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https://github.com/Barenboim/json-parser

JSON parser in standard C
https://github.com/Barenboim/json-parser

c99 json

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JSON parser in standard C

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README 

        
[中文版说明](/README_cn.md)

# Json Parser in Standard C (C99)

This json parser was created for the project of [C++ Workflow](https://github.com/sogou/workflow).  

# Build tests

~~~bash

$ make

~~~

# Run tests

### Parse and print json document:

~~~bash

$ ./parse_json < xxx.json

~~~

### Test parsing speed:

~~~bash

$ time ./test_speed  < xxx.json

~~~

# Main Interfaces



### JSON value related

~~~c

/* Parse JSON text and create a JSON value. Returns NULL on parsing

   failures (Invalid JSON, nesting too deep, memory allocation failure).

   @text: JSON text string */

json_value_t *json_value_parse(const char *text);



/* Destroy the JSON value

   @val: JSON value. Typically created by the parsing function. */

void json_value_destroy(json_value_t *val);



/* Get JSON value's type

     Return values:

     JSON_VALUE_STRING: string

     JSON_VALUE_NUMBER: number

     JSON_VALUE_OBJECT: JSON object

     JSON_VALUE_ARRAY: JSON array

     JSON_VALUE_TRUE: true

     JSON_VALUE_FALSE: false

     JSON_VALUE_NULL: null

   @val: JSON value */

int json_value_type(const json_value_t *val);



/* Obtain the JSON string. The function returns the string or

   returns NULL if the type of @val is not JSON_VALUE_STRING.

   @val: JSON value */

const char *json_value_string(const json_value_t *val);



/* Obtain the JSON number. The function returns the number or

   returns NAN if the type of @val is not JSON_VALUE_NUMBER.

   @val: JSON value */

double json_value_number(const json_value_t *val);



/* Obtain JSON object. The function returns the JSON object or

   returns NULL if the type of @val is not JSON_VALUE_OBJECT.

   @val: JSON value

   Note: The returned pointer to JSON object is not const.

         You may extend the object using buiding functions. */

json_object_t *json_value_object(const json_value_t *val);



/* Obtain JSON arary. The function returns the JSON array or

   returns NULL if the type of @val is not JSON_VALUE_ARRAY.

   @val: JSON value

   Note: The returned pointer to the JSON array is not const and

         can been extended by using building functions. */

json_array_t *json_value_array(const json_value_t *val);



~~~

### JSON object related

~~~c

/* Get the size of the JSON object.

   @obj: JSON object */

int json_object_size(const json_object_t *obj);



/* Find the JSON value under the key @name. Returns NULL if @name

   can not be found. The time complexity of this function is

   O(log(n)), where n is the size of the JSON object.

   @name: The key to find

   @obj: JSON object

   Note: The returned pointer to JSON value is const. */

const json_value_t *json_object_find(const char *name, const json_object_t *obj);



/* Traversing the JSON object forward or backward

   @name: Temporary (const char *) pointer for each key

   @val: Temporary (const json_value_t *) pointer for each JSON value

   @obj: JSON object

   NOTE: These are not functions, but macros of looping. */

json_object_for_each(name, val, obj)

json_object_for_each_prev(name, val, obj)

~~~



### JSON array related

~~~c

/* Get the size of the JSON array.

   @arr：JSON array */

int json_array_size(const json_array_t *arr);



/* Traversing the JSON array forward or backward

   @val: Temporary (const json_value_t *) pointer for each JSON value

   @arr: JSON array

   NOTE: These are not functions, but macros of looping. */

json_array_for_each(val, arr)

json_array_for_each_prev(val, arr)

~~~



### Building JSON

All the following functions return NULL on failure of allocating memory.

~~~c

/* Create a JSON value.

   @type: JSON value's type.

   Note: Variable argument. Example:

     v_str = json_value_create(JSON_VALUE_STRING, "hello");

     v_num = json_value_create(JSON_VALUE_NUMBER, 3.14);

     v_int = json_value_create(JSON_VALUE_NUMBER, (double)100);

     v_obj = json_value_create(JSON_VALUE_OBJECT);

     v_arr = json_value_create(JSON_VALUE_ARRAY);

     v_true = json_value_create(JSON_VALUE_TRUE);

   The returned value is not const and has to be destroyed. */

json_value_t *json_value_create(int type, ...);



/* Extend the JSON object. Returns the value that's added.

   @obj: JSON object

   @name: New member's name

   @type: New member's value type or zero which means another JSON value

   Note: Variable argument. Example:

     v_num = json_object_append(obj, "pi", JSON_VALUE_NUMBER, 3.14);

     v_obj = json_object_append(obj, "user", JSON_VALUE_OBJECT);

     v_from_doc = json_object_append(obj, "doc", 0, json_value_parse("{\"data\" : [1, 2, 3]}")); */

const json_value_t *json_object_append(json_object_t *obj, const char *name,

                                       int type, ...);



/* Remove a JSON value from a JSON object and return the value.

   @val: JSON value to be removed.

   @obj: JSON object

   Note: The returned value is not const and need to be destroyed,

         or appended to another JSON object or JSON array. */

json_value_t *json_object_remove(const json_value_t *val,

                                 json_object_t *obj);



/* Extend the JSON array. Return the value that's added.

   @arr: JSON array

   @type: New member's value type or zero which means another JSON value

   Note: Variable argument. Example:

     v_str = json_array_append(arr, JSON_VALUE_STRING, "hello");

     equal to:

     v_str = json_array_append(arr, 0, json_value_create(JSON_VALUE_STRING, "hello")); */

const json_value_t *json_array_append(json_array_t *arr, int type, ...);



/* Remove a JSON value from a JSON array and return the value.

   @val: JSON value to be removed

   @arr: JSON array

   Note: The returned value is not const and need to be destroyed,

         or appended to another JSON object or JSON array. */

json_value_t *json_array_remove(const json_value_t *val,

                                json_object_t *arr);



~~~

# A beautiful C++ wrapper

https://github.com/wfrest/Json