system_cmds-790.tar.gz

[apple/system_cmds.git] / lsmp.tproj / json.h

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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_ */