This document contains all the API usage and examples for the yyjson library.
API Design
API prefix
All public functions and structs are prefixed with yyjson_
, and all constants are prefixed with YYJSON_
.
API for immutable/mutable data
The library have 2 types of data structures: immutable and mutable:
When reading a JSON, yyjson returns immutable documents and values.
When building a JSON, yyjson creates mutable documents and values.
The document holds the memory for all its JSON values and strings.
For most immutable APIs, you can just add a mut
after yyjson_
to get the mutable version, for example:
yyjson_api_inline bool yyjson_is_str(yyjson_val *val)
Definition: yyjson.h:4694
yyjson_api_inline char * yyjson_mut_write(const yyjson_mut_doc *doc, yyjson_write_flag flg, size_t *len)
Definition: yyjson.h:1230
yyjson_api_inline char * yyjson_write(const yyjson_doc *doc, yyjson_write_flag flg, size_t *len)
Definition: yyjson.h:1126
yyjson_api_inline bool yyjson_mut_is_str(yyjson_mut_val *val)
Definition: yyjson.h:5237
Definition: yyjson.h:4362
Definition: yyjson.h:5119
Definition: yyjson.h:5071
Definition: yyjson.h:4357
The library also provides some functions to convert values between immutable and mutable:
yyjson_api yyjson_mut_val * yyjson_val_mut_copy(yyjson_mut_doc *doc, yyjson_val *val)
yyjson_api yyjson_mut_doc * yyjson_doc_mut_copy(yyjson_doc *doc, const yyjson_alc *alc)
yyjson_api yyjson_doc * yyjson_mut_doc_imut_copy(yyjson_mut_doc *doc, const yyjson_alc *alc)
yyjson_api yyjson_doc * yyjson_mut_val_imut_copy(yyjson_mut_val *val, const yyjson_alc *alc)
API for string
The library supports strings with or without null-terminator ('\0').
When you need to use a string without a null-terminator or when you explicitly know the length of the string, you can use the function that ends with n
, for example:
yyjson_api_inline bool yyjson_equals_str(yyjson_val *val, const char *str)
Definition: yyjson.h:4780
yyjson_api_inline bool yyjson_equals_strn(yyjson_val *val, const char *str, size_t len)
Definition: yyjson.h:4787
When creating JSON, yyjson treats strings as constants for better performance. However, if your string will be modified, you should use a function with a cpy
to copy the string to the document, for example:
yyjson_api_inline yyjson_mut_val * yyjson_mut_strn(yyjson_mut_doc *doc, const char *str, size_t len)
Definition: yyjson.h:5541
yyjson_api_inline yyjson_mut_val * yyjson_mut_strncpy(yyjson_mut_doc *doc, const char *str, size_t len)
Definition: yyjson.h:5561
yyjson_api_inline yyjson_mut_val * yyjson_mut_strcpy(yyjson_mut_doc *doc, const char *str)
Definition: yyjson.h:5555
yyjson_api_inline yyjson_mut_val * yyjson_mut_str(yyjson_mut_doc *doc, const char *str)
Definition: yyjson.h:5535
Reading JSON
The library provides 4 functions for reading JSON.
Each function accepts an input of UTF-8 data or a file,
returns a document if it successful or NULL
if it fails.
Read JSON from string
The dat
should be a UTF-8 string, null-terminator is not required.
The len
is the byte length of dat
.
The flg
is reader flag, pass 0 if you don't need it, see reader flag
for details.
If input is invalid, NULL
is returned.
size_t len,
uint32_t yyjson_read_flag
Definition: yyjson.h:622
yyjson_api_inline yyjson_doc * yyjson_read(const char *dat, size_t len, yyjson_read_flag flg)
Definition: yyjson.h:827
Sample code:
const char *str = "[1,2,3,4]";
if (doc) {...}
yyjson_api_inline void yyjson_doc_free(yyjson_doc *doc)
Definition: yyjson.h:4640
Read JSON from file
The path
is JSON file path.
The flg
is reader flag, pass 0 if you don't need it, see reader flag
for details.
The alc
is memory allocator, pass NULL if you don't need it, see memory allocator
for details.
The err
is a pointer to receive error message, pass NULL if you don't need it.
If input is invalid, NULL
is returned.
yyjson_api yyjson_doc * yyjson_read_file(const char *path, yyjson_read_flag flg, const yyjson_alc *alc, yyjson_read_err *err)
Sample code:
Read JSON from file pointer
The fp
is file pointer. The data will be read from the current position of the FILE to the end.
The flg
is reader flag, pass 0 if you don't need it, see reader flag
for details.
The alc
is memory allocator, pass NULL if you don't need it, see memory allocator
for details.
The err
is a pointer to receive error message, pass NULL if you don't need it.
If input is invalid, NULL
is returned.
yyjson_api yyjson_doc * yyjson_read_fp(FILE *fp, yyjson_read_flag flg, const yyjson_alc *alc, yyjson_read_err *err)
Sample code:
FILE *fp = fdopen(fd, "rb");
if (fp) fclose(fp);
if (doc) {...}
Read JSON with options
The dat
should be a UTF-8 string, you can pass a const string if you don't use YYJSON_READ_INSITU
flag.
The len
is the dat
's length in bytes.
The flg
is reader flag, pass 0 if you don't need it, see reader flag
for details.
The alc
is memory allocator, pass NULL if you don't need it, see memory allocator
for details.
The err
is a pointer to receive error message, pass NULL if you don't need it.
size_t len,
yyjson_api yyjson_doc * yyjson_read_opts(char *dat, size_t len, yyjson_read_flag flg, const yyjson_alc *alc, yyjson_read_err *err)
Sample code:
const char *dat = your_file.bytes;
size_t len = your_file.size;
yyjson_err err;
if (doc) {...}
else printf("read error: %s code: %u at position: %ld\n", err.msg, err.code, err.pos);
static const yyjson_read_flag YYJSON_READ_ALLOW_INF_AND_NAN
Definition: yyjson.h:656
static const yyjson_read_flag YYJSON_READ_ALLOW_COMMENTS
Definition: yyjson.h:652
Reader flag
The library provides a set of flags for JSON reader.
You can use a single flag, or combine multiple flags with bitwise |
operator.
● YYJSON_READ_NOFLAG = 0
This is the default flag for JSON reader (RFC-8259 or ECMA-404 compliant):
- Read positive integer as
uint64_t
.
- Read negative integer as
int64_t
.
- Read floating-point number as
double
with correct rounding.
- Read integer which cannot fit in
uint64_t
or int64_t
as double
.
- Report error if double number is infinity.
- Report error if string contains invalid UTF-8 character or BOM.
- Report error on trailing commas, comments,
Inf
and NaN
literals.
● YYJSON_READ_INSITU
Read the input data in-situ.
This option allows the reader to modify and use the input data to store string values, which can slightly improve reading speed. However, the caller must ensure that the input data is held until the document is freed. The input data must be padded with at least YYJSON_PADDING_SIZE
bytes. For example: [1,2]
should be [1,2]\0\0\0\0
, input length should be 5.
