonObjectConst
• JsonDocument was missing in the ArduinoJson namespace
• Added memoryUsage() to JsonArray, JsonObject, and JsonVariant
• Added nesting() to JsonArray, JsonDocument, JsonObject, and JsonVariant
• Replaced JsonDocument::nestingLimit with an additional parameter to deserializeJson() and deserializeMsgPack()
• Fixed uninitialized variant in JsonDocument
• Fixed StaticJsonDocument copy constructor and copy assignment
• The copy constructor of DynamicJsonDocument chooses the capacity according to the memory usage of the source, not from the capacity of the source.
• Added the ability to create/assign a StaticJsonDocument/DynamicJsonDocument from a JsonArray/JsonObject/JsonVariant
• Added JsonDocument::isNull()
• Added JsonDocument::operator[]
• Added ARDUINOJSON_TAB to configure the indentation character
• Reduced the size of the pretty JSON serializer
• Added add(), createNestedArray() and createNestedObject() to JsonVariant
• JsonVariant automatically promotes to JsonObject or JsonArray on write. Calling JsonVariant::to<T>() is not required anymore.
• JsonDocument now support the same operations as JsonVariant. Calling JsonDocument::as<T>() is not required anymore.
• Fixed example JsonHttpClient.ino
• User can now use a JsonString as a key or a value

BREAKING CHANGES

DynamicJsonDocument's constructor

The parameter to the constructor of DynamicJsonDocument is now mandatory

Old code:

DynamicJsonDocument doc;

New code:

DynamicJsonDocument doc(1024);

Nesting limit

JsonDocument::nestingLimit was replaced with a new parameter to deserializeJson() and deserializeMsgPack().

Old code:

doc.nestingLimit = 15;
deserializeJson(doc, input);

New code:

deserializeJson(doc, input, DeserializationOption::NestingLimit(15));

v6.7.0-beta (2018-12-07)

• Removed the automatic expansion of DynamicJsonDocument, it now has a fixed capacity.
• Restored the monotonic allocator because the code was getting too big
• Reduced the memory usage
• Reduced the code size
• Renamed JsonKey to JsonString
• Removed spurious files in the Particle library

v6.6.0-beta (2018-11-13)

• Removed JsonArray::is<T>(i) and JsonArray::set(i,v)
• Removed JsonObject::is<T>(k) and JsonObject::set(k,v)
• Replaced T JsonArray::get<T>(i) with JsonVariant JsonArray::get(i)
• Replaced T JsonObject::get<T>(k) with JsonVariant JsonObject::get(k)
• Added JSON_STRING_SIZE()
• Replacing or removing a value now releases the memory
• Added DeserializationError::code() to be used in switch statements (issue #846)

v6.5.0-beta (2018-10-13)

• Added implicit conversion from JsonArray and JsonObject to JsonVariant
• Allow mixed configuration in compilation units (issue #809)
• Fixed object keys not being duplicated
• JsonPair::key() now returns a JsonKey
• Increased the default capacity of DynamicJsonDocument
• Fixed JsonVariant::is<String>() (closes #763)
• Added JsonArrayConst, JsonObjectConst, and JsonVariantConst
• Added copy-constructor and copy-assignment-operator for JsonDocument (issue #827)

v6.4.0-beta (2018-09-11)

• Copy JsonArray and JsonObject, instead of storing pointers (issue #780)
• Added JsonVariant::to<JsonArray>() and JsonVariant::to<JsonObject>()

v6.3.0-beta (2018-08-31)

• Implemented reference semantics for JsonVariant
• Replaced JsonPair's key and value with key() and value()
• Fixed serializeJson(obj[key], dst) (issue #794)

BREAKING CHANGES

JsonVariant

JsonVariant now has a semantic similar to JsonObject and JsonArray. It's a reference to a value stored in the JsonDocument. As a consequence, a JsonVariant cannot be used as a standalone variable anymore.

