Json to Tlv and Tlv to Json Converters Implemented in CPP

This implementation is equivalent to the Kotlin implementation in:
src/controller/java/src/chip/jsontlv/

Note that NOT all TLV configurations are supported by the current implementation. Here is the list of limitations:
   - TLV Lists are not supported
   - Multi-Dimensional TLV Arrays are not supported
   - All elements in an array MUST be of the same type
   - The top-level TLV element MUST be a single structure with AnonymousTag
   - The following tags are supported:
       - AnonymousTag are only used with TLV Array elements or a top-level structure.
       - ContextSpecificTag are used only with TLV Structure elements.
       - CommonProfileTag are used only with TLV Structure elements.
   - Infinity Float/Double values are not supported.

Added README.md file that describes the format.

Added unit tests for TLV to JSON, JSON to TLV, JSON to TLV back to JSON conversion cases.

.github/.wordlist.txt

@@ -154,6 +154,7 @@ blocklist
 blockquote
 bluetoothd
 bluez
+BOOL
 BooleanState
 bootable
 Bootloader

.gitmodules

@@ -308,3 +308,6 @@
  url = https://github.com/google/perfetto.git
  branch = master
  platforms = linux,android
+[submodule "third_party/json/repo"]
+ path = third_party/json/repo
+ url = https://github.com/nlohmann/json.git

build_overrides/json.gni

@@ -0,0 +1,17 @@
+# Copyright (c) 2023 Project CHIP Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+declare_args() {
+ json_root = "//third_party/json"
+}

examples/build_overrides/json.gni

@@ -0,0 +1,17 @@
+# Copyright (c) 2023 Project CHIP Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+declare_args() {
+ json_root = "//third_party/connectedhomeip/third_party/json"
+}

scripts/tools/check_includes_config.py

@@ -156,5 +156,10 @@
  'src/controller/ExamplePersistentStorage.cpp': {'fstream'},
 
  # Library meant for non-embedded
- 'src/tracing/log_json/log_json_tracing.cpp': {'string', 'sstream'}
+ 'src/tracing/log_json/log_json_tracing.cpp': {'string', 'sstream'},
+
+ # Not intended for embedded clients
+ 'src/lib/support/jsontlv/JsonToTlv.cpp': {'sstream'},
+ 'src/lib/support/jsontlv/JsonToTlv.h': {'string'},
+ 'src/lib/support/jsontlv/TlvToJson.h': {'string'}
 }

src/lib/core/TLVReader.h

@@ -857,6 +857,13 @@ class DLL_EXPORT TLVReader
  */
  TLVBackingStore * GetBackingStore() { return mBackingStore; }
 
+ /**
+ * Returns true if the current TLV element type is a double.
+ *
+ * @return @p true if the current TLV element type is a double; otherwise @p false.
+ */
+ bool IsElementDouble() { return ElementType() == TLVElementType::FloatingPointNumber64; }
+
  /**
  * Gets the point in the underlying input buffer that corresponds to the reader's current position.
  *

src/lib/support/jsontlv/BUILD.gn

@@ -1,4 +1,4 @@
-# Copyright (c) 2020 Project CHIP Authors
+# Copyright (c) 2020-2023 Project CHIP Authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -14,18 +14,24 @@
 
 import("//build_overrides/chip.gni")
 import("//build_overrides/jsoncpp.gni")
+import("//build_overrides/json.gni")
 
 config("jsontlv_config") {
 }
 
 static_library("jsontlv") {
- sources = [ "TlvJson.cpp" ]
+ sources = [
+ "JsonToTlv.cpp",
+ "TlvJson.cpp",
+ "TlvToJson.cpp"
+ ]
 
  public_configs = [ ":jsontlv_config" ]
 
  public_deps = [
  "${chip_root}/src/lib/core",
  jsoncpp_root,
+ json_root,
  ]
 
  cflags = [ "-Wconversion" ]