75459410ed
Add "struct json_writer" and a series of jw_ routines to compose JSON data into a string buffer. The resulting string may then be printed by commands wanting to support a JSON-like output format. The json_writer is limited to correctly formatting structured data for output. It does not attempt to build an object model of the JSON data. We say "JSON-like" because we do not enforce the Unicode (usually UTF-8) requirement on string fields. Internally, Git does not necessarily have Unicode/UTF-8 data for most fields, so it is currently unclear the best way to enforce that requirement. For example, on Linux pathnames can contain arbitrary 8-bit character data, so a command like "status" would not know how to encode the reported pathnames. We may want to revisit this (or double encode such strings) in the future. Helped-by: Eric Sunshine <sunshine@sunshineco.com> Helped-by: René Scharfe <l.s.r@web.de> Helped-by: Wink Saville <wink@saville.com> Helped-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
106 lines
4.1 KiB
C
106 lines
4.1 KiB
C
#ifndef JSON_WRITER_H
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#define JSON_WRITER_H
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/*
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* JSON data structures are defined at:
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* [1] http://www.ietf.org/rfc/rfc7159.txt
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* [2] http://json.org/
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*
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* The JSON-writer API allows one to build JSON data structures using a
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* simple wrapper around a "struct strbuf" buffer. It is intended as a
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* simple API to build output strings; it is not intended to be a general
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* object model for JSON data. In particular, it does not re-order keys
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* in an object (dictionary), it does not de-dup keys in an object, and
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* it does not allow lookup or parsing of JSON data.
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*
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* All string values (both keys and string r-values) are properly quoted
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* and escaped if they contain special characters.
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*
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* These routines create compact JSON data (with no unnecessary whitespace,
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* newlines, or indenting). If you get an unexpected response, verify
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* that you're not expecting a pretty JSON string.
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*
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* Both "JSON objects" (aka sets of k/v pairs) and "JSON array" can be
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* constructed using a 'begin append* end' model.
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*
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* Nested objects and arrays can either be constructed bottom up (by
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* creating sub object/arrays first and appending them to the super
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* object/array) -or- by building them inline in one pass. This is a
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* personal style and/or data shape choice.
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*
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* See t/helper/test-json-writer.c for various usage examples.
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*
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* LIMITATIONS:
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* ============
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*
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* The JSON specification [1,2] defines string values as Unicode data
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* and probably UTF-8 encoded. The current json-writer API does not
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* enforce this and will write any string as received. However, it will
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* properly quote and backslash-escape them as necessary. It is up to
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* the caller to UTF-8 encode their strings *before* passing them to this
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* API. This layer should not have to try to guess the encoding or locale
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* of the given strings.
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*/
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struct json_writer
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{
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/*
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* Buffer of the in-progress JSON currently being composed.
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*/
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struct strbuf json;
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/*
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* Simple stack of the currently open array and object forms.
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* This is a string of '{' and '[' characters indicating the
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* currently unterminated forms. This is used to ensure the
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* properly closing character is used when popping a level and
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* to know when the JSON is completely closed.
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*/
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struct strbuf open_stack;
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unsigned int need_comma:1;
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unsigned int pretty:1;
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};
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#define JSON_WRITER_INIT { STRBUF_INIT, STRBUF_INIT, 0, 0 }
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void jw_init(struct json_writer *jw);
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void jw_release(struct json_writer *jw);
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void jw_object_begin(struct json_writer *jw, int pretty);
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void jw_array_begin(struct json_writer *jw, int pretty);
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void jw_object_string(struct json_writer *jw, const char *key,
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const char *value);
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void jw_object_intmax(struct json_writer *jw, const char *key, intmax_t value);
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void jw_object_double(struct json_writer *jw, const char *key, int precision,
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double value);
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void jw_object_true(struct json_writer *jw, const char *key);
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void jw_object_false(struct json_writer *jw, const char *key);
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void jw_object_bool(struct json_writer *jw, const char *key, int value);
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void jw_object_null(struct json_writer *jw, const char *key);
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void jw_object_sub_jw(struct json_writer *jw, const char *key,
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const struct json_writer *value);
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void jw_object_inline_begin_object(struct json_writer *jw, const char *key);
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void jw_object_inline_begin_array(struct json_writer *jw, const char *key);
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void jw_array_string(struct json_writer *jw, const char *value);
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void jw_array_intmax(struct json_writer *jw, intmax_t value);
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void jw_array_double(struct json_writer *jw, int precision, double value);
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void jw_array_true(struct json_writer *jw);
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void jw_array_false(struct json_writer *jw);
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void jw_array_bool(struct json_writer *jw, int value);
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void jw_array_null(struct json_writer *jw);
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void jw_array_sub_jw(struct json_writer *jw, const struct json_writer *value);
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void jw_array_argc_argv(struct json_writer *jw, int argc, const char **argv);
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void jw_array_argv(struct json_writer *jw, const char **argv);
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void jw_array_inline_begin_object(struct json_writer *jw);
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void jw_array_inline_begin_array(struct json_writer *jw);
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int jw_is_terminated(const struct json_writer *jw);
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void jw_end(struct json_writer *jw);
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#endif /* JSON_WRITER_H */
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