#include <jsoncons/json_options.hpp>
template<
class CharT
> class basic_json_options;
Specifies options for reading and writing JSON text.
| Option | Reading | Writing |
|---|---|---|
| decode_escaped_unicode | Interpret escaped unicode in JSON strings | |
| nan_to_str | Substitute string with NaN, if enabled |
Sets a string replacement for NaN when writing JSON |
| inf_to_str | Substitute string with infinity, if enabled |
Sets a string replacement for infinity when writing JSON |
| neginf_to_str | Substitute string with negative infinity, if enabled |
Sets a string replacement for negative infinity when writing JSON |
| nan_to_num | Sets a number replacement for NaN when writing JSON |
|
| inf_to_num | Sets a number replacement for Infinity when writing JSON |
|
| neginf_to_num | Sets a number replacement for Negative Infinity when writing JSON |
|
| max_nesting_depth | Maximum nesting depth allowed when parsing JSON | Maximum nesting depth allowed when serializing JSON |
| lossless_number | If true, parse numbers with exponents and fractional parts as strings with semantic tagging semantic_tag::bigdec. Defaults to false. |
|
| err_handler (since 0.171.0) | Defines an error handler for parsing JSON. Defaults to default_json_parsing. |
|
| indent_size | The indent size, the default is 4 | |
| spaces_around_colon | Indicates space option for name separator (:). Default is space after. |
|
| spaces_around_comma | Indicates space option for array value and object name/value pair separators (,). Default is space after. |
|
| pad_inside_object_braces | Default is false |
|
| pad_inside_array_brackets | Default is false |
|
| bigint_format | Overrides bignum format when serializing json. The default is bigint_chars_format::base10. | |
| byte_string_format | Overrides byte string format when serializing json. The default is byte_string_chars_format::base64url. | |
| float_format | Overrides floating point format when serializing to JSON. The default is float_chars_format::general. | |
| precision | Overrides floating point precision when serializing json. The default is shortest representation. | |
| escape_all_non_ascii | Escape all non-ascii characters. The default is false. |
|
| escape_solidus | Escape the solidus ('/') character. The default is false. |
|
| new_line_chars | Defaults to "\n" | |
| line_length_limit | ||
| object_object_line_splits | For an object whose parent is an object, set whether that object is split on a new line, or if its members are split on multiple lines. The default is line_split_kind::multi_line. | |
| array_object_line_splits | For an object whose parent is an array, set whether that object is split on a new line, or if its members are split on multiple lines. The default is line_split_kind::multi_line. | |
| object_array_line_splits | For an array whose parent is an object, set whether that array is split on a new line, or if its elements are split on multiple lines. The default is line_split_kind::same_line. | |
| array_array_line_splits | For an array whose parent is an array, set whether that array is split on a new line, or if its elements are split on multiple lines. The default is line_split_kind::new_line. |
The default floating point format is float_chars_format::general.
The default precision is shortest representation, e.g. 1.1 read will remain 1.1 when written, and not become 1.1000000000000001 (an equivalent but longer representation.)
Trailing zeros are removed, except one immediately following the decimal point. The period character (‘.’) is always used as the decimal point, non English locales are ignored.
Aliases for common character types are provided:
| Type | Definition |
|---|---|
json_options |
basic_json_options<char> |
wjson_options |
basic_json_options<wchar_t> |
static const uint8_t indent_size_default = 4;
The default size indent is 4
static const size_t line_length_limit_default = 120;
The default line length limit is 120
| Member type | Definition |
|---|---|
char_type |
CharT |
string_type |
std::basic_string<CharT> |
basic_json_options()
Constructs a basic_json_options with default values.
basic_json_options(const basic_json_options& other)
Copy constructor.
basic_json_options(basic_json_options&& other)
Move constructor.
void max_nesting_depth(int depth)
The maximum nesting depth allowed when decoding and encoding JSON. Default is 1024. Parsing can have an arbitrarily large depth limited only by available memory. Serializing a basic_json to JSON is limited by stack size.
basic_json_options& decode_escaped_unicode(bool value);
Indicates whether to interpret escaped unicode in JSON strings. Defaults to true.
basic_json_options& nan_to_str(const string_type& value, bool enable_inverse = true);
Sets a string replacement for NaN when writing JSON, and indicate whether it is also
to be used when reading JSON.
