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# Source code for sphinx.environment

    # -*- coding: utf-8 -*-
    """
        sphinx.environment
        ~~~~~~~~~~~~~~~~~~

        Global creation environment.

        :copyright: Copyright 2007-2016 by the Sphinx team, see AUTHORS.
        :license: BSD, see LICENSE for details.
    """

    import re
    import os
    import sys
    import time
    import types
    import bisect
    import codecs
    import string
    import unicodedata
    from os import path
    from glob import glob
    from itertools import groupby

    from six import iteritems, itervalues, text_type, class_types, next
    from six.moves import cPickle as pickle
    from docutils import nodes
    from docutils.io import NullOutput
    from docutils.core import Publisher
    from docutils.utils import Reporter, relative_path, get_source_line
    from docutils.parsers.rst import roles, directives
    from docutils.parsers.rst.languages import en as english
    from docutils.parsers.rst.directives.html import MetaBody
    from docutils.frontend import OptionParser

    from sphinx import addnodes
    from sphinx.io import SphinxStandaloneReader, SphinxDummyWriter, SphinxFileInput
    from sphinx.util import url_re, get_matching_docs, docname_join, split_into, \
        FilenameUniqDict, split_index_msg
    from sphinx.util.nodes import clean_astext, make_refnode, WarningStream, is_translatable
    from sphinx.util.osutil import SEP, getcwd, fs_encoding, ensuredir
    from sphinx.util.images import guess_mimetype
    from sphinx.util.i18n import find_catalog_files, get_image_filename_for_language, \
        search_image_for_language
    from sphinx.util.console import bold, purple
    from sphinx.util.matching import compile_matchers
    from sphinx.util.parallel import ParallelTasks, parallel_available, make_chunks
    from sphinx.util.websupport import is_commentable
    from sphinx.errors import SphinxError, ExtensionError
    from sphinx.locale import _
    from sphinx.versioning import add_uids, merge_doctrees
    from sphinx.transforms import SphinxContentsFilter

    orig_role_function = roles.role
    orig_directive_function = directives.directive

    class ElementLookupError(Exception):
        pass

    default_settings = {
        'embed_stylesheet': False,
        'cloak_email_addresses': True,
        'pep_base_url': 'https://www.python.org/dev/peps/',
        'rfc_base_url': 'https://tools.ietf.org/html/',
        'input_encoding': 'utf-8-sig',
        'doctitle_xform': False,
        'sectsubtitle_xform': False,
        'halt_level': 5,
        'file_insertion_enabled': True,
    }

    # This is increased every time an environment attribute is added
    # or changed to properly invalidate pickle files.
    #
    # NOTE: increase base version by 2 to have distinct numbers for Py2 and 3
    ENV_VERSION = 47 + (sys.version_info[0] - 2)

    dummy_reporter = Reporter('', 4, 4)

    versioning_conditions = {
        'none': False,
        'text': is_translatable,
        'commentable': is_commentable,
    }

    class NoUri(Exception):
        """Raised by get_relative_uri if there is no URI available."""
        pass

    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.
        """

        # --------- ENVIRONMENT PERSISTENCE ----------------------------------------

        @staticmethod
        def frompickle(srcdir, config, filename):
            picklefile = open(filename, 'rb')
            try:
                env = pickle.load(picklefile)
            finally:
                picklefile.close()
            if env.version != ENV_VERSION:
                raise IOError('build environment version not current')
            if env.srcdir != srcdir:
                raise IOError('source directory has changed')
            env.config.values = config.values
            return env

        def topickle(self, filename):
            # remove unpicklable attributes
            warnfunc = self._warnfunc
            self.set_warnfunc(None)
            values = self.config.values
            del self.config.values
            domains = self.domains
            del self.domains
            picklefile = open(filename, 'wb')
            # remove potentially pickling-problematic values from config
            for key, val in list(vars(self.config).items()):
                if key.startswith('_') or \
                   isinstance(val, types.ModuleType) or \
                   isinstance(val, types.FunctionType) or \
                   isinstance(val, class_types):
                    del self.config[key]
            try:
                pickle.dump(self, picklefile, pickle.HIGHEST_PROTOCOL)
            finally:
                picklefile.close()
            # reset attributes
            self.domains = domains
            self.config.values = values
            self.set_warnfunc(warnfunc)

        # --------- ENVIRONMENT INITIALIZATION -------------------------------------

        def __init__(self, srcdir, doctreedir, config):
            self.doctreedir = doctreedir
            self.srcdir = srcdir
            self.config = config

            # the method of doctree versioning; see set_versioning_method
            self.versioning_condition = None
            self.versioning_compare = None

            # the application object; only set while update() runs
            self.app = None

            # all the registered domains, set by the application
            self.domains = {}

            # the docutils settings for building
            self.settings = default_settings.copy()
            self.settings['env'] = self

            # the function to write warning messages with
            self._warnfunc = None

            # this is to invalidate old pickles
            self.version = ENV_VERSION

            # All "docnames" here are /-separated and relative and exclude
            # the source suffix.

            self.found_docs = set()     # contains all existing docnames
            self.all_docs = {}          # docname -> mtime at the time of reading
                                        # contains all read docnames
            self.dependencies = {}      # docname -> set of dependent file
                                        # names, relative to documentation root
            self.reread_always = set()  # docnames to re-read unconditionally on
                                        # next build

            # File metadata
            self.metadata = {}          # docname -> dict of metadata items

            # TOC inventory
            self.titles = {}            # docname -> title node
            self.longtitles = {}        # docname -> title node; only different if
                                        # set differently with title directive
            self.tocs = {}              # docname -> table of contents nodetree
            self.toc_num_entries = {}   # 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 = {}    # docname -> dict of sectionid -> number
            self.toc_fignumbers = {}    # docname -> dict of figtype ->
                                        # dict of figureid -> number

            self.toctree_includes = {}  # docname -> list of toctree includefiles
            self.files_to_rebuild = {}  # docname -> set of files
                                        # (containing its TOCs) to rebuild too
            self.glob_toctrees = set()  # docnames that have :glob: toctrees
            self.numbered_toctrees = set()  # docnames that have :numbered: toctrees

            # domain-specific inventories, here to be pickled
            self.domaindata = {}        # domainname -> domain-specific dict

            # Other inventories
            self.citations = {}         # citation name -> docname, labelid
            self.indexentries = {}      # docname -> list of
                                        # (type, string, target, aliasname)
            self.versionchanges = {}    # version -> list of (type, docname,
                                        # lineno, module, descname, content)

            # these map absolute path -> (docnames, unique filename)
            self.images = FilenameUniqDict()
            self.dlfiles = FilenameUniqDict()

            # temporary data storage while reading a document
            self.temp_data = {}
            # 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 = {}

        def set_warnfunc(self, func):
            self._warnfunc = func
            self.settings['warning_stream'] = WarningStream(func)

        def set_versioning_method(self, method, compare):
            """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.
            """
            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 warn(self, docname, msg, lineno=None, **kwargs):
            """Emit a warning.