Old code:

JsonVariant myValue = 42;

New code:

DynamicJsonDocument doc;
JsonVariant myValue = doc.to<JsonVariant>();
myValue.set(42);

JsonPair

Old code:

for(JsonPair p : myObject) {
  Serial.println(p.key);
  Serial.println(p.value.as<int>());
}

New code:

for(JsonPair p : myObject) {
  Serial.println(p.key());
  Serial.println(p.value().as<int>());
}

CAUTION: the key is now read only!

v6.2.3-beta (2018-07-19)

• Fixed exception when using Flash strings as object keys (issue #784)

v6.2.2-beta (2018-07-18)

• Fixed invalid application of 'sizeof' to incomplete type '__FlashStringHelper' (issue #783)
• Fixed char[] not duplicated when passed to JsonVariant::operator[]

v6.2.1-beta (2018-07-17)

• Fixed JsonObject not inserting keys of type String (issue #782)

v6.2.0-beta (2018-07-12)

• Disabled lazy number deserialization (issue #772)
• Fixed JsonVariant::is<int>() that returned true for empty strings
• Improved float serialization when -fsingle-precision-constant is used
• Renamed function RawJson() to serialized()
• serializeMsgPack() now supports values marked with serialized()

BREAKING CHANGES

Non quoted strings

Non quoted strings are now forbidden in values, but they are still allowed in keys. For example, {key:"value"} is accepted, but {key:value} is not.

Preformatted values

Old code:

object["values"] = RawJson("[1,2,3,4]");

New code:

object["values"] = serialized("[1,2,3,4]");

v6.1.0-beta (2018-07-02)

• Return JsonArray and JsonObject by value instead of reference (issue #309)
• Replaced success() with isNull()

BREAKING CHANGES

Old code:

JsonObject& obj = doc.to<JsonObject>();
JsonArray& arr = obj.createNestedArray("key");
if (!arr.success()) {
  Serial.println("Not enough memory");
  return;
}

New code:

JsonObject obj = doc.to<JsonObject>();
JsonArray arr = obj.createNestedArray("key");
if (arr.isNull()) {
  Serial.println("Not enough memory");
  return;
}

v6.0.1-beta (2018-06-11)

• Fixed conflicts with isnan() and isinf() macros (issue #752)

v6.0.0-beta (2018-06-07)

• Added DynamicJsonDocument and StaticJsonDocument
• Added deserializeJson()
• Added serializeJson() and serializeJsonPretty()
• Added measureJson() and measureJsonPretty()
• Added serializeMsgPack(), deserializeMsgPack() and measureMsgPack() (issue #358)
• Added example MsgPackParser.ino (issue #358)
• Added support for non zero-terminated strings (issue #704)
• Removed JsonBuffer::parseArray(), parseObject() and parse()
• Removed JsonBuffer::createArray() and createObject()
• Removed printTo() and prettyPrintTo()
• Removed measureLength() and measurePrettyLength()
• Removed all deprecated features

BREAKING CHANGES

Deserialization

Old code:

DynamicJsonBuffer jb;
JsonObject& obj = jb.parseObject(json);
if (obj.success()) {

}

New code:

DynamicJsonDocument doc;
DeserializationError error = deserializeJson(doc, json);
if (error) {

}
JsonObject& obj = doc.as<JsonObject>();

Serialization

Old code:

DynamicJsonBuffer jb;
JsonObject& obj = jb.createObject();
obj["key"] = "value";
obj.printTo(Serial);

New code:

DynamicJsonDocument obj;
JsonObject& obj = doc.to<JsonObject>();
obj["key"] = "value";
serializeJson(doc, Serial);

v5.13.2

• Fixed JsonBuffer::parse() not respecting nesting limit correctly (issue #693)
• Fixed inconsistencies in nesting level counting (PR #695 from Zhenyu Wu)
• Fixed null values that could be pass to strcmp() (PR #745 from Mike Karlesky)
• Added macros ARDUINOJSON_VERSION, ARDUINOJSON_VERSION_MAJOR...

v5.13.1

• Fixed JsonVariant::operator|(int) that returned the default value if the variant contained a double (issue #675)
• Allowed non-quoted key to contain underscores (issue #665)

v5.13.0

• Changed the rules of string duplication (issue #658)
• RawJson() accepts any kind of string and obeys to the same rules for duplication
• Changed the return type of strdup() to const char* to prevent double duplication
• Marked strdup() as deprecated

New rules for string duplication

type	duplication
const char*	no
char*	no yes
String	yes
std::string	yes
const __FlashStringHelper*	yes

These new rules make JsonBuffer::strdup() useless.

v5.12.0

• Added JsonVariant::operator| to return a default value (see below)
• Added a clear error message when compiled as C instead of C++ (issue #629)
• Added detection of MPLAB XC compiler (issue #629)
• Added detection of Keil ARM Compiler (issue #629)
• Added an example that shows how to save and load a configuration file
• Reworked all other examples

How to use the new feature?

