Added JsonArray::clear() (fixes #1597)

Author: bblanchon

CHANGELOG.md

@@ -11,6 +11,7 @@ HEAD
 * 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)
 
 v6.18.0 (2021-05-05)
 -------

extras/tests/JsonArray/CMakeLists.txt

@@ -4,6 +4,7 @@
 
 add_executable(JsonArrayTests 
 	add.cpp
+	clear.cpp
 	copyArray.cpp
 	createNested.cpp
 	equals.cpp

extras/tests/JsonArray/clear.cpp

@@ -0,0 +1,25 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+TEST_CASE("JsonArray::clear()") {
+  SECTION("No-op on null JsonArray") {
+    JsonArray array;
+    array.clear();
+    REQUIRE(array.isNull() == true);
+    REQUIRE(array.size() == 0);
+  }
+
+  SECTION("Removes all elements") {
+    StaticJsonDocument<64> doc;
+    JsonArray array = doc.to<JsonArray>();
+    array.add(1);
+    array.add(2);
+    array.clear();
+    REQUIRE(array.size() == 0);
+    REQUIRE(array.isNull() == false);
+  }
+}

extras/tests/JsonObject/CMakeLists.txt

@@ -3,6 +3,7 @@
 # MIT License
 
 add_executable(JsonObjectTests 
+	clear.cpp
 	containsKey.cpp
 	copy.cpp
 	createNestedArray.cpp

extras/tests/JsonObject/clear.cpp

@@ -0,0 +1,25 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+TEST_CASE("JsonObject::clear()") {
+  SECTION("No-op on null JsonObject") {
+    JsonObject obj;
+    obj.clear();
+    REQUIRE(obj.isNull() == true);
+    REQUIRE(obj.size() == 0);
+  }
+
+  SECTION("Removes all elements") {
+    StaticJsonDocument<64> doc;
+    JsonObject obj = doc.to<JsonObject>();
+    obj["hello"] = 1;
+    obj["world"] = 2;
+    obj.clear();
+    REQUIRE(obj.size() == 0);
+    REQUIRE(obj.isNull() == false);
+  }
+}

src/ArduinoJson/Array/ArrayRef.hpp

@@ -161,6 +161,12 @@ class ArrayRef : public ArrayRefBase<CollectionData>,
     _data->removeElement(index);
   }
 
+  void clear() const {
+    if (!_data)
+      return;
+    _data->clear();
+  }
+
  private:
   MemoryPool* _pool;
 };