text: """
      sphinx.environment
      ~~~~~~~~~~~~~~~~~~
  
      Global creation environment.
  
      :copyright: Copyright 2007-2019 by the Sphinx team, see AUTHORS.
      :license: BSD, see LICENSE for details.
  """
  
  import os
  import pickle
  import warnings
  from collections import defaultdict
  from copy import copy
  from os import path
  
  from sphinx import addnodes
  from sphinx.deprecation import RemovedInSphinx40Warning
  from sphinx.environment.adapters.toctree import TocTree
  from sphinx.errors import SphinxError, BuildEnvironmentError, DocumentError, ExtensionError
  from sphinx.locale import __
  from sphinx.transforms import SphinxTransformer
  from sphinx.util import DownloadFiles, FilenameUniqDict
  from sphinx.util import logging
  from sphinx.util.docutils import LoggingReporter
  from sphinx.util.i18n import CatalogRepository, docname_to_domain
  from sphinx.util.nodes import is_translatable
  
  if False:
      # For type annotation
      from typing import Any, Callable, Dict, IO, Iterator, List, Optional, Set, Tuple, Union  # NOQA
      from docutils import nodes  # NOQA
      from sphinx.application import Sphinx  # NOQA
      from sphinx.builders import Builder  # NOQA
      from sphinx.config import Config  # NOQA
      from sphinx.event import EventManager  # NOQA
      from sphinx.domains import Domain  # NOQA
      from sphinx.project import Project  # NOQA
  
  logger = logging.getLogger(__name__)
  
  default_settings = {
      'embed_stylesheet': False,
      'cloak_email_addresses': True,
      'pep_base_url': 'https://www.python.org/dev/peps/',
      'pep_references': None,
      'rfc_base_url': 'https://tools.ietf.org/html/',
      'rfc_references': None,
      'input_encoding': 'utf-8-sig',
      'doctitle_xform': False,
      'sectsubtitle_xform': False,
      'halt_level': 5,
      'file_insertion_enabled': True,
      'smartquotes_locales': [],
  }  # type: Dict[str, Any]
  
  # This is increased every time an environment attribute is added
  # or changed to properly invalidate pickle files.
  ENV_VERSION = 56
  
  # config status
  CONFIG_OK = 1
  CONFIG_NEW = 2
  CONFIG_CHANGED = 3
  CONFIG_EXTENSIONS_CHANGED = 4
  
  CONFIG_CHANGED_REASON = {
      CONFIG_NEW: __('new config'),
      CONFIG_CHANGED: __('config changed'),
      CONFIG_EXTENSIONS_CHANGED: __('extensions changed'),
  }
  
  
  versioning_conditions = {
      'none': False,
      'text': is_translatable,
  }  # type: Dict[str, Union[bool, Callable]]
  
  
  class BuildEnvironment:
      """
      The environment in which the ReST files are translated.
      Stores an inventory of cross-file targets and provides doctree
      transformations to resolve links to them.
      """
  
      domains = None  # type: Dict[str, Domain]
  
      # --------- ENVIRONMENT INITIALIZATION -------------------------------------
  
      def __init__(self, app=None):
          # type: (Sphinx) -> None
          self.app = None             # type: Sphinx
          self.doctreedir = None      # type: str
          self.srcdir = None          # type: str
          self.config = None          # type: Config
          self.config_status = None   # type: int
          self.events = None          # type: EventManager
          self.project = None         # type: Project
          self.version = None         # type: Dict[str, str]
  
          # the method of doctree versioning; see set_versioning_method
          self.versioning_condition = None  # type: Union[bool, Callable]
          self.versioning_compare = None  # type: bool
  
          # all the registered domains, set by the application
          self.domains = {}
  
          # the docutils settings for building
          self.settings = default_settings.copy()
          self.settings['env'] = self
  
          # All "docnames" here are /-separated and relative and exclude
          # the source suffix.
  
          self.all_docs = {}          # type: Dict[str, float]
                                      # docname -> mtime at the time of reading
                                      # contains all read docnames
          self.dependencies = defaultdict(set)    # type: Dict[str, Set[str]]
                                      # docname -> set of dependent file
                                      # names, relative to documentation root
          self.included = defaultdict(set)        # type: Dict[str, Set[str]]
                                      # docname -> set of included file
                                      # docnames included from other documents
          self.reread_always = set()  # type: Set[str]
                                      # docnames to re-read unconditionally on
                                      # next build
  
          # File metadata
          self.metadata = defaultdict(dict)       # type: Dict[str, Dict[str, Any]]
                                                  # docname -> dict of metadata items
  
