Added ARDUINOJSON_ENABLE_COMMENTS to enable support for comments

CHANGELOG.md

@@ -6,11 +6,24 @@ HEAD
 
 * 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)
 
+> ### 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.
+>
+> ```c++
+> #define ARDUINOJSON_ENABLE_COMMENTS 1
+> #include <ArduinoJson.h>
+> ```
 
 v6.13.0 (2019-11-01)
 -------

extras/tests/JsonDeserializer/array.cpp

@@ -170,155 +170,6 @@ TEST_CASE("deserialize JSON array") {
     }
   }
 
-  SECTION("Block comments") {
-    SECTION("Before opening bracket") {
-      DeserializationError err =
-          deserializeJson(doc, "/*COMMENT*/  [\"hello\"]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(1 == arr.size());
-      REQUIRE(arr[0] == "hello");
-    }
-
-    SECTION("After opening bracket") {
-      DeserializationError err =
-          deserializeJson(doc, "[/*COMMENT*/ \"hello\"]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(1 == arr.size());
-      REQUIRE(arr[0] == "hello");
-    }
-
-    SECTION("Before closing bracket") {
-      DeserializationError err = deserializeJson(doc, "[\"hello\"/*COMMENT*/]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(1 == arr.size());
-      REQUIRE(arr[0] == "hello");
-    }
-
-    SECTION("After closing bracket") {
-      DeserializationError err = deserializeJson(doc, "[\"hello\"]/*COMMENT*/");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(1 == arr.size());
-      REQUIRE(arr[0] == "hello");
-    }
-
-    SECTION("Before comma") {
-      DeserializationError err =
-          deserializeJson(doc, "[\"hello\"/*COMMENT*/,\"world\"]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(2 == arr.size());
-      REQUIRE(arr[0] == "hello");
-      REQUIRE(arr[1] == "world");
-    }
-
-    SECTION("After comma") {
-      DeserializationError err =
-          deserializeJson(doc, "[\"hello\",/*COMMENT*/ \"world\"]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(2 == arr.size());
-      REQUIRE(arr[0] == "hello");
-      REQUIRE(arr[1] == "world");
-    }
-
-    SECTION("/*/") {
-      DeserializationError err = deserializeJson(doc, "[/*/\n]");
-      REQUIRE(err == DeserializationError::IncompleteInput);
-    }
-
-    SECTION("Unfinished comment") {
-      DeserializationError err = deserializeJson(doc, "[/*COMMENT]");
-      REQUIRE(err == DeserializationError::IncompleteInput);
-    }
-
-    SECTION("Final slash missing") {
-      DeserializationError err = deserializeJson(doc, "[/*COMMENT*]");
-      REQUIRE(err == DeserializationError::IncompleteInput);
-    }
-  }
-
-  SECTION("Trailing comments") {
-    SECTION("Before opening bracket") {
-      DeserializationError err =
-          deserializeJson(doc, "//COMMENT\n\t[\"hello\"]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(1 == arr.size());
-      REQUIRE(arr[0] == "hello");
-    }
-
-    SECTION("After opening bracket") {
-      DeserializationError err = deserializeJson(doc, "[//COMMENT\n\"hello\"]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(1 == arr.size());
-      REQUIRE(arr[0] == "hello");
-    }
-
-    SECTION("Before closing bracket") {
-      DeserializationError err =
-          deserializeJson(doc, "[\"hello\"//COMMENT\r\n]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(1 == arr.size());
-      REQUIRE(arr[0] == "hello");
-    }
-
-    SECTION("After closing bracket") {
-      DeserializationError err = deserializeJson(doc, "[\"hello\"]//COMMENT\n");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(1 == arr.size());
-      REQUIRE(arr[0] == "hello");
-    }
-
-    SECTION("Before comma") {
-      DeserializationError err =
-          deserializeJson(doc, "[\"hello\"//COMMENT\n,\"world\"]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(2 == arr.size());
-      REQUIRE(arr[0] == "hello");
-      REQUIRE(arr[1] == "world");
-    }
-
-    SECTION("After comma") {
-      DeserializationError err =
-          deserializeJson(doc, "[\"hello\",//COMMENT\n\"world\"]");
-      JsonArray arr = doc.as<JsonArray>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(2 == arr.size());
-      REQUIRE(arr[0] == "hello");
-      REQUIRE(arr[1] == "world");
-    }
-
-    SECTION("Invalid comment") {
-      DeserializationError err = deserializeJson(doc, "[/COMMENT\n]");
-      REQUIRE(err == DeserializationError::InvalidInput);
-    }
-
-    SECTION("End document with comment") {
-      DeserializationError err = deserializeJson(doc, "[//COMMENT");
-      REQUIRE(err == DeserializationError::IncompleteInput);
-    }
-  }
-
   SECTION("Premature null-terminator") {
     SECTION("After opening bracket") {
       DeserializationError err = deserializeJson(doc, "[");

