update.py

#!/usr/bin/env python3

import sys, os
import json
import subprocess
import urllib.request
import hashlib

# Go to the directory this script is stored in
os.chdir(os.path.dirname(os.path.realpath(__file__)))

# Download release data
releases = json.loads(str(urllib.request.urlopen('https://api.github.com/repos/nlohmann/json/releases').read(), 'utf-8'))

# Fetch all releases and the corresponding URL
release_url_map = []
for release in releases:
	for asset in release['assets']:
		if asset['name'] == 'json.hpp':
			release_url_map.append((release['tag_name'], asset['browser_download_url'], release['body']))

# List all git tags
process = subprocess.Popen(['git', 'tag'], stdout=subprocess.PIPE)
tags, _ = process.communicate()
tags = set(filter(None, str(tags, 'utf-8').split("\n")))
print("Releases already contained in this repository are " + str(tags))

# Go over the release_url_map in reverse order; if a release is not yet a Git
# tag, download the file, commit and add a tag
did_update = False
for tag, url, body in release_url_map[::-1]:
	if not tag in tags:
		print("Downloading release " + tag + " from " + url)
		os.makedirs('src', mode=0o777, exist_ok=True)
		data = urllib.request.urlopen(url).read();
		with open('src/json.hpp', 'wb') as f:
			f.write(data)

		# Try to download the json_fwd.hpp header -- only exists since release
		# v3.1.0
		has_json_fwd = False
		try:
			json_fwd_url = 'https://github.com/nlohmann/json/raw/{}/include/nlohmann/json_fwd.hpp'.format(tag);
			print("Trying to download " + json_fwd_url)
			data = urllib.request.urlopen(json_fwd_url).read();
			with open('src/json_fwd.hpp', 'wb') as f:
				f.write(data)
			has_json_fwd = True
		except:
			pass

		subprocess.call(['git', 'add', 'src/json.hpp'])
		if has_json_fwd:
			subprocess.call(['git', 'add', 'src/json_fwd.hpp'])
		subprocess.call(['git', 'commit', '-m', 'Upstream release ' + tag])
		subprocess.call(['git', 'tag', '-a', tag, '-m', body])

		did_update = True

# Push the updated Git repository
if did_update:
	subprocess.call(['git', 'push', '--tags'])
	subprocess.call(['git', 'push'])