Sample code:
size_t dat_len = ...;
read_from_socket(buf, ...);
if (doc) {...}
free(buf);
static const yyjson_read_flag YYJSON_READ_INSITU
Definition: yyjson.h:640
#define YYJSON_PADDING_SIZE
Definition: yyjson.h:517
● YYJSON_READ_STOP_WHEN_DONE
Stop parsing when reaching the end of a JSON document instead of issues an error if there's additional content after it.
This option is useful for parsing small pieces of JSON within larger data, such as NDJSON.
Sample code:
size_t file_size = ...;
char *dat = malloc(file_size + 4);
your_read_file(dat, file);
memset(dat + file_size, 0, 4);
char *hdr = dat;
char *end = dat + file_size;
while (true) {
if (!doc) break;
your_doc_process(doc);
}
free(dat);
yyjson_api_inline size_t yyjson_doc_get_read_size(yyjson_doc *doc)
Definition: yyjson.h:4632
static const yyjson_read_flag YYJSON_READ_STOP_WHEN_DONE
Definition: yyjson.h:645
● YYJSON_READ_ALLOW_TRAILING_COMMAS
Allow a single trailing comma at the end of an object or array (non-standard), for example:
{
"a": 1,
"b": 2,
}
[
"a",
"b",
]
● YYJSON_READ_ALLOW_COMMENTS
Allow C-style single line and multiple line comments (non-standard), for example:
{
"name": "Harry", // single line comment
"id": /* multiple line comment */ 123
}
● YYJSON_READ_ALLOW_INF_AND_NAN
Allow nan/inf number or case-insensitive literal (non-standard), for example:
{
"large": 123e999,
"nan1": NaN,
"nan2": nan,
"inf1:" Inf,
"inf2": -Infinity
}
● YYJSON_READ_NUMBER_AS_RAW
Read all numbers as raw strings without parsing. This flag is useful if you want to handle number parsing yourself. You can use the following functions to extract raw strings:
yyjson_api_inline bool yyjson_is_raw(yyjson_val *val)
Definition: yyjson.h:4654
yyjson_api_inline const char * yyjson_get_raw(yyjson_val *val)
Definition: yyjson.h:4744
yyjson_api_inline size_t yyjson_get_len(yyjson_val *val)
Definition: yyjson.h:4776
● YYJSON_READ_BIGNUM_AS_RAW
Read big numbers as raw strings. This flag is useful if you want to parse these big numbers yourself. These big numbers include integers that cannot be represented by int64_t
and uint64_t
, and floating-point numbers that cannot be represented by finite double
.
Note that this flag will be overridden by YYJSON_READ_NUMBER_AS_RAW
flag.
● YYJSON_READ_ALLOW_INVALID_UNICODE
Allow reading invalid unicode when parsing string values (non-standard), for example:
"\x80xyz"
"\xF0\x81\x81\x81"
This flag permits invalid characters to appear in the string values, but it still reports errors for invalid escape sequences. It does not impact the performance of correctly encoded strings.
Warning: when using this option, be aware that strings within JSON values may contain incorrect encoding, so you need to handle these strings carefully to avoid security risks.
Writing JSON
The library provides 4 sets of functions for writing JSON.
Each function accepts an input of JSON document or root value, and returns a UTF-8 string or file.
Write JSON to string
The doc/val
is JSON document or root value, if you pass NULL, you will get NULL result.
The flg
is writer flag, pass 0 if you don't need it, see writer flag
for details.
The len
is a pointer to receive output length (not including the null-terminator), pass NULL if you don't need it.
This function returns a new JSON string, or NULL if error occurs.
The string is encoded as UTF-8 with a null-terminator.
You should use free() or alc->free() to release it when it's no longer needed.
yyjson_api_inline char * yyjson_val_write(const yyjson_val *val, yyjson_write_flag flg, size_t *len)
Definition: yyjson.h:1335
yyjson_api_inline char * yyjson_mut_val_write(const yyjson_mut_val *val, yyjson_write_flag flg, size_t *len)
Definition: yyjson.h:1437
uint32_t yyjson_write_flag
Definition: yyjson.h:954
Sample code 1:
printf("%s\n", json);
free(json);
static const yyjson_write_flag YYJSON_WRITE_PRETTY
Definition: yyjson.h:964
Sample code 2:
printf("%s\n", json);
free(json);
yyjson_api_inline void yyjson_mut_doc_set_root(yyjson_mut_doc *doc, yyjson_mut_val *root)
Definition: yyjson.h:5186
yyjson_api_inline bool yyjson_mut_arr_add_int(yyjson_mut_doc *doc, yyjson_mut_val *arr, int64_t num)
Definition: yyjson.h:6140
yyjson_api yyjson_mut_doc * yyjson_mut_doc_new(const yyjson_alc *alc)
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr(yyjson_mut_doc *doc)
Definition: yyjson.h:5678
Write JSON to file
The path
is output JSON file path, If the path is invalid, you will get an error. If the file is not empty, the content will be discarded.
The doc/val
is JSON document or root value, if you pass NULL, you will get an error.
The flg
is writer flag, pass 0 if you don't need it, see writer flag
for details.
The alc
is memory allocator, pass NULL if you don't need it, see memory allocator
for details.
The err
is a pointer to receive error message, pass NULL if you don't need it.
This function returns true on success, or false if error occurs.
yyjson_api bool yyjson_write_file(const char *path, const yyjson_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
yyjson_api bool yyjson_val_write_file(const char *path, const yyjson_val *val, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
yyjson_api bool yyjson_mut_write_file(const char *path, const yyjson_mut_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
yyjson_api bool yyjson_mut_val_write_file(const char *path, const yyjson_mut_val *val, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
Definition: yyjson.h:1020
Sample code:
Write JSON to file pointer
The fp
is output file pointer, The data will be written to the current position of the file.
The doc/val
is JSON document or root value, if you pass NULL, you will get an error.
The flg
is writer flag, pass 0 if you don't need it, see writer flag
for details.
The alc
is memory allocator, pass NULL if you don't need it, see memory allocator
for details.
The err
is a pointer to receive error message, pass NULL if you don't need it.
This function returns true on success, or false if error occurs.
yyjson_api bool yyjson_write_fp(FILE *fp, const yyjson_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
yyjson_api bool yyjson_val_write_fp(FILE *fp, const yyjson_val *val, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
yyjson_api bool yyjson_mut_write_fp(FILE *fp, const yyjson_mut_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
yyjson_api bool yyjson_mut_val_write_fp(FILE *fp, const yyjson_mut_val *val, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
Sample code:
FILE *fp = fdopen(fd, "wb");
if (fp) fclose(fp);
if (suc) printf("OK");
Write JSON with options
The doc/val
is JSON document or root value, if you pass NULL, you will get NULL result.
The flg
is writer flag, pass 0 if you don't need it, see writer flag
for details.
The alc
is memory allocator, pass NULL if you don't need it, see memory allocator
for details.