If you have a block like this:

const char* ssid = root["ssid"];
if (!ssid)
  ssid = "default ssid";

You can simplify like that:

const char* ssid = root["ssid"] | "default ssid";

v5.11.2

• Fixed DynamicJsonBuffer::clear() not resetting allocation size (issue #561)
• Fixed incorrect rounding for float values (issue #588)

v5.11.1

• Removed dependency on PGM_P as Particle 0.6.2 doesn't define it (issue #546)
• Fixed warning "dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]"
• Fixed warning "floating constant exceeds range of 'float' [-Woverflow]" (issue #544)
• Fixed warning "this statement may fall through" [-Wimplicit-fallthrough=] (issue #539)
• Removed ARDUINOJSON_DOUBLE_IS_64BITS as it became useless.
• Fixed too many decimals places in float serialization (issue #543)

v5.11.0

• Made JsonBuffer non-copyable (PR #524 by @luisrayas3)
• Added StaticJsonBuffer::clear()
• Added DynamicJsonBuffer::clear()

v5.10.1

• Fixed IntelliSense errors in Visual Micro (issue #483)
• Fixed compilation in IAR Embedded Workbench (issue #515)
• Fixed reading "true" as a float (issue #516)
• Added ARDUINOJSON_DOUBLE_IS_64BITS
• Added ARDUINOJSON_EMBEDDED_MODE

v5.10.0

• Removed configurable number of decimal places (issues #288, #427 and #506)
• Changed exponentiation thresholds to 1e7 and 1e-5 (issues #288, #427 and #506)
• JsonVariant::is<double>() now returns true for integers
• Fixed error IsBaseOf is not a member of ArduinoJson::TypeTraits (issue #495)
• Fixed error forming reference to reference (issue #495)

BREAKING CHANGES ⚠️

Old syntax	New syntax
double_with_n_digits(3.14, 2)	3.14
float_with_n_digits(3.14, 2)	3.14f
obj.set("key", 3.14, 2)	obj["key"] = 3.14
arr.add(3.14, 2)	arr.add(3.14)

Input	Old output	New output
3.14159	3.14	3.14159
42.0	42.00	42
0.0	0.00	0

Expression	Old result	New result
JsonVariant(42).is<int>()	true	true
JsonVariant(42).is<float>()	false	true
JsonVariant(42).is<double>()	false	true

v5.9.0

• Added JsonArray::remove(iterator) (issue #479)
• Added JsonObject::remove(iterator)
• Renamed JsonArray::removeAt(size_t) into remove(size_t)
• Renamed folder include/ to src/
• Fixed warnings floating constant exceeds range of floatand floating constant truncated to zero (issue #483)
• Removed Print class and converted printTo() to a template method (issue #276)
• Removed example IndentedPrintExample.ino
• Now compatible with Particle 0.6.1, thanks to Jacob Nite (issue #294 and PR #461 by @foodbag)

v5.8.4

• Added custom implementation of strtod() (issue #453)
• Added custom implementation of strtol() (issue #465)
• char is now treated as an integral type (issue #337, #370)

v5.8.3

• Fixed an access violation in DynamicJsonBuffer when memory allocation fails (issue #433)
• Added operators == and != for two JsonVariants (issue #436)
• Fixed JsonVariant::operator[const FlashStringHelper*] (issue #441)

v5.8.2

• Fixed parsing of comments (issue #421)
• Fixed ignored Stream timeout (issue #422)
• Made sure we don't read more that necessary (issue #422)
• Fixed error when the key of a JsonObject is a char[] (issue #423)
• Reduced code size when using const references
• Fixed error with string of type unsigned char* (issue #428)
• Added deprecated attribute on asArray(), asObject() and asString() (issue #420)