            This differs from using ``app.warn()`` in that the warning may not
            be emitted instantly, but collected for emitting all warnings after
            the update of the environment.
            """
            # strange argument order is due to backwards compatibility
            self._warnfunc(msg, (docname, lineno), **kwargs)

        def warn_node(self, msg, node, **kwargs):
            """Like :meth:`warn`, but with source information taken from *node*."""
            self._warnfunc(msg, '%s:%s' % get_source_line(node), **kwargs)

        def clear_doc(self, docname):
            """Remove all traces of a source file in the inventory."""
            if docname in self.all_docs:
                self.all_docs.pop(docname, None)
                self.reread_always.discard(docname)
                self.metadata.pop(docname, None)
                self.dependencies.pop(docname, None)
                self.titles.pop(docname, None)
                self.longtitles.pop(docname, None)
                self.tocs.pop(docname, None)
                self.toc_secnumbers.pop(docname, None)
                self.toc_fignumbers.pop(docname, None)
                self.toc_num_entries.pop(docname, None)
                self.toctree_includes.pop(docname, None)
                self.indexentries.pop(docname, None)
                self.glob_toctrees.discard(docname)
                self.numbered_toctrees.discard(docname)
                self.images.purge_doc(docname)
                self.dlfiles.purge_doc(docname)

                for subfn, fnset in list(self.files_to_rebuild.items()):
                    fnset.discard(docname)
                    if not fnset:
                        del self.files_to_rebuild[subfn]
                for key, (fn, _ignore) in list(self.citations.items()):
                    if fn == docname:
                        del self.citations[key]
                for version, changes in self.versionchanges.items():
                    new = [change for change in changes if change[1] != docname]
                    changes[:] = new

            for domain in self.domains.values():
                domain.clear_doc(docname)

        def merge_info_from(self, docnames, other, app):
            """Merge global information gathered about *docnames* while reading them
            from the *other* environment.

            This possibly comes from a parallel build process.
            """
            docnames = set(docnames)
            for docname in docnames:
                self.all_docs[docname] = other.all_docs[docname]
                if docname in other.reread_always:
                    self.reread_always.add(docname)
                self.metadata[docname] = other.metadata[docname]
                if docname in other.dependencies:
                    self.dependencies[docname] = other.dependencies[docname]
                self.titles[docname] = other.titles[docname]
                self.longtitles[docname] = other.longtitles[docname]
                self.tocs[docname] = other.tocs[docname]
                self.toc_num_entries[docname] = other.toc_num_entries[docname]
                # toc_secnumbers and toc_fignumbers are not assigned during read
                if docname in other.toctree_includes:
                    self.toctree_includes[docname] = other.toctree_includes[docname]
                self.indexentries[docname] = other.indexentries[docname]
                if docname in other.glob_toctrees:
                    self.glob_toctrees.add(docname)
                if docname in other.numbered_toctrees:
                    self.numbered_toctrees.add(docname)

            self.images.merge_other(docnames, other.images)
            self.dlfiles.merge_other(docnames, other.dlfiles)

            for subfn, fnset in other.files_to_rebuild.items():
                self.files_to_rebuild.setdefault(subfn, set()).update(fnset & docnames)
            for key, data in other.citations.items():
                # XXX duplicates?
                if data[0] in docnames:
                    self.citations[key] = data
            for version, changes in other.versionchanges.items():
                self.versionchanges.setdefault(version, []).extend(
                    change for change in changes if change[1] in docnames)

            for domainname, domain in self.domains.items():
                domain.merge_domaindata(docnames, other.domaindata[domainname])
            app.emit('env-merge-info', self, docnames, other)

        def doc2path(self, docname, base=True, suffix=None):
            """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.
            """
            docname = docname.replace(SEP, path.sep)
            if suffix is None:
                for candidate_suffix in self.config.source_suffix:
                    if path.isfile(path.join(self.srcdir, docname) +
                                   candidate_suffix):
                        suffix = candidate_suffix
                        break
                else:
                    # document does not exist
                    suffix = self.config.source_suffix[0]
            if base is True:
                return path.join(self.srcdir, docname) + suffix
            elif base is None:
                return docname + suffix
            else:
                return path.join(base, docname) + suffix

        def relfn2path(self, filename, docname=None):
            """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)
            try:
                # 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))
            except UnicodeDecodeError:
                # the source directory is a bytestring with non-ASCII characters;
                # let's try to encode the rel_fn in the file system encoding
                enc_rel_fn = rel_fn.encode(sys.getfilesystemencoding())
                return rel_fn, path.abspath(path.join(self.srcdir, enc_rel_fn))

        def find_files(self, config):
            """Find all source files in the source dir and put them in
            self.found_docs.
            """
            matchers = compile_matchers(
                config.exclude_patterns[:] +
                config.templates_path +
                config.html_extra_path +
                ['**/_sources', '.#*', '**/.#*', '*.lproj/**']
            )
            self.found_docs = set(get_matching_docs(
                self.srcdir, config.source_suffix, exclude_matchers=matchers))

            # add catalog mo file dependency
            for docname in self.found_docs:
                catalog_files = find_catalog_files(
                    docname,
                    self.srcdir,
                    self.config.locale_dirs,
                    self.config.language,
                    self.config.gettext_compact)
                for filename in catalog_files:
                    self.dependencies.setdefault(docname, set()).add(filename)

        def get_outdated_files(self, config_changed):
            """Return (added, changed, removed) sets."""
            # clear all files no longer present
            removed = set(self.all_docs) - self.found_docs

            added = set()
            changed = set()

            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
                    if not path.isfile(self.doc2path(docname, self.doctreedir,
                                                     '.doctree')):
                        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.get(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 EnvironmentError:
                            # give it another chance
                            changed.add(docname)
                            break

            return added, changed, removed

        def update(self, config, srcdir, doctreedir, app):
            """(Re-)read all files new or changed since last update.

            Store all environment docnames in the canonical format (ie using SEP as
            a separator in place of os.path.sep).
            """
            config_changed = False
            if self.config is None:
                msg = '[new config] '
                config_changed = True
            else:
                # check if a config value was changed that affects how
                # doctrees are read
                for key, descr in iteritems(config.values):
                    if descr[1] != 'env':
                        continue
                    if self.config[key] != config[key]:
                        msg = '[config changed] '
                        config_changed = True
                        break
                else:
                    msg = ''
                # this value is not covered by the above loop because it is handled
                # specially by the config class
                if self.config.extensions != config.extensions:
                    msg = '[extensions changed] '
                    config_changed = True
            # the source and doctree directories may have been relocated
            self.srcdir = srcdir
            self.doctreedir = doctreedir
            self.find_files(config)
            self.config = config

            # this cache also needs to be updated every time
            self._nitpick_ignore = set(self.config.nitpick_ignore)

            app.info(bold('updating environment: '), nonl=1)

            added, changed, removed = self.get_outdated_files(config_changed)

            # allow user intervention as well
            for docs in app.emit('env-get-outdated', self, added, changed, removed):
                changed.update(set(docs) & self.found_docs)

            # if files were added or removed, all documents with globbed toctrees
            # must be reread
            if added or removed:
                # ... but not those that already were removed
                changed.update(self.glob_toctrees & self.found_docs)

            msg += '%s added, %s changed, %s removed' % (len(added), len(changed),
                                                         len(removed))
            app.info(msg)

            self.app = app

            # clear all files no longer present
            for docname in removed:
                app.emit('env-purge-doc', self, docname)
                self.clear_doc(docname)

            # read all new and changed files
            docnames = sorted(added | changed)
            # allow changing and reordering the list of docs to read
            app.emit('env-before-read-docs', self, docnames)