The len
is a pointer to receive output length (not including the null-terminator), pass NULL if you don't need it.
The err
is a pointer to receive error message, pass NULL if you don't need it.
This function returns a new JSON string, or NULL if error occurs.
The string is encoded as UTF-8 with a null-terminator.
You should use free() or alc->free() to release it when it's no longer needed.
yyjson_api char * yyjson_write_opts(const yyjson_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, size_t *len, yyjson_write_err *err)
yyjson_api char * yyjson_val_write_opts(const yyjson_val *val, yyjson_write_flag flg, const yyjson_alc *alc, size_t *len, yyjson_write_err *err)
yyjson_api char * yyjson_mut_write_opts(const yyjson_mut_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, size_t *len, yyjson_write_err *err)
yyjson_api char * yyjson_mut_val_write_opts(const yyjson_mut_val *val, yyjson_write_flag flg, const yyjson_alc *alc, size_t *len, yyjson_write_err *err)
Sample code:
char buf[64 * 1024];
size_t len;
if (json) {
printf("suc: %lu\n%s\n", len, json);
} else {
printf(
"err: %u msg:%s\n", err.
code, err.
msg);
}
void(* free)(void *ctx, void *ptr)
Definition: yyjson.h:537
void * ctx
Definition: yyjson.h:539
const char * msg
Definition: yyjson.h:1024
yyjson_api bool yyjson_alc_pool_init(yyjson_alc *alc, void *buf, size_t size)
static const yyjson_write_flag YYJSON_WRITE_ESCAPE_UNICODE
Definition: yyjson.h:967
yyjson_write_code code
Definition: yyjson.h:1022
Writer flag
The library provides a set of flags for JSON writer.
You can use a single flag, or combine multiple flags with bitwise |
operator.
● YYJSON_WRITE_NOFLAG = 0
This is the default flag for JSON writer:
- Writes JSON in minified format.
- Reports an error on encountering
inf
or nan
number.
- Reports an error on encountering invalid UTF-8 strings.
- Does not escape unicode or slashes.
● YYJSON_WRITE_PRETTY
Writes JSON with a pretty format uing a 4-space indent.
● YYJSON_WRITE_PRETTY_TWO_SPACES
Writes JSON with a pretty format uing a 2-space indent. This flag will override YYJSON_WRITE_PRETTY
flag.
● YYJSON_WRITE_ESCAPE_UNICODE
Escape unicode as \uXXXX
, making the output ASCII-only, for example:
["Alizée, 😊"]
["Aliz\\u00E9e, \\uD83D\\uDE0A"]
● YYJSON_WRITE_ESCAPE_SLASHES
Escapes the forward slash character /
as \/
, for example:
["https://github.com"]
["https:\/\/github.com"]
● YYJSON_WRITE_ALLOW_INF_AND_NAN
Writes inf/nan numbers as Infinity
and NaN
literals instead of reporting errors.
Note that this output is NOT standard JSON and may be rejected by other JSON libraries, for example:
{"not_a_number":NaN,"large_number":Infinity}
● YYJSON_WRITE_INF_AND_NAN_AS_NULL
Writes inf/nan numbers as null
literals instead of reporting errors.
This flag will override YYJSON_WRITE_ALLOW_INF_AND_NAN
flag, for example:
{"not_a_number":null,"large_number":null}
● YYJSON_WRITE_ALLOW_INVALID_UNICODE
Allows invalid unicode when encoding string values.
Invalid characters within string values will be copied byte by byte. If YYJSON_WRITE_ESCAPE_UNICODE
flag is also set, invalid characters will be escaped as \uFFFD
(replacement character).
This flag does not affect the performance of correctly encoded string.
Accessing JSON Document
JSON Document
You can access the content of a document with the following functions:
yyjson_api_inline size_t yyjson_doc_get_val_count(yyjson_doc *doc)
Definition: yyjson.h:4636
yyjson_api_inline yyjson_val * yyjson_doc_get_root(yyjson_doc *doc)
Definition: yyjson.h:4628
A document holds all the memory for its internal values and strings. When you no longer need it, you should release the document and free up all the memory:
JSON Value
Each JSON Value has a type and subtype, as specified in the table:
Type | Subtype | |
YYJSON_TYPE_NONE | | Invalid value |
YYJSON_TYPE_RAW | | Raw string |
YYJSON_TYPE_NULL | | null literal |
YYJSON_TYPE_BOOL | YYJSON_SUBTYPE_FALSE | false literal |
YYJSON_TYPE_BOOL | YYJSON_SUBTYPE_TRUE | true literal |
YYJSON_TYPE_NUM | YYJSON_SUBTYPE_UINT | uint64_t nummer |
YYJSON_TYPE_NUM | YYJSON_SUBTYPE_SINT | int64_t number |
YYJSON_TYPE_NUM | YYJSON_SUBTYPE_REAL | double number |
YYJSON_TYPE_STR | | String value |
YYJSON_TYPE_ARR | | Array value |
YYJSON_TYPE_OBJ | | Object value |
Note that YYJSON_TYPE_NONE
does not appear when the JSON is successfully parsed, and YYJSON_TYPE_RAW
only appears when the corresponding flag is used. All other types are JSON-standard types.
The following functions can be used to determine the type of a JSON value.
uint8_t yyjson_subtype
Definition: yyjson.h:498
yyjson_api_inline bool yyjson_is_ctn(yyjson_val *val)
Definition: yyjson.h:4706
yyjson_api_inline uint8_t yyjson_get_tag(yyjson_val *val)
Definition: yyjson.h:4724
yyjson_api_inline bool yyjson_is_bool(yyjson_val *val)
Definition: yyjson.h:4670
yyjson_api_inline bool yyjson_is_real(yyjson_val *val)
Definition: yyjson.h:4686
yyjson_api_inline const char * yyjson_get_type_desc(yyjson_val *val)
Definition: yyjson.h:4728
uint8_t yyjson_type
Definition: yyjson.h:487
yyjson_api_inline bool yyjson_is_int(yyjson_val *val)
Definition: yyjson.h:4682
yyjson_api_inline bool yyjson_is_true(yyjson_val *val)
Definition: yyjson.h:4662
yyjson_api_inline bool yyjson_is_false(yyjson_val *val)
Definition: yyjson.h:4666
yyjson_api_inline yyjson_subtype yyjson_get_subtype(yyjson_val *val)
Definition: yyjson.h:4720
yyjson_api_inline yyjson_type yyjson_get_type(yyjson_val *val)
Definition: yyjson.h:4716
yyjson_api_inline bool yyjson_is_null(yyjson_val *val)
Definition: yyjson.h:4658
yyjson_api_inline bool yyjson_is_sint(yyjson_val *val)
Definition: yyjson.h:4678
yyjson_api_inline bool yyjson_is_uint(yyjson_val *val)
Definition: yyjson.h:4674
yyjson_api_inline bool yyjson_is_arr(yyjson_val *val)
Definition: yyjson.h:4698
yyjson_api_inline bool yyjson_is_num(yyjson_val *val)
Definition: yyjson.h:4690
yyjson_api_inline bool yyjson_is_obj(yyjson_val *val)
Definition: yyjson.h:4702
The following functions can be used to get the contents of the JSON value.
