json: add JSON encoder

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/525>
This commit is contained in:
Igor V. Kovalenko 2021-03-13 11:23:43 +03:00 committed by PulseAudio Marge Bot
parent 1df4a311d4
commit 0ba768b2e9
5 changed files with 1135 additions and 0 deletions

View file

@ -44,6 +44,30 @@ struct pa_json_object {
};
};
/* JSON encoder context type */
typedef enum pa_json_context_type {
/* Top-level context of empty encoder. JSON element can be added. */
PA_JSON_CONTEXT_EMPTY = 0,
/* Top-level context of encoder with an element. JSON element cannot be added. */
PA_JSON_CONTEXT_TOP = 1,
/* JSON array context. JSON elements can be added. */
PA_JSON_CONTEXT_ARRAY = 2,
/* JSON object context. JSON object members can be added. */
PA_JSON_CONTEXT_OBJECT = 3,
} pa_json_context_type_t;
typedef struct encoder_context {
pa_json_context_type_t type;
int counter;
struct encoder_context *next;
} encoder_context;
/* JSON encoder structure, a wrapper for pa_strbuf and encoder context */
struct pa_json_encoder {
pa_strbuf *buffer;
encoder_context *context;
};
static const char* parse_value(const char *str, const char *end, pa_json_object **obj, unsigned int depth);
static pa_json_object* json_object_new(void) {
@ -526,6 +550,11 @@ const pa_json_object* pa_json_object_get_object_member(const pa_json_object *o,
return pa_hashmap_get(o->object_values, name);
}
const pa_hashmap *pa_json_object_get_object_member_hashmap(const pa_json_object *o) {
pa_assert(pa_json_object_get_type(o) == PA_JSON_TYPE_OBJECT);
return o->object_values;
}
int pa_json_object_get_array_length(const pa_json_object *o) {
pa_assert(pa_json_object_get_type(o) == PA_JSON_TYPE_ARRAY);
return pa_idxset_size(o->array_values);
@ -591,3 +620,443 @@ bool pa_json_object_equal(const pa_json_object *o1, const pa_json_object *o2) {
pa_assert_not_reached();
}
}
/* Write functions. The functions are wrapper functions around pa_strbuf,
* so that the client does not need to use pa_strbuf directly. */
static void json_encoder_context_push(pa_json_encoder *encoder, pa_json_context_type_t type) {
pa_assert(encoder);
encoder_context *head = pa_xnew0(encoder_context, 1);
head->type = type;
head->next = encoder->context;
encoder->context = head;
}
/* Returns type of context popped off encoder context stack. */
static pa_json_context_type_t json_encoder_context_pop(pa_json_encoder *encoder) {
encoder_context *head;
pa_json_context_type_t type;
pa_assert(encoder);
pa_assert(encoder->context);
type = encoder->context->type;
head = encoder->context->next;
pa_xfree(encoder->context);
encoder->context = head;
return type;
}
pa_json_encoder *pa_json_encoder_new(void) {
pa_json_encoder *encoder;
encoder = pa_xnew(pa_json_encoder, 1);
encoder->buffer = pa_strbuf_new();
encoder->context = NULL;
json_encoder_context_push(encoder, PA_JSON_CONTEXT_EMPTY);
return encoder;
}
void pa_json_encoder_free(pa_json_encoder *encoder) {
pa_json_context_type_t type;
pa_assert(encoder);
/* should have exactly one encoder context left at this point */
pa_assert(encoder->context);
type = json_encoder_context_pop(encoder);
pa_assert(encoder->context == NULL);
pa_assert(type == PA_JSON_CONTEXT_TOP || type == PA_JSON_CONTEXT_EMPTY);
if (type == PA_JSON_CONTEXT_EMPTY)
pa_log_warn("JSON encoder is empty.");
if (encoder->buffer)
pa_strbuf_free(encoder->buffer);
pa_xfree(encoder);
}
char *pa_json_encoder_to_string_free(pa_json_encoder *encoder) {
char *result;
pa_assert(encoder);
result = pa_strbuf_to_string_free(encoder->buffer);
encoder->buffer = NULL;
pa_json_encoder_free(encoder);
return result;
}
static void json_encoder_insert_delimiter(pa_json_encoder *encoder) {
pa_assert(encoder);
if (encoder->context->counter++)
pa_strbuf_putc(encoder->buffer, ',');
}
/* Escapes p to create valid JSON string.