          # TOC inventory
          self.titles = {}            # type: Dict[str, nodes.title]
                                      # docname -> title node
          self.longtitles = {}        # type: Dict[str, nodes.title]
                                      # docname -> title node; only different if
                                      # set differently with title directive
          self.tocs = {}              # type: Dict[str, nodes.bullet_list]
                                      # docname -> table of contents nodetree
          self.toc_num_entries = {}   # type: Dict[str, int]
                                      # docname -> number of real entries
  
          # used to determine when to show the TOC
          # in a sidebar (don't show if it's only one item)
          self.toc_secnumbers = {}    # type: Dict[str, Dict[str, Tuple[int, ...]]]
                                      # docname -> dict of sectionid -> number
          self.toc_fignumbers = {}    # type: Dict[str, Dict[str, Dict[str, Tuple[int, ...]]]]
                                      # docname -> dict of figtype ->
                                      # dict of figureid -> number
  
          self.toctree_includes = {}  # type: Dict[str, List[str]]
                                      # docname -> list of toctree includefiles
          self.files_to_rebuild = {}  # type: Dict[str, Set[str]]
                                      # docname -> set of files
                                      # (containing its TOCs) to rebuild too
          self.glob_toctrees = set()  # type: Set[str]
                                      # docnames that have :glob: toctrees
          self.numbered_toctrees = set()  # type: Set[str]
                                          # docnames that have :numbered: toctrees
  
          # domain-specific inventories, here to be pickled
          self.domaindata = {}        # type: Dict[str, Dict]
                                      # domainname -> domain-specific dict
  
          # Other inventories
          self.indexentries = {}      # type: Dict[str, List[Tuple[str, str, str, str, str]]]
                                      # docname -> list of
                                      # (type, str, target, aliasname)
  
          # these map absolute path -> (docnames, unique filename)
          self.images = FilenameUniqDict()    # type: FilenameUniqDict
          self.dlfiles = DownloadFiles()      # type: DownloadFiles
                                              # filename -> (set of docnames, destination)
  
          # the original URI for images
          self.original_image_uri = {}  # type: Dict[str, str]
  
          # temporary data storage while reading a document
          self.temp_data = {}         # type: Dict[str, Any]
          # context for cross-references (e.g. current module or class)
          # this is similar to temp_data, but will for example be copied to
          # attributes of "any" cross references
          self.ref_context = {}       # type: Dict[str, Any]
  
          # set up environment
          if app:
              self.setup(app)
  
      def __getstate__(self):
          # type: () -> Dict
          """Obtains serializable data for pickling."""
          __dict__ = self.__dict__.copy()
          __dict__.update(app=None, domains={}, events=None)  # clear unpickable attributes
          return __dict__
  
      def __setstate__(self, state):
          # type: (Dict) -> None
          self.__dict__.update(state)
  
      def setup(self, app):
          # type: (Sphinx) -> None
          """Set up BuildEnvironment object."""
          if self.version and self.version != app.registry.get_envversion(app):
              raise BuildEnvironmentError(__('build environment version not current'))
          elif self.srcdir and self.srcdir != app.srcdir:
              raise BuildEnvironmentError(__('source directory has changed'))
  
          if self.project:
              app.project.restore(self.project)
  
          self.app = app
          self.doctreedir = app.doctreedir
          self.events = app.events
          self.srcdir = app.srcdir
          self.project = app.project
          self.version = app.registry.get_envversion(app)
  
          # initialize domains
          self.domains = {}
          for domain in app.registry.create_domains(self):
              self.domains[domain.name] = domain
  
          # initialize config
          self._update_config(app.config)
  
          # initialie settings
          self._update_settings(app.config)
  
      def _update_config(self, config):
          # type: (Config) -> None
          """Update configurations by new one."""
          self.config_status = CONFIG_OK
          if self.config is None:
              self.config_status = CONFIG_NEW
          elif self.config.extensions != config.extensions:
              self.config_status = CONFIG_EXTENSIONS_CHANGED
          else:
              # check if a config value was changed that affects how
              # doctrees are read
              for item in config.filter('env'):
                  if self.config[item.name] != item.value:
                      self.config_status = CONFIG_CHANGED
                      break
  
          self.config = config
  
      def _update_settings(self, config):
          # type: (Config) -> None
          """Update settings by new config."""
          self.settings['input_encoding'] = config.source_encoding
          self.settings['trim_footnote_reference_space'] = config.trim_footnote_reference_space
          self.settings['language_code'] = config.language or 'en'
  
          # Allow to disable by 3rd party extension (workaround)
          self.settings.setdefault('smart_quotes', True)
  
      def set_versioning_method(self, method, compare):
          # type: (Union[str, Callable], bool) -> None
          """This sets the doctree versioning method for this environment.
  
