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   1#ifndef JSON_WRITER_H
   2#define JSON_WRITER_H
   3
   4/*
   5 * JSON data structures are defined at:
   6 * [1] http://www.ietf.org/rfc/rfc7159.txt
   7 * [2] http://json.org/
   8 *
   9 * The JSON-writer API allows one to build JSON data structures using a
  10 * simple wrapper around a "struct strbuf" buffer.  It is intended as a
  11 * simple API to build output strings; it is not intended to be a general
  12 * object model for JSON data.  In particular, it does not re-order keys
  13 * in an object (dictionary), it does not de-dup keys in an object, and
  14 * it does not allow lookup or parsing of JSON data.
  15 *
  16 * All string values (both keys and string r-values) are properly quoted
  17 * and escaped if they contain special characters.
  18 *
  19 * These routines create compact JSON data (with no unnecessary whitespace,
  20 * newlines, or indenting).  If you get an unexpected response, verify
  21 * that you're not expecting a pretty JSON string.
  22 *
  23 * Both "JSON objects" (aka sets of k/v pairs) and "JSON array" can be
  24 * constructed using a 'begin append* end' model.
  25 *
  26 * Nested objects and arrays can either be constructed bottom up (by
  27 * creating sub object/arrays first and appending them to the super
  28 * object/array) -or- by building them inline in one pass.  This is a
  29 * personal style and/or data shape choice.
  30 *
  31 * See t/helper/test-json-writer.c for various usage examples.
  32 *
  33 * LIMITATIONS:
  34 * ============
  35 *
  36 * The JSON specification [1,2] defines string values as Unicode data
  37 * and probably UTF-8 encoded.  The current json-writer API does not
  38 * enforce this and will write any string as received.  However, it will
  39 * properly quote and backslash-escape them as necessary.  It is up to
  40 * the caller to UTF-8 encode their strings *before* passing them to this
  41 * API.  This layer should not have to try to guess the encoding or locale
  42 * of the given strings.
  43 */
  44
  45#include "strbuf.h"
  46
  47struct json_writer
  48{
  49        /*
  50         * Buffer of the in-progress JSON currently being composed.
  51         */
  52        struct strbuf json;
  53
  54        /*
  55         * Simple stack of the currently open array and object forms.
  56         * This is a string of '{' and '[' characters indicating the
  57         * currently unterminated forms.  This is used to ensure the
  58         * properly closing character is used when popping a level and
  59         * to know when the JSON is completely closed.
  60         */
  61        struct strbuf open_stack;
  62
  63        unsigned int need_comma:1;
  64        unsigned int pretty:1;
  65};
  66
  67#define JSON_WRITER_INIT { STRBUF_INIT, STRBUF_INIT, 0, 0 }
  68
  69void jw_init(struct json_writer *jw);
  70void jw_release(struct json_writer *jw);
  71
  72void jw_object_begin(struct json_writer *jw, int pretty);
  73void jw_array_begin(struct json_writer *jw, int pretty);
  74
  75void jw_object_string(struct json_writer *jw, const char *key,
  76                      const char *value);
  77void jw_object_intmax(struct json_writer *jw, const char *key, intmax_t value);
  78void jw_object_double(struct json_writer *jw, const char *key, int precision,
  79                      double value);
  80void jw_object_true(struct json_writer *jw, const char *key);
  81void jw_object_false(struct json_writer *jw, const char *key);
  82void jw_object_bool(struct json_writer *jw, const char *key, int value);
  83void jw_object_null(struct json_writer *jw, const char *key);
  84void jw_object_sub_jw(struct json_writer *jw, const char *key,
  85                      const struct json_writer *value);
  86
  87void jw_object_inline_begin_object(struct json_writer *jw, const char *key);
  88void jw_object_inline_begin_array(struct json_writer *jw, const char *key);
  89
  90void jw_array_string(struct json_writer *jw, const char *value);
  91void jw_array_intmax(struct json_writer *jw, intmax_t value);
  92void jw_array_double(struct json_writer *jw, int precision, double value);
  93void jw_array_true(struct json_writer *jw);
  94void jw_array_false(struct json_writer *jw);
  95void jw_array_bool(struct json_writer *jw, int value);
  96void jw_array_null(struct json_writer *jw);
  97void jw_array_sub_jw(struct json_writer *jw, const struct json_writer *value);
  98void jw_array_argc_argv(struct json_writer *jw, int argc, const char **argv);
  99void jw_array_argv(struct json_writer *jw, const char **argv);
 100
 101void jw_array_inline_begin_object(struct json_writer *jw);
 102void jw_array_inline_begin_array(struct json_writer *jw);
 103
 104int jw_is_terminated(const struct json_writer *jw);
 105void jw_end(struct json_writer *jw);
 106
 107#endif /* JSON_WRITER_H */