Re: [PATCH v3] json_writer: new routines to create data in JSON format

2018-03-23 Thread Jeff Hostetler 



On 3/23/2018 1:18 PM, Jonathan Nieder wrote:

g...@jeffhostetler.com wrote:


From: Jeff Hostetler 

Add basic routines to generate data in JSON format.

Signed-off-by: Jeff Hostetler 


If I understand the cover letter correctly, this is a JSON-like
format, not actual JSON.  Am I understanding correctly?

What are the requirements for consuming this output?  Will a typical
JSON library be able to handle it without trouble?  If not, is there
some subset of cases where a typical JSON library is able to handle it
without trouble?


I'll add text to the commit message and the .h file explaining
the Unicode limitation in the next reroll.



Can you say a little about the motivation here?  (I know you already
put some of that in the cover letter, but since that doesn't become
part of permanent history, it doesn't help the audience that matters.)


I'll add a note about that to the commit message.
Thanks.



This would also be easier to review if there were an application of it
in the same series.  It's fine to send an RFC like this without such
an application, but I think we should hold off on merging it until we
have one.  Having an application makes review much easier since we can
see how the API works in practice, how well the approach fits what
users need, etc.


That's fine.  I'm planning to push up another patch series next week
that builds upon this, so hopefully that will help.



Thanks and hope that helps,
Jonathan


Thanks,
Jeff

Re: [PATCH v3] json_writer: new routines to create data in JSON format

2018-03-23 Thread Jonathan Nieder 
g...@jeffhostetler.com wrote:

> From: Jeff Hostetler 
>
> Add basic routines to generate data in JSON format.
>
> Signed-off-by: Jeff Hostetler 

If I understand the cover letter correctly, this is a JSON-like
format, not actual JSON.  Am I understanding correctly?

What are the requirements for consuming this output?  Will a typical
JSON library be able to handle it without trouble?  If not, is there
some subset of cases where a typical JSON library is able to handle it
without trouble?

Can you say a little about the motivation here?  (I know you already
put some of that in the cover letter, but since that doesn't become
part of permanent history, it doesn't help the audience that matters.)

This would also be easier to review if there were an application of it
in the same series.  It's fine to send an RFC like this without such
an application, but I think we should hold off on merging it until we
have one.  Having an application makes review much easier since we can
see how the API works in practice, how well the approach fits what
users need, etc.

Thanks and hope that helps,
Jonathan

[PATCH v3] json_writer: new routines to create data in JSON format

2018-03-23 Thread git 
From: Jeff Hostetler 

Add basic routines to generate data in JSON format.

Signed-off-by: Jeff Hostetler 
---
 Makefile|   2 +
 json-writer.c   | 321 +
 json-writer.h   |  86 +
 t/helper/test-json-writer.c | 420 
 t/t0019-json-writer.sh  | 213 ++
 5 files changed, 1042 insertions(+)
 create mode 100644 json-writer.c
 create mode 100644 json-writer.h
 create mode 100644 t/helper/test-json-writer.c
 create mode 100755 t/t0019-json-writer.sh