* The caller has to free the returned string. */
static char *pa_json_escape(const char *p) {
const char *s;
char *out_string, *output;
int char_count = strlen(p);
/* Maximum number of characters in output string
* including trailing 0. */
char_count = 2 * char_count + 1;
/* allocate output string */
out_string = pa_xmalloc(char_count);
output = out_string;
/* write output string */
for (s = p; *s; ++s) {
switch (*s) {
case '"':
*output++ = '\\';
*output++ = '"';
break;
case '\\':
*output++ = '\\';
*output++ = '\\';
break;
case '\b':
*output++ = '\\';
*output++ = 'b';
break;
case '\f':
*output++ = '\\';
*output++ = 'f';
break;
case '\n':
*output++ = '\\';
*output++ = 'n';
break;
case '\r':
*output++ = '\\';
*output++ = 'r';
break;
case '\t':
*output++ = '\\';
*output++ = 't';
break;
default:
if (*s < 0x20 || *s > 0x7E) {
pa_log("Invalid non-ASCII character: 0x%x", (unsigned int) *s);
pa_xfree(out_string);
return NULL;
}
*output++ = *s;
break;
}
}
*output = 0;
return out_string;
}
static void json_write_string_escaped(pa_json_encoder *encoder, const char *value) {
char *escaped_value;
pa_assert(encoder);
escaped_value = pa_json_escape(value);
pa_strbuf_printf(encoder->buffer, "\"%s\"", escaped_value);
pa_xfree(escaped_value);
}
/* Writes an opening curly brace */
void pa_json_encoder_begin_element_object(pa_json_encoder *encoder) {
pa_assert(encoder);
pa_assert(encoder->context->type != PA_JSON_CONTEXT_TOP);
if (encoder->context->type == PA_JSON_CONTEXT_EMPTY)
encoder->context->type = PA_JSON_CONTEXT_TOP;
json_encoder_insert_delimiter(encoder);
pa_strbuf_putc(encoder->buffer, '{');
json_encoder_context_push(encoder, PA_JSON_CONTEXT_OBJECT);
}
/* Writes an opening curly brace */
void pa_json_encoder_begin_member_object(pa_json_encoder *encoder, const char *name) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_OBJECT);
pa_assert(name && name[0]);
json_encoder_insert_delimiter(encoder);
json_write_string_escaped(encoder, name);
pa_strbuf_putc(encoder->buffer, ':');
pa_strbuf_putc(encoder->buffer, '{');
json_encoder_context_push(encoder, PA_JSON_CONTEXT_OBJECT);
}
/* Writes a closing curly brace */
void pa_json_encoder_end_object(pa_json_encoder *encoder) {
pa_json_context_type_t type;
pa_assert(encoder);
type = json_encoder_context_pop(encoder);
pa_assert(type == PA_JSON_CONTEXT_OBJECT);
pa_strbuf_putc(encoder->buffer, '}');
}
/* Writes an opening bracket */
void pa_json_encoder_begin_element_array(pa_json_encoder *encoder) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type != PA_JSON_CONTEXT_TOP);
if (encoder->context->type == PA_JSON_CONTEXT_EMPTY)
encoder->context->type = PA_JSON_CONTEXT_TOP;
json_encoder_insert_delimiter(encoder);
pa_strbuf_putc(encoder->buffer, '[');
json_encoder_context_push(encoder, PA_JSON_CONTEXT_ARRAY);
}
/* Writes member name and an opening bracket */
void pa_json_encoder_begin_member_array(pa_json_encoder *encoder, const char *name) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_OBJECT);
pa_assert(name && name[0]);
json_encoder_insert_delimiter(encoder);
json_write_string_escaped(encoder, name);
pa_strbuf_putc(encoder->buffer, ':');
pa_strbuf_putc(encoder->buffer, '[');
json_encoder_context_push(encoder, PA_JSON_CONTEXT_ARRAY);
}
/* Writes a closing bracket */
void pa_json_encoder_end_array(pa_json_encoder *encoder) {
pa_json_context_type_t type;
pa_assert(encoder);
type = json_encoder_context_pop(encoder);
pa_assert(type == PA_JSON_CONTEXT_ARRAY);
pa_strbuf_putc(encoder->buffer, ']');
}
void pa_json_encoder_add_element_string(pa_json_encoder *encoder, const char *value) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_EMPTY || encoder->context->type == PA_JSON_CONTEXT_ARRAY);
if (encoder->context->type == PA_JSON_CONTEXT_EMPTY)
encoder->context->type = PA_JSON_CONTEXT_TOP;
json_encoder_insert_delimiter(encoder);
json_write_string_escaped(encoder, value);
}
void pa_json_encoder_add_member_string(pa_json_encoder *encoder, const char *name, const char *value) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_OBJECT);
pa_assert(name && name[0]);
json_encoder_insert_delimiter(encoder);
json_write_string_escaped(encoder, name);
pa_strbuf_putc(encoder->buffer, ':');
/* Null value is written as empty element */
if (!value)
value = "";
json_write_string_escaped(encoder, value);
}
static void json_write_null(pa_json_encoder *encoder) {