            # check if we should do parallel or serial read
            par_ok = False
            if parallel_available and len(docnames) > 5 and app.parallel > 1:
                par_ok = True
                for extname, md in app._extension_metadata.items():
                    ext_ok = md.get('parallel_read_safe')
                    if ext_ok:
                        continue
                    if ext_ok is None:
                        app.warn('the %s extension does not declare if it '
                                 'is safe for parallel reading, assuming it '
                                 'isn\'t - please ask the extension author to '
                                 'check and make it explicit' % extname)
                        app.warn('doing serial read')
                    else:
                        app.warn('the %s extension is not safe for parallel '
                                 'reading, doing serial read' % extname)
                    par_ok = False
                    break
            if par_ok:
                self._read_parallel(docnames, app, nproc=app.parallel)
            else:
                self._read_serial(docnames, app)

            if config.master_doc not in self.all_docs:
                raise SphinxError('master file %s not found' %
                                  self.doc2path(config.master_doc))

            self.app = None

            for retval in app.emit('env-updated', self):
                if retval is not None:
                    docnames.extend(retval)

            return sorted(docnames)

        def _read_serial(self, docnames, app):
            for docname in app.status_iterator(docnames, 'reading sources... ',
                                               purple, len(docnames)):
                # remove all inventory entries for that file
                app.emit('env-purge-doc', self, docname)
                self.clear_doc(docname)
                self.read_doc(docname, app)

        def _read_parallel(self, docnames, app, nproc):
            # clear all outdated docs at once
            for docname in docnames:
                app.emit('env-purge-doc', self, docname)
                self.clear_doc(docname)

            def read_process(docs):
                self.app = app
                self.warnings = []
                self.set_warnfunc(lambda *args, **kwargs: self.warnings.append((args, kwargs)))
                for docname in docs:
                    self.read_doc(docname, app)
                # allow pickling self to send it back
                self.set_warnfunc(None)
                del self.app
                del self.domains
                del self.config.values
                del self.config
                return self

            def merge(docs, otherenv):
                warnings.extend(otherenv.warnings)
                self.merge_info_from(docs, otherenv, app)

            tasks = ParallelTasks(nproc)
            chunks = make_chunks(docnames, nproc)

            warnings = []
            for chunk in app.status_iterator(
                    chunks, 'reading sources... ', purple, len(chunks)):
                tasks.add_task(read_process, chunk, merge)

            # make sure all threads have finished
            app.info(bold('waiting for workers...'))
            tasks.join()

            for warning, kwargs in warnings:
                self._warnfunc(*warning, **kwargs)

        def check_dependents(self, already):
            to_rewrite = self.assign_section_numbers() + self.assign_figure_numbers()
            for docname in set(to_rewrite):
                if docname not in already:
                    yield docname

        # --------- SINGLE FILE READING --------------------------------------------

        def warn_and_replace(self, error):
            """Custom decoding error handler that warns and replaces."""
            linestart = error.object.rfind(b'\n', 0, error.start)
            lineend = error.object.find(b'\n', error.start)
            if lineend == -1:
                lineend = len(error.object)
            lineno = error.object.count(b'\n', 0, error.start) + 1
            self.warn(self.docname, 'undecodable source characters, '
                      'replacing with "?": %r' %
                      (error.object[linestart+1:error.start] + b'>>>' +
                       error.object[error.start:error.end] + b'<<<' +
                       error.object[error.end:lineend]), lineno)
            return (u'?', error.end)

        def lookup_domain_element(self, type, name):
            """Lookup a markup element (directive or role), given its name which can
            be a full name (with domain).
            """
            name = name.lower()
            # explicit domain given?
            if ':' in name:
                domain_name, name = name.split(':', 1)
                if domain_name in self.domains:
                    domain = self.domains[domain_name]
                    element = getattr(domain, type)(name)
                    if element is not None:
                        return element, []
            # else look in the default domain
            else:
                def_domain = self.temp_data.get('default_domain')
                if def_domain is not None:
                    element = getattr(def_domain, type)(name)
                    if element is not None:
                        return element, []
            # always look in the std domain
            element = getattr(self.domains['std'], type)(name)
            if element is not None:
                return element, []
            raise ElementLookupError

        def patch_lookup_functions(self):
            """Monkey-patch directive and role dispatch, so that domain-specific
            markup takes precedence.
            """
            def directive(name, lang_module, document):
                try:
                    return self.lookup_domain_element('directive', name)
                except ElementLookupError:
                    return orig_directive_function(name, lang_module, document)

            def role(name, lang_module, lineno, reporter):
                try:
                    return self.lookup_domain_element('role', name)
                except ElementLookupError:
                    return orig_role_function(name, lang_module, lineno, reporter)

            directives.directive = directive
            roles.role = role

        def read_doc(self, docname, app=None):
            """Parse a file and add/update inventory entries for the doctree."""

            self.temp_data['docname'] = docname
            # defaults to the global default, but can be re-set in a document
            self.temp_data['default_domain'] = \
                self.domains.get(self.config.primary_domain)

            self.settings['input_encoding'] = self.config.source_encoding
            self.settings['trim_footnote_reference_space'] = \
                self.config.trim_footnote_reference_space
            self.settings['gettext_compact'] = self.config.gettext_compact

            self.patch_lookup_functions()

            docutilsconf = path.join(self.srcdir, 'docutils.conf')
            # read docutils.conf from source dir, not from current dir
            OptionParser.standard_config_files[1] = docutilsconf
            if path.isfile(docutilsconf):
                self.note_dependency(docutilsconf)

            if self.config.default_role:
                role_fn, messages = roles.role(self.config.default_role, english,
                                               0, dummy_reporter)
                if role_fn:
                    roles._roles[''] = role_fn
                else:
                    self.warn(docname, 'default role %s not found' %
                              self.config.default_role)

            codecs.register_error('sphinx', self.warn_and_replace)

            # publish manually
            reader = SphinxStandaloneReader(self.app, parsers=self.config.source_parsers)
            pub = Publisher(reader=reader,
                            writer=SphinxDummyWriter(),
                            destination_class=NullOutput)
            pub.set_components(None, 'restructuredtext', None)
            pub.process_programmatic_settings(None, self.settings, None)
            src_path = self.doc2path(docname)
            source = SphinxFileInput(app, self, source=None, source_path=src_path,
                                     encoding=self.config.source_encoding)
            pub.source = source
            pub.settings._source = src_path
            pub.set_destination(None, None)
            pub.publish()
            doctree = pub.document

            # post-processing
            self.filter_messages(doctree)
            self.process_dependencies(docname, doctree)
            self.process_images(docname, doctree)
            self.process_downloads(docname, doctree)
            self.process_metadata(docname, doctree)
            self.process_refonly_bullet_lists(docname, doctree)
            self.create_title_from(docname, doctree)
            self.note_indexentries_from(docname, doctree)
            self.note_citations_from(docname, doctree)
            self.build_toc_from(docname, doctree)
            for domain in itervalues(self.domains):
                domain.process_doc(self, docname, doctree)

            # allow extension-specific post-processing
            if app:
                app.emit('doctree-read', doctree)

            # store time of reading, for outdated files detection
            # (Some filesystems have coarse timestamp resolution;
            # therefore time.time() can be older than filesystem's timestamp.
            # For example, FAT32 has 2sec timestamp resolution.)
            self.all_docs[docname] = max(
                time.time(), path.getmtime(self.doc2path(docname)))

            if self.versioning_condition:
                old_doctree = None
                if self.versioning_compare:
                    # get old doctree
                    try:
                        f = open(self.doc2path(docname,
                                               self.doctreedir, '.doctree'), 'rb')
                        try:
                            old_doctree = pickle.load(f)
                        finally:
                            f.close()
                    except EnvironmentError:
                        pass

                # add uids for versioning
                if not self.versioning_compare or old_doctree is None:
                    list(add_uids(doctree, self.versioning_condition))
                else:
                    list(merge_doctrees(
                        old_doctree, doctree, self.versioning_condition))

            # make it picklable
            doctree.reporter = None
            doctree.transformer = None
            doctree.settings.warning_stream = None
            doctree.settings.env = None
            doctree.settings.record_dependencies = None
            for metanode in doctree.traverse(MetaBody.meta):
                # docutils' meta nodes aren't picklable because the class is nested
                metanode.__class__ = addnodes.meta

            # cleanup
            self.temp_data.clear()
            self.ref_context.clear()
            roles._roles.pop('', None)  # if a document has set a local default role

