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/*
* Copyright (c) 2017 Apple Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* The contents of this file constitute Original Code as defined in and
* are subject to the Apple Public Source License Version 1.1 (the
* "License"). You may not use this file except in compliance with the
* License. Please obtain a copy of the License at
* http://www.apple.com/publicsource and read it before using this file.
*
* This Original Code and all software distributed under the License are
* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
* License for the specific language governing rights and limitations
* under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
/*
* Provides a stream-based API for generating JSON output
*
* Handles tedious tasks like worrying about comma placement (and avoiding trailing commas).
* Assumes strings are already escaped (if necessary) and does no error checking (thus it
* may produce invalid JSON when used improperly).
*
* As a convenience, when the provided `json` stream is NULL (i.e. it was never initialized
* by `JSON_OPEN`) these APIs will do nothing.
*
* Example usage:
*
* JSON_t json = JSON_OPEN("/path/to/output.json")
* JSON_OBJECT_BEGIN(json); // root object
*
* JSON_OBJECT_SET(json, version, %.1f, 1.0);
* JSON_OBJECT_SET_BOOL(json, has_fruit, 1);
*
* // Note the required quotes for strings (formatted or not)
* char *mystr = "hello";
* JSON_OBJECT_SET(json, formatted_string, "%s", mystr);
* JSON_OBJECT_SET(json, literal_string, "my literal string");
*
* JSON_KEY(json, fruit_array);
* JSON_ARRAY_BEGIN(json); // fruit_array
* JSON_ARRAY_APPEND(json, "my literal string");
* JSON_ARRAY_APPEND(json, "<0x%08llx>", 0xface);
* JSON_ARRAY_APPEND(json, %d, 3);
* JSON_ARRAY_END(json); // fruit_array
*
* JSON_OBJECT_END(json); // root object
* JSON_CLOSE(json);
*/
#ifndef _JSON_H_
#define _JSON_H_
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#define _JSON_IF(json, code) \
if (json != NULL) { \
code; \
}
#define _JSON_COMMA(json) \
if (json->require_comma) { \
fprintf(json->stream, ","); \
}
struct _JSON {
FILE* stream;
bool require_comma;
};
typedef struct _JSON * JSON_t;
#pragma mark Open/Close
/* Return a new JSON_t stream */
static inline JSON_t JSON_OPEN(const char *path) {
JSON_t p = malloc(sizeof(struct _JSON));
p->stream = fopen(path, "w+");
p->require_comma = false;
return p;
}
/* Close an existing JSON stream, removing trailing commas */
#define JSON_CLOSE(json) _JSON_IF(json, fclose(json->stream); free(json))
#pragma mark Keys/Values
/* Output the `key` half of a key/value pair */
#define JSON_KEY(json, key) _JSON_IF(json, _JSON_COMMA(json); fprintf(json->stream, "\"" #key "\":"); json->require_comma = false)
/* Output the `value` half of a key/value pair */
#define JSON_VALUE(json, format, ...) _JSON_IF(json, fprintf(json->stream, #format, ##__VA_ARGS__); json->require_comma = true)
#define _JSON_BEGIN(json, character) _JSON_COMMA(json); fprintf(json->stream, #character); json->require_comma = false;
#define _JSON_END(json, character) fprintf(json->stream, #character); json->require_comma = true;
#define _JSON_BOOL(val) ( val ? "true" : "false" )
#pragma mark Objects
/* Start a new JSON object */
#define JSON_OBJECT_BEGIN(json) _JSON_IF(json, _JSON_BEGIN(json, {))
/* Set a value in the current JSON object */
#define JSON_OBJECT_SET(json, key, format, ...) _JSON_IF(json, JSON_KEY(json, key); JSON_VALUE(json, format, ##__VA_ARGS__))
/* Set a boolean in the current JSON object */
#define JSON_OBJECT_SET_BOOL(json, key, value) JSON_OBJECT_SET(json, key, %s, _JSON_BOOL(value))
/* End the current JSON object */
#define JSON_OBJECT_END(json) _JSON_IF(json, _JSON_END(json, }))
#pragma mark Arrays
/* Start a new JSON array */
#define JSON_ARRAY_BEGIN(json) _JSON_IF(json, _JSON_BEGIN(json, [))
/* Append a value to the current JSON array */
#define JSON_ARRAY_APPEND(json, format, ...) _JSON_IF(json, _JSON_COMMA(json); JSON_VALUE(json, format, ##__VA_ARGS__))
/* End the current JSON array */
#define JSON_ARRAY_END(json) _JSON_IF(json, _JSON_END(json, ]))
#endif /* _JSON_H_ */
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