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json c语言开发,Parson - 用C语言编写的轻量级JSON库

施刚毅
2023-12-01

About

Parson is a lighweight json library written in C.

Features

Full JSON support

Lightweight (only 2 files)

Simple API

Addressing json values with dot notation (similar to C structs or objects in most OO languages, e.g. "objectA.objectB.value")

C89 compatible

Test suites

Installation

Run:

git clone https://github.com/kgabis/parson.git

and copy parson.h and parson.c to you source code tree.

Run make test to compile and run tests.

Examples

Parsing JSON

Here is a function, which prints basic commit info (date, sha and author) from a github repository.

void print_commits_info(const char *username, const char *repo) {

JSON_Value *root_value;

JSON_Array *commits;

JSON_Object *commit;

size_t i;

char curl_command[512];

char cleanup_command[256];

char output_filename[] = "commits.json";

/* it ain't pretty, but it's not a libcurl tutorial */

sprintf(curl_command,

"curl -s \"https://api.github.com/repos/%s/%s/commits\" > %s",

username, repo, output_filename);

sprintf(cleanup_command, "rm -f %s", output_filename);

system(curl_command);

/* parsing json and validating output */

root_value = json_parse_file(output_filename);

if (json_value_get_type(root_value) != JSONArray) {

system(cleanup_command);

return;

}

/* getting array from root value and printing commit info */

commits = json_value_get_array(root_value);

printf("%-10.10s %-10.10s %s\n", "Date", "SHA", "Author");

for (i = 0; i < json_array_get_count(commits); i++) {

commit = json_array_get_object(commits, i);

printf("%.10s %.10s %s\n",

json_object_dotget_string(commit, "commit.author.date"),

json_object_get_string(commit, "sha"),

json_object_dotget_string(commit, "commit.author.name"));

}

/* cleanup code */

json_value_free(root_value);

system(cleanup_command);

}

Calling print_commits_info("torvalds", "linux"); prints:

Date SHA Author

2012-10-15 dd8e8c4a2c David Rientjes

2012-10-15 3ce9e53e78 Michal Marek

2012-10-14 29bb4cc5e0 Randy Dunlap

2012-10-15 325adeb55e Ralf Baechle

2012-10-14 68687c842c Russell King

2012-10-14 ddffeb8c4d Linus Torvalds

...

Persistence

In this example I'm using parson to save user information to a file and then load it and validate later.

void persistence_example(void) {

JSON_Value *schema = json_parse_string("{\"name\":\"\"}");

JSON_Value *user_data = json_parse_file("user_data.json");

char buf[256];

const char *name = NULL;

if (user_data == NULL || json_validate(schema, user_data) != JSONSuccess) {

puts("Enter your name:");

scanf("%s", buf);

user_data = json_value_init_object();

json_object_set_string(json_object(user_data), "name", buf);

json_serialize_to_file(user_data, "user_data.json");

}

name = json_object_get_string(json_object(user_data), "name");

printf("Hello, %s.", name);

json_value_free(schema);

json_value_free(user_data);

return;

}

Serialization

Creating JSON values is very simple thanks to the dot notation. Object hierarchy is automatically created when addressing specific fields. In the following example I create a simple JSON value containing basic information about a person.

void serialization_example(void) {

JSON_Value *root_value = json_value_init_object();

JSON_Object *root_object = json_value_get_object(root_value);

char *serialized_string = NULL;

json_object_set_string(root_object, "name", "John Smith");

json_object_set_number(root_object, "age", 25);

json_object_dotset_string(root_object, "address.city", "Cupertino");

json_object_dotset_value(root_object, "contact.emails", json_parse_string("[\"email@example.com\",\"email2@example.com\"]"));

serialized_string = json_serialize_to_string_pretty(root_value);

puts(serialized_string);

json_free_serialized_string(serialized_string);

json_value_free(root_value);

}

Output:

{

"name": "John Smith",

"age": 25,

"address": {

"city": "Cupertino"

},

"contact": {

"emails": [

"email@example.com",

"email2@example.com"

]

}

}

Contributing

I will always merge working bug fixes. However, if you want to add something new to the API, please create an "issue" on github for this first so we can discuss if it should end up in the library before you start implementing it. Remember to follow parson's code style and write appropriate tests.

My other projects

ape - simple programming language implemented in C library

kgflags - easy to use command-line flag parsing library

agnes - header-only NES emulation library

License

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