jenny
is a JSON generator.
jenny
is built first and foremost for embedded applications where the heap is
limited and you generally want to avoid allocations. malloc() is not used here!
Here's how it works:
First, you define your JSON structure and what variables you want in it. For
example, here is test.jenny
:
{
"int": "$this_is_an_int, int$",
"string": "$this_is_a_string, string$"
}
(By the way, you can use a JSON validator to check that this is valid JSON.
jenny
does not check!)
Then, you use ./jenny
to generate a .c
file:
./jenny < test.jenny
{
{ .type = JENNY_CHUNK, .u.chunk = "{\n \"int\": "},
{ .type = JENNY_VAR, .u.var = { .p = &this_is_an_int, .type = JENNY_INT_TYPE }},
{ .type = JENNY_CHUNK, .u.chunk = ",\n \"string\": "},
{ .type = JENNY_VAR, .u.var = { .p = &this_is_a_string, .type = JENNY_STRING_TYPE }},
{ .type = JENNY_CHUNK, .u.chunk = "\n}\n"},
{ .type = JENNY_END }
}
Then, you #include
the C file and use the jenny
API to output the JSON to
any write() -ish function that you want. In this case, I'm wrapping write
itself to print to STDOUT:
#include <unistd.h>
#include "jenny.h"
int this_is_an_int = 20;
char *this_is_a_string = "\"abc\n\t\\123";
jenny_t test[] =
#include "test.jenny.c"
ssize_t write_wrapper(void *p_fd, const void *p, size_t len) {
return write(*(int *)p_fd, p, len);
}
int main(void) {
int fd = STDOUT_FILENO;
jenny(test, write_wrapper, &fd);
return 0;
}