yyjson_api_inline int yyjson_get_int(yyjson_val *val)
Definition: yyjson.h:4760
yyjson_api_inline double yyjson_get_real(yyjson_val *val)
Definition: yyjson.h:4764
yyjson_api_inline const char * yyjson_get_str(yyjson_val *val)
Definition: yyjson.h:4772
yyjson_api_inline bool yyjson_get_bool(yyjson_val *val)
Definition: yyjson.h:4748
yyjson_api_inline uint64_t yyjson_get_uint(yyjson_val *val)
Definition: yyjson.h:4752
yyjson_api_inline double yyjson_get_num(yyjson_val *val)
Definition: yyjson.h:4768
yyjson_api_inline int64_t yyjson_get_sint(yyjson_val *val)
Definition: yyjson.h:4756
The following functions can be used to modify the content of a JSON value.
Warning: For immutable documents, these functions will break the immutable
convention, you should use this set of APIs with caution (e.g. make sure the document is only accessed in a single thread).
yyjson_api_inline bool yyjson_set_null(yyjson_val *val)
Definition: yyjson.h:4809
yyjson_api_inline bool yyjson_set_raw(yyjson_val *val, const char *raw, size_t len)
Definition: yyjson.h:4802
yyjson_api_inline bool yyjson_set_uint(yyjson_val *val, uint64_t num)
Definition: yyjson.h:4821
yyjson_api_inline bool yyjson_set_str(yyjson_val *val, const char *str)
Definition: yyjson.h:4845
yyjson_api_inline bool yyjson_set_strn(yyjson_val *val, const char *str, size_t len)
Definition: yyjson.h:4852
yyjson_api_inline bool yyjson_set_real(yyjson_val *val, double num)
Definition: yyjson.h:4839
yyjson_api_inline bool yyjson_set_sint(yyjson_val *val, int64_t num)
Definition: yyjson.h:4827
yyjson_api_inline bool yyjson_set_bool(yyjson_val *val, bool num)
Definition: yyjson.h:4815
yyjson_api_inline bool yyjson_set_int(yyjson_val *val, int num)
Definition: yyjson.h:4833
JSON Array
The following functions can be used to access a JSON array.
Note that accessing elements by index may take a linear search time. Therefore, if you need to iterate through an array, it is recommended to use the iterator API.
yyjson_api_inline size_t yyjson_arr_size(yyjson_val *arr)
Definition: yyjson.h:4866
yyjson_api_inline yyjson_val * yyjson_arr_get_last(yyjson_val *arr)
Definition: yyjson.h:4894
yyjson_api_inline yyjson_val * yyjson_arr_get(yyjson_val *arr, size_t idx)
Definition: yyjson.h:4870
yyjson_api_inline yyjson_val * yyjson_arr_get_first(yyjson_val *arr)
Definition: yyjson.h:4885
JSON Array Iterator
There are two ways to traverse an array:
Sample code 1 (iterator API):
your_func(val);
}
yyjson_api_inline yyjson_arr_iter yyjson_arr_iter_with(yyjson_val *arr)
Definition: yyjson.h:4928
yyjson_api_inline yyjson_val * yyjson_arr_iter_next(yyjson_arr_iter *iter)
Definition: yyjson.h:4938
Definition: yyjson.h:1697
Sample code 2 (foreach macro):
size_t idx, max;
your_func(idx, val);
}
#define yyjson_arr_foreach(arr, idx, max, val)
Definition: yyjson.h:1753
There's also mutable version API to traverse an mutable array:
Sample code 1 (mutable iterator API):
if (your_val_is_unused(val)) {
}
}
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_iter_remove(yyjson_mut_arr_iter *iter)
Definition: yyjson.h:5655
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_iter_next(yyjson_mut_arr_iter *iter)
Definition: yyjson.h:5643
yyjson_api_inline yyjson_mut_arr_iter yyjson_mut_arr_iter_with(yyjson_mut_val *arr)
Definition: yyjson.h:5632
Definition: yyjson.h:2377
Sample code 2 (mutable foreach macro):
size_t idx, max;
your_func(idx, val);
}
#define yyjson_mut_arr_foreach(arr, idx, max, val)
Definition: yyjson.h:2447
JSON Object
The following functions can be used to access a JSON object.
Note that accessing elements by key may take a linear search time. Therefore, if you need to iterate through an object, it is recommended to use the iterator API.
yyjson_api_inline yyjson_val * yyjson_obj_get(yyjson_val *obj, const char *key)
Definition: yyjson.h:4959
yyjson_api_inline yyjson_val * yyjson_obj_iter_get(yyjson_obj_iter *iter, const char *key)
Definition: yyjson.h:5025
yyjson_api_inline yyjson_val * yyjson_obj_getn(yyjson_val *obj, const char *key, size_t key_len)
Definition: yyjson.h:4964
yyjson_api_inline yyjson_obj_iter yyjson_obj_iter_with(yyjson_val *obj)
Definition: yyjson.h:5001
yyjson_api_inline size_t yyjson_obj_size(yyjson_val *obj)
Definition: yyjson.h:4955
Definition: yyjson.h:1821
JSON Object Iterator
There are two ways to traverse an object:
Sample code 1 (iterator API):
your_func(key, val);
}
yyjson_api_inline yyjson_val * yyjson_obj_iter_get_val(yyjson_val *key)
Definition: yyjson.h:5021
yyjson_api_inline yyjson_val * yyjson_obj_iter_next(yyjson_obj_iter *iter)
Definition: yyjson.h:5011
Sample code 2 (foreach macro):
size_t idx, max;
your_func(key, val);
}
#define yyjson_obj_foreach(obj, idx, max, key, val)
Definition: yyjson.h:1924
There's also mutable version API to traverse an mutable object:
Sample code 1 (mutable iterator API):
if (your_key_is_unused(key)) {
}
}
yyjson_api_inline yyjson_mut_val * yyjson_mut_obj_iter_next(yyjson_mut_obj_iter *iter)
Definition: yyjson.h:6282
yyjson_api_inline yyjson_mut_val * yyjson_mut_obj_iter_remove(yyjson_mut_obj_iter *iter)
Definition: yyjson.h:6299
yyjson_api_inline yyjson_mut_val * yyjson_mut_obj_iter_get_val(yyjson_mut_val *key)
Definition: yyjson.h:6294
yyjson_api_inline yyjson_mut_obj_iter yyjson_mut_obj_iter_with(yyjson_mut_val *obj)
Definition: yyjson.h:6271
Definition: yyjson.h:3179
Sample code 2 (mutable foreach macro):
size_t idx, max;
your_func(key, val);
}
Creating JSON Document
The yyjson_mut_doc
and related APIs are used to build JSON documents.