extras/tests/JsonDeserializer/input_types.cpp

@@ -41,7 +41,7 @@ TEST_CASE("deserializeJson(std::istream&)") {
   DynamicJsonDocument doc(4096);
 
   SECTION("array") {
-    std::istringstream json(" [ 42 /* comment */ ] ");
+    std::istringstream json(" [ 42 ] ");
 
     DeserializationError err = deserializeJson(doc, json);
     JsonArray arr = doc.as<JsonArray>();
@@ -52,7 +52,7 @@ TEST_CASE("deserializeJson(std::istream&)") {
   }
 
   SECTION("object") {
-    std::istringstream json(" { hello : 'world' // comment\n }");
+    std::istringstream json(" { hello : 'world' }");
 
     DeserializationError err = deserializeJson(doc, json);
     JsonObject obj = doc.as<JsonObject>();

extras/tests/JsonDeserializer/misc.cpp

@@ -61,26 +61,6 @@ TEST_CASE("deserializeJson(DynamicJsonDocument&)") {
     }
   }
 
-  SECTION("Comments") {
-    SECTION("Just a trailing comment") {
-      DeserializationError err = deserializeJson(doc, "// comment");
-
-      REQUIRE(err == DeserializationError::IncompleteInput);
-    }
-
-    SECTION("Just a block comment") {
-      DeserializationError err = deserializeJson(doc, "/*comment*/");
-
-      REQUIRE(err == DeserializationError::IncompleteInput);
-    }
-
-    SECTION("Just a slash") {
-      DeserializationError err = deserializeJson(doc, "/");
-
-      REQUIRE(err == DeserializationError::InvalidInput);
-    }
-  }
-
   SECTION("Premature null-terminator") {
     SECTION("In escape sequence") {
       DeserializationError err = deserializeJson(doc, "\"\\");
@@ -88,12 +68,6 @@ TEST_CASE("deserializeJson(DynamicJsonDocument&)") {
       REQUIRE(err == DeserializationError::IncompleteInput);
     }
 
-    SECTION("In block comment") {
-      DeserializationError err = deserializeJson(doc, "/* comment");
-
-      REQUIRE(err == DeserializationError::IncompleteInput);
-    }
-
     SECTION("In double quoted string") {
       DeserializationError err = deserializeJson(doc, "\"hello");
 
@@ -114,12 +88,6 @@ TEST_CASE("deserializeJson(DynamicJsonDocument&)") {
       REQUIRE(err == DeserializationError::IncompleteInput);
     }
 
