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https://github.com/lcsmuller/jsmn-find
Tiny, zero-allocation JSON tokenizer written in ANSI C
https://github.com/lcsmuller/jsmn-find
ansi c c89 deserialization embedded hacktoberfest jsmn jsmn-token-extraction json parser tokenizer
Last synced: about 1 month ago
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Tiny, zero-allocation JSON tokenizer written in ANSI C
- Host: GitHub
- URL: https://github.com/lcsmuller/jsmn-find
- Owner: lcsmuller
- License: mit
- Created: 2022-01-10T13:41:14.000Z (almost 3 years ago)
- Default Branch: master
- Last Pushed: 2024-05-06T04:17:26.000Z (7 months ago)
- Last Synced: 2024-09-30T01:22:30.480Z (about 2 months ago)
- Topics: ansi, c, c89, deserialization, embedded, hacktoberfest, jsmn, jsmn-token-extraction, json, parser, tokenizer
- Language: C
- Homepage:
- Size: 143 KB
- Stars: 9
- Watchers: 2
- Forks: 1
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# JSMN-FIND
jsmn-find is an ANSI C add-on for the minimalistic JSON tokenizer
[jsmn](https://github.com/zserge/jsmn), it offers a familiar and
zero-allocation design. Its serializer counterpart can be found
at [json-build](https://github.com/lcsmuller/json-build).
## Dependencies
* [jsmn](https://github.com/zserge/jsmn) - Minimalistic JSON parser
## Included Dependencies
* [chash](https://github.com/c-ware/chash) - Type-safe, stackful hashtable
## Design
jsmn-find organizes jsmn's JSON tokens under a hashtable so that they can be
searched for in linear time.
## Usage
Download `jsmn-find.h` and the [dependencies](#dependencies) should be visible
to your linker search path:
#### load (zero-allocation)
```c
#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();
```
#### auto load (allocate memory for jsmn tokens and jsmnf pairs as necessary)
```c
#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);
```
#### find by key
```c
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);
}
}
}
```
#### index access for arrays
```c
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);
}
```
#### find by path
```c
// 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.
```c
/* 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"
```
## API
* `jsmnf_init()` - initialize a `jsmnf_loader`
* `jsmnf_load()` - populate `jsmnf_pair` array with JSMN tokens
* `jsmnf_find()` - locate a `jsmnf_pair` by its associated key
* `jsmnf_find_path()` - locate a `jsmnf_pair` by its full key path
### Misc
* `jsmn_parse_auto()` - `jsmn_parse()` counterpart that allocates the necessary amount of tokens
* `jsmnf_load_auto()` - `jsmn_load()` counterpart that allocates the necessary amount of pairs
* `jsmnf_unescape()` - unescape a Unicode string
## Other Info
This software is distributed under [MIT license](www.opensource.org/licenses/mit-license.php),
so feel free to integrate it in your commercial products.