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authorVincent Ambo <Vincent Ambo>2020-01-11T23·36+0000
committerVincent Ambo <Vincent Ambo>2020-01-11T23·36+0000
commit1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5 (patch)
treee3accb9beed5c4c1b5a05c99db71ab2841f0ed04 /json-writer.h
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+#ifndef JSON_WRITER_H
+#define JSON_WRITER_H
+
+/*
+ * JSON data structures are defined at:
+ * [1] http://www.ietf.org/rfc/rfc7159.txt
+ * [2] http://json.org/
+ *
+ * The JSON-writer API allows one to build JSON data structures using a
+ * simple wrapper around a "struct strbuf" buffer.  It is intended as a
+ * simple API to build output strings; it is not intended to be a general
+ * object model for JSON data.  In particular, it does not re-order keys
+ * in an object (dictionary), it does not de-dup keys in an object, and
+ * it does not allow lookup or parsing of JSON data.
+ *
+ * All string values (both keys and string r-values) are properly quoted
+ * and escaped if they contain special characters.
+ *
+ * These routines create compact JSON data (with no unnecessary whitespace,
+ * newlines, or indenting).  If you get an unexpected response, verify
+ * that you're not expecting a pretty JSON string.
+ *
+ * Both "JSON objects" (aka sets of k/v pairs) and "JSON array" can be
+ * constructed using a 'begin append* end' model.
+ *
+ * Nested objects and arrays can either be constructed bottom up (by
+ * creating sub object/arrays first and appending them to the super
+ * object/array) -or- by building them inline in one pass.  This is a
+ * personal style and/or data shape choice.
+ *
+ * See t/helper/test-json-writer.c for various usage examples.
+ *
+ * LIMITATIONS:
+ * ============
+ *
+ * The JSON specification [1,2] defines string values as Unicode data
+ * and probably UTF-8 encoded.  The current json-writer API does not
+ * enforce this and will write any string as received.  However, it will
+ * properly quote and backslash-escape them as necessary.  It is up to
+ * the caller to UTF-8 encode their strings *before* passing them to this
+ * API.  This layer should not have to try to guess the encoding or locale
+ * of the given strings.
+ */
+
+#include "strbuf.h"
+
+struct json_writer
+{
+	/*
+	 * Buffer of the in-progress JSON currently being composed.
+	 */
+	struct strbuf json;
+
+	/*
+	 * Simple stack of the currently open array and object forms.
+	 * This is a string of '{' and '[' characters indicating the
+	 * currently unterminated forms.  This is used to ensure the
+	 * properly closing character is used when popping a level and
+	 * to know when the JSON is completely closed.
+	 */
+	struct strbuf open_stack;
+
+	unsigned int need_comma:1;
+	unsigned int pretty:1;
+};
+
+#define JSON_WRITER_INIT { STRBUF_INIT, STRBUF_INIT, 0, 0 }
+
+void jw_init(struct json_writer *jw);
+void jw_release(struct json_writer *jw);
+
+void jw_object_begin(struct json_writer *jw, int pretty);
+void jw_array_begin(struct json_writer *jw, int pretty);
+
+void jw_object_string(struct json_writer *jw, const char *key,
+		      const char *value);
+void jw_object_intmax(struct json_writer *jw, const char *key, intmax_t value);
+void jw_object_double(struct json_writer *jw, const char *key, int precision,
+		      double value);
+void jw_object_true(struct json_writer *jw, const char *key);
+void jw_object_false(struct json_writer *jw, const char *key);
+void jw_object_bool(struct json_writer *jw, const char *key, int value);
+void jw_object_null(struct json_writer *jw, const char *key);
+void jw_object_sub_jw(struct json_writer *jw, const char *key,
+		      const struct json_writer *value);
+
+void jw_object_inline_begin_object(struct json_writer *jw, const char *key);
+void jw_object_inline_begin_array(struct json_writer *jw, const char *key);
+
+void jw_array_string(struct json_writer *jw, const char *value);
+void jw_array_intmax(struct json_writer *jw, intmax_t value);
+void jw_array_double(struct json_writer *jw, int precision, double value);
+void jw_array_true(struct json_writer *jw);
+void jw_array_false(struct json_writer *jw);
+void jw_array_bool(struct json_writer *jw, int value);
+void jw_array_null(struct json_writer *jw);
+void jw_array_sub_jw(struct json_writer *jw, const struct json_writer *value);
+void jw_array_argc_argv(struct json_writer *jw, int argc, const char **argv);
+void jw_array_argv(struct json_writer *jw, const char **argv);
+
+void jw_array_inline_begin_object(struct json_writer *jw);
+void jw_array_inline_begin_array(struct json_writer *jw);
+
+int jw_is_terminated(const struct json_writer *jw);
+void jw_end(struct json_writer *jw);
+
+#endif /* JSON_WRITER_H */