            # save the parsed doctree
            doctree_filename = self.doc2path(docname, self.doctreedir,
                                             '.doctree')
            ensuredir(path.dirname(doctree_filename))
            f = open(doctree_filename, 'wb')
            try:
                pickle.dump(doctree, f, pickle.HIGHEST_PROTOCOL)
            finally:
                f.close()

        # utilities to use while reading a document

        @property
        def docname(self):
            """Returns the docname of the document currently being parsed."""
            return self.temp_data['docname']

        @property
        def currmodule(self):
            """Backwards compatible alias.  Will be removed."""
            self.warn(self.docname, 'env.currmodule is being referenced by an '
                      'extension; this API will be removed in the future')
            return self.ref_context.get('py:module')

        @property
        def currclass(self):
            """Backwards compatible alias.  Will be removed."""
            self.warn(self.docname, 'env.currclass is being referenced by an '
                      'extension; this API will be removed in the future')
            return self.ref_context.get('py:class')

        def new_serialno(self, category=''):
            """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):
            """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.setdefault(self.docname, set()).add(filename)

        def note_reread(self):
            """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 note_versionchange(self, type, version, node, lineno):
            self.versionchanges.setdefault(version, []).append(
                (type, self.temp_data['docname'], lineno,
                 self.ref_context.get('py:module'),
                 self.temp_data.get('object'), node.astext()))

        # post-processing of read doctrees

        def filter_messages(self, doctree):
            """Filter system messages from a doctree."""
            filterlevel = self.config.keep_warnings and 2 or 5
            for node in doctree.traverse(nodes.system_message):
                if node['level'] < filterlevel:
                    self.app.debug('%s [filtered system message]', node.astext())
                    node.parent.remove(node)

        def process_dependencies(self, docname, doctree):
            """Process docutils-generated dependency info."""
            cwd = getcwd()
            frompath = path.join(path.normpath(self.srcdir), 'dummy')
            deps = doctree.settings.record_dependencies
            if not deps:
                return
            for dep in deps.list:
                # the dependency path is relative to the working dir, so get
                # one relative to the srcdir
                if isinstance(dep, bytes):
                    dep = dep.decode(fs_encoding)
                relpath = relative_path(frompath,
                                        path.normpath(path.join(cwd, dep)))
                self.dependencies.setdefault(docname, set()).add(relpath)

        def process_downloads(self, docname, doctree):
            """Process downloadable file paths. """
            for node in doctree.traverse(addnodes.download_reference):
                targetname = node['reftarget']
                rel_filename, filename = self.relfn2path(targetname, docname)
                self.dependencies.setdefault(docname, set()).add(rel_filename)
                if not os.access(filename, os.R_OK):
                    self.warn_node('download file not readable: %s' % filename,
                                   node)
                    continue
                uniquename = self.dlfiles.add_file(docname, filename)
                node['filename'] = uniquename

        def process_images(self, docname, doctree):
            """Process and rewrite image URIs."""
            def collect_candidates(imgpath, candidates):
                globbed = {}
                for filename in glob(imgpath):
                    new_imgpath = relative_path(path.join(self.srcdir, 'dummy'),
                                                filename)
                    try:
                        mimetype = guess_mimetype(filename)
                        if mimetype not in candidates:
                            globbed.setdefault(mimetype, []).append(new_imgpath)
                    except (OSError, IOError) as err:
                        self.warn_node('image file %s not readable: %s' %
                                       (filename, err), node)
                for key, files in iteritems(globbed):
                    candidates[key] = sorted(files, key=len)[0]  # select by similarity

            for node in doctree.traverse(nodes.image):
                # Map the mimetype to the corresponding image.  The writer may
                # choose the best image from these candidates.  The special key * is
                # set if there is only single candidate to be used by a writer.
                # The special key ? is set for nonlocal URIs.
                node['candidates'] = candidates = {}
                imguri = node['uri']
                if imguri.find('://') != -1:
                    self.warn_node('nonlocal image URI found: %s' % imguri, node)
                    candidates['?'] = imguri
                    continue
                rel_imgpath, full_imgpath = self.relfn2path(imguri, docname)
                if self.config.language:
                    # substitute figures (ex. foo.png -> foo.en.png)
                    i18n_full_imgpath = search_image_for_language(full_imgpath, self)
                    if i18n_full_imgpath != full_imgpath:
                        full_imgpath = i18n_full_imgpath
                        rel_imgpath = relative_path(path.join(self.srcdir, 'dummy'),
                                                    i18n_full_imgpath)
                # set imgpath as default URI
                node['uri'] = rel_imgpath
                if rel_imgpath.endswith(os.extsep + '*'):
                    if self.config.language:
                        # Search language-specific figures at first
                        i18n_imguri = get_image_filename_for_language(imguri, self)
                        _, full_i18n_imgpath = self.relfn2path(i18n_imguri, docname)
                        collect_candidates(full_i18n_imgpath, candidates)

                    collect_candidates(full_imgpath, candidates)
                else:
                    candidates['*'] = rel_imgpath

                # map image paths to unique image names (so that they can be put
                # into a single directory)
                for imgpath in itervalues(candidates):
                    self.dependencies.setdefault(docname, set()).add(imgpath)
                    if not os.access(path.join(self.srcdir, imgpath), os.R_OK):
                        self.warn_node('image file not readable: %s' % imgpath,
                                       node)
                        continue
                    self.images.add_file(docname, imgpath)

        def process_metadata(self, docname, doctree):
            """Process the docinfo part of the doctree as metadata.

            Keep processing minimal -- just return what docutils says.
            """
            self.metadata[docname] = md = {}
            try:
                docinfo = doctree[0]
            except IndexError:
                # probably an empty document
                return
            if docinfo.__class__ is not nodes.docinfo:
                # nothing to see here
                return
            for node in docinfo:
                # nodes are multiply inherited...
                if isinstance(node, nodes.authors):
                    md['authors'] = [author.astext() for author in node]
                elif isinstance(node, nodes.TextElement):  # e.g. author
                    md[node.__class__.__name__] = node.astext()
                else:
                    name, body = node
                    md[name.astext()] = body.astext()
            for name, value in md.items():
                if name in ('tocdepth',):
                    try:
                        value = int(value)
                    except ValueError:
                        value = 0
                    md[name] = value

            del doctree[0]

        def process_refonly_bullet_lists(self, docname, doctree):
            """Change refonly bullet lists to use compact_paragraphs.

            Specifically implemented for 'Indices and Tables' section, which looks
            odd when html_compact_lists is false.
            """
            if self.config.html_compact_lists:
                return

            class RefOnlyListChecker(nodes.GenericNodeVisitor):
                """Raise `nodes.NodeFound` if non-simple list item is encountered.