-    SECTION("In block comment") {
-      DeserializationError err = deserializeJson(doc, "/* comment */", 10);
-
-      REQUIRE(err == DeserializationError::IncompleteInput);
-    }
-
     SECTION("In double quoted string") {
       DeserializationError err = deserializeJson(doc, "\"hello\"", 6);
 

extras/tests/JsonDeserializer/object.cpp

@@ -281,212 +281,6 @@ TEST_CASE("deserialize JSON object") {
     }
   }
 
-  SECTION("Block comments") {
-    SECTION("Before opening brace") {
-      DeserializationError err =
-          deserializeJson(doc, "/*COMMENT*/ {\"hello\":\"world\"}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("After opening brace") {
-      DeserializationError err =
-          deserializeJson(doc, "{/*COMMENT*/\"hello\":\"world\"}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("Before colon") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\"/*COMMENT*/:\"world\"}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("After colon") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\":/*COMMENT*/\"world\"}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("Before closing brace") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\":\"world\"/*COMMENT*/}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("After closing brace") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\":\"world\"}/*COMMENT*/");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("Before comma") {
-      DeserializationError err = deserializeJson(
-          doc, "{\"hello\":\"world\"/*COMMENT*/,\"answer\":42}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-      REQUIRE(obj["answer"] == 42);
-    }
-
-    SECTION("After comma") {
-      DeserializationError err = deserializeJson(
-          doc, "{\"hello\":\"world\",/*COMMENT*/\"answer\":42}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-      REQUIRE(obj["answer"] == 42);
-    }
-  }
-
-  SECTION("Trailing comments") {
-    SECTION("Before opening brace") {
-      DeserializationError err =
-          deserializeJson(doc, "//COMMENT\n {\"hello\":\"world\"}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("After opening brace") {
-      DeserializationError err =
-          deserializeJson(doc, "{//COMMENT\n\"hello\":\"world\"}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("Before colon") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\"//COMMENT\n:\"world\"}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("After colon") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\"://COMMENT\n\"world\"}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("Before closing brace") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\":\"world\"//COMMENT\n}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("After closing brace") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\":\"world\"}//COMMENT\n");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("Before comma") {
-      DeserializationError err = deserializeJson(
-          doc, "{\"hello\":\"world\"//COMMENT\n,\"answer\":42}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-      REQUIRE(obj["answer"] == 42);
-    }
-
-    SECTION("After comma") {
-      DeserializationError err = deserializeJson(
-          doc, "{\"hello\":\"world\",//COMMENT\n\"answer\":42}");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-      REQUIRE(obj["answer"] == 42);
-    }
-  }
-
-  SECTION("Dangling slash") {
-    SECTION("Before opening brace") {
-      DeserializationError err = deserializeJson(doc, "/{\"hello\":\"world\"}");
-
-      REQUIRE(err == DeserializationError::InvalidInput);
-    }
-
-    SECTION("After opening brace") {
-      DeserializationError err = deserializeJson(doc, "{/\"hello\":\"world\"}");
-
-      REQUIRE(err == DeserializationError::InvalidInput);
-    }
-
-    SECTION("Before colon") {
-      DeserializationError err = deserializeJson(doc, "{\"hello\"/:\"world\"}");
-
-      REQUIRE(err == DeserializationError::InvalidInput);
-    }
-
-    SECTION("After colon") {
-      DeserializationError err = deserializeJson(doc, "{\"hello\":/\"world\"}");
-
-      REQUIRE(err == DeserializationError::InvalidInput);
-    }
-
-    SECTION("Before closing brace") {
-      DeserializationError err = deserializeJson(doc, "{\"hello\":\"world\"/}");
-
-      REQUIRE(err == DeserializationError::InvalidInput);
-    }
-
-    SECTION("After closing brace") {
-      DeserializationError err = deserializeJson(doc, "{\"hello\":\"world\"}/");
-      JsonObject obj = doc.as<JsonObject>();
-
-      REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(obj["hello"] == "world");
-    }
-
-    SECTION("Before comma") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\":\"world\"/,\"answer\":42}");
-
-      REQUIRE(err == DeserializationError::InvalidInput);
-    }
-
-    SECTION("After comma") {
-      DeserializationError err =
-          deserializeJson(doc, "{\"hello\":\"world\",/\"answer\":42}");
-
-      REQUIRE(err == DeserializationError::InvalidInput);
-    }
-  }
-
   SECTION("Should clear the JsonObject") {
     deserializeJson(doc, "{\"hello\":\"world\"}");
     deserializeJson(doc, "{}");