Please note that yyjson_mut_doc
uses a memory pool to hold all strings and values. The pool can only be created, grown, or freed in its entirety. Therefore, yyjson_mut_doc
is more suitable for write-once than mutation of an existing document.
JSON objects and arrays are composed of linked lists, so each yyjson_mut_val
can only be added to one object or array.
Sample code:
yyjson_api_inline yyjson_mut_val * yyjson_mut_obj(yyjson_mut_doc *doc)
Definition: yyjson.h:6349
yyjson_api void yyjson_mut_doc_free(yyjson_mut_doc *doc)
yyjson_api_inline yyjson_mut_val * yyjson_mut_int(yyjson_mut_doc *doc, int64_t num)
Definition: yyjson.h:5517
yyjson_api_inline bool yyjson_mut_obj_add(yyjson_mut_val *obj, yyjson_mut_val *key, yyjson_mut_val *val)
Definition: yyjson.h:6505
yyjson_api_inline bool yyjson_mut_arr_append(yyjson_mut_val *arr, yyjson_mut_val *val)
Definition: yyjson.h:5899
Mutable Document
The following functions are used to create, modify, copy, and destroy a JSON document.
yyjson_api yyjson_mut_val * yyjson_mut_val_mut_copy(yyjson_mut_doc *doc, yyjson_mut_val *val)
yyjson_api yyjson_mut_doc * yyjson_mut_doc_mut_copy(yyjson_mut_doc *doc, const yyjson_alc *alc)
yyjson_api bool yyjson_mut_doc_set_val_pool_size(yyjson_mut_doc *doc, size_t count)
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_get_root(yyjson_mut_doc *doc)
Definition: yyjson.h:5182
yyjson_api bool yyjson_mut_doc_set_str_pool_size(yyjson_mut_doc *doc, size_t len)
JSON Value Creation
The following functions are used to create mutable JSON value, the value's memory is held by the document.
yyjson_api_inline yyjson_mut_val * yyjson_mut_true(yyjson_mut_doc *doc)
Definition: yyjson.h:5457
yyjson_api_inline yyjson_mut_val * yyjson_mut_real(yyjson_mut_doc *doc, double num)
Definition: yyjson.h:5522
yyjson_api_inline yyjson_mut_val * yyjson_mut_false(yyjson_mut_doc *doc)
Definition: yyjson.h:5468
yyjson_api_inline yyjson_mut_val * yyjson_mut_bool(yyjson_mut_doc *doc, bool val)
Definition: yyjson.h:5479
yyjson_api_inline yyjson_mut_val * yyjson_mut_null(yyjson_mut_doc *doc)
Definition: yyjson.h:5446
yyjson_api_inline yyjson_mut_val * yyjson_mut_uint(yyjson_mut_doc *doc, uint64_t num)
Definition: yyjson.h:5491
yyjson_api_inline yyjson_mut_val * yyjson_mut_sint(yyjson_mut_doc *doc, int64_t num)
Definition: yyjson.h:5504
JSON Array Creation
The following functions are used to create mutable JSON array.
int vals[3] = {-1, 0, 1};
const char strs[3] = {"Jan", "Feb", "Mar"};
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_sint(yyjson_mut_doc *doc, const int64_t *vals, size_t count)
Definition: yyjson.h:5717
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_uint8(yyjson_mut_doc *doc, const uint8_t *vals, size_t count)
Definition: yyjson.h:5764
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_sint64(yyjson_mut_doc *doc, const int64_t *vals, size_t count)
Definition: yyjson.h:5756
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_strn(yyjson_mut_doc *doc, const char **vals, const size_t *lens, size_t count)
Definition: yyjson.h:5822
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_float(yyjson_mut_doc *doc, const float *vals, size_t count)
Definition: yyjson.h:5796
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_sint32(yyjson_mut_doc *doc, const int32_t *vals, size_t count)
Definition: yyjson.h:5748
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_real(yyjson_mut_doc *doc, const double *vals, size_t count)
Definition: yyjson.h:5727
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_sint16(yyjson_mut_doc *doc, const int16_t *vals, size_t count)
Definition: yyjson.h:5740
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_uint16(yyjson_mut_doc *doc, const uint16_t *vals, size_t count)
Definition: yyjson.h:5772
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_strcpy(yyjson_mut_doc *doc, const char **vals, size_t count)
Definition: yyjson.h:5832
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_uint64(yyjson_mut_doc *doc, const uint64_t *vals, size_t count)
Definition: yyjson.h:5788
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_uint(yyjson_mut_doc *doc, const uint64_t *vals, size_t count)
Definition: yyjson.h:5722
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_sint8(yyjson_mut_doc *doc, const int8_t *vals, size_t count)
Definition: yyjson.h:5732
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_uint32(yyjson_mut_doc *doc, const uint32_t *vals, size_t count)
Definition: yyjson.h:5780
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_double(yyjson_mut_doc *doc, const double *vals, size_t count)
Definition: yyjson.h:5804
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_strncpy(yyjson_mut_doc *doc, const char **vals, const size_t *lens, size_t count)
Definition: yyjson.h:5846
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_str(yyjson_mut_doc *doc, const char **vals, size_t count)
Definition: yyjson.h:5812
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_with_bool(yyjson_mut_doc *doc, const bool *vals, size_t count)
Definition: yyjson.h:5710
JSON Array Modification
The following functions are used to modify the contents of a JSON array.