          Versioning methods are a builder property; only builders with the same
          versioning method can share the same doctree directory.  Therefore, we
          raise an exception if the user tries to use an environment with an
          incompatible versioning method.
          """
          condition = None  # type: Union[bool, Callable]
          if callable(method):
              condition = method
          else:
              if method not in versioning_conditions:
                  raise ValueError('invalid versioning method: %r' % method)
              condition = versioning_conditions[method]
  
          if self.versioning_condition not in (None, condition):
              raise SphinxError(__('This environment is incompatible with the '
                                   'selected builder, please choose another '
                                   'doctree directory.'))
          self.versioning_condition = condition
          self.versioning_compare = compare
  
      def clear_doc(self, docname):
          # type: (str) -> None
          """Remove all traces of a source file in the inventory."""
          if docname in self.all_docs:
              self.all_docs.pop(docname, None)
              self.included.pop(docname, None)
              self.reread_always.discard(docname)
  
          for domain in self.domains.values():
              domain.clear_doc(docname)
  
      def merge_info_from(self, docnames, other, app):
          # type: (List[str], BuildEnvironment, Sphinx) -> None
          """Merge global information gathered about *docnames* while reading them
          from the *other* environment.
  
          This possibly comes from a parallel build process.
          """
          docnames = set(docnames)  # type: ignore
          for docname in docnames:
              self.all_docs[docname] = other.all_docs[docname]
              self.included[docname] = other.included[docname]
              if docname in other.reread_always:
                  self.reread_always.add(docname)
  
          for domainname, domain in self.domains.items():
              domain.merge_domaindata(docnames, other.domaindata[domainname])
          self.events.emit('env-merge-info', self, docnames, other)
  
      def path2doc(self, filename):
          # type: (str) -> Optional[str]
          """Return the docname for the filename if the file is document.
  
          *filename* should be absolute or relative to the source directory.
          """
          return self.project.path2doc(filename)
  
      def doc2path(self, docname, base=True, suffix=None):
          # type: (str, Union[bool, str], str) -> str
          """Return the filename for the document name.
  
          If *base* is True, return absolute path under self.srcdir.
          If *base* is None, return relative path to self.srcdir.
          If *base* is a path string, return absolute path under that.
          If *suffix* is not None, add it instead of config.source_suffix.
          """
          if suffix:
              warnings.warn('The suffix argument for doc2path() is deprecated.',
                            RemovedInSphinx40Warning)
          if base not in (True, None):
              warnings.warn('The string style base argument for doc2path() is deprecated.',
                            RemovedInSphinx40Warning)
  
          pathname = self.project.doc2path(docname, base is True)
          if suffix:
              filename, _ = path.splitext(pathname)
              pathname = filename + suffix
          if base and base is not True:
              pathname = path.join(base, pathname)  # type: ignore
          return pathname
  
      def relfn2path(self, filename, docname=None):
          # type: (str, str) -> Tuple[str, str]
          """Return paths to a file referenced from a document, relative to
          documentation root and absolute.
  
          In the input "filename", absolute filenames are taken as relative to the
          source dir, while relative filenames are relative to the dir of the
          containing document.
          """
          if filename.startswith('/') or filename.startswith(os.sep):
              rel_fn = filename[1:]
          else:
              docdir = path.dirname(self.doc2path(docname or self.docname,
                                                  base=None))
              rel_fn = path.join(docdir, filename)
          # the path.abspath() might seem redundant, but otherwise artifacts
          # such as ".." will remain in the path
          return rel_fn, path.abspath(path.join(self.srcdir, rel_fn))
  
      @property
      def found_docs(self):
          # type: () -> Set[str]
          """contains all existing docnames."""
          return self.project.docnames
  
      def find_files(self, config, builder):
          # type: (Config, Builder) -> None
          """Find all source files in the source dir and put them in
          self.found_docs.
          """
          try:
              exclude_paths = (self.config.exclude_patterns +
                               self.config.templates_path +
                               builder.get_asset_paths())
              self.project.discover(exclude_paths)
  