extras/tests/MixedConfiguration/CMakeLists.txt

@@ -18,6 +18,8 @@ add_executable(MixedConfigurationTests
 	use_long_long_0.cpp
 	use_long_long_1.cpp
 	enable_progmem_1.cpp
+	enable_comments_1.cpp
+	enable_comments_0.cpp
 )
 
 target_link_libraries(MixedConfigurationTests catch)

extras/tests/MixedConfiguration/enable_comments_0.cpp

@@ -0,0 +1,54 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2020
+// MIT License
+
+#define ARDUINOJSON_ENABLE_COMMENTS 0
+#include <ArduinoJson.h>
+
+#include <catch.hpp>
+
+TEST_CASE("Comments should produce InvalidInput") {
+  DynamicJsonDocument doc(2048);
+
+  const char* testCases[] = {
+      "/*COMMENT*/  [\"hello\"]",
+      "[/*COMMENT*/ \"hello\"]",
+      "[\"hello\"/*COMMENT*/]",
+      "[\"hello\"/*COMMENT*/,\"world\"]",
+      "[\"hello\",/*COMMENT*/ \"world\"]",
+      "[/*/\n]",
+      "[/*COMMENT]",
+      "[/*COMMENT*]",
+      "//COMMENT\n\t[\"hello\"]",
+      "[//COMMENT\n\"hello\"]",
+      "[\"hello\"//COMMENT\r\n]",
+      "[\"hello\"//COMMENT\n,\"world\"]",
+      "[\"hello\",//COMMENT\n\"world\"]",
+      "[/COMMENT\n]",
+      "[//COMMENT",
+      "/*COMMENT*/ {\"hello\":\"world\"}",
+      "{/*COMMENT*/\"hello\":\"world\"}",
+      "{\"hello\"/*COMMENT*/:\"world\"}",
+      "{\"hello\":/*COMMENT*/\"world\"}",
+      "{\"hello\":\"world\"/*COMMENT*/}",
+      "//COMMENT\n {\"hello\":\"world\"}",
+      "{//COMMENT\n\"hello\":\"world\"}",
+      "{\"hello\"//COMMENT\n:\"world\"}",
+      "{\"hello\"://COMMENT\n\"world\"}",
+      "{\"hello\":\"world\"//COMMENT\n}",
+      "/{\"hello\":\"world\"}",
+      "{/\"hello\":\"world\"}",
+      "{\"hello\"/:\"world\"}",
+      "{\"hello\":/\"world\"}",
+      "{\"hello\":\"world\"/}",
+      "{\"hello\":\"world\"/,\"answer\":42}",
+      "{\"hello\":\"world\",/\"answer\":42}",
+  };
+  const size_t testCount = sizeof(testCases) / sizeof(testCases[0]);
+
+  for (size_t i = 0; i < testCount; i++) {
+    const char* input = testCases[i];
+    CAPTURE(input);
+    REQUIRE(deserializeJson(doc, input) == DeserializationError::InvalidInput);
+  }
+}