basic_json_options& inf_to_str(const string_type& value, bool enable_inverse = true);
Sets a string replacement for infinity when writing JSON, and indicate whether it is also to be used when reading JSON.
basic_json_options& neginf_to_str(const string_type& value, bool enable_inverse = true); (4)
Sets a string replacement for negative infinity when writing JSON, and indicate whether it is also to be used when reading JSON.
basic_json_options& nan_to_num(const string_type& value);
Sets a number replacement for NaN when writing JSON
basic_json_options& inf_to_num(const string_type& value);
Sets a number replacement for Infinity when writing JSON
basic_json_options& neginf_to_num(const string_type& value);
Sets a number replacement for Negative Infinity when writing JSON
basic_json_options& lossless_number(bool value);
If set to true, parse numbers with exponents and fractional parts as strings with semantic tagging semantic_tag::bigdec.
Defaults to false.
basic_json_options& indent_size(uint8_t value)
The indent size, the default is 4.
basic_json_options& spaces_around_colon(spaces_option value)
Indicates space option for name separator (:). Default
is space after.
basic_json_options& spaces_around_comma(spaces_option value)
Indicates space option for array value and object name/value pair separators (,). Default
is space after.
basic_json_options& pad_inside_object_braces(bool value)
Default is false
basic_json_options& pad_inside_array_brackets(bool value)
Default is false
basic_json_options& bigint_format(bigint_chars_format value)
Overrides bignum format when serializing json. The default is bigint_chars_format::base10.
basic_json_options& byte_string_format(byte_string_chars_format value)
Overrides byte string format when serializing json. The default is byte_string_chars_format::base64url.
basic_json_options& float_format(float_chars_format value);
Overrides floating point format when serializing to JSON. The default is float_chars_format::general.
basic_json_options& precision(int8_t value)
Overrides floating point precision when serializing json. The default is shortest representation.
basic_json_options& escape_all_non_ascii(bool value)
Escape all non-ascii characters. The default is false.
basic_json_options& escape_solidus(bool value)
Escape the solidus ('/') character. The default is false.
basic_json_options& new_line_chars(const string_type& value)
Defaults to "\n"
basic_json_options& line_length_limit(std::size_t value)
basic_json_options& object_object_line_splits(line_split_kind value)
For an object whose parent is an object, set whether that object is split on a new line, or if its members are split on multiple lines. The default is line_split_kind::multi_line.
basic_json_options& array_object_line_splits(line_split_kind value)
For an object whose parent is an array, set whether that object is split on a new line, or if its members are split on multiple lines. The default is line_split_kind::multi_line.
basic_json_options& object_array_line_splits(line_split_kind value)
For an array whose parent is an object, set whether that array is split on a new line, or if its elements are split on multiple lines. The default is line_split_kind::same_line.
basic_json_options& array_array_line_splits(line_split_kind value)
For an array whose parent is an array, set whether that array is split on a new line, or if its elements are split on multiple lines. The default is line_split_kind::new_line.
json obj;
obj["field1"] = std::sqrt(-1.0);
obj["field2"] = 1.79e308*1000;
obj["field3"] = -1.79e308*1000;
std::cout << obj << std::endl;Output:
{"field1":null,"field2":null,"field3":null}json obj;
obj["field1"] = std::sqrt(-1.0);
obj["field2"] = 1.79e308*1000;
obj["field3"] = -1.79e308*1000;
auto options = json_options{}
.nan_to_num("null"); // default is "null"
.inf_to_num("1e9999"); // default is "null"
std::cout << pretty_print(obj,options) << std::endl;Output:
{
"field1":null,
"field2":1e9999,
"field3":-1e9999
}By default, jsoncons parses a number with an exponent or fractional part
into a double precision floating point number. If you wish, you can
keep the number as a string with semantic tagging bigdec,
using the lossless_number option. You can then put it into a float,
double, a boost multiprecision number, or whatever type you want.