              # Current implementation is applying translated messages in the reading
              # phase.Therefore, in order to apply the updated message catalog, it is
              # necessary to re-process from the reading phase. Here, if dependency
              # is set for the doc source and the mo file, it is processed again from
              # the reading phase when mo is updated. In the future, we would like to
              # move i18n process into the writing phase, and remove these lines.
              if builder.use_message_catalog:
                  # add catalog mo file dependency
                  repo = CatalogRepository(self.srcdir, self.config.locale_dirs,
                                           self.config.language, self.config.source_encoding)
                  for docname in self.found_docs:
                      domain = docname_to_domain(docname, self.config.gettext_compact)
                      for catalog in repo.catalogs:
                          if catalog.domain == domain:
                              self.dependencies[docname].add(catalog.mo_path)
          except OSError as exc:
              raise DocumentError(__('Failed to scan documents in %s: %r') % (self.srcdir, exc))
  
      def get_outdated_files(self, config_changed):
          # type: (bool) -> Tuple[Set[str], Set[str], Set[str]]
          """Return (added, changed, removed) sets."""
          # clear all files no longer present
          removed = set(self.all_docs) - self.found_docs
  
          added = set()  # type: Set[str]
          changed = set()  # type: Set[str]
  
          if config_changed:
              # config values affect e.g. substitutions
              added = self.found_docs
          else:
              for docname in self.found_docs:
                  if docname not in self.all_docs:
                      added.add(docname)
                      continue
                  # if the doctree file is not there, rebuild
                  filename = path.join(self.doctreedir, docname + '.doctree')
                  if not path.isfile(filename):
                      changed.add(docname)
                      continue
                  # check the "reread always" list
                  if docname in self.reread_always:
                      changed.add(docname)
                      continue
                  # check the mtime of the document
                  mtime = self.all_docs[docname]
                  newmtime = path.getmtime(self.doc2path(docname))
                  if newmtime > mtime:
                      changed.add(docname)
                      continue
                  # finally, check the mtime of dependencies
                  for dep in self.dependencies[docname]:
                      try:
                          # this will do the right thing when dep is absolute too
                          deppath = path.join(self.srcdir, dep)
                          if not path.isfile(deppath):
                              changed.add(docname)
                              break
                          depmtime = path.getmtime(deppath)
                          if depmtime > mtime:
                              changed.add(docname)
                              break
                      except OSError:
                          # give it another chance
                          changed.add(docname)
                          break
  
          return added, changed, removed
  
      def check_dependents(self, app, already):
          # type: (Sphinx, Set[str]) -> Iterator[str]
          to_rewrite = []  # type: List[str]
          for docnames in self.events.emit('env-get-updated', self):
              to_rewrite.extend(docnames)
          for docname in set(to_rewrite):
              if docname not in already:
                  yield docname
  
      # --------- SINGLE FILE READING --------------------------------------------
  
      def prepare_settings(self, docname):
          # type: (str) -> None
          """Prepare to set up environment for reading."""
          self.temp_data['docname'] = docname
          # defaults to the global default, but can be re-set in a document
          self.temp_data['default_role'] = self.config.default_role
          self.temp_data['default_domain'] = \
              self.domains.get(self.config.primary_domain)
  
      # utilities to use while reading a document
  
      @property
      def docname(self):
          # type: () -> str
          """Returns the docname of the document currently being parsed."""
          return self.temp_data['docname']
  
      def new_serialno(self, category=''):
          # type: (str) -> int
          """Return a serial number, e.g. for index entry targets.
  
          The number is guaranteed to be unique in the current document.
          """
          key = category + 'serialno'
          cur = self.temp_data.get(key, 0)
          self.temp_data[key] = cur + 1
          return cur
  
      def note_dependency(self, filename):
          # type: (str) -> None
          """Add *filename* as a dependency of the current document.
  
          This means that the document will be rebuilt if this file changes.
  
          *filename* should be absolute or relative to the source directory.
          """
          self.dependencies[self.docname].add(filename)
  
      def note_included(self, filename):
          # type: (str) -> None
          """Add *filename* as a included from other document.
  
          This means the document is not orphaned.
  
          *filename* should be absolute or relative to the source directory.
          """
          self.included[self.docname].add(self.path2doc(filename))
  
      def note_reread(self):
          # type: () -> None
          """Add the current document to the list of documents that will
          automatically be re-read at the next build.
          """
          self.reread_always.add(self.docname)
  
      def get_domain(self, domainname):
          # type: (str) -> Domain
          """Return the domain instance with the specified name.
  
