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#include <stdbool.h>
#include <stdio.h>
#include <talloc.h>
#include "sprinter.h"
struct sprinter_json {
struct sprinter vtable;
FILE *stream;
/* Top of the state stack, or NULL if the printer is not currently
* inside any aggregate types. */
struct json_state *state;
/* A flag to signify that a separator should be inserted in the
* output as soon as possible.
*/
notmuch_bool_t insert_separator;
};
struct json_state {
struct json_state *parent;
/* True if nothing has been printed in this aggregate yet.
* Suppresses the comma before a value. */
notmuch_bool_t first;
/* The character that closes the current aggregate. */
char close;
};
/* Helper function to set up the stream to print a value. If this
* value follows another value, prints a comma. */
static struct sprinter_json *
json_begin_value (struct sprinter *sp)
{
struct sprinter_json *spj = (struct sprinter_json *) sp;
if (spj->state) {
if (! spj->state->first) {
fputc (',', spj->stream);
if (spj->insert_separator) {
fputc ('\n', spj->stream);
spj->insert_separator = FALSE;
} else {
fputc (' ', spj->stream);
}
} else {
spj->state->first = FALSE;
}
}
return spj;
}
/* Helper function to begin an aggregate type. Prints the open
* character and pushes a new state frame. */
static void
json_begin_aggregate (struct sprinter *sp, char open, char close)
{
struct sprinter_json *spj = json_begin_value (sp);
struct json_state *state = talloc (spj, struct json_state);
fputc (open, spj->stream);
state->parent = spj->state;
state->first = TRUE;
state->close = close;
spj->state = state;
}
static void
json_begin_map (struct sprinter *sp)
{
json_begin_aggregate (sp, '{', '}');
}
static void
json_begin_list (struct sprinter *sp)
{
json_begin_aggregate (sp, '[', ']');
}
static void
json_end (struct sprinter *sp)
{
struct sprinter_json *spj = (struct sprinter_json *) sp;
struct json_state *state = spj->state;
fputc (spj->state->close, spj->stream);
spj->state = state->parent;
talloc_free (state);
if (spj->state == NULL)
fputc ('\n', spj->stream);
}
/* This implementation supports embedded NULs as allowed by the JSON
* specification and Unicode. Support for *parsing* embedded NULs
* varies, but is generally not a problem outside of C-based parsers
* (Python's json module and Emacs' json.el take embedded NULs in
* stride). */
static void
json_string_len (struct sprinter *sp, const char *val, size_t len)
{
static const char *const escapes[] = {
['\"'] = "\\\"", ['\\'] = "\\\\", ['\b'] = "\\b",
['\f'] = "\\f", ['\n'] = "\\n", ['\t'] = "\\t"
};
struct sprinter_json *spj = json_begin_value (sp);
fputc ('"', spj->stream);
for (; len; ++val, --len) {
unsigned char ch = *val;
if (ch < ARRAY_SIZE (escapes) && escapes[ch])
fputs (escapes[ch], spj->stream);
else if (ch >= 32)
fputc (ch, spj->stream);
else
fprintf (spj->stream, "\\u%04x", ch);
}
fputc ('"', spj->stream);
}
static void
json_string (struct sprinter *sp, const char *val)
{
if (val == NULL)
val = "";
json_string_len (sp, val, strlen (val));
}
static void
json_integer (struct sprinter *sp, int val)
{
struct sprinter_json *spj = json_begin_value (sp);
fprintf (spj->stream, "%d", val);
}
static void
json_boolean (struct sprinter *sp, notmuch_bool_t val)
{
struct sprinter_json *spj = json_begin_value (sp);
fputs (val ? "true" : "false", spj->stream);
}
static void
json_null (struct sprinter *sp)
{
struct sprinter_json *spj = json_begin_value (sp);
fputs ("null", spj->stream);
}
static void
json_map_key (struct sprinter *sp, const char *key)
{
struct sprinter_json *spj = (struct sprinter_json *) sp;
json_string (sp, key);
fputs (": ", spj->stream);
spj->state->first = TRUE;
}
static void
json_set_prefix (unused (struct sprinter *sp), unused (const char *name))
{
}
static void
json_separator (struct sprinter *sp)
{
struct sprinter_json *spj = (struct sprinter_json *) sp;
spj->insert_separator = TRUE;
}
struct sprinter *
sprinter_json_create (const void *ctx, FILE *stream)
{
static const struct sprinter_json template = {
.vtable = {
.begin_map = json_begin_map,
.begin_list = json_begin_list,
.end = json_end,
.string = json_string,
.string_len = json_string_len,
.integer = json_integer,
.boolean = json_boolean,
.null = json_null,
.map_key = json_map_key,
.separator = json_separator,
.set_prefix = json_set_prefix,
.is_text_printer = FALSE,
}
};
struct sprinter_json *res;
res = talloc (ctx, struct sprinter_json);
if (! res)
return NULL;
*res = template;
res->stream = stream;
return &res->vtable;
}
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