Added JsonVariant::clear()

CHANGELOG.md

@@ -17,6 +17,7 @@ HEAD
 * Fixed segfault after `variant.set(serialized((char*)0))`
 * Detect `IncompleteInput` in `false`, `true`, and `null`
 * Added `JsonDocument::size()`
+* Added `JsonVariant::clear()`
 
 v6.8.0-beta (2019-01-30)
 -----------

src/ArduinoJson/Array/ElementProxy.hpp

@@ -47,6 +47,10 @@ class ElementProxy : public VariantOperators<ElementProxy<TArray> >,
     return *this;
   }
 
+  FORCE_INLINE void clear() const {
+    getUpstreamElement().clear();
+  }
+
   FORCE_INLINE bool isNull() const {
     return getUpstreamElement().isNull();
   }

src/ArduinoJson/Object/MemberProxy.hpp

@@ -49,6 +49,10 @@ class MemberProxy : public VariantOperators<MemberProxy<TObject, TStringRef> >,
     return *this;
   }
 
+  FORCE_INLINE void clear() const {
+    getUpstreamMember().clear();
+  }
+
   FORCE_INLINE bool isNull() const {
     return getUpstreamMember().isNull();
   }

src/ArduinoJson/Variant/VariantRef.hpp

@@ -136,6 +136,10 @@ class VariantRef : public VariantRefBase<VariantData>,
   // Creates an uninitialized VariantRef
   FORCE_INLINE VariantRef() : base_type(0), _pool(0) {}
 
+  FORCE_INLINE void clear() const {
+    return variantSetNull(_data);
+  }
+
   // set(bool value)
   FORCE_INLINE bool set(bool value) const {
     return variantSetBoolean(_data, value);

test/ElementProxy/CMakeLists.txt

@@ -4,6 +4,7 @@
 
 add_executable(ElementProxyTests
 	add.cpp
+	clear.cpp
 	set.cpp
 	size.cpp
 )

test/ElementProxy/clear.cpp

@@ -0,0 +1,28 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2019
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+using namespace ARDUINOJSON_NAMESPACE;
+
+TEST_CASE("ElementProxy::clear()") {
+  DynamicJsonDocument doc(4096);
+  doc.addElement();
+  ElementProxy<JsonDocument&> ep = doc[0];
+
+  SECTION("size goes back to zero") {
+    ep.add(42);
+    ep.clear();
+
+    REQUIRE(ep.size() == 0);
+  }
+
+  SECTION("isNull() return true") {
+    ep.add("hello");
+    ep.clear();
+
+    REQUIRE(ep.isNull() == true);
+  }
+}

test/JsonVariant/CMakeLists.txt

@@ -5,6 +5,7 @@
 add_executable(JsonVariantTests
 	add.cpp
 	as.cpp
+	clear.cpp
 	compare.cpp
 	copy.cpp
 	createNested.cpp

test/JsonVariant/clear.cpp

@@ -0,0 +1,28 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2019
+// MIT License
+
+#include <ArduinoJson.h>
+#include <stdint.h>
+#include <catch.hpp>
+
+static const char* null = 0;
+
+TEST_CASE("JsonVariant::clear()") {
+  DynamicJsonDocument doc(4096);
+  JsonVariant var = doc.to<JsonVariant>();
+
+  SECTION("size goes back to zero") {
+    var.add(42);
+    var.clear();
+
+    REQUIRE(var.size() == 0);
+  }
+
+  SECTION("isNull() return true") {
+    var.add("hello");
+    var.clear();
+
+    REQUIRE(var.isNull() == true);
+  }
+}

test/MemberProxy/CMakeLists.txt

@@ -4,6 +4,7 @@
 
 add_executable(MemberProxyTests
 	add.cpp
+	clear.cpp
 	subscript.cpp
 	set.cpp
 	size.cpp

test/MemberProxy/clear.cpp

@@ -0,0 +1,27 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2019
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+using namespace ARDUINOJSON_NAMESPACE;
+
+TEST_CASE("MemberProxy::clear()") {
+  DynamicJsonDocument doc(4096);
+  MemberProxy<JsonDocument&, const char*> mp = doc["hello"];
+
+  SECTION("size goes back to zero") {
+    mp.add(42);
+    mp.clear();
+
+    REQUIRE(mp.size() == 0);
+  }
+
+  SECTION("isNull() return true") {
+    mp.add("hello");
+    mp.clear();
+
+    REQUIRE(mp.isNull() == true);
+  }
+}