File syn_json_write.h¶

FileList > src > syntropic > util > syn_json_write.h

Streaming JSON builder — zero-alloc, caller-provided buffer. More...

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

Classes¶

Type	Name
struct	SYN_JsonWriter Streaming JSON writer — tracks nesting, commas, and overflow.

Public Functions¶

Type	Name
void	syn_json_arr_close (SYN_JsonWriter * w) Close a JSON array `]` .
void	syn_json_arr_open (SYN_JsonWriter * w) Open a JSON array `[` .
void	syn_json_init (SYN_JsonWriter * w, char * buf, size_t capacity) Initialize a JSON writer.
void	syn_json_key (SYN_JsonWriter * w, const char * key) Write a bare key `"key":` for nested objects/arrays.
void	syn_json_key_bool (SYN_JsonWriter * w, const char * key, bool val) Write `"key":true` or`"key":false` .
void	syn_json_key_int (SYN_JsonWriter * w, const char * key, int32_t val) Write `"key":123` .
void	syn_json_key_null (SYN_JsonWriter * w, const char * key) Write `"key":null` .
void	syn_json_key_str (SYN_JsonWriter * w, const char * key, const char * val) Write `"key":"value"` . Escapes`"` and`\\` in value.
void	syn_json_key_uint (SYN_JsonWriter * w, const char * key, uint32_t val) Write `"key":123` (unsigned).
void	syn_json_obj_close (SYN_JsonWriter * w) Close a JSON object `}` .
void	syn_json_obj_open (SYN_JsonWriter * w) Open a JSON object `{` .
void	syn_json_val_bool (SYN_JsonWriter * w, bool val) Append a boolean value to an array.
void	syn_json_val_int (SYN_JsonWriter * w, int32_t val) Append an integer value to an array.
void	syn_json_val_str (SYN_JsonWriter * w, const char * val) Append a string value to an array.
void	syn_json_val_uint (SYN_JsonWriter * w, uint32_t val) Append an unsigned integer value to an array.

Public Static Functions¶

Type	Name
size_t	syn_json_len (const SYN_JsonWriter * w) Get the number of bytes written.
bool	syn_json_ok (const SYN_JsonWriter * w) Check if the writer is in a valid state (no overflow).
const char *	syn_json_str (const SYN_JsonWriter * w) Get the null-terminated output string.

Macros¶

Type	Name
define	SYN_JSON_MAX_DEPTH `8`

Detailed Description¶

Builds JSON output incrementally into a fixed buffer. Handles auto-commas, nesting, and overflow detection. No parser — this is write-only for building API responses, telemetry payloads, etc.

** **

char buf[256];
SYN_JsonWriter w;
syn_json_init(&w, buf, sizeof(buf));
syn_json_obj_open(&w);
  syn_json_key_str(&w, "device", "esp32");
  syn_json_key_int(&w, "uptime", 12345);
  syn_json_key_bool(&w, "wifi", true);
syn_json_obj_close(&w);
// buf = {"device":"esp32","uptime":12345,"wifi":true}

Public Functions Documentation¶

function syn_json_arr_close¶

Close a JSON array ] .

void syn_json_arr_close (
    SYN_JsonWriter * w
)

Parameters:

w Writer.

function syn_json_arr_open¶

Open a JSON array [ .

void syn_json_arr_open (
    SYN_JsonWriter * w
)

Parameters:

w Writer.

function syn_json_init¶

Initialize a JSON writer.

void syn_json_init (
    SYN_JsonWriter * w,
    char * buf,
    size_t capacity
)

Parameters:

w Writer instance.
buf Output buffer.
capacity Buffer size in bytes.

function syn_json_key¶

Write a bare key "key": for nested objects/arrays.

void syn_json_key (
    SYN_JsonWriter * w,
    const char * key
)

Follow with syn_json_obj_open() or syn_json_arr_open().

Parameters:

w Writer.
key JSON key.

function syn_json_key_bool¶

Write "key":true or"key":false .

void syn_json_key_bool (
    SYN_JsonWriter * w,
    const char * key,
    bool val
)

Parameters:

w Writer.
key JSON key.
val Boolean value.

function syn_json_key_int¶

Write "key":123 .

void syn_json_key_int (
    SYN_JsonWriter * w,
    const char * key,
    int32_t val
)

Parameters:

w Writer.
key JSON key.
val Integer value.

function syn_json_key_null¶

Write "key":null .

void syn_json_key_null (
    SYN_JsonWriter * w,
    const char * key
)

Parameters:

w Writer.
key JSON key.

function syn_json_key_str¶

Write "key":"value" . Escapes" and\\ in value.

void syn_json_key_str (
    SYN_JsonWriter * w,
    const char * key,
    const char * val
)

Parameters:

w Writer.
key JSON key.
val String value.

function syn_json_key_uint¶

Write "key":123 (unsigned).

void syn_json_key_uint (
    SYN_JsonWriter * w,
    const char * key,
    uint32_t val
)

Parameters:

w Writer.
key JSON key.
val Unsigned integer value.

function syn_json_obj_close¶

Close a JSON object } .

void syn_json_obj_close (
    SYN_JsonWriter * w
)

Parameters:

w Writer.

function syn_json_obj_open¶

Open a JSON object { .

void syn_json_obj_open (
    SYN_JsonWriter * w
)

Parameters:

w Writer.

function syn_json_val_bool¶

Append a boolean value to an array.

void syn_json_val_bool (
    SYN_JsonWriter * w,
    bool val
)

Parameters:

w Writer.
val Boolean value.

function syn_json_val_int¶

Append an integer value to an array.

void syn_json_val_int (
    SYN_JsonWriter * w,
    int32_t val
)

Parameters:

w Writer.
val Integer value.

function syn_json_val_str¶

Append a string value to an array.

void syn_json_val_str (
    SYN_JsonWriter * w,
    const char * val
)

Parameters:

w Writer.
val String value.

function syn_json_val_uint¶

Append an unsigned integer value to an array.

void syn_json_val_uint (
    SYN_JsonWriter * w,
    uint32_t val
)

Parameters:

w Writer.
val Unsigned value.

Public Static Functions Documentation¶

function syn_json_len¶

Get the number of bytes written.

static inline size_t syn_json_len (
    const SYN_JsonWriter * w
)

Parameters:

w Writer.

Returns:

Byte count.

function syn_json_ok¶

Check if the writer is in a valid state (no overflow).

static inline bool syn_json_ok (
    const SYN_JsonWriter * w
)

Parameters:

w Writer.

Returns:

true if no overflow occurred.

function syn_json_str¶

Get the null-terminated output string.

static inline const char * syn_json_str (
    const SYN_JsonWriter * w
)

Parameters:

w Writer.

Returns:

Pointer to the output buffer.

Macro Definition Documentation¶

define SYN_JSON_MAX_DEPTH¶

#define SYN_JSON_MAX_DEPTH `8`

Maximum nesting depth

The documentation for this class was generated from the following file src/syntropic/util/syn_json_write.h