extras/tests/MixedConfiguration/enable_comments_1.cpp

@@ -0,0 +1,405 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2020
+// MIT License
+
+#define ARDUINOJSON_ENABLE_COMMENTS 1
+#include <ArduinoJson.h>
+
+#include <catch.hpp>
+
+TEST_CASE("Comments in arrays") {
+  DynamicJsonDocument doc(2048);
+
+  SECTION("Block comments") {
+    SECTION("Before opening bracket") {
+      DeserializationError err =
+          deserializeJson(doc, "/*COMMENT*/  [\"hello\"]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(1 == arr.size());
+      REQUIRE(arr[0] == "hello");
+    }
+
+    SECTION("After opening bracket") {
+      DeserializationError err =
+          deserializeJson(doc, "[/*COMMENT*/ \"hello\"]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(1 == arr.size());
+      REQUIRE(arr[0] == "hello");
+    }
+
+    SECTION("Before closing bracket") {
+      DeserializationError err = deserializeJson(doc, "[\"hello\"/*COMMENT*/]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(1 == arr.size());
+      REQUIRE(arr[0] == "hello");
+    }
+
+    SECTION("After closing bracket") {
+      DeserializationError err = deserializeJson(doc, "[\"hello\"]/*COMMENT*/");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(1 == arr.size());
+      REQUIRE(arr[0] == "hello");
+    }
+
+    SECTION("Before comma") {
+      DeserializationError err =
+          deserializeJson(doc, "[\"hello\"/*COMMENT*/,\"world\"]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(2 == arr.size());
+      REQUIRE(arr[0] == "hello");
+      REQUIRE(arr[1] == "world");
+    }
+
+    SECTION("After comma") {
+      DeserializationError err =
+          deserializeJson(doc, "[\"hello\",/*COMMENT*/ \"world\"]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(2 == arr.size());
+      REQUIRE(arr[0] == "hello");
+      REQUIRE(arr[1] == "world");
+    }
+
+    SECTION("/*/") {
+      DeserializationError err = deserializeJson(doc, "[/*/\n]");
+      REQUIRE(err == DeserializationError::IncompleteInput);
+    }
+
+    SECTION("Unfinished comment") {
+      DeserializationError err = deserializeJson(doc, "[/*COMMENT]");
+      REQUIRE(err == DeserializationError::IncompleteInput);
+    }
+
+    SECTION("Final slash missing") {
+      DeserializationError err = deserializeJson(doc, "[/*COMMENT*]");
+      REQUIRE(err == DeserializationError::IncompleteInput);
+    }
+  }
+
+  SECTION("Trailing comments") {
+    SECTION("Before opening bracket") {
+      DeserializationError err =
+          deserializeJson(doc, "//COMMENT\n\t[\"hello\"]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(1 == arr.size());
+      REQUIRE(arr[0] == "hello");
+    }
+
+    SECTION("After opening bracket") {
+      DeserializationError err = deserializeJson(doc, "[//COMMENT\n\"hello\"]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(1 == arr.size());
+      REQUIRE(arr[0] == "hello");
+    }
+
+    SECTION("Before closing bracket") {
+      DeserializationError err =
+          deserializeJson(doc, "[\"hello\"//COMMENT\r\n]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(1 == arr.size());
+      REQUIRE(arr[0] == "hello");
+    }
+
+    SECTION("After closing bracket") {
+      DeserializationError err = deserializeJson(doc, "[\"hello\"]//COMMENT\n");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(1 == arr.size());
+      REQUIRE(arr[0] == "hello");
+    }
+
+    SECTION("Before comma") {
+      DeserializationError err =
+          deserializeJson(doc, "[\"hello\"//COMMENT\n,\"world\"]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(2 == arr.size());
+      REQUIRE(arr[0] == "hello");
+      REQUIRE(arr[1] == "world");
+    }
+
+    SECTION("After comma") {
+      DeserializationError err =
+          deserializeJson(doc, "[\"hello\",//COMMENT\n\"world\"]");
+      JsonArray arr = doc.as<JsonArray>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(2 == arr.size());
+      REQUIRE(arr[0] == "hello");
+      REQUIRE(arr[1] == "world");
+    }
+
+    SECTION("Invalid comment") {
+      DeserializationError err = deserializeJson(doc, "[/COMMENT\n]");
+      REQUIRE(err == DeserializationError::InvalidInput);
+    }
+
+    SECTION("End document with comment") {
+      DeserializationError err = deserializeJson(doc, "[//COMMENT");
+      REQUIRE(err == DeserializationError::IncompleteInput);
+    }
+  }
+}
+
+TEST_CASE("Comments in objects") {
+  DynamicJsonDocument doc(2048);
+
+  SECTION("Block comments") {
+    SECTION("Before opening brace") {
+      DeserializationError err =
+          deserializeJson(doc, "/*COMMENT*/ {\"hello\":\"world\"}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("After opening brace") {
+      DeserializationError err =
