node/tools/compress_json.py

34 lines
900 B
Python

#!/usr/bin/env python
import json
import struct
import sys
import zlib
try:
xrange # Python 2
PY2 = True
except NameError:
PY2 = False
xrange = range # Python 3
if __name__ == '__main__':
with open(sys.argv[1]) as fp:
obj = json.load(fp)
text = json.dumps(obj, separators=(',', ':')).encode('utf-8')
data = zlib.compress(text, zlib.Z_BEST_COMPRESSION)
# To make decompression a little easier, we prepend the compressed data
# with the size of the uncompressed data as a 24 bits BE unsigned integer.
assert len(text) < 1 << 24, 'Uncompressed JSON must be < 16 MiB.'
data = struct.pack('>I', len(text))[1:4] + data
step = 20
slices = (data[i:i+step] for i in xrange(0, len(data), step))
slices = [','.join(str(ord(c) if PY2 else c) for c in s) for s in slices]
text = ',\n'.join(slices)
with open(sys.argv[2], 'w') as fp:
fp.write(text)