deploy: d8d47be4a5

api/basic_json/error_handler_t/index.md

@@ -4,18 +4,27 @@
 enum class error_handler_t {
     strict,
     replace,
-    ignore
+    ignore,
+    keep
 };
 ```
 
-This enumeration is used in the [`dump`](https://json.nlohmann.me/api/basic_json/dump/index.md) function to choose how to treat decoding errors while serializing a `basic_json` value. Three values are differentiated:
+This enumeration is used to choose how to treat ill-formed UTF-8 in a string value or object key:
 
-strict : throw a `type_error` exception in case of invalid UTF-8
+- [`dump`](https://json.nlohmann.me/api/basic_json/dump/index.md) uses it while serializing a `basic_json` value to text.
+- [`to_cbor`](https://json.nlohmann.me/api/basic_json/to_cbor/index.md), [`to_msgpack`](https://json.nlohmann.me/api/basic_json/to_msgpack/index.md), [`to_ubjson`](https://json.nlohmann.me/api/basic_json/to_ubjson/index.md), [`to_bjdata`](https://json.nlohmann.me/api/basic_json/to_bjdata/index.md), and [`to_bson`](https://json.nlohmann.me/api/basic_json/to_bson/index.md) use it while serializing a `basic_json` value to that binary format. Their default is `keep`, as no binary writer checked before this parameter was added. CBOR, UBJSON, BJData, and BSON require valid UTF-8, so for these four the default is `strict` if [`JSON_STRICT_BINARY_UTF8`](https://json.nlohmann.me/api/macros/json_strict_binary_utf8/index.md) is enabled; MessagePack's specification explicitly allows a string to contain ill-formed UTF-8, so `to_msgpack` stays at `keep`. `to_bon8` does not take this parameter: BON8 always validates, since UTF-8 lead bytes are structural to that format.
+- [`from_cbor`](https://json.nlohmann.me/api/basic_json/from_cbor/index.md), [`from_msgpack`](https://json.nlohmann.me/api/basic_json/from_msgpack/index.md), [`from_ubjson`](https://json.nlohmann.me/api/basic_json/from_ubjson/index.md), [`from_bjdata`](https://json.nlohmann.me/api/basic_json/from_bjdata/index.md), and [`from_bson`](https://json.nlohmann.me/api/basic_json/from_bson/index.md) use it while parsing that binary format, to decide whether to check a string value or object key for well-formed UTF-8 at all; by default (`keep`) they do not, as no binary reader did before this parameter was added. `from_bon8` does not take this parameter, for the same reason `to_bon8` does not.
+
+Four values are differentiated:
+
+strict : throw a `type_error`/`parse_error` exception in case of invalid UTF-8
 
 replace : replace invalid UTF-8 sequences with U+FFFD (� REPLACEMENT CHARACTER)
 
 ignore : ignore invalid UTF-8 sequences; all valid bytes are copied to the output unchanged, and invalid bytes are dropped
 
+keep : keep invalid UTF-8 sequences unchanged; only meaningful for the binary formats mentioned above, since \[`dump`\] (dump.md) itself must produce text, and `keep` there writes the ill-formed bytes to the output as is, so the result is then not valid UTF-8 (but still equals the input bytes exactly, including around any well-formed characters, which are still escaped as usual)
+
 ## Examples
 
 Example
@@ -45,7 +54,8 @@ int main()
               << j_invalid.dump(-1, ' ', false, json::error_handler_t::replace)
               << "\nstring with ignored invalid characters: "
               << j_invalid.dump(-1, ' ', false, json::error_handler_t::ignore)
-              << '\n';
+              << "\nstring with the invalid byte kept as is (" << j_invalid.dump(-1, ' ', false, json::error_handler_t::keep).size()
+              << " bytes, not valid UTF-8 itself)\n";
 }
 ```
 
@@ -55,6 +65,7 @@ Output:
 [json.exception.type_error.316] invalid UTF-8 byte at index 2: 0xA9
 string with replaced invalid characters: "ä�ü"
 string with ignored invalid characters: "äü"
+string with the invalid byte kept as is (7 bytes, not valid UTF-8 itself)
 ```
 
 ## See also
@@ -65,3 +76,4 @@ string with ignored invalid characters: "äü"
 ## Version history
 
 - Added in version 3.4.0.
+- Added `keep`, and made this enumeration apply to the binary readers and writers in addition to `dump`, in version 3.13.0.