Files
tippecanoe/geojson-loop.cpp
T
Erica FischerandCursor f366b2c4aa Subclass json_object so primitives shrink from 168 to 24 bytes
The previous "every member in a struct" layout cost 168 bytes per
json_object, even for JSON_NULL / JSON_TRUE / JSON_FALSE nodes that
have no payload. Splitting json_object into a small base class plus
json_number / json_string / json_array / json_hash subclasses brings
each instance down to just the size of its actual contents:

  json_object (base, TRUE / FALSE / NULL)   24 bytes
  json_number                                48 bytes
  json_string                                48 bytes
  json_array  (empty)                        48 bytes
  json_hash   (empty)                        72 bytes

Other size wins along the way:

* Drop enable_shared_from_this<json_object> (its embedded weak_ptr
  was 16 bytes per node). json_pull now keeps an explicit
  container_stack and the parser no longer needs to resurrect a
  shared_ptr from a raw `parent` walk.
* Remove the unused `refcon` slot from the string variant.
* No virtual destructor: shared_ptr keeps the deleter from the
  original std::make_shared<json_xxx> call, so destroying a
  shared_ptr<json_object> still runs the right subclass dtor.

The base class exposes type-tagged accessors (o->string(),
o->number(), o->array(), o->keys(), o->values(), o->large_signed(),
o->large_unsigned()) that assert the type matches and downcast to
the appropriate subclass storage. All call sites were swept from
the old `o->value.X.Y` field paths to these accessors. A raw-pointer
overload of json_hash_get() replaces the few external uses of
shared_from_this() that survived in geojson-loop.cpp.

Co-authored-by: Cursor <cursoragent@cursor.com>
2026-05-30 17:49:08 -07:00

192 lines
4.7 KiB
C++

#ifdef MTRACE
#include <mcheck.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <errno.h>
#include "geojson-loop.hpp"
#include "jsonpull/jsonpull.h"
// XXX duplicated
#define GEOM_TYPES 6
static const char *geometry_names[GEOM_TYPES] = {
"Point",
"MultiPoint",
"LineString",
"MultiLineString",
"Polygon",
"MultiPolygon",
};
// XXX duplicated
static void json_context(json_object_ptr j) {
std::string s = json_stringify(j);
if (s.size() >= 500) {
s.resize(497);
s.append("...");
}
fprintf(stderr, "in JSON object %s\n", s.c_str());
}
void parse_json(json_feature_action *jfa, json_pull_ptr jp) {
long long found_hashes = 0;
long long found_features = 0;
long long found_geometries = 0;
while (1) {
json_object_ptr j = json_read(jp);
if (j == nullptr) {
if (jp->error != nullptr) {
fprintf(stderr, "%s:%d: %s: ", jfa->fname.c_str(), jp->line, jp->error);
if (jp->root != nullptr) {
json_context(jp->root);
} else {
fprintf(stderr, "\n");
}
}
jp->root.reset();
break;
}
if (j->type == JSON_HASH) {
found_hashes++;
if (found_hashes == 50 && found_features == 0 && found_geometries == 0) {
fprintf(stderr, "%s:%d: Warning: not finding any GeoJSON features or geometries in input yet after 50 objects.\n", jfa->fname.c_str(), jp->line);
}
}
json_object_ptr type = json_hash_get(j, "type");
if (type == nullptr || type->type != JSON_STRING) {
continue;
}
if (found_features == 0) {
int i;
int is_geometry = 0;
for (i = 0; i < GEOM_TYPES; i++) {
if (type->string() == geometry_names[i]) {
is_geometry = 1;
break;
}
}
if (is_geometry) {
if (j->parent != nullptr) {
if (j->parent->type == JSON_ARRAY && j->parent->parent != nullptr) {
if (j->parent->parent->type == JSON_HASH) {
json_object_ptr geometries = json_hash_get(j->parent->parent, "geometries");
if (geometries != nullptr) {
// Parent of Parent must be a GeometryCollection
is_geometry = 0;
}
}
} else if (j->parent->type == JSON_HASH) {
json_object_ptr geometry = json_hash_get(j->parent, "geometry");
if (geometry != nullptr) {
// Parent must be a Feature
is_geometry = 0;
}
}
}
}
if (is_geometry) {
json_object *jo = j.get();
while (jo != nullptr) {
if (jo->parent != nullptr && jo->parent->type == JSON_HASH) {
if (json_hash_get(jo->parent, "properties").get() == jo) {
// Ancestor is the value corresponding to a properties key
is_geometry = 0;
break;
}
}
jo = jo->parent;
}
}
if (is_geometry) {
if (found_features != 0 && found_geometries == 0) {
fprintf(stderr, "%s:%d: Warning: found a mixture of features and bare geometries\n", jfa->fname.c_str(), jp->line);
}
found_geometries++;
jfa->add_feature(j, false, nullptr, nullptr, nullptr, j);
json_free(j);
continue;
}
}
if (type->string() != "Feature") {
if (type->string() == "FeatureCollection") {
jfa->check_crs(j);
json_free(j);
}
continue;
}
if (found_features == 0 && found_geometries != 0) {
fprintf(stderr, "%s:%d: Warning: found a mixture of features and bare geometries\n", jfa->fname.c_str(), jp->line);
}
found_features++;
json_object_ptr geometry = json_hash_get(j, "geometry");
if (geometry == nullptr) {
fprintf(stderr, "%s:%d: feature with no geometry: ", jfa->fname.c_str(), jp->line);
json_context(j);
json_free(j);
continue;
}
json_object_ptr properties = json_hash_get(j, "properties");
if (properties == nullptr || (properties->type != JSON_HASH && properties->type != JSON_NULL)) {
fprintf(stderr, "%s:%d: feature without properties hash: ", jfa->fname.c_str(), jp->line);
json_context(j);
json_free(j);
continue;
}
bool is_feature = true;
{
json_object *jo = j.get();
while (jo != nullptr) {
if (jo->parent != nullptr && jo->parent->type == JSON_HASH) {
if (json_hash_get(jo->parent, "properties").get() == jo) {
// Ancestor is the value corresponding to a properties key
is_feature = false;
break;
}
}
jo = jo->parent;
}
}
if (!is_feature) {
continue;
}
json_object_ptr tippecanoe = json_hash_get(j, "tippecanoe");
json_object_ptr id = json_hash_get(j, "id");
json_object_ptr geometries = json_hash_get(geometry, "geometries");
if (geometries != nullptr && geometries->type == JSON_ARRAY) {
jfa->add_feature(geometries, true, properties, id, tippecanoe, j);
} else {
jfa->add_feature(geometry, false, properties, id, tippecanoe, j);
}
json_free(j);
/* XXX check for any non-features in the outer object */
}
}