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, 6 insertions, 1 deletions

diff --git a/include/qpdf/JSON.hh b/include/qpdf/JSON.hh
index a1a61ee4..fdacd442 100644
--- a/include/qpdf/JSON.hh
+++ b/include/qpdf/JSON.hh
@@ -92,6 +92,11 @@ class JSON
         std::string const& key,
         JSON const& value,
         size_t depth = 0);
+    // Write just the key of a new dictionary item, useful if writing
+    // nested structures. Calls writeNext.
+    QPDF_DLL
+    static void writeDictionaryKey(
+        Pipeline* p, bool& first, std::string const& key, size_t depth = 0);
     QPDF_DLL
     static void writeArrayItem(
         Pipeline*, bool& first, JSON const& element, size_t depth = 0);
@@ -101,7 +106,7 @@ class JSON
     // for the parent object. Then start a new first for the nested
     // item.
     QPDF_DLL
-    static void writeNext(Pipeline* p, bool& first, size_t depth);
+    static void writeNext(Pipeline* p, bool& first, size_t depth = 0);
 
     // The JSON spec calls dictionaries "objects", but that creates
     // too much confusion when referring to instances of the JSON