Objects json: write incrementally and in numeric order

The following script was used to adjust test data:

----------
#!/usr/bin/env python3
import json
import sys
import re

def json_dumps(data):
    return json.dumps(data, ensure_ascii=False,
                      indent=2, separators=(',', ': '))

for filename in sys.argv[1:]:
    with open(filename, 'r') as f:
        data = json.loads(f.read())
    if 'objects' not in data:
        continue
    trailer = None
    to_sort = []
    for k, v in data['objects'].items():
        if k == 'trailer':
            trailer = v
        else:
            m = re.match(r'^(\d+) \d+ R', k)
            if m:
                to_sort.append([int(m.group(1)), k, v])
    newobjects = {x[1]: x[2] for x in sorted(to_sort)}
    if trailer is not None:
        newobjects['trailer'] = trailer
    data['objects'] = newobjects
print(json_dumps(data))
----------

1 files changed, 11 insertions, 9 deletions

diff --git a/libqpdf/QPDFJob.cc b/libqpdf/QPDFJob.cc
index 5621ef5e..63fa0c34 100644
--- a/libqpdf/QPDFJob.cc
+++ b/libqpdf/QPDFJob.cc
@@ -1044,20 +1044,23 @@ QPDFJob::getWantedJSONObjects()
 void
 QPDFJob::doJSONObjects(Pipeline* p, bool& first, QPDF& pdf)
 {
+    JSON::writeDictionaryKey(p, first, "objects", 0);
+    bool first_object = true;
+    JSON::writeDictionaryOpen(p, first_object, 1);
     bool all_objects = m->json_objects.empty();
     std::set<QPDFObjGen> wanted_og = getWantedJSONObjects();
-    JSON j_objects = JSON::makeDictionary();
-    if (all_objects || m->json_objects.count("trailer")) {
-        j_objects.addDictionaryMember(
-            "trailer", pdf.getTrailer().getJSON(true));
-    }
     std::vector<QPDFObjectHandle> objects = pdf.getAllObjects();
     for (auto& obj: objects) {
         if (all_objects || wanted_og.count(obj.getObjGen())) {
-            j_objects.addDictionaryMember(obj.unparse(), obj.getJSON(true));
+            JSON::writeDictionaryItem(
+                p, first_object, obj.unparse(), obj.getJSON(true), 1);
         }
     }
-    JSON::writeDictionaryItem(p, first, "objects", j_objects, 0);
+    if (all_objects || m->json_objects.count("trailer")) {
+        JSON::writeDictionaryItem(
+            p, first_object, "trailer", pdf.getTrailer().getJSON(true), 1);
+    }
+    JSON::writeDictionaryClose(p, first_object, 1);
 }
 
 void
@@ -1090,8 +1093,7 @@ QPDFJob::doJSONObjectinfo(Pipeline* p, bool& first, QPDF& pdf)
 void
 QPDFJob::doJSONPages(Pipeline* p, bool& first, QPDF& pdf)
 {
-    JSON::writeNext(p, first, 0);
-    *p << "\"pages\": ";
+    JSON::writeDictionaryKey(p, first, "pages", 0);
     bool first_page = true;
     JSON::writeArrayOpen(p, first_page, 1);
     QPDFPageDocumentHelper pdh(pdf);