                Here 'simple' means a list item containing only a paragraph with a
                single reference in it.
                """

                def default_visit(self, node):
                    raise nodes.NodeFound

                def visit_bullet_list(self, node):
                    pass

                def visit_list_item(self, node):
                    children = []
                    for child in node.children:
                        if not isinstance(child, nodes.Invisible):
                            children.append(child)
                    if len(children) != 1:
                        raise nodes.NodeFound
                    if not isinstance(children[0], nodes.paragraph):
                        raise nodes.NodeFound
                    para = children[0]
                    if len(para) != 1:
                        raise nodes.NodeFound
                    if not isinstance(para[0], addnodes.pending_xref):
                        raise nodes.NodeFound
                    raise nodes.SkipChildren

                def invisible_visit(self, node):
                    """Invisible nodes should be ignored."""
                    pass

            def check_refonly_list(node):
                """Check for list with only references in it."""
                visitor = RefOnlyListChecker(doctree)
                try:
                    node.walk(visitor)
                except nodes.NodeFound:
                    return False
                else:
                    return True

            for node in doctree.traverse(nodes.bullet_list):
                if check_refonly_list(node):
                    for item in node.traverse(nodes.list_item):
                        para = item[0]
                        ref = para[0]
                        compact_para = addnodes.compact_paragraph()
                        compact_para += ref
                        item.replace(para, compact_para)

        def create_title_from(self, docname, document):
            """Add a title node to the document (just copy the first section title),
            and store that title in the environment.
            """
            titlenode = nodes.title()
            longtitlenode = titlenode
            # explicit title set with title directive; use this only for
            # the <title> tag in HTML output
            if 'title' in document:
                longtitlenode = nodes.title()
                longtitlenode += nodes.Text(document['title'])
            # look for first section title and use that as the title
            for node in document.traverse(nodes.section):
                visitor = SphinxContentsFilter(document)
                node[0].walkabout(visitor)
                titlenode += visitor.get_entry_text()
                break
            else:
                # document has no title
                titlenode += nodes.Text('<no title>')
            self.titles[docname] = titlenode
            self.longtitles[docname] = longtitlenode

        def note_indexentries_from(self, docname, document):
            entries = self.indexentries[docname] = []
            for node in document.traverse(addnodes.index):
                try:
                    for entry in node['entries']:
                        split_index_msg(entry[0], entry[1])
                except ValueError as exc:
                    self.warn_node(exc, node)
                    node.parent.remove(node)
                else:
                    for entry in node['entries']:
                        if len(entry) == 5:
                            # Since 1.4: new index structure including index_key (5th column)
                            entries.append(entry)
                        else:
                            entries.append(entry + (None,))

        def note_citations_from(self, docname, document):
            for node in document.traverse(nodes.citation):
                label = node[0].astext()
                if label in self.citations:
                    self.warn_node('duplicate citation %s, ' % label +
                                   'other instance in %s' % self.doc2path(
                                       self.citations[label][0]), node)
                self.citations[label] = (docname, node['ids'][0])

        def note_toctree(self, docname, toctreenode):
            """Note a TOC tree directive in a document and gather information about
            file relations from it.
            """
            if toctreenode['glob']:
                self.glob_toctrees.add(docname)
            if toctreenode.get('numbered'):
                self.numbered_toctrees.add(docname)
            includefiles = toctreenode['includefiles']
            for includefile in includefiles:
                # note that if the included file is rebuilt, this one must be
                # too (since the TOC of the included file could have changed)
                self.files_to_rebuild.setdefault(includefile, set()).add(docname)
            self.toctree_includes.setdefault(docname, []).extend(includefiles)

        def build_toc_from(self, docname, document):
            """Build a TOC from the doctree and store it in the inventory."""
            numentries = [0]  # nonlocal again...

            def traverse_in_section(node, cls):
                """Like traverse(), but stay within the same section."""
                result = []
                if isinstance(node, cls):
                    result.append(node)
                for child in node.children:
                    if isinstance(child, nodes.section):
                        continue
                    result.extend(traverse_in_section(child, cls))
                return result

            def build_toc(node, depth=1):
                entries = []
                for sectionnode in node:
                    # find all toctree nodes in this section and add them
                    # to the toc (just copying the toctree node which is then
                    # resolved in self.get_and_resolve_doctree)
                    if isinstance(sectionnode, addnodes.only):
                        onlynode = addnodes.only(expr=sectionnode['expr'])
                        blist = build_toc(sectionnode, depth)
                        if blist:
                            onlynode += blist.children
                            entries.append(onlynode)
                        continue
                    if not isinstance(sectionnode, nodes.section):
                        for toctreenode in traverse_in_section(sectionnode,
                                                               addnodes.toctree):
                            item = toctreenode.copy()
                            entries.append(item)
                            # important: do the inventory stuff
                            self.note_toctree(docname, toctreenode)
                        continue
                    title = sectionnode[0]
                    # copy the contents of the section title, but without references
                    # and unnecessary stuff
                    visitor = SphinxContentsFilter(document)
                    title.walkabout(visitor)
                    nodetext = visitor.get_entry_text()
                    if not numentries[0]:
                        # for the very first toc entry, don't add an anchor
                        # as it is the file's title anyway
                        anchorname = ''
                    else:
                        anchorname = '#' + sectionnode['ids'][0]
                    numentries[0] += 1
                    # make these nodes:
                    # list_item -> compact_paragraph -> reference
                    reference = nodes.reference(
                        '', '', internal=True, refuri=docname,
                        anchorname=anchorname, *nodetext)
                    para = addnodes.compact_paragraph('', '', reference)
                    item = nodes.list_item('', para)
                    sub_item = build_toc(sectionnode, depth + 1)
                    item += sub_item
                    entries.append(item)
                if entries:
                    return nodes.bullet_list('', *entries)
                return []
            toc = build_toc(document)
            if toc:
                self.tocs[docname] = toc
            else:
                self.tocs[docname] = nodes.bullet_list('')
            self.toc_num_entries[docname] = numentries[0]

        def get_toc_for(self, docname, builder):
            """Return a TOC nodetree -- for use on the same page only!"""
            tocdepth = self.metadata[docname].get('tocdepth', 0)
            try:
                toc = self.tocs[docname].deepcopy()
                self._toctree_prune(toc, 2, tocdepth)
            except KeyError:
                # the document does not exist anymore: return a dummy node that
                # renders to nothing
                return nodes.paragraph()
            self.process_only_nodes(toc, builder, docname)
            for node in toc.traverse(nodes.reference):
                node['refuri'] = node['anchorname'] or '#'
            return toc

        def get_toctree_for(self, docname, builder, collapse, **kwds):
            """Return the global TOC nodetree."""
            doctree = self.get_doctree(self.config.master_doc)
            toctrees = []
            if 'includehidden' not in kwds:
                kwds['includehidden'] = True
            if 'maxdepth' not in kwds:
                kwds['maxdepth'] = 0
            kwds['collapse'] = collapse
            for toctreenode in doctree.traverse(addnodes.toctree):
                toctree = self.resolve_toctree(docname, builder, toctreenode,
                                               prune=True, **kwds)
                if toctree:
                    toctrees.append(toctree)
            if not toctrees:
                return None
            result = toctrees[0]
            for toctree in toctrees[1:]:
                result.extend(toctree.children)
            return result

        def get_domain(self, domainname):
            """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):
            """Read the doctree for a file from the pickle and return it."""
            doctree_filename = self.doc2path(docname, self.doctreedir, '.doctree')
            f = open(doctree_filename, 'rb')
            try:
                doctree = pickle.load(f)
            finally:
                f.close()
            doctree.settings.env = self
            doctree.reporter = Reporter(self.doc2path(docname), 2, 5,
                                        stream=WarningStream(self._warnfunc))
            return doctree

        def get_and_resolve_doctree(self, docname, builder, doctree=None,
                                    prune_toctrees=True, includehidden=False):
            """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.resolve_references(doctree, docname, builder)