yyjson_api_inline bool yyjson_mut_arr_add_str(yyjson_mut_doc *doc, yyjson_mut_val *arr, const char *str)
Definition: yyjson.h:6160
yyjson_api_inline bool yyjson_mut_arr_add_true(yyjson_mut_doc *doc, yyjson_mut_val *arr)
Definition: yyjson.h:6092
yyjson_api_inline bool yyjson_mut_arr_prepend(yyjson_mut_val *arr, yyjson_mut_val *val)
Definition: yyjson.h:5918
yyjson_api_inline bool yyjson_mut_arr_add_strncpy(yyjson_mut_doc *doc, yyjson_mut_val *arr, const char *str, size_t len)
Definition: yyjson.h:6190
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_remove(yyjson_mut_val *arr, size_t idx)
Definition: yyjson.h:5965
yyjson_api_inline bool yyjson_mut_arr_clear(yyjson_mut_val *arr)
Definition: yyjson.h:6052
yyjson_api_inline bool yyjson_mut_arr_add_strcpy(yyjson_mut_doc *doc, yyjson_mut_val *arr, const char *str)
Definition: yyjson.h:6180
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_replace(yyjson_mut_val *arr, size_t idx, yyjson_mut_val *val)
Definition: yyjson.h:5937
yyjson_api_inline bool yyjson_mut_arr_add_bool(yyjson_mut_doc *doc, yyjson_mut_val *arr, bool val)
Definition: yyjson.h:6110
yyjson_api_inline bool yyjson_mut_arr_add_uint(yyjson_mut_doc *doc, yyjson_mut_val *arr, uint64_t num)
Definition: yyjson.h:6120
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_add_arr(yyjson_mut_doc *doc, yyjson_mut_val *arr)
Definition: yyjson.h:6200
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_remove_last(yyjson_mut_val *arr)
Definition: yyjson.h:6008
yyjson_api_inline bool yyjson_mut_arr_add_false(yyjson_mut_doc *doc, yyjson_mut_val *arr)
Definition: yyjson.h:6101
yyjson_api_inline bool yyjson_mut_arr_add_strn(yyjson_mut_doc *doc, yyjson_mut_val *arr, const char *str, size_t len)
Definition: yyjson.h:6170
yyjson_api_inline bool yyjson_mut_arr_add_real(yyjson_mut_doc *doc, yyjson_mut_val *arr, double num)
Definition: yyjson.h:6150
yyjson_api_inline bool yyjson_mut_arr_add_val(yyjson_mut_val *arr, yyjson_mut_val *val)
Definition: yyjson.h:6078
yyjson_api_inline bool yyjson_mut_arr_add_sint(yyjson_mut_doc *doc, yyjson_mut_val *arr, int64_t num)
Definition: yyjson.h:6130
yyjson_api_inline bool yyjson_mut_arr_remove_range(yyjson_mut_val *arr, size_t idx, size_t len)
Definition: yyjson.h:6030
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_add_obj(yyjson_mut_doc *doc, yyjson_mut_val *arr)
Definition: yyjson.h:6209
yyjson_api_inline bool yyjson_mut_arr_insert(yyjson_mut_val *arr, yyjson_mut_val *val, size_t idx)
Definition: yyjson.h:5868
yyjson_api_inline yyjson_mut_val * yyjson_mut_arr_remove_first(yyjson_mut_val *arr)
Definition: yyjson.h:5989
yyjson_api_inline bool yyjson_mut_arr_add_null(yyjson_mut_doc *doc, yyjson_mut_val *arr)
Definition: yyjson.h:6083
JSON Object Creation
The following functions are used to create mutable JSON object.
const char **keys,
const char **vals,
size_t count);
const char keys[] = {"name", "type", "id"};
const char *vals[] = {"Harry", "student", "123456"};
const char **kv_pairs,
size_t pair_count);
const char *pairs[] = {"name", "Harry", "type", "student", "id", "123456"};
yyjson_api_inline yyjson_mut_val * yyjson_mut_obj_with_str(yyjson_mut_doc *doc, const char **keys, const char **vals, size_t count)
Definition: yyjson.h:6360
yyjson_api_inline yyjson_mut_val * yyjson_mut_obj_with_kv(yyjson_mut_doc *doc, const char **kv_pairs, size_t pair_count)
Definition: yyjson.h:6391
JSON Object Modification
The following functions are used to modify the contents of a JSON object.
yyjson_api_inline bool yyjson_mut_obj_add_strncpy(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, const char *val, size_t len)
Definition: yyjson.h:6753
yyjson_api_inline bool yyjson_mut_obj_rename_keyn(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, size_t len, const char *new_key, size_t new_len)
Definition: yyjson.h:6809
yyjson_api_inline bool yyjson_mut_obj_add_sint(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, int64_t val)
Definition: yyjson.h:6687
yyjson_api_inline bool yyjson_mut_obj_add_strn(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, const char *val, size_t len)
Definition: yyjson.h:6728
yyjson_api_inline bool yyjson_mut_obj_add_false(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key)
Definition: yyjson.h:6660
yyjson_api_inline bool yyjson_mut_obj_add_int(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, int64_t val)
Definition: yyjson.h:6697
yyjson_api_inline bool yyjson_mut_obj_add_uint(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, uint64_t val)
Definition: yyjson.h:6677
yyjson_api_inline yyjson_mut_val * yyjson_mut_obj_remove_str(yyjson_mut_val *obj, const char *key)
Definition: yyjson.h:6776
yyjson_api_inline yyjson_mut_val * yyjson_mut_obj_remove(yyjson_mut_val *obj, yyjson_mut_val *key)
Definition: yyjson.h:6565
#define yyjson_api_inline
Definition: yyjson.h:308
yyjson_api_inline bool yyjson_mut_obj_add_null(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key)
Definition: yyjson.h:6644
yyjson_api_inline bool yyjson_mut_obj_add_true(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key)
Definition: yyjson.h:6652
yyjson_api_inline bool yyjson_mut_obj_add_str(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, const char *val)
Definition: yyjson.h:6717
yyjson_api_inline bool yyjson_mut_obj_add_real(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, double val)
Definition: yyjson.h:6707
yyjson_api_inline bool yyjson_mut_obj_add_bool(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, bool val)
Definition: yyjson.h:6668
yyjson_api_inline bool yyjson_mut_obj_add_strcpy(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, const char *val)
Definition: yyjson.h:6740
yyjson_api_inline bool yyjson_mut_obj_put(yyjson_mut_val *obj, yyjson_mut_val *key, yyjson_mut_val *val)
Definition: yyjson.h:6516
yyjson_api_inline yyjson_mut_val * yyjson_mut_obj_remove_strn(yyjson_mut_val *obj, const char *key, size_t len)
Definition: yyjson.h:6781
yyjson_api_inline bool yyjson_mut_obj_rename_key(yyjson_mut_doc *doc, yyjson_mut_val *obj, const char *key, const char *new_key)
Definition: yyjson.h:6800
yyjson_api_inline bool yyjson_mut_obj_clear(yyjson_mut_val *obj)
Definition: yyjson.h:6594
JSON Pointer and Patch
JSON Pointer
The library supports querying JSON values using JSON Pointer
(RFC 6901).
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_ptr_getn(yyjson_mut_doc *doc, const char *ptr, size_t len)
Definition: yyjson.h:6947
yyjson_api_inline yyjson_val * yyjson_ptr_getx(yyjson_val *val, const char *ptr, size_t len, yyjson_ptr_err *err)
Definition: yyjson.h:6923
yyjson_api_inline yyjson_val * yyjson_doc_ptr_getx(yyjson_doc *doc, const char *ptr, size_t len, yyjson_ptr_err *err)
Definition: yyjson.h:6890
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_ptr_get(yyjson_mut_doc *doc, const char *ptr)
Definition: yyjson.h:6941
yyjson_api_inline yyjson_val * yyjson_doc_ptr_getn(yyjson_doc *doc, const char *ptr, size_t len)
Definition: yyjson.h:6885
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_ptr_getx(yyjson_mut_doc *doc, const char *ptr, size_t len, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:6953
yyjson_api_inline yyjson_mut_val * yyjson_mut_ptr_getn(yyjson_mut_val *val, const char *ptr, size_t len)
Definition: yyjson.h:6985
yyjson_api_inline yyjson_val * yyjson_ptr_get(yyjson_val *val, const char *ptr)
Definition: yyjson.h:6912
yyjson_api_inline yyjson_mut_val * yyjson_mut_ptr_get(yyjson_mut_val *val, const char *ptr)
Definition: yyjson.h:6979
yyjson_api_inline yyjson_val * yyjson_doc_ptr_get(yyjson_doc *doc, const char *ptr)
Definition: yyjson.h:6879
yyjson_api_inline yyjson_val * yyjson_ptr_getn(yyjson_val *val, const char *ptr, size_t len)
Definition: yyjson.h:6918
yyjson_api_inline yyjson_mut_val * yyjson_mut_ptr_getx(yyjson_mut_val *val, const char *ptr, size_t len, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:6991
Definition: yyjson.h:3714
Definition: yyjson.h:3686
For example, given the JSON document:
{
"size" : 3,
"users" : [
{"id": 1, "name": "Harry"},
{"id": 2, "name": "Ron"},
{"id": 3, "name": "Hermione"}
]
}
The following JSON strings evaluate to the accompanying values:
Pointer | Matched Value |
"" | the whole document |
"/size" | 3 |
"/users/0" | {"id": 1, "name": "Harry"} |
"/users/1/name" | "Ron" |
"/no_match" | NULL |
"no_slash" | NULL |
"/" | NULL (match to empty key: root[""]) |
if (!val2) printf(
"err %d: %s\n", err.
