Re: [PATCH v8 1/2] json_writer: new routines to create data in JSON format
- From
René Scharfe <l.s.r@web.de>
- Date
- Jun 8, 2018, 20:07 UTC
- Message-ID
- <0690b5a8-6c1c-e664-bb89-5d4e48258ddb@web.de>
- In-Reply-To
- <20180607141209.24423-2-git@jeffhostetler.com>
Am 07.06.2018 um 16:12 schrieb git@jeffhostetler.com:
Show 8 quoted lines
> From: Jeff Hostetler <jeffhost@microsoft.com>
> +/*
> + * Add comma if we have already seen a member at this level.
> + */
> +static inline void maybe_add_comma(struct json_writer *jw)
> +{
> + if (!jw->open_stack.len)
> + return;This is impossible. maybe_add_comma() is only called directly after assert_in_object() and assert_in_object(), which abort if open_stack is empty.
> + if (jw->first_stack.buf[jw->first_stack.len - 1] == '1') > + jw->first_stack.buf[jw->first_stack.len - 1] = '0'; > + else > + strbuf_addch(&jw->json, ',');
You only need a binary flag to indicate if a comma is needed, not a stack. We need a comma at the current level if and only if we already wrote a child item. If we finish a level then we do need a comma at the previous level because we just wrote a sub-object or sub-array there. And that should cover all cases. Am I missing something?
I get a sense of déjà vu, by the way. :)
Here's what I mean: --- json-writer.c | 17 ++++++----------- json-writer.h | 13 +++++-------- 2 files changed, 11 insertions(+), 19 deletions(-)
diff --git a/json-writer.c b/json-writer.c index f35ce1912a..14a4e89188 100644 --- a/json-writer.c +++ b/json-writer.c @@ -5,7 +5,7 @@ void jw_init(struct json_writer *jw) { strbuf_reset(&jw->json); strbuf_reset(&jw->open_stack); - strbuf_reset(&jw->first_stack); + jw->need_comma = 0; jw->pretty = 0; } @@ -13,7 +13,6 @@ void jw_release(struct json_writer *jw) { strbuf_release(&jw->json); strbuf_release(&jw->open_stack); - strbuf_release(&jw->first_stack); } /* @@ -69,7 +68,7 @@ static inline void begin(struct json_writer *jw, char ch_open, int pretty) strbuf_addch(&jw->json, ch_open); strbuf_addch(&jw->open_stack, ch_open); - strbuf_addch(&jw->first_stack, '1'); + jw->need_comma = 0; } /* @@ -99,12 +98,10 @@ static inline void assert_in_array(const struct json_writer *jw) */ static inline void maybe_add_comma(struct json_writer *jw) { - if (!jw->open_stack.len) - return; - if (jw->first_stack.buf[jw->first_stack.len - 1] == '1') - jw->first_stack.buf[jw->first_stack.len - 1] = '0'; - else + if (jw->need_comma) strbuf_addch(&jw->json, ','); + else + jw->need_comma = 1; } static inline void fmt_double(struct json_writer *jw, int precision, @@ -397,8 +394,6 @@ void jw_end(struct json_writer *jw) char ch_open; int len; - if (jw->open_stack.len != jw->first_stack.len) - BUG("jwon-writer: open_ and first_ stacks out of sync"); if (!jw->open_stack.len) BUG("json-writer: too many jw_end(): '%s'", jw->json.buf); @@ -406,7 +401,7 @@ void jw_end(struct json_writer *jw) ch_open = jw->open_stack.buf[len]; strbuf_setlen(&jw->open_stack, len); - strbuf_setlen(&jw->first_stack, len); + jw->need_comma = 1; if (jw->pretty) strbuf_addch(&jw->json, '\n'); diff --git a/json-writer.h b/json-writer.h index af9c2612f8..c437462ba8 100644 --- a/json-writer.h +++ b/json-writer.h @@ -59,18 +59,15 @@ struct json_writer struct strbuf open_stack; /* - * Another simple stack of the currently open array and object - * forms. This is used in parallel to "open_stack" (same length). - * It contains a string of '1' and '0' where '1' indicates that - * the next child-element seen will be the first child (and does - * not need a leading comma). + * Indicates if the next child item needs a leading comma. + * Only the first item of arrays and objects doesn't need one. */ - struct strbuf first_stack; + unsigned int need_comma:1; - int pretty; + unsigned int pretty:1; }; -#define JSON_WRITER_INIT { STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, 0 } +#define JSON_WRITER_INIT { STRBUF_INIT, STRBUF_INIT, 0, 0 } void jw_init(struct json_writer *jw); void jw_release(struct json_writer *jw);
-- 2.17.1