            # now, resolve all toctree nodes
            for toctreenode in doctree.traverse(addnodes.toctree):
                result = self.resolve_toctree(docname, builder, toctreenode,
                                              prune=prune_toctrees,
                                              includehidden=includehidden)
                if result is None:
                    toctreenode.replace_self([])
                else:
                    toctreenode.replace_self(result)

            return doctree

        def _toctree_prune(self, node, depth, maxdepth, collapse=False):
            """Utility: Cut a TOC at a specified depth."""
            for subnode in node.children[:]:
                if isinstance(subnode, (addnodes.compact_paragraph,
                                        nodes.list_item)):
                    # for <p> and <li>, just recurse
                    self._toctree_prune(subnode, depth, maxdepth, collapse)
                elif isinstance(subnode, nodes.bullet_list):
                    # for <ul>, determine if the depth is too large or if the
                    # entry is to be collapsed
                    if maxdepth > 0 and depth > maxdepth:
                        subnode.parent.replace(subnode, [])
                    else:
                        # cull sub-entries whose parents aren't 'current'
                        if (collapse and depth > 1 and
                                'iscurrent' not in subnode.parent):
                            subnode.parent.remove(subnode)
                        else:
                            # recurse on visible children
                            self._toctree_prune(subnode, depth+1, maxdepth,  collapse)

        def get_toctree_ancestors(self, docname):
            parent = {}
            for p, children in iteritems(self.toctree_includes):
                for child in children:
                    parent[child] = p
            ancestors = []
            d = docname
            while d in parent and d not in ancestors:
                ancestors.append(d)
                d = parent[d]
            return ancestors

        def resolve_toctree(self, docname, builder, toctree, prune=True, maxdepth=0,
                            titles_only=False, collapse=False, includehidden=False):
            """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.
            """
            if toctree.get('hidden', False) and not includehidden:
                return None

            # For reading the following two helper function, it is useful to keep
            # in mind the node structure of a toctree (using HTML-like node names
            # for brevity):
            #
            # <ul>
            #   <li>
            #     <p><a></p>
            #     <p><a></p>
            #     ...
            #     <ul>
            #       ...
            #     </ul>
            #   </li>
            # </ul>
            #
            # The transformation is made in two passes in order to avoid
            # interactions between marking and pruning the tree (see bug #1046).

            toctree_ancestors = self.get_toctree_ancestors(docname)

            def _toctree_add_classes(node, depth):
                """Add 'toctree-l%d' and 'current' classes to the toctree."""
                for subnode in node.children:
                    if isinstance(subnode, (addnodes.compact_paragraph,
                                            nodes.list_item)):
                        # for <p> and <li>, indicate the depth level and recurse
                        subnode['classes'].append('toctree-l%d' % (depth-1))
                        _toctree_add_classes(subnode, depth)
                    elif isinstance(subnode, nodes.bullet_list):
                        # for <ul>, just recurse
                        _toctree_add_classes(subnode, depth+1)
                    elif isinstance(subnode, nodes.reference):
                        # for <a>, identify which entries point to the current
                        # document and therefore may not be collapsed
                        if subnode['refuri'] == docname:
                            if not subnode['anchorname']:
                                # give the whole branch a 'current' class
                                # (useful for styling it differently)
                                branchnode = subnode
                                while branchnode:
                                    branchnode['classes'].append('current')
                                    branchnode = branchnode.parent
                            # mark the list_item as "on current page"
                            if subnode.parent.parent.get('iscurrent'):
                                # but only if it's not already done
                                return
                            while subnode:
                                subnode['iscurrent'] = True
                                subnode = subnode.parent

            def _entries_from_toctree(toctreenode, parents,
                                      separate=False, subtree=False):
                """Return TOC entries for a toctree node."""
                refs = [(e[0], e[1]) for e in toctreenode['entries']]
                entries = []
                for (title, ref) in refs:
                    try:
                        refdoc = None
                        if url_re.match(ref):
                            if title is None:
                                title = ref
                            reference = nodes.reference('', '', internal=False,
                                                        refuri=ref, anchorname='',
                                                        *[nodes.Text(title)])
                            para = addnodes.compact_paragraph('', '', reference)
                            item = nodes.list_item('', para)
                            toc = nodes.bullet_list('', item)
                        elif ref == 'self':
                            # 'self' refers to the document from which this
                            # toctree originates
                            ref = toctreenode['parent']
                            if not title:
                                title = clean_astext(self.titles[ref])
                            reference = nodes.reference('', '', internal=True,
                                                        refuri=ref,
                                                        anchorname='',
                                                        *[nodes.Text(title)])
                            para = addnodes.compact_paragraph('', '', reference)
                            item = nodes.list_item('', para)
                            # don't show subitems
                            toc = nodes.bullet_list('', item)
                        else:
                            if ref in parents:
                                self.warn(ref, 'circular toctree references '
                                          'detected, ignoring: %s <- %s' %
                                          (ref, ' <- '.join(parents)))
                                continue
                            refdoc = ref
                            toc = self.tocs[ref].deepcopy()
                            maxdepth = self.metadata[ref].get('tocdepth', 0)
                            if ref not in toctree_ancestors or (prune and maxdepth > 0):
                                self._toctree_prune(toc, 2, maxdepth, collapse)
                            self.process_only_nodes(toc, builder, ref)
                            if title and toc.children and len(toc.children) == 1:
                                child = toc.children[0]
                                for refnode in child.traverse(nodes.reference):
                                    if refnode['refuri'] == ref and \
                                       not refnode['anchorname']:
                                        refnode.children = [nodes.Text(title)]
                        if not toc.children:
                            # empty toc means: no titles will show up in the toctree
                            self.warn_node(
                                'toctree contains reference to document %r that '
                                'doesn\'t have a title: no link will be generated'
                                % ref, toctreenode)
                    except KeyError:
                        # this is raised if the included file does not exist
                        self.warn_node(
                            'toctree contains reference to nonexisting document %r'
                            % ref, toctreenode)
                    else:
                        # if titles_only is given, only keep the main title and
                        # sub-toctrees
                        if titles_only:
                            # delete everything but the toplevel title(s)
                            # and toctrees
                            for toplevel in toc:
                                # nodes with length 1 don't have any children anyway
                                if len(toplevel) > 1:
                                    subtrees = toplevel.traverse(addnodes.toctree)
                                    toplevel[1][:] = subtrees
                        # resolve all sub-toctrees
                        for subtocnode in toc.traverse(addnodes.toctree):
                            if not (subtocnode.get('hidden', False) and
                                    not includehidden):
                                i = subtocnode.parent.index(subtocnode) + 1
                                for item in _entries_from_toctree(
                                        subtocnode, [refdoc] + parents,
                                        subtree=True):
                                    subtocnode.parent.insert(i, item)
                                    i += 1
                                subtocnode.parent.remove(subtocnode)
                        if separate:
                            entries.append(toc)
                        else:
                            entries.extend(toc.children)
                if not subtree and not separate:
                    ret = nodes.bullet_list()
                    ret += entries
                    return [ret]
                return entries

            maxdepth = maxdepth or toctree.get('maxdepth', -1)
            if not titles_only and toctree.get('titlesonly', False):
                titles_only = True
            if not includehidden and toctree.get('includehidden', False):
                includehidden = True

            # NOTE: previously, this was separate=True, but that leads to artificial
            # separation when two or more toctree entries form a logical unit, so
            # separating mode is no longer used -- it's kept here for history's sake
            tocentries = _entries_from_toctree(toctree, [], separate=False)
            if not tocentries:
                return None

            newnode = addnodes.compact_paragraph('', '')
            caption = toctree.attributes.get('caption')
            if caption:
                newnode += nodes.caption(caption, '', *[nodes.Text(caption)])
            newnode.extend(tocentries)
            newnode['toctree'] = True

            # prune the tree to maxdepth, also set toc depth and current classes
            _toctree_add_classes(newnode, 1)
            self._toctree_prune(newnode, 1, prune and maxdepth or 0, collapse)