v5.8.1

• Fixed error when assigning a volatile int to a JsonVariant (issue #415)
• Fixed errors with Variable Length Arrays (issue #416)
• Fixed error when both ARDUINOJSON_ENABLE_STD_STREAM and ARDUINOJSON_ENABLE_ARDUINO_STREAM are set to 1
• Fixed error "Stream does not name a type" (issue #412)

v5.8.0

• Added operator == to compare JsonVariant and strings (issue #402)
• Added support for Stream (issue #300)
• Reduced memory consumption by not duplicating spaces and comments

BREAKING CHANGES ⚠️

JsonBuffer::parseObject() and JsonBuffer::parseArray() have been pulled down to the derived classes DynamicJsonBuffer and StaticJsonBufferBase.

This means that if you have code like:

void myFunction(JsonBuffer& jsonBuffer);

you need to replace it with one of the following:

void myFunction(DynamicJsonBuffer& jsonBuffer);
void myFunction(StaticJsonBufferBase& jsonBuffer);
template<typename TJsonBuffer> void myFunction(TJsonBuffer& jsonBuffer);

v5.7.3

• Added an printTo(char[N]) and prettyPrintTo(char[N]) (issue #292)
• Added ability to set a nested value like this: root["A"]["B"] = "C" (issue #352)
• Renamed *.ipp to *Impl.hpp because they were ignored by Arduino IDE (issue #396)

v5.7.2

• Made PROGMEM available on more platforms (issue #381)
• Fixed PROGMEM causing an exception on ESP8266 (issue #383)

v5.7.1

• Added support for PROGMEM (issue #76)
• Fixed compilation error when index is not an int (issue #381)

v5.7.0

• Templatized all functions using String or std::string
• Removed ArduinoJson::String
• Removed JsonVariant::defaultValue<T>()
• Removed non-template JsonObject::get() and JsonArray.get()
• Fixed support for StringSumHelper (issue #184)
• Replaced ARDUINOJSON_USE_ARDUINO_STRING by ARDUINOJSON_ENABLE_STD_STRING and ARDUINOJSON_ENABLE_ARDUINO_STRING (issue #378)
• Added example StringExample.ino to show where String can be used
• Increased default nesting limit to 50 when compiled for a computer (issue #349)

BREAKING CHANGES ⚠️

The non-template functions JsonObject::get() and JsonArray.get() have been removed. This means that you need to explicitely tell the type you expect in return.

Old code:

#define ARDUINOJSON_USE_ARDUINO_STRING 0
JsonVariant value1 = myObject.get("myKey");
JsonVariant value2 = myArray.get(0);

New code:

#define ARDUINOJSON_ENABLE_ARDUINO_STRING 0
#define ARDUINOJSON_ENABLE_STD_STRING 1
JsonVariant value1 = myObject.get<JsonVariant>("myKey");
JsonVariant value2 = myArray.get<JsonVariant>(0);

v5.6.7

• Fixed array[idx].as<JsonVariant>() and object[key].as<JsonVariant>()
• Fixed return value of JsonObject::set() (issue #350)
• Fixed undefined behavior in Prettyfier and Print (issue #354)
• Fixed parser that incorrectly rejected floats containing a + (issue #349)

v5.6.6

• Fixed -Wparentheses warning introduced in v5.6.5 (PR #335 by @nuket)
• Added .mbedignore for ARM mbdeb (PR #334 by @nuket)
• Fixed JsonVariant::success() which didn't propagate JsonArray::success() nor JsonObject::success() (issue #342).

