Shell interface to Closure compiler (in Python)

js-compile.py

#!/usr/bin/env python

import json
import sys

try: # Py3
  from urllib.parse import urlencode
  from urllib.request import urlopen
  from urllib.request import Request
except ImportError: # Py2
  from urllib import urlencode
  from urllib2 import urlopen
  from urllib2 import Request


URL = 'https://closure-compiler.appspot.com/compile'


def main():
  import argparse
  parser = argparse.ArgumentParser()
  parser.add_argument('files', type=str, nargs='+',
                      help='.js files to cat and compile together')
  parser.add_argument('--advanced', '-a', action='store_true',
                      help='whether to use advanced compilation')
  parser.add_argument('--strict', '-s', action='store_true',
                      help='whether to run in strict mode')
  parser.add_argument('--closure', '-c', action='store_true',
                      help='whether to include closure library')
  parser.add_argument('--externs', '-e', type=str, nargs='*',
                      default=[], help='externs .js files')
  parser.add_argument('--ignore', '-i', type=str, action='append',
                      help='warning/error to ignore')
  parser.add_argument('--exports', '-x', action='store_true',
                      help='whether to generate exports')
  parser.add_argument('--named', '-n', action='store_true',
                      help='send named files to compiler')
  args = parser.parse_args()

  # Read content of all files.
  def read(path):
    with open(path) as f:
      return f.read()
  content = [(x, read(x)) for x in args.files]
  externs = [read(x) for x in args.externs]

  # Build CompilerOptions, for compile() call.
  options = CompilerOptions()
  options.advancedLevel = args.advanced
  options.closureLibrary = args.closure
  options.strictMode = args.strict
  options.generateExports = args.exports
  options.namedFiles = args.named

  # Run compile step, and render output code!
  out = compile(content, externs, options)
  if 'compiledCode' in out:
    print(out['compiledCode'])

  # Render each valid response message to stderr.
  modes = (('errors', bcolors.FAIL), ('warnings', bcolors.WARNING))
  for category, color in modes:
    for msg in out.get(category, []):
      if msg['file']:
        msg['file'] = filepath(args.files, msg['file'])

      if args.ignore and msg['type'] in args.ignore:
        continue

      writemsg(sys.stderr, msg, color)

  # Look for server errors.
  if 'serverErrors' in out:
    # TODO: Format this so it doesn't look like Java has failed locally (!).
    for err in out['serverErrors']:
      sys.stderr.write(err['error'])

  # Return non-zero only if there is no code.
  if 'compiledCode' not in out:
    sys.exit(1)


class bcolors:
  HEADER = '\033[95m'
  OKBLUE = '\033[94m'
  OKGREEN = '\033[92m'
  WARNING = '\033[93m'
  FAIL = '\033[91m'
  ENDC = '\033[0m'


def writemsg(out, msg, color=bcolors.WARNING):
  if not msg['file'] and msg['lineno'] < 0:
    out.write('{}\n'.format(msg['type']))
  else:
    out.write('{}:{} ({})\n'.format(msg['file'], msg['lineno'], msg['type']))
  if 'warning' in msg:
    out.write('{}\n'.format(msg['warning']))
  if 'error' in msg:
    out.write('{}\n'.format(msg['error']))
  if msg['line']:
    out.write('{}{}\n'.format(color, msg['line']))
    out.write('{}{}^\n'.format(bcolors.OKGREEN, msg['charno'] * ' '))
  out.write('{}\n'.format(bcolors.ENDC))
  out.flush()


def filepath(files, response):
  """Finds the filepath from an array of files and a response.
  
  Args:
    files: contains a list of paths
    response: contains either 'Input_<n>' or other text

  Returns: name of file
  """
  if not response:
    return ''
  PREFIX = 'Input_'
  if response.startswith(PREFIX):
    index = int(response[len(PREFIX):])
    return files[index]
  return response


class CompilerOptions:
  language = 6
  languageOut = 5
  advancedLevel = False
  closureLibrary = False
  strictMode = False
  generateExports = False
  namedFiles = False


def compile(content, externs, options):
  level = (options.advancedLevel and 'ADVANCED' or 'SIMPLE') + '_OPTIMIZATIONS'
  params = [
    ('compilation_level', level),
    ('output_format', 'json'),
    ('output_info', 'compiled_code'),
    ('output_info', 'warnings'),
    ('output_info', 'errors'),
    ('warning_level', 'verbose'),
    ('generate_exports', options.generateExports),
    ('use_closure_library', options.closureLibrary and 'true' or 'false'),
  ]
  for name, data in content:
    if options.namedFiles and len(name):
      params.append(('js_code:' + name, data))
    else:
      params.append(('js_code', data))

  for key, lang in [('language', options.language), ('language_out', options.languageOut)]:
    s = 'ES{}'.format(lang)
    if options.strictMode:
      s += '_STRICT'
    params.append((key, s))

  if externs:
    externs = '\n'.join(externs)
    params.append(('js_externs', externs))

  request = Request(URL)
  request.add_header('Content-Type',
                     'application/x-www-form-urlencoded;charset=utf-8')

  data = urlencode(params).encode('utf-8')
  response = urlopen(request, data)
  if response.getcode() != 200:
    raise Exception('response status was: ' + response.status)
  raw = response.read().decode('utf-8')
  return json.loads(raw)


if __name__ == '__main__':
  main()