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/**
* @file json.h
* @brief Minimal JSON reader, internal to this library.
*
* Read-only, allocation-per-node, no streaming and no writer. It is here
* because C ships no JSON parser and the shapes this client has to read are
* small and fixed. It handles the whole grammar it is fed: UTF-8 throughout,
* `\uXXXX` escapes with surrogate pairs, and the full number syntax.
*/
#ifndef CEPIS_JSON_H
#define CEPIS_JSON_H
#include <stdbool.h>
#include <stddef.h>
/** Deepest nesting accepted, so a hostile body cannot exhaust the stack. */
#define JSON_MAX_DEPTH 64
/** Kind of a ::json_value_t. */
typedef enum json_type {
JSON_NULL,
JSON_BOOL,
JSON_NUMBER,
JSON_STRING,
JSON_ARRAY,
JSON_OBJECT
} json_type_t;
typedef struct json_value json_value_t;
/** A parsed JSON value. Owns everything it points at. */
struct json_value {
json_type_t type;
union {
bool boolean;
double number;
/** NUL-terminated UTF-8, escapes already decoded. */
char *string;
struct {
json_value_t **items;
size_t count;
} array;
struct {
char **keys;
json_value_t **values;
size_t count;
} object;
} as;
};
/**
* @brief Parse @p len bytes of JSON.
* @return The root value, owned by the caller, or `NULL` when @p text is not
* one complete JSON value followed only by whitespace.
*/
json_value_t *json_parse(const char *text, size_t len);
/** @brief Release a value and everything below it. `NULL` is ignored. */
void json_free(json_value_t *value);
/**
* @brief Look a key up in an object.
* @return The member, borrowed from @p object, or `NULL` when @p object is not
* an object or has no such key. The first match wins.
*/
const json_value_t *json_object_get(const json_value_t *object,
const char *key);
/** @brief The string a value holds, or `NULL` when it is not a string. */
const char *json_as_string(const json_value_t *value);
/**
* @brief Read a value as a number, accepting a numeric string.
* @return `false` when the value is absent or cannot be read as a number, in
* which case @p out is untouched.
*/
bool json_as_double(const json_value_t *value, double *out);
/** @brief Like ::json_as_double, truncating towards zero. */
bool json_as_llong(const json_value_t *value, long long *out);
#endif
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