v5.6.5

• as<char*>() now returns true when input is null (issue #330)

v5.6.4

• Fixed error in float serialization (issue #324)

v5.6.3

• Improved speed of float serialization (about twice faster)
• Added as<JsonArray>() as a synonym for as<JsonArray&>()... (issue #291)
• Fixed call of overloaded isinf(double&) is ambiguous (issue #284)

v5.6.2

• Fixed build when another lib does #undef isnan (issue #284)

v5.6.1

• Added missing #pragma once (issue #310)

v5.6.0

• ArduinoJson is now a header-only library (issue #199)

v5.5.1

• Fixed compilation error with Intel Galileo (issue #299)

v5.5.0

• Added JsonVariant::success() (issue #279)
• Renamed JsonVariant::invalid<T>() to JsonVariant::defaultValue<T>()

v5.4.0

• Changed ::String to ArduinoJson::String (issue #275)
• Changed ::Print to ArduinoJson::Print too

v5.3.0

• Added custom implementation of ftoa (issues #266, #267, #269 and #270)
• Added JsonVariant JsonBuffer::parse() (issue #265)
• Fixed unsigned long printed as signed long (issue #170)

v5.2.0

• Added JsonVariant::as<char*>() as a synonym for JsonVariant::as<const char*>() (issue #257)
• Added example JsonHttpClient (issue #256)
• Added JsonArray::copyTo() and JsonArray::copyFrom() (issue #254)
• Added RawJson() to insert pregenerated JSON portions (issue #259)

v5.1.1

• Removed String duplication when one replaces a value in a JsonObject (PR #232 by @ulion)

v5.1.0

• Added support of long long (issue #171)
• Moved all build settings to ArduinoJson/Configuration.hpp

BREAKING CHANGE ⚠️

If you defined ARDUINOJSON_ENABLE_STD_STREAM, you now need to define it to 1.

v5.0.8

• Made the library compatible with PlatformIO (issue #181)
• Fixed JsonVariant::is<bool>() that was incorrectly returning false (issue #214)

v5.0.7

• Made library easier to use from a CMake project: simply add_subdirectory(ArduinoJson/src)
• Changed String to be a typedef of std::string (issues #142 and #161)

BREAKING CHANGES ⚠️

• JsonVariant(true).as<String>() now returns "true" instead of "1"
• JsonVariant(false).as<String>() now returns "false" instead of "0"

v5.0.6

• Added parameter to DynamicJsonBuffer constructor to set initial size (issue #152)
• Fixed warning about library category in Arduino 1.6.6 (issue #147)
• Examples: Added a loop to wait for serial port to be ready (issue #156)

v5.0.5

• Added overload JsonObjectSuscript::set(value, decimals) (issue #143)
• Use float instead of double to reduce the size of JsonVariant (issue #134)

v5.0.4

• Fixed ambiguous overload with JsonArraySubscript and JsonObjectSubscript (issue #122)

v5.0.3

• Fixed printTo(String) which wrote numbers instead of strings (issue #120)
• Fixed return type of JsonArray::is<T>() and some others (issue #121)

v5.0.2

• Fixed segmentation fault in parseObject(String) and parseArray(String), when the StaticJsonBuffer is too small to hold a copy of the string
• Fixed Clang warning "register specifier is deprecated" (issue #102)
• Fixed GCC warning "declaration shadows a member" (issue #103)
• Fixed memory alignment, which made ESP8266 crash (issue #104)
• Fixed compilation on Visual Studio 2010 and 2012 (issue #107)

v5.0.1

• Fixed compilation with Arduino 1.0.6 (issue #99)

v5.0.0

• Added support of String class (issues #55, #56, #70, #77)
• Added JsonBuffer::strdup() to make a copy of a string (issues #10, #57)
• Implicitly call strdup() for String but not for char* (issues #84, #87)
• Added support of non standard JSON input (issue #44)
• Added support of comments in JSON input (issue #88)
• Added implicit cast between numerical types (issues #64, #69, #93)
• Added ability to read number values as string (issue #90)
• Redesigned JsonVariant to leverage converting constructors instead of assignment operators (issue #66)
• Switched to new the library layout (requires Arduino 1.0.6 or above)

BREAKING CHANGES ⚠️

• JsonObject::add() was renamed to set()
• JsonArray::at() and JsonObject::at() were renamed to get()
• Number of digits of floating point value are now set with double_with_n_digits()

Personal note about the String class: Support of the String class has been added to the library because many people use it in their programs. However, you should not see this as an invitation to use the String class. The String class is bad because it uses dynamic memory allocation. Compared to static allocation, it compiles to a bigger, slower program, and is less predictable. You certainly don't want that in an embedded environment!