code, err.
msg);
const char * msg
Definition: yyjson.h:3690
yyjson_ptr_code code
Definition: yyjson.h:3688
The library also supports modifying JSON values using JSON Pointer
.
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_ptr_remove(yyjson_mut_doc *doc, const char *ptr)
Definition: yyjson.h:7299
yyjson_api_inline bool yyjson_mut_ptr_setx(yyjson_mut_val *val, const char *ptr, size_t len, yyjson_mut_val *new_val, yyjson_mut_doc *doc, bool create_parent, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:7193
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_ptr_replace(yyjson_mut_doc *doc, const char *ptr, yyjson_mut_val *new_val)
Definition: yyjson.h:7222
yyjson_api_inline bool yyjson_mut_doc_ptr_setn(yyjson_mut_doc *doc, const char *ptr, size_t len, yyjson_mut_val *new_val)
Definition: yyjson.h:7122
yyjson_api_inline bool yyjson_mut_ptr_addx(yyjson_mut_val *val, const char *ptr, size_t len, yyjson_mut_val *new_val, yyjson_mut_doc *doc, bool create_parent, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:7089
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_ptr_removex(yyjson_mut_doc *doc, const char *ptr, size_t len, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:7310
yyjson_api_inline yyjson_mut_val * yyjson_mut_ptr_removen(yyjson_mut_val *val, const char *ptr, size_t len)
Definition: yyjson.h:7344
yyjson_api_inline yyjson_mut_val * yyjson_mut_ptr_replacex(yyjson_mut_val *val, const char *ptr, size_t len, yyjson_mut_val *new_val, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:7277
yyjson_api_inline bool yyjson_mut_doc_ptr_setx(yyjson_mut_doc *doc, const char *ptr, size_t len, yyjson_mut_val *new_val, bool create_parent, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:7128
yyjson_api_inline bool yyjson_mut_ptr_set(yyjson_mut_val *val, const char *ptr, yyjson_mut_val *new_val, yyjson_mut_doc *doc)
Definition: yyjson.h:7178
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_ptr_removen(yyjson_mut_doc *doc, const char *ptr, size_t len)
Definition: yyjson.h:7305
yyjson_api_inline bool yyjson_mut_doc_ptr_addn(yyjson_mut_doc *doc, const char *ptr, size_t len, yyjson_mut_val *new_val)
Definition: yyjson.h:7020
yyjson_api_inline yyjson_mut_val * yyjson_mut_ptr_removex(yyjson_mut_val *val, const char *ptr, size_t len, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:7350
yyjson_api_inline bool yyjson_mut_doc_ptr_set(yyjson_mut_doc *doc, const char *ptr, yyjson_mut_val *new_val)
Definition: yyjson.h:7115
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_ptr_replacen(yyjson_mut_doc *doc, const char *ptr, size_t len, yyjson_mut_val *new_val)
Definition: yyjson.h:7228
yyjson_api_inline yyjson_mut_val * yyjson_mut_ptr_remove(yyjson_mut_val *val, const char *ptr)
Definition: yyjson.h:7338
yyjson_api_inline bool yyjson_mut_ptr_addn(yyjson_mut_val *val, const char *ptr, size_t len, yyjson_mut_val *new_val, yyjson_mut_doc *doc)
Definition: yyjson.h:7082
yyjson_api_inline bool yyjson_mut_ptr_add(yyjson_mut_val *val, const char *ptr, yyjson_mut_val *new_val, yyjson_mut_doc *doc)
Definition: yyjson.h:7074
yyjson_api_inline bool yyjson_mut_ptr_setn(yyjson_mut_val *val, const char *ptr, size_t len, yyjson_mut_val *new_val, yyjson_mut_doc *doc)
Definition: yyjson.h:7186
yyjson_api_inline bool yyjson_mut_doc_ptr_addx(yyjson_mut_doc *doc, const char *ptr, size_t len, yyjson_mut_val *new_val, bool create_parent, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:7027
yyjson_api_inline yyjson_mut_val * yyjson_mut_ptr_replace(yyjson_mut_val *val, const char *ptr, yyjson_mut_val *new_val)
Definition: yyjson.h:7266
yyjson_api_inline bool yyjson_mut_doc_ptr_add(yyjson_mut_doc *doc, const char *ptr, yyjson_mut_val *new_val)
Definition: yyjson.h:7013
yyjson_api_inline yyjson_mut_val * yyjson_mut_doc_ptr_replacex(yyjson_mut_doc *doc, const char *ptr, size_t len, yyjson_mut_val *new_val, yyjson_ptr_ctx *ctx, yyjson_ptr_err *err)
Definition: yyjson.h:7233
yyjson_api_inline yyjson_mut_val * yyjson_mut_ptr_replacen(yyjson_mut_val *val, const char *ptr, size_t len, yyjson_mut_val *new_val)
Definition: yyjson.h:7272
For example:
All the above functions ending with x
can be used to get the result context ctx
, and the error message err
. For example:
if (err.
code) printf(
"err: %s\n", err.
msg);
yyjson_api_inline bool yyjson_mut_is_null(yyjson_mut_val *val)
Definition: yyjson.h:5201
yyjson_api_inline bool yyjson_ptr_ctx_remove(yyjson_ptr_ctx *ctx)
Definition: yyjson.h:7459
JSON Patch
The library supports JSON Patch (RFC 6902). Specification and example: https://tools.ietf.org/html/rfc6902
yyjson_api yyjson_mut_val * yyjson_patch(yyjson_mut_doc *doc, yyjson_val *orig, yyjson_val *patch, yyjson_patch_err *err)
yyjson_api yyjson_mut_val * yyjson_mut_patch(yyjson_mut_doc *doc, yyjson_mut_val *orig, yyjson_mut_val *patch, yyjson_patch_err *err)
Definition: yyjson.h:4274
JSON Merge Patch
The library supports JSON Merge Patch (RFC 7386). Specification and example: https://tools.ietf.org/html/rfc7386
yyjson_api yyjson_mut_val * yyjson_merge_patch(yyjson_mut_doc *doc, yyjson_val *orig, yyjson_val *patch)
yyjson_api yyjson_mut_val * yyjson_mut_merge_patch(yyjson_mut_doc *doc, yyjson_mut_val *orig, yyjson_mut_val *patch)
Number Processing
Number reader
The library has a built-in high-performance number reader,
it will read numbers according to these rules by default:
- Positive integers are read as
uint64_t
. If an overflow occurs, it is converted to double
.