          Raises an ExtensionError if the domain is not registered.
          """
          try:
              return self.domains[domainname]
          except KeyError:
              raise ExtensionError(__('Domain %r is not registered') % domainname)
  
      # --------- RESOLVING REFERENCES AND TOCTREES ------------------------------
  
      def get_doctree(self, docname):
          # type: (str) -> nodes.document
          """Read the doctree for a file from the pickle and return it."""
          filename = path.join(self.doctreedir, docname + '.doctree')
          with open(filename, 'rb') as f:
              doctree = pickle.load(f)
          doctree.settings.env = self
          doctree.reporter = LoggingReporter(self.doc2path(docname))
          return doctree
  
      def get_and_resolve_doctree(self, docname, builder, doctree=None,
                                  prune_toctrees=True, includehidden=False):
          # type: (str, Builder, nodes.document, bool, bool) -> nodes.document
          """Read the doctree from the pickle, resolve cross-references and
          toctrees and return it.
          """
          if doctree is None:
              doctree = self.get_doctree(docname)
  
          # resolve all pending cross-references
          self.apply_post_transforms(doctree, docname)
  
          # now, resolve all toctree nodes
          for toctreenode in doctree.traverse(addnodes.toctree):
              result = TocTree(self).resolve(docname, builder, toctreenode,
                                             prune=prune_toctrees,
                                             includehidden=includehidden)
              if result is None:
                  toctreenode.replace_self([])
              else:
                  toctreenode.replace_self(result)
  
          return doctree
  
      def resolve_toctree(self, docname, builder, toctree, prune=True, maxdepth=0,
                          titles_only=False, collapse=False, includehidden=False):
          # type: (str, Builder, addnodes.toctree, bool, int, bool, bool, bool) -> nodes.Node
          """Resolve a *toctree* node into individual bullet lists with titles
          as items, returning None (if no containing titles are found) or
          a new node.
  
          If *prune* is True, the tree is pruned to *maxdepth*, or if that is 0,
          to the value of the *maxdepth* option on the *toctree* node.
          If *titles_only* is True, only toplevel document titles will be in the
          resulting tree.
          If *collapse* is True, all branches not containing docname will
          be collapsed.
          """
          return TocTree(self).resolve(docname, builder, toctree, prune,
                                       maxdepth, titles_only, collapse,
                                       includehidden)
  
      def resolve_references(self, doctree, fromdocname, builder):
          # type: (nodes.document, str, Builder) -> None
          self.apply_post_transforms(doctree, fromdocname)
  
      def apply_post_transforms(self, doctree, docname):
          # type: (nodes.document, str) -> None
          """Apply all post-transforms."""
          try:
              # set env.docname during applying post-transforms
              backup = copy(self.temp_data)
              self.temp_data['docname'] = docname
  
              transformer = SphinxTransformer(doctree)
              transformer.set_environment(self)
              transformer.add_transforms(self.app.registry.get_post_transforms())
              transformer.apply_transforms()
          finally:
              self.temp_data = backup
  
          # allow custom references to be resolved
          self.events.emit('doctree-resolved', doctree, docname)
  
      def collect_relations(self):
          # type: () -> Dict[str, List[str]]
          traversed = set()
  
          def traverse_toctree(parent, docname):
              # type: (str, str) -> Iterator[Tuple[str, str]]
              if parent == docname:
                  logger.warning(__('self referenced toctree found. Ignored.'), location=docname)
                  return
  
              # traverse toctree by pre-order
              yield parent, docname
              traversed.add(docname)
  
              for child in (self.toctree_includes.get(docname) or []):
                  for subparent, subdocname in traverse_toctree(docname, child):
                      if subdocname not in traversed:
                          yield subparent, subdocname
                          traversed.add(subdocname)
  
          relations = {}
          docnames = traverse_toctree(None, self.config.master_doc)
          prevdoc = None
          parent, docname = next(docnames)
          for nextparent, nextdoc in docnames:
              relations[docname] = [parent, prevdoc, nextdoc]
              prevdoc = docname
              docname = nextdoc
              parent = nextparent
  
          relations[docname] = [parent, prevdoc, None]
  
          return relations
  
      def check_consistency(self):
          # type: () -> None
          """Do consistency checks."""
          included = set().union(*self.included.values())  # type: ignore
          for docname in sorted(self.all_docs):
              if docname not in self.files_to_rebuild:
                  if docname == self.config.master_doc:
                      # the master file is not included anywhere ;)
                      continue
                  if docname in included:
                      # the document is included from other documents
                      continue
                  if 'orphan' in self.metadata[docname]:
                      continue
                  logger.warning(__('document isn\'t included in any toctree'),
                                 location=docname)
  
          # call check-consistency for all extensions
          for domain in self.domains.values():
              domain.check_consistency()
          self.events.emit('env-check-consistency', self)
  