            # set the target paths in the toctrees (they are not known at TOC
            # generation time)
            for refnode in newnode.traverse(nodes.reference):
                if not url_re.match(refnode['refuri']):
                    refnode['refuri'] = builder.get_relative_uri(
                        docname, refnode['refuri']) + refnode['anchorname']
            return newnode

        def resolve_references(self, doctree, fromdocname, builder):
            for node in doctree.traverse(addnodes.pending_xref):
                contnode = node[0].deepcopy()
                newnode = None

                typ = node['reftype']
                target = node['reftarget']
                refdoc = node.get('refdoc', fromdocname)
                domain = None

                try:
                    if 'refdomain' in node and node['refdomain']:
                        # let the domain try to resolve the reference
                        try:
                            domain = self.domains[node['refdomain']]
                        except KeyError:
                            raise NoUri
                        newnode = domain.resolve_xref(self, refdoc, builder,
                                                      typ, target, node, contnode)
                    # really hardwired reference types
                    elif typ == 'any':
                        newnode = self._resolve_any_reference(builder, node, contnode)
                    elif typ == 'doc':
                        newnode = self._resolve_doc_reference(builder, node, contnode)
                    elif typ == 'citation':
                        newnode = self._resolve_citation(builder, refdoc, node, contnode)
                    # no new node found? try the missing-reference event
                    if newnode is None:
                        newnode = builder.app.emit_firstresult(
                            'missing-reference', self, node, contnode)
                        # still not found? warn if node wishes to be warned about or
                        # we are in nit-picky mode
                        if newnode is None:
                            self._warn_missing_reference(refdoc, typ, target, node, domain)
                except NoUri:
                    newnode = contnode
                node.replace_self(newnode or contnode)

            # remove only-nodes that do not belong to our builder
            self.process_only_nodes(doctree, builder, fromdocname)

            # allow custom references to be resolved
            builder.app.emit('doctree-resolved', doctree, fromdocname)

        def _warn_missing_reference(self, refdoc, typ, target, node, domain):
            warn = node.get('refwarn')
            if self.config.nitpicky:
                warn = True
                if self._nitpick_ignore:
                    dtype = domain and '%s:%s' % (domain.name, typ) or typ
                    if (dtype, target) in self._nitpick_ignore:
                        warn = False
                    # for "std" types also try without domain name
                    if (not domain or domain.name == 'std') and \
                       (typ, target) in self._nitpick_ignore:
                        warn = False
            if not warn:
                return
            if domain and typ in domain.dangling_warnings:
                msg = domain.dangling_warnings[typ]
            elif typ == 'doc':
                msg = 'unknown document: %(target)s'
            elif typ == 'citation':
                msg = 'citation not found: %(target)s'
            elif node.get('refdomain', 'std') not in ('', 'std'):
                msg = '%s:%s reference target not found: %%(target)s' % \
                      (node['refdomain'], typ)
            else:
                msg = '%r reference target not found: %%(target)s' % typ
            self.warn_node(msg % {'target': target}, node, type='ref', subtype=typ)

        def _resolve_doc_reference(self, builder, node, contnode):
            # directly reference to document by source name;
            # can be absolute or relative
            docname = docname_join(node['refdoc'], node['reftarget'])
            if docname in self.all_docs:
                if node['refexplicit']:
                    # reference with explicit title
                    caption = node.astext()
                else:
                    caption = clean_astext(self.titles[docname])
                innernode = nodes.inline(caption, caption)
                innernode['classes'].append('doc')
                newnode = nodes.reference('', '', internal=True)
                newnode['refuri'] = builder.get_relative_uri(node['refdoc'], docname)
                newnode.append(innernode)
                return newnode

        def _resolve_citation(self, builder, fromdocname, node, contnode):
            docname, labelid = self.citations.get(node['reftarget'], ('', ''))
            if docname:
                try:
                    newnode = make_refnode(builder, fromdocname,
                                           docname, labelid, contnode)
                    return newnode
                except NoUri:
                    # remove the ids we added in the CitationReferences
                    # transform since they can't be transfered to
                    # the contnode (if it's a Text node)
                    if not isinstance(contnode, nodes.Element):
                        del node['ids'][:]
                    raise
            elif 'ids' in node:
                # remove ids attribute that annotated at
                # transforms.CitationReference.apply.
                del node['ids'][:]

        def _resolve_any_reference(self, builder, node, contnode):
            """Resolve reference generated by the "any" role."""
            refdoc = node['refdoc']
            target = node['reftarget']
            results = []
            # first, try resolving as :doc:
            doc_ref = self._resolve_doc_reference(builder, node, contnode)
            if doc_ref:
                results.append(('doc', doc_ref))
            # next, do the standard domain (makes this a priority)
            results.extend(self.domains['std'].resolve_any_xref(
                self, refdoc, builder, target, node, contnode))
            for domain in self.domains.values():
                if domain.name == 'std':
                    continue  # we did this one already
                try:
                    results.extend(domain.resolve_any_xref(self, refdoc, builder,
                                                           target, node, contnode))
                except NotImplementedError:
                    # the domain doesn't yet support the new interface
                    # we have to manually collect possible references (SLOW)
                    for role in domain.roles:
                        res = domain.resolve_xref(self, refdoc, builder, role, target,
                                                  node, contnode)
                        if res and isinstance(res[0], nodes.Element):
                            results.append(('%s:%s' % (domain.name, role), res))
            # now, see how many matches we got...
            if not results:
                return None
            if len(results) > 1:
                nice_results = ' or '.join(':%s:' % r[0] for r in results)
                self.warn_node('more than one target found for \'any\' cross-'
                               'reference %r: could be %s' % (target, nice_results),
                               node)
            res_role, newnode = results[0]
            # Override "any" class with the actual role type to get the styling
            # approximately correct.
            res_domain = res_role.split(':')[0]
            if newnode and newnode[0].get('classes'):
                newnode[0]['classes'].append(res_domain)
                newnode[0]['classes'].append(res_role.replace(':', '-'))
            return newnode

        def process_only_nodes(self, doctree, builder, fromdocname=None):
            # A comment on the comment() nodes being inserted: replacing by [] would
            # result in a "Losing ids" exception if there is a target node before
            # the only node, so we make sure docutils can transfer the id to
            # something, even if it's just a comment and will lose the id anyway...
            for node in doctree.traverse(addnodes.only):
                try:
                    ret = builder.tags.eval_condition(node['expr'])
                except Exception as err:
                    self.warn_node('exception while evaluating only '
                                   'directive expression: %s' % err, node)
                    node.replace_self(node.children or nodes.comment())
                else:
                    if ret:
                        node.replace_self(node.children or nodes.comment())
                    else:
                        node.replace_self(nodes.comment())

        def assign_section_numbers(self):
            """Assign a section number to each heading under a numbered toctree."""
            # a list of all docnames whose section numbers changed
            rewrite_needed = []

            assigned = set()
            old_secnumbers = self.toc_secnumbers
            self.toc_secnumbers = {}

            def _walk_toc(node, secnums, depth, titlenode=None):
                # titlenode is the title of the document, it will get assigned a
                # secnumber too, so that it shows up in next/prev/parent rellinks
                for subnode in node.children:
                    if isinstance(subnode, nodes.bullet_list):
                        numstack.append(0)
                        _walk_toc(subnode, secnums, depth-1, titlenode)
                        numstack.pop()
                        titlenode = None
                    elif isinstance(subnode, nodes.list_item):
                        _walk_toc(subnode, secnums, depth, titlenode)
                        titlenode = None
                    elif isinstance(subnode, addnodes.only):
                        # at this stage we don't know yet which sections are going
                        # to be included; just include all of them, even if it leads
                        # to gaps in the numbering
                        _walk_toc(subnode, secnums, depth, titlenode)
                        titlenode = None
                    elif isinstance(subnode, addnodes.compact_paragraph):
                        numstack[-1] += 1
                        if depth > 0:
                            number = tuple(numstack)
                        else:
                            number = None
                        secnums[subnode[0]['anchorname']] = \
                            subnode[0]['secnumber'] = number
                        if titlenode:
                            titlenode['secnumber'] = number
                            titlenode = None
                    elif isinstance(subnode, addnodes.toctree):
                        _walk_toctree(subnode, depth)

            def _walk_toctree(toctreenode, depth):
                if depth == 0:
                    return
                for (title, ref) in toctreenode['entries']:
                    if url_re.match(ref) or ref == 'self' or ref in assigned:
                        # don't mess with those
                        continue
                    if ref in self.tocs:
                        secnums = self.toc_secnumbers[ref] = {}
                        assigned.add(ref)
                        _walk_toc(self.tocs[ref], secnums, depth,
                                  self.titles.get(ref))
                        if secnums != old_secnumbers.get(ref):
                            rewrite_needed.append(ref)

            for docname in self.numbered_toctrees:
                assigned.add(docname)
                doctree = self.get_doctree(docname)
                for toctreenode in doctree.traverse(addnodes.toctree):
                    depth = toctreenode.get('numbered', 0)
                    if depth:
                        # every numbered toctree gets new numbering
                        numstack = [0]
                        _walk_toctree(toctreenode, depth)

            return rewrite_needed

        def assign_figure_numbers(self):
            """Assign a figure number to each figure under a numbered toctree."""