diff --git a/Makefile b/Makefile
index 1a9b23b..57f58e6 100644
--- a/Makefile
+++ b/Makefile
@@ -662,6 +662,7 @@ TEST_PROGRAMS_NEED_X += test-fake-ssh
 TEST_PROGRAMS_NEED_X += test-genrandom
 TEST_PROGRAMS_NEED_X += test-hashmap
 TEST_PROGRAMS_NEED_X += test-index-version
+TEST_PROGRAMS_NEED_X += test-json-writer
 TEST_PROGRAMS_NEED_X += test-lazy-init-name-hash
 TEST_PROGRAMS_NEED_X += test-line-buffer
 TEST_PROGRAMS_NEED_X += test-match-trees
@@ -815,6 +816,7 @@ LIB_OBJS += hashmap.o
 LIB_OBJS += help.o
 LIB_OBJS += hex.o
 LIB_OBJS += ident.o
+LIB_OBJS += json-writer.o
 LIB_OBJS += kwset.o
 LIB_OBJS += levenshtein.o
 LIB_OBJS += line-log.o
diff --git a/json-writer.c b/json-writer.c
new file mode 100644
index 000..1861382
--- /dev/null
+++ b/json-writer.c
@@ -0,0 +1,321 @@
+#include "cache.h"
+#include "json-writer.h"
+
+static char ch_open[2]  = { '{', '[' };
+static char ch_close[2] = { '}', ']' };
+
+/*
+ * Append JSON-quoted version of the given string to 'out'.
+ */
+static void append_quoted_string(struct strbuf *out, const char *in)
+{
+   strbuf_addch(out, '"');
+   for (/**/; *in; in++) {
+   unsigned char c = (unsigned char)*in;
+   if (c == '"')
+   strbuf_add(out, "\\\"", 2);
+   else if (c == '\\')
+   strbuf_add(out, "", 2);
+   else if (c == '\n')
+   strbuf_add(out, "\\n", 2);
+   else if (c == '\r')
+   strbuf_add(out, "\\r", 2);
+   else if (c == '\t')
+   strbuf_add(out, "\\t", 2);
+   else if (c == '\f')
+   strbuf_add(out, "\\f", 2);
+   else if (c == '\b')
+   strbuf_add(out, "\\b", 2);
+   else if (c < 0x20)
+   strbuf_addf(out, "\\u%04x", c);
+   else
+   strbuf_addch(out, c);
+   }
+   strbuf_addch(out, '"');
+}
+
+
+static inline void begin(struct json_writer *jw, int is_array)
+{
+   ALLOC_GROW(jw->level, jw->nr + 1, jw->alloc);
+
+   jw->level[jw->nr].is_array = !!is_array;
+   jw->level[jw->nr].is_empty = 1;
+
+   strbuf_addch(>json, ch_open[!!is_array]);
+
+   jw->nr++;
+}
+
+/*
+ * Assert that we have an open object at this level.
+ */
+static void inline assert_in_object(const struct json_writer *jw, const char 
*key)
+{
+   if (!jw->nr)
+   die("json-writer: object: missing jw_object_begin(): '%s'", 
key);
+   if (jw->level[jw->nr - 1].is_array)
+   die("json-writer: object: not in object: '%s'", key);
+}
+
+/*
+ * Assert that we have an open array at this level.
+ */
+static void inline assert_in_array(const struct json_writer *jw)
+{
+   if (!jw->nr)
+   die("json-writer: array: missing jw_begin()");
+   if (!jw->level[jw->nr - 1].is_array)
+   die("json-writer: array: not in array");
+}
+
+/*
+ * Add comma if we have already seen a member at this level.
+ */
+static void inline maybe_add_comma(struct json_writer *jw)
+{
+   if (jw->level[jw->nr - 1].is_empty)
+   jw->level[jw->nr - 1].is_empty = 0;
+   else
+   strbuf_addch(>json, ',');
+}
+
+/*
+ * Assert that the given JSON object or JSON array has been properly
+ * terminated.  (Has closing bracket.)
+ */
+static void inline assert_is_terminated(const struct json_writer *jw)
+{
+   if (jw->nr)
+   die("json-writer: object: missing jw_end(): '%s'", 
jw->json.buf);
+}
+
+void jw_object_begin(struct json_writer *jw)
+{
+   begin(jw, 0);
+}
+
+void jw_object_string(struct json_writer *jw, const char *key, const char 
*value)
+{
+   assert_in_object(jw, key);
+   maybe_add_comma(jw);
+
+   append_quoted_string(>json, key);
+   strbuf_addch(>json, ':');
+   append_quoted_string(>json, value);
+}
+
+void jw_object_int(struct json_writer *jw, const char *key, int value)
+{
+   assert_in_object(jw, key);
+   maybe_add_comma(jw);
+
+   append_quoted_string(>json, key);
+   strbuf_addf(>json, ":%d", value);
+}
+
+void jw_object_uint64(struct json_writer *jw, const char *key, uint64_t value)
+{
+   assert_in_object(jw, key);
+   maybe_add_comma(jw);
+
+   append_quoted_string(>json, key);
+