grpc/tools/buildgen/mako_renderer.py

#!/usr/bin/env python2.7
# Copyright 2015, Google Inc.
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"""Simple Mako renderer.

Just a wrapper around the mako rendering library.

"""

import getopt
import imp
import os
import cPickle as pickle
import shutil
import sys


from mako.lookup import TemplateLookup
from mako.runtime import Context
from mako.template import Template
import bunch
import yaml


# Imports a plugin
def import_plugin(name):
  _, base_ex = os.path.split(name)
  base, _ = os.path.splitext(base_ex)

  with open(name, 'r') as plugin_file:
    plugin_code = plugin_file.read()
  plugin_module = imp.new_module(base)
  exec plugin_code in plugin_module.__dict__
  return plugin_module


def out(msg):
  print >> sys.stderr, msg


def showhelp():
  out('mako-renderer.py [-o out] [-m cache] [-P preprocessed_input] [-d dict] [-d dict...]'
      ' [-t template] [-w preprocessed_output]')


def main(argv):
  got_input = False
  module_directory = None
  preprocessed_output = None
  dictionary = {}
  json_dict = {}
  got_output = False
  plugins = []
  output_name = None
  got_preprocessed_input = False

  try:
    opts, args = getopt.getopt(argv, 'hm:d:o:p:t:P:w:')
  except getopt.GetoptError:
    out('Unknown option')
    showhelp()
    sys.exit(2)

  for opt, arg in opts:
    if opt == '-h':
      out('Displaying showhelp')
      showhelp()
      sys.exit()
    elif opt == '-o':
      if got_output:
        out('Got more than one output')
        showhelp()
        sys.exit(3)
      got_output = True
      output_name = arg
    elif opt == '-m':
      if module_directory is not None:
        out('Got more than one cache directory')
        showhelp()
        sys.exit(4)
      module_directory = arg
    elif opt == '-P':
      assert not got_preprocessed_input
      assert json_dict == {}
      sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(sys.argv[0]), 'plugins')))
      with open(arg, 'r') as dict_file:
        dictionary = pickle.load(dict_file)
      got_preprocessed_input = True
    elif opt == '-d':
      assert not got_preprocessed_input
      with open(arg, 'r') as dict_file:
        bunch.merge_json(json_dict, yaml.load(dict_file.read()))
    elif opt == '-p':
      plugins.append(import_plugin(arg))
    elif opt == '-w':
      preprocessed_output = arg

  if not got_preprocessed_input:
    for plugin in plugins:
      plugin.mako_plugin(json_dict)
    for k, v in json_dict.items():
      dictionary[k] = bunch.to_bunch(v)

  if preprocessed_output:
    with open(preprocessed_output, 'w') as dict_file:
      pickle.dump(dictionary, dict_file)

  cleared_dir = False
  for arg in args:
    got_input = True
    with open(arg) as f:
      srcs = list(yaml.load_all(f.read()))
    for src in srcs:
      if isinstance(src, basestring):
        assert len(srcs) == 1
        template = Template(src,
                            filename=arg,
                            module_directory=module_directory,
                            lookup=TemplateLookup(directories=['.']))
        with open(output_name, 'w') as output_file:
          template.render_context(Context(output_file, **dictionary))
      else:
        # we have optional control data: this template represents
        # a directory
        if not cleared_dir:
          if not os.path.exists(output_name):
            pass
          elif os.path.isfile(output_name):
            os.unlink(output_name)
          else:
            shutil.rmtree(output_name, ignore_errors=True)
          cleared_dir = True
        items = []
        if 'foreach' in src:
          for el in dictionary[src['foreach']]:
            if 'cond' in src:
              args = dict(dictionary)
              args['selected'] = el
              if not eval(src['cond'], {}, args):
                continue
            items.append(el)
          assert items
        else:
          items = [None]
        for item in items:
          args = dict(dictionary)
          args['selected'] = item
          item_output_name = os.path.join(
              output_name, Template(src['output_name']).render(**args))
          if not os.path.exists(os.path.dirname(item_output_name)):
            os.makedirs(os.path.dirname(item_output_name))
          template = Template(src['template'],
                              filename=arg,
                              module_directory=module_directory,
                              lookup=TemplateLookup(directories=['.']))
          with open(item_output_name, 'w') as output_file:
            template.render_context(Context(output_file, **args))

  if not got_input and not preprocessed_output:
    out('Got nothing to do')
    showhelp()

if __name__ == '__main__':
  main(sys.argv[1:])