            rewrite_needed = []

            assigned = set()
            old_fignumbers = self.toc_fignumbers
            self.toc_fignumbers = {}
            fignum_counter = {}

            def get_section_number(docname, section):
                anchorname = '#' + section['ids'][0]
                secnumbers = self.toc_secnumbers.get(docname, {})
                if anchorname in secnumbers:
                    secnum = secnumbers.get(anchorname)
                else:
                    secnum = secnumbers.get('')

                return secnum or tuple()

            def get_next_fignumber(figtype, secnum):
                counter = fignum_counter.setdefault(figtype, {})

                secnum = secnum[:self.config.numfig_secnum_depth]
                counter[secnum] = counter.get(secnum, 0) + 1
                return secnum + (counter[secnum],)

            def register_fignumber(docname, secnum, figtype, fignode):
                self.toc_fignumbers.setdefault(docname, {})
                fignumbers = self.toc_fignumbers[docname].setdefault(figtype, {})
                figure_id = fignode['ids'][0]

                fignumbers[figure_id] = get_next_fignumber(figtype, secnum)

            def _walk_doctree(docname, doctree, secnum):
                for subnode in doctree.children:
                    if isinstance(subnode, nodes.section):
                        next_secnum = get_section_number(docname, subnode)
                        if next_secnum:
                            _walk_doctree(docname, subnode, next_secnum)
                        else:
                            _walk_doctree(docname, subnode, secnum)
                        continue
                    elif isinstance(subnode, addnodes.toctree):
                        for title, subdocname in subnode['entries']:
                            if url_re.match(subdocname) or subdocname == 'self':
                                # don't mess with those
                                continue

                            _walk_doc(subdocname, secnum)

                        continue

                    figtype = self.domains['std'].get_figtype(subnode)
                    if figtype and subnode['ids']:
                        register_fignumber(docname, secnum, figtype, subnode)

                    _walk_doctree(docname, subnode, secnum)

            def _walk_doc(docname, secnum):
                if docname not in assigned:
                    assigned.add(docname)
                    doctree = self.get_doctree(docname)
                    _walk_doctree(docname, doctree, secnum)

            if self.config.numfig:
                _walk_doc(self.config.master_doc, tuple())
                for docname, fignums in iteritems(self.toc_fignumbers):
                    if fignums != old_fignumbers.get(docname):
                        rewrite_needed.append(docname)

            return rewrite_needed

        def create_index(self, builder, group_entries=True,
                         _fixre=re.compile(r'(.*) ([(][^()]*[)])')):
            """Create the real index from the collected index entries."""
            new = {}

            def add_entry(word, subword, link=True, dic=new, key=None):
                # Force the word to be unicode if it's a ASCII bytestring.
                # This will solve problems with unicode normalization later.
                # For instance the RFC role will add bytestrings at the moment
                word = text_type(word)
                entry = dic.get(word)
                if not entry:
                    dic[word] = entry = [[], {}, key]
                if subword:
                    add_entry(subword, '', link=link, dic=entry[1], key=key)
                elif link:
                    try:
                        uri = builder.get_relative_uri('genindex', fn) + '#' + tid
                    except NoUri:
                        pass
                    else:
                        # maintain links in sorted/deterministic order
                        bisect.insort(entry[0], (main, uri))

            for fn, entries in iteritems(self.indexentries):
                # new entry types must be listed in directives/other.py!
                for type, value, tid, main, index_key in entries:
                    try:
                        if type == 'single':
                            try:
                                entry, subentry = split_into(2, 'single', value)
                            except ValueError:
                                entry, = split_into(1, 'single', value)
                                subentry = ''
                            add_entry(entry, subentry, key=index_key)
                        elif type == 'pair':
                            first, second = split_into(2, 'pair', value)
                            add_entry(first, second, key=index_key)
                            add_entry(second, first, key=index_key)
                        elif type == 'triple':
                            first, second, third = split_into(3, 'triple', value)
                            add_entry(first, second+' '+third, key=index_key)
                            add_entry(second, third+', '+first, key=index_key)
                            add_entry(third, first+' '+second, key=index_key)
                        elif type == 'see':
                            first, second = split_into(2, 'see', value)
                            add_entry(first, _('see %s') % second, link=False,
                                      key=index_key)
                        elif type == 'seealso':
                            first, second = split_into(2, 'see', value)
                            add_entry(first, _('see also %s') % second, link=False,
                                      key=index_key)
                        else:
                            self.warn(fn, 'unknown index entry type %r' % type)
                    except ValueError as err:
                        self.warn(fn, str(err))

            # sort the index entries; put all symbols at the front, even those
            # following the letters in ASCII, this is where the chr(127) comes from
            def keyfunc(entry, lcletters=string.ascii_lowercase + '_'):
                lckey = unicodedata.normalize('NFD', entry[0].lower())
                if lckey[0:1] in lcletters:
                    lckey = chr(127) + lckey
                # ensure a determinstic order *within* letters by also sorting on
                # the entry itself
                return (lckey, entry[0])
            newlist = sorted(new.items(), key=keyfunc)

            if group_entries:
                # fixup entries: transform
                #   func() (in module foo)
                #   func() (in module bar)
                # into
                #   func()
                #     (in module foo)
                #     (in module bar)
                oldkey = ''
                oldsubitems = None
                i = 0
                while i < len(newlist):
                    key, (targets, subitems, _key) = newlist[i]
                    # cannot move if it has subitems; structure gets too complex
                    if not subitems:
                        m = _fixre.match(key)
                        if m:
                            if oldkey == m.group(1):
                                # prefixes match: add entry as subitem of the
                                # previous entry
                                oldsubitems.setdefault(m.group(2), [[], {}, _key])[0].\
                                    extend(targets)
                                del newlist[i]
                                continue
                            oldkey = m.group(1)
                        else:
                            oldkey = key
                    oldsubitems = subitems
                    i += 1

            # group the entries by letter
            def keyfunc2(item, letters=string.ascii_uppercase + '_'):
                # hack: mutating the subitems dicts to a list in the keyfunc
                k, v = item
                v[1] = sorted((si, se) for (si, (se, void, void)) in iteritems(v[1]))
                if v[2] is None:
                    # now calculate the key
                    letter = unicodedata.normalize('NFD', k[0])[0].upper()
                    if letter in letters:
                        return letter
                    else:
                        # get all other symbols under one heading
                        return _('Symbols')
                else:
                    return v[2]
            return [(key_, list(group))
                    for (key_, group) in groupby(newlist, keyfunc2)]

        def collect_relations(self):
            traversed = set()

            def traverse_toctree(parent, docname):
                # 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):
            """Do consistency checks."""
            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 'orphan' in self.metadata[docname]:
                        continue
                    self.warn(docname, 'document isn\'t included in any toctree')