int main()
{
std::string s = R"(
{
"a" : 12.00,
"b" : 1.23456789012345678901234567890
}
)";
// Default
json j = json::parse(s);
std::cout.precision(15);
// Access as string
std::cout << "(1) a: " << j["a"].as<std::string>() << ", b: " << j["b"].as<std::string>() << "\n";
// Access as double
std::cout << "(2) a: " << j["a"].as<double>() << ", b: " << j["b"].as<double>() << "\n\n";
// Using lossless_number option
auto options = json_options{}
.lossless_number(true);
json j2 = json::parse(s, options);
// Access as string
std::cout << "(3) a: " << j2["a"].as<std::string>() << ", b: " << j2["b"].as<std::string>() << "\n";
// Access as double
std::cout << "(4) a: " << j2["a"].as<double>() << ", b: " << j2["b"].as<double>() << "\n\n";
}Output:
(1) a: 12.0, b: 1.2345678901234567
(2) a: 12, b: 1.23456789012346
(3) a: 12.00, b: 1.23456789012345678901234567890
(4) a: 12, b: 1.23456789012346
json j;
j["verts"] = json(json_array_arg, {1, 2, 3});
j["normals"] = json(json_array_arg, {1, 0, 1});
j["uvs"] = json(json_array_arg, {0, 0, 1, 1});
std::cout << "Default (same line)" << std::endl;
std::cout << pretty_print(j) << std::endl;
std::cout << "New line" << std::endl;
auto options1 = json_options{}
.object_array_line_splits(line_split_kind::new_line);
std::cout << pretty_print(j,options1) << std::endl;
std::cout << "Multi line" << std::endl;
auto options2 = json_options{}
.object_array_line_splits(line_split_kind::multi_line);
std::cout << pretty_print(j,options2) << std::endl;Output:
Default (same line)
{
"normals": [1,0,1],
"uvs": [0,0,1,1],
"verts": [1,2,3]
}New line
{
"normals": [
1,0,1
],
"uvs": [
0,0,1,1
],
"verts": [
1,2,3
]
}Multi line
{
"normals": [
1,
0,
1
],
"uvs": [
0,
0,
1,
1
],
"verts": [
1,
2,
3
]
} json j;
j["data"]["id"] = json(json_array_arg, {0,1,2,3,4,5,6,7});
j["data"]["item"] = json(json_array_arg, {json(json_array_arg, {2}),
json(json_array_arg, {4,5,2,3}),
json(json_array_arg, {4}),
json(json_array_arg, {4,5,2,3}),
json(json_array_arg, {2}),
json(json_array_arg, {4,5,3}),
json(json_array_arg, {2}),
json(json_array_arg, {4,3})});
std::cout << "Default (new line)" << std::endl;
std::cout << pretty_print(j) << std::endl;
std::cout << "Same line" << std::endl;
auto options1 = json_options{}
.array_array_line_splits(line_split_kind::same_line);
std::cout << pretty_print(j, options1) << std::endl;
std::cout << "Multi line" << std::endl;
auto options2 = json_options{}
.array_array_line_splits(line_split_kind::multi_line);
std::cout << pretty_print(j, options2) << std::endl;Output:
Default (new line)
{
"data": {
"id": [0,1,2,3,4,5,6,7],
"item": [
[2],
[4,5,2,3],
[4],
[4,5,2,3],
[2],
[4,5,3],
[2],
[4,3]
]
}
}Same line
{
"data": {
"id": [0,1,2,3,4,5,6,7],
"item": [[2],[4,5,2,3],[4],[4,5,2,3],[2],[4,5,3],[2],[4,3]]
}
}Multi line
{
"data": {
"id": [
0,1,2,3,4,5,6,7
],
"item": [
[
2
],
[
4,
5,
2,
3
],
[
4
],
[
4,
5,
2,
3
],
[
2
],
[
4,
5,
3
],
[
2
],
[
4,
3
]
]
}
}int main()
{
std::string s = R"(
{
"first" : 1,
"second" : 2,
}
)";
// Default
try
{
auto j = json::parse(s);
}
catch (const ser_error& e)
{
std::cout << "(1) " << e.what() << "\n\n";
}
// Allow trailing commas
// until 0.170.0
// auto j = json::parse(s, allow_trailing_commas());
// since 0.171.0
auto options = json_options{}
.err_handler(allow_trailing_commas());
auto j = json::parse(s, options);
std::cout << "(2) " << j << "\n\n";
}Output:
(1) Extra comma at line 5 and column 5
(2) {"first":1,"second":2}