+          deserializeJson(doc, "{/*COMMENT*/\"hello\":\"world\"}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("Before colon") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\"/*COMMENT*/:\"world\"}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("After colon") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\":/*COMMENT*/\"world\"}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("Before closing brace") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\":\"world\"/*COMMENT*/}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("After closing brace") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\":\"world\"}/*COMMENT*/");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("Before comma") {
+      DeserializationError err = deserializeJson(
+          doc, "{\"hello\":\"world\"/*COMMENT*/,\"answer\":42}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+      REQUIRE(obj["answer"] == 42);
+    }
+
+    SECTION("After comma") {
+      DeserializationError err = deserializeJson(
+          doc, "{\"hello\":\"world\",/*COMMENT*/\"answer\":42}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+      REQUIRE(obj["answer"] == 42);
+    }
+  }
+
+  SECTION("Trailing comments") {
+    SECTION("Before opening brace") {
+      DeserializationError err =
+          deserializeJson(doc, "//COMMENT\n {\"hello\":\"world\"}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("After opening brace") {
+      DeserializationError err =
+          deserializeJson(doc, "{//COMMENT\n\"hello\":\"world\"}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("Before colon") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\"//COMMENT\n:\"world\"}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("After colon") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\"://COMMENT\n\"world\"}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("Before closing brace") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\":\"world\"//COMMENT\n}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("After closing brace") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\":\"world\"}//COMMENT\n");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("Before comma") {
+      DeserializationError err = deserializeJson(
+          doc, "{\"hello\":\"world\"//COMMENT\n,\"answer\":42}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+      REQUIRE(obj["answer"] == 42);
+    }
+
+    SECTION("After comma") {
+      DeserializationError err = deserializeJson(
+          doc, "{\"hello\":\"world\",//COMMENT\n\"answer\":42}");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+      REQUIRE(obj["answer"] == 42);
+    }
+  }
+
+  SECTION("Dangling slash") {
+    SECTION("Before opening brace") {
+      DeserializationError err = deserializeJson(doc, "/{\"hello\":\"world\"}");
+
+      REQUIRE(err == DeserializationError::InvalidInput);
+    }
+
+    SECTION("After opening brace") {
+      DeserializationError err = deserializeJson(doc, "{/\"hello\":\"world\"}");
+
+      REQUIRE(err == DeserializationError::InvalidInput);
+    }
+
+    SECTION("Before colon") {
+      DeserializationError err = deserializeJson(doc, "{\"hello\"/:\"world\"}");
+
+      REQUIRE(err == DeserializationError::InvalidInput);
+    }
+
+    SECTION("After colon") {
+      DeserializationError err = deserializeJson(doc, "{\"hello\":/\"world\"}");
+
+      REQUIRE(err == DeserializationError::InvalidInput);
+    }
+
+    SECTION("Before closing brace") {
+      DeserializationError err = deserializeJson(doc, "{\"hello\":\"world\"/}");
+
+      REQUIRE(err == DeserializationError::InvalidInput);
+    }
+
+    SECTION("After closing brace") {
+      DeserializationError err = deserializeJson(doc, "{\"hello\":\"world\"}/");
+      JsonObject obj = doc.as<JsonObject>();
+
+      REQUIRE(err == DeserializationError::Ok);
+      REQUIRE(obj["hello"] == "world");
+    }
+
+    SECTION("Before comma") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\":\"world\"/,\"answer\":42}");
+
+      REQUIRE(err == DeserializationError::InvalidInput);
+    }
+
+    SECTION("After comma") {
+      DeserializationError err =
+          deserializeJson(doc, "{\"hello\":\"world\",/\"answer\":42}");
+
+      REQUIRE(err == DeserializationError::InvalidInput);
+    }
+  }
+}
+
+TEST_CASE("Comments alone") {
+  DynamicJsonDocument doc(2048);
+
+  SECTION("Just a trailing comment") {
+    DeserializationError err = deserializeJson(doc, "// comment");
+
+    REQUIRE(err == DeserializationError::IncompleteInput);
+  }
+
+  SECTION("Just a block comment") {
+    DeserializationError err = deserializeJson(doc, "/*comment*/");
+
+    REQUIRE(err == DeserializationError::IncompleteInput);
+  }
+
+  SECTION("Just a slash") {
+    DeserializationError err = deserializeJson(doc, "/");
+
+    REQUIRE(err == DeserializationError::InvalidInput);
+  }
+
+  SECTION("Premature terminator") {
+    DeserializationError err = deserializeJson(doc, "/* comment");
+
+    REQUIRE(err == DeserializationError::IncompleteInput);
+  }
+
+  SECTION("Premature end on sized input") {
+    DeserializationError err = deserializeJson(doc, "/* comment */", 10);
+
+    REQUIRE(err == DeserializationError::IncompleteInput);
+  }
+}

