Rename third_party/webpagereplay to third_party/web-page-replay

telemetry/third_party/webpagereplay/rules_parser.py

-# Copyright 2015 Google Inc. All Rights Reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-r"""Rules parser.
-
-The input syntax is:
-  [{"comment": ignored_value},
-   {"rule_class_name1": {"arg1": value, "arg2": value, ...}},
-   {"rule_class_name2": {"arg1": value, "arg2": value, ...}},
-   ...]
-E.g.:
-  [{"comment": "this text is ignored"},
-   {"SendStatus": {"url": "example\\.com/ss.*", "status": 204}},
-   {"ModifyUrl": {"url": "(example\\.com)(/.*)", "new_url": "{1}"}}
-  ]
-"""
-
-import json
-import re
-
-
-class Error(Exception):
-  pass
-
-
-class Rules(object):
-
-  """A parsed sequence of Rule objects."""
-
-  def __init__(self, file_obj=None, allowed_imports=None):
-    """Initializes from the given file object.
-
-    Args:
-      file_obj: A file object.
-      allowed_imports: A set of strings, defaults to {'rules'}.
-        Use {'*'} to allow any import path.
-    """
-    if allowed_imports is None:
-      allowed_imports = {'rules'}
-    self._rules = [] if file_obj is None else _Load(file_obj, allowed_imports)
-
-  def Contains(self, rule_type_name):
-    """Returns true if any rule matches the given type name.
-
-    Args:
-      rule_type_name: a string.
-    Returns:
-      True if any rule matches, else False.
-    """
-    return any(rule for rule in self._rules if rule.IsType(rule_type_name))
-
-  def Find(self, rule_type_name):
-    """Returns a _Rule object containing all rules with the given type name.
-
-    Args:
-      rule_type_name: a string.
-    Returns:
-      A callable object that expects two arguments:
-        request: the httparchive ArchivedHttpRequest
-        response: the httparchive ArchivedHttpResponse
-      and returns the rule return_value of the first rule that returns
-      should_stop == True, or the last rule's return_value if all rules returns
-      should_stop == False.
-    """
-    matches = [rule for rule in self._rules if rule.IsType(rule_type_name)]
-    return _Rule(matches)
-
-  def __str__(self):
-    return _ToString(self._rules)
-
-  def __repr__(self):
-    return str(self)
-
-
-class _Rule(object):
-  """Calls a sequence of Rule objects until one returns should_stop."""
-
-  def __init__(self, rules):
-    self._rules = rules
-
-  def __call__(self, request, response):
-    """Calls the rules until one returns should_stop.
-
-    Args:
-      request: the httparchive ArchivedHttpRequest.
-      response: the httparchive ArchivedHttpResponse, which may be None.
-    Returns:
-      The rule return_value of the first rule that returns should_stop == True,
-      or the last rule's return_value if all rules return should_stop == False.
-    """
-    return_value = None
-    for rule in self._rules:
-      should_stop, return_value = rule.ApplyRule(
-          return_value, request, response)
-      if should_stop:
-        break
-    return return_value
-
-  def __str__(self):
-    return _ToString(self._rules)
-
-  def __repr__(self):
-    return str(self)
-
-
-def _ToString(rules):
-  """Formats a sequence of Rule objects into a string."""
-  return '[\n%s\n]' % '\n'.join('%s' % rule for rule in rules)
-
-
-def _Load(file_obj, allowed_imports):
-  """Parses and evaluates all rules in the given file.
-
-  Args:
-    file_obj: a file object.
-    allowed_imports: a sequence of strings, e.g.: {'rules'}.
-  Returns:
-    a list of rules.
-  """
-  rules = []
-  entries = json.load(file_obj)
-  if not isinstance(entries, list):
-    raise Error('Expecting a list, not %s', type(entries))
-  for i, entry in enumerate(entries):
-    if not isinstance(entry, dict):
-      raise Error('%s: Expecting a dict, not %s', i, type(entry))
-    if len(entry) != 1:
-      raise Error('%s: Expecting 1 item, not %d', i, len(entry))
-    name, args = next(entry.iteritems())
-    if not isinstance(name, basestring):
-      raise Error('%s: Expecting a string TYPE, not %s', i, type(name))
-    if not re.match(r'(\w+\.)*\w+$', name):
-      raise Error('%s: Expecting a classname TYPE, not %s', i, name)
-    if name == 'comment':
-      continue
-    if not isinstance(args, dict):
-      raise Error('%s: Expecting a dict ARGS, not %s', i, type(args))
-    fullname = str(name)
-    if '.' not in fullname:
-      fullname = 'rules.%s' % fullname
-
-    modulename, classname = fullname.rsplit('.', 1)
-    if '*' not in allowed_imports and modulename not in allowed_imports:
-      raise Error('%s: Package %r is not in allowed_imports', i, modulename)
-
-    module = __import__(modulename, fromlist=[classname])
-    clazz = getattr(module, classname)
-
-    missing = {s for s in ('IsType', 'ApplyRule') if not hasattr(clazz, s)}
-    if missing:
-      raise Error('%s: %s lacks %s', i, clazz.__name__, ' and '.join(missing))
-
-    rule = clazz(**args)
-
-    rules.append(rule)
-  return rules