jsmn-find is an ANSI C add-on for the minimalistic JSON tokenizer jsmn, it offers a familiar and zero-allocation design. Its serializer counterpart can be found at json-build.
- jsmn - Minimalistic JSON parser
- chash - Type-safe, stackful hashtable
jsmn-find organizes jsmn's JSON tokens under a hashtable so that they can be searched for in linear time.
Download jsmn-find.h and the dependencies should be visible
to your linker search path:
#include "jsmn.h"
#include "jsmn-find.h"
...
jsmn_parser parser;
jsmntok_t tokens[256];
jsmn_init(&parser);
r = jsmn_parse(&parser, json, strlen(json), tokens, 256);
if (r < 0) error();
// populate jsmnf_pairs with the jsmn tokens
jsmnf_loader loader;
jsmnf_pair pairs[256];
jsmnf_init(&loader);
r = jsmnf_load(&loader, json, tokens, parser.toknext, pairs, 256);
if (r < 0) error();#include "jsmn.h"
#include "jsmn-find.h"
...
jsmn_parser parser;
jsmntok_t *toks = NULL;
unsigned num_tokens = 0;
jsmn_init(&parser);
r = jsmn_parse_auto(&parser, json, strlen(json), &toks, &num_tokens);
if (r <= 0) error();
// populate jsmnf_pairs with the jsmn tokens
jsmnf_loader loader;
jsmnf_pair *pairs = NULL;
unsigned num_pairs = 0;
jsmnf_init(&loader);
r = jsmnf_load_auto(&loader, json, toks, num_tokens, &pairs, &num_pairs);
if (r <= 0) error();
...
free(toks);
free(pairs);jsmnf_pair *f;
// assume the JSON : { "foo": { "bar": [ true, null, null ] } }
if ((f = jsmnf_find(pairs, json, "foo", strlen("foo")))) {
// Found: { "bar" : [ true, null, null ] }
printf("Found: %.*s\n", (int)f->v.len, json + f->v.pos);
if ((f = jsmnf_find(f, json, "bar", 3))) {
// Found: [ true, null, null ]
printf("Found: %.*s\n", (int)f->v.len, json + f->v.pos);
if ((f = jsmn_find(f, json, "0", 1))) {
// Found: true
printf("Found: %.*s\n", (int)f->v.len, json + f->v.pos);
}
}
}jsmnf_pair *f;
// assume the JSON : [ false, [ true ] ]
f = &pairs->fields[1];
printf("Found: %.*s\n", (int)f->v.len, json + f->v.pos); // Found: [ true ]
f = &f->fields[0]; // get nested array
printf("Found: %.*s\n", (int)f->v.len, json + f->v.pos); // Found: true
// looping over array
for (int i = 0; pairs->size; ++i) {
f = &pairs->fields[i];
printf("%.*s ", (int)f->v.len, json + f->v.pos);
}// assume the JSON : [ false, false, [ false, [ { "b":true } ] ] ]
char *path[] = { "2", "1", "0", "b" }; // array keys are the same as its indexes
jsmnf_pair *f;
if ((f = jsmnf_find_path(pairs, json, path, sizeof(path) / sizeof *path))) {
// Found: true
printf("Found: %.*s\n", (int)f->v.len, json + f->v.pos);
}jsmn-find is single-header and should be compatible with jsmn additional macros for more complex uses cases. #define JSMN_STATIC hides all jsmn-find API symbols by making them static. Also, if you want to include jsmn-find.h from multiple C files, to avoid duplication of symbols you may define JSMN_HEADER macro.
/* In every .c file that uses jsmn include only declarations: */
#define JSMN_HEADER
#include "jsmn.h"
#include "jsmn-find.h"
/* Additionally, create one jsmn-find.c file for jsmn-find implementation: */
#include "jsmn.h"
#include "jsmn-find.h"jsmnf_init()- initialize ajsmnf_loaderjsmnf_load()- populatejsmnf_pairarray with JSMN tokensjsmnf_find()- locate ajsmnf_pairby its associated keyjsmnf_find_path()- locate ajsmnf_pairby its full key path
jsmn_parse_auto()-jsmn_parse()counterpart that allocates the necessary amount of tokensjsmnf_load_auto()-jsmn_load()counterpart that allocates the necessary amount of pairsjsmnf_unescape()- unescape a Unicode string
This software is distributed under MIT license, so feel free to integrate it in your commercial products.
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