src/ArduinoJson/Configuration.hpp

@@ -165,6 +165,11 @@
 #define ARDUINOJSON_DECODE_UNICODE 0
 #endif
 
+// Ignore comments in input
+#ifndef ARDUINOJSON_ENABLE_COMMENTS
+#define ARDUINOJSON_ENABLE_COMMENTS 0
+#endif
+
 // Support NaN in JSON
 #ifndef ARDUINOJSON_ENABLE_NAN
 #define ARDUINOJSON_ENABLE_NAN 0

src/ArduinoJson/Json/JsonDeserializer.hpp

@@ -357,6 +357,7 @@ class JsonDeserializer {
           move();
           continue;
 
+#if ARDUINOJSON_ENABLE_COMMENTS
         // comments
         case '/':
           move();  // skip '/'
@@ -394,6 +395,7 @@ class JsonDeserializer {
               return DeserializationError::InvalidInput;
           }
           break;
+#endif
 
         default:
           return DeserializationError::Ok;

src/ArduinoJson/Namespace.hpp

@@ -14,13 +14,14 @@
 #define ARDUINOJSON_CONCAT8(A, B, C, D, E, F, G, H)    \
   ARDUINOJSON_CONCAT2(ARDUINOJSON_CONCAT4(A, B, C, D), \
                       ARDUINOJSON_CONCAT4(E, F, G, H))
-#define ARDUINOJSON_CONCAT11(A, B, C, D, E, F, G, H, I, J, K) \
+#define ARDUINOJSON_CONCAT12(A, B, C, D, E, F, G, H, I, J, K, L) \
-  ARDUINOJSON_CONCAT8(A, B, C, D, E, F, G, ARDUINOJSON_CONCAT4(H, I, J, K))
+  ARDUINOJSON_CONCAT8(A, B, C, D, E, F, G,                       \
+                      ARDUINOJSON_CONCAT4(H, I, J, ARDUINOJSON_CONCAT2(K, L)))
 
 #define ARDUINOJSON_NAMESPACE                                            \
-  ARDUINOJSON_CONCAT11(                                                  \
+  ARDUINOJSON_CONCAT12(                                                  \
       ArduinoJson, ARDUINOJSON_VERSION_MAJOR, ARDUINOJSON_VERSION_MINOR, \
       ARDUINOJSON_VERSION_REVISION, _, ARDUINOJSON_USE_LONG_LONG,        \
       ARDUINOJSON_USE_DOUBLE, ARDUINOJSON_DECODE_UNICODE,                \
       ARDUINOJSON_ENABLE_NAN, ARDUINOJSON_ENABLE_INFINITY,               \
-      ARDUINOJSON_ENABLE_PROGMEM)
+      ARDUINOJSON_ENABLE_PROGMEM, ARDUINOJSON_ENABLE_COMMENTS)