pa_assert(encoder);
pa_strbuf_puts(encoder->buffer, "null");
}
void pa_json_encoder_add_element_null(pa_json_encoder *encoder) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_EMPTY || encoder->context->type == PA_JSON_CONTEXT_ARRAY);
if (encoder->context->type == PA_JSON_CONTEXT_EMPTY)
encoder->context->type = PA_JSON_CONTEXT_TOP;
json_encoder_insert_delimiter(encoder);
json_write_null(encoder);
}
void pa_json_encoder_add_member_null(pa_json_encoder *encoder, const char *name) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_OBJECT);
pa_assert(name && name[0]);
json_encoder_insert_delimiter(encoder);
json_write_string_escaped(encoder, name);
pa_strbuf_putc(encoder->buffer, ':');
json_write_null(encoder);
}
static void json_write_bool(pa_json_encoder *encoder, bool value) {
pa_assert(encoder);
pa_strbuf_puts(encoder->buffer, value ? "true" : "false");
}
void pa_json_encoder_add_element_bool(pa_json_encoder *encoder, bool value) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_EMPTY || encoder->context->type == PA_JSON_CONTEXT_ARRAY);
if (encoder->context->type == PA_JSON_CONTEXT_EMPTY)
encoder->context->type = PA_JSON_CONTEXT_TOP;
json_encoder_insert_delimiter(encoder);
json_write_bool(encoder, value);
}
void pa_json_encoder_add_member_bool(pa_json_encoder *encoder, const char *name, bool value) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_OBJECT);
pa_assert(name && name[0]);
json_encoder_insert_delimiter(encoder);
json_write_string_escaped(encoder, name);
pa_strbuf_putc(encoder->buffer, ':');
json_write_bool(encoder, value);
}
static void json_write_int(pa_json_encoder *encoder, int64_t value) {
pa_assert(encoder);
pa_strbuf_printf(encoder->buffer, "%"PRId64, value);
}
void pa_json_encoder_add_element_int(pa_json_encoder *encoder, int64_t value) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_EMPTY || encoder->context->type == PA_JSON_CONTEXT_ARRAY);
if (encoder->context->type == PA_JSON_CONTEXT_EMPTY)
encoder->context->type = PA_JSON_CONTEXT_TOP;
json_encoder_insert_delimiter(encoder);
json_write_int(encoder, value);
}
void pa_json_encoder_add_member_int(pa_json_encoder *encoder, const char *name, int64_t value) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_OBJECT);
pa_assert(name && name[0]);
json_encoder_insert_delimiter(encoder);
json_write_string_escaped(encoder, name);
pa_strbuf_putc(encoder->buffer, ':');
json_write_int(encoder, value);
}
static void json_write_double(pa_json_encoder *encoder, double value, int precision) {
pa_assert(encoder);
pa_strbuf_printf(encoder->buffer, "%.*f", precision, value);
}
void pa_json_encoder_add_element_double(pa_json_encoder *encoder, double value, int precision) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_EMPTY || encoder->context->type == PA_JSON_CONTEXT_ARRAY);
if (encoder->context->type == PA_JSON_CONTEXT_EMPTY)
encoder->context->type = PA_JSON_CONTEXT_TOP;
json_encoder_insert_delimiter(encoder);
json_write_double(encoder, value, precision);
}
void pa_json_encoder_add_member_double(pa_json_encoder *encoder, const char *name, double value, int precision) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_OBJECT);
pa_assert(name && name[0]);
json_encoder_insert_delimiter(encoder);
json_write_string_escaped(encoder, name);
pa_strbuf_putc(encoder->buffer, ':');
json_write_double(encoder, value, precision);
}
static void json_write_raw(pa_json_encoder *encoder, const char *raw_string) {
pa_assert(encoder);
pa_strbuf_puts(encoder->buffer, raw_string);
}
void pa_json_encoder_add_element_raw_json(pa_json_encoder *encoder, const char *raw_json_string) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_EMPTY || encoder->context->type == PA_JSON_CONTEXT_ARRAY);
if (encoder->context->type == PA_JSON_CONTEXT_EMPTY)
encoder->context->type = PA_JSON_CONTEXT_TOP;
json_encoder_insert_delimiter(encoder);
json_write_raw(encoder, raw_json_string);
}
void pa_json_encoder_add_member_raw_json(pa_json_encoder *encoder, const char *name, const char *raw_json_string) {
pa_assert(encoder);
pa_assert(encoder->context);
pa_assert(encoder->context->type == PA_JSON_CONTEXT_OBJECT);
pa_assert(name && name[0]);
json_encoder_insert_delimiter(encoder);
json_write_string_escaped(encoder, name);
pa_strbuf_putc(encoder->buffer, ':');
json_write_raw(encoder, raw_json_string);
}