- Negative integers are read as
int64_t
. If an overflow occurs, it is converted to double
.
- Floating-point numbers are read as
double
with correct rounding.
- If a
double
number overflow (reaches infinity), an error is reported.
- If a number does not conform to the JSON standard, an error is reported.
There are 3 flags that can be used to adjust the number parsing strategy:
YYJSON_READ_ALLOW_INF_AND_NAN
: read nan/inf number or literal as double
(non-standard).
YYJSON_READ_NUMBER_AS_RAW
: read all numbers as raw strings without parsing.
YYJSON_READ_BIGBER_AS_RAW
: read big numbers (overflow or infinity) as raw strings without parsing.
See the Reader flag
section for more details.
Number writer
The library has a built-in high-performance number writer,
it will write numbers according to these rules by default:
- Positive integers are written without a sign.
- Negative integers are written with a negative sign.
- Floating-point numbers are written using the ECMAScript format, with the following modifications:
- If the number is
Infinity
or NaN
, an error is reported.
- The negative sign of
-0.0
is preserved to maintain input information.
- The positive sign in the exponent part is removed.
- The floating-point number writer will generate the shortest correctly rounded decimal representation.
There are 2 flags that can be used to adjust the number writing strategy:
YYJSON_WRITE_ALLOW_INF_AND_NAN
write inf/nan numbers as Infinity
and NaN
literals without error (non-standard).
YYJSON_WRITE_INF_AND_NAN_AS_NULL
write inf/nan numbers as null
literal.
See the "Writer flag" section for more details.
Text Processing
Character Encoding
This library only supports UTF-8 encoding without BOM, as specified in RFC 8259:
JSON text exchanged between systems that are not part of a closed ecosystem MUST be encoded using UTF-8. Implementations MUST NOT add a byte order mark (U+FEFF) to the beginning of a networked-transmitted JSON text.
By default, yyjson performs strict UTF-8 encoding validation on input strings. If an invalid character is encountered, an error will be reported.
You can use YYJSON_READ_ALLOW_INVALID_UNICODE
and YYJSON_WRITE_ALLOW_INVALID_UNICODE
flags to allow invalid Unicode encoding. However, please note that if you enable these flags, the resulting value from yyjson may contain invalid characters, which can be used by other code and may introduce security risks.
NUL Character
This library supports the NUL
character (also known as the null terminator
, or Unicode U+0000
, ASCII \0
) inside strings.
When reading JSON, \u0000
will be unescaped to NUL
character. If a string contains the NUL
character, the length obtained with strlen()
will be inaccurate, and you should use yyjson_get_len()
to get the actual length.
When building JSON, the input string is treated as null-terminated by default. If you need to pass in a string that contains the NUL
character, you should use the API with the n
suffix and provide the actual length of the string.
For example:
Memory Allocator
The library does not directly call libc's memory allocation functions (malloc/realloc/free). Instead, when memory allocation is required, yyjson's API takes a parameter named alc
that allows the caller to pass in an allocator. If the alc
is NULL, yyjson will use the default memory allocator, which is a simple wrapper of libc's functions.
Using a custom memory allocator allows you to have more control over memory allocation, here are a few examples:
Single allocator for multiple JSON
If you need to parse multiple small JSON, you can use a single allocator with pre-allocated buffer to avoid frequent memory allocation.
Sample code:
size_t max_json_size = 64 * 1024;
void *buf = malloc(buf_size);
for(int i = 0, i < your_json_file_count; i++) {
const char *your_json_file_path = ...;
...
}
free(buf);
yyjson_api_inline size_t yyjson_read_max_memory_usage(size_t len, yyjson_read_flag flg)
Definition: yyjson.h:872
Stack memory allocator
If the JSON is small enough, you can use stack memory to read or write it.
Sample code:
char buf[128 * 1024];
...
yyjson_doc_free(doc);
Use a third-party allocator library
You can use a third-party high-performance memory allocator for yyjson, such as jemalloc, tcmalloc, mimalloc. You can also refer to the following code to implement your own allocator.
Sample code:
#include <mimalloc.h>
static void *priv_malloc(void *ctx, size_t size) {
return mi_malloc(size);
}
static void *priv_realloc(void *ctx, void *ptr, size_t old_size, size_t size) {
return mi_realloc(ptr, size);
}
static void priv_free(void *ctx, void *ptr) {
mi_free(ptr);
}
priv_malloc,
priv_realloc,
priv_free,
NULL
};
yyjson_doc *doc = yyjson_doc_read_opts(dat, len, 0, &PRIV_ALC, NULL);
...
yyjson_doc_free(doc);
char *json = yyjson_doc_write(doc, 0, alc, NULL, NULL);
...
alc->free(alc->
ctx, json);
Stack Memory Usage
Most functions in the library use fixed-size stack memory. This includes functions for JSON reading and writing, as well as JSON Pointer handling.
However, a few functions use recursion and may cause a stack overflow if the object level is too deep. These functions are marked with the following warning in the header file:
- Warning
- This function is recursive and may cause a stack overflow if the object level is too deep.
Null Check
The library's public APIs perform a null check
for every input parameter to prevent crashes.
For example, when reading a JSON, you don't need to perform null checks or type checks on each value:
if (!str) printf("err!");
However, if you are certain that a value is non-null and matches the expected type, you can use the unsafe
prefix API to avoid the null check.
For example, when iterating over an array or object, the value and key must be non-null:
size_t idx, max;
if (unsafe_yyjson_equals_str(key, "id") &&
unsafe_yyjson_is_uint(val) &&
unsafe_yyjson_get_uint(val) == 1234) {
...
}
}
Thread Safety
The library does not use global variables. Therefore, if you can ensure that the input parameters of a function are thread-safe, then the function calls are also thread-safe.
In general, yyjson_doc
and yyjson_val
are immutable and thread-safe, while yyjson_mut_doc
and yyjson_mut_val
are mutable and not thread-safe.
Locale Independence
The library is designed to be locale-independent.
However, there are certain conditions that you should be aware of:
- You use libc's
setlocale()
function to change the locale.
- Your environment does not adhere the IEEE 754 floating-point standard (e.g. some IBM mainframes), or you explicitly set
YYJSON_DISABLE_FAST_FP_CONV
during build, in such case yyjson will use strtod()
to parse floating-point numbers.
If both of these conditions are met, it is recommended to avoid calling setlocale()
while another thread is parsing JSON. Otherwise, an error may be returned during JSON floating-point number parsing.