OpenSystemsDevelopment / qpdf

This script was used on 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 'objectinfo' not in data:
        continue
    trailer = None
    to_sort = []
    for k, v in data['objectinfo'].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])
    newobjectinfo = {x[1]: x[2] for x in sorted(to_sort)}
    if trailer is not None:
        newobjectinfo['trailer'] = trailer
    data['objectinfo'] = newobjectinfo
print(json_dumps(data))
----------

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))
----------

This commit just changes the order in which fields are written to the
json without changing their content. All the json files in the test
suite were modified with this script to ensure that we didn't get any
changes other than ordering.

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

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())
    newdata = {}
    for i in ('version', 'parameters', 'pages', 'pagelabels',
              'acroform', 'attachments', 'encrypt', 'outlines',
              'objects', 'objectinfo'):
        if i in data:
            newdata[i] = data[i]
print(json_dumps(newdata))
----------

Testing json against schema requires an in-memory copy, so do it only
when requested by the test suite.

We used to have to do that, but for quite some time, the code that
gets images has no longer required it.

Prevent my future self or other contributors from using assert in
tests and then having that assert not do anything because of the
NDEBUG macro.

Bidirectional base64; will be used by JSON v2.