text: # Copyright 2013-2018 Lawrence Livermore National Security, LLC and other
  # Spack Project Developers. See the top-level COPYRIGHT file for details.
  #
  # SPDX-License-Identifier: (Apache-2.0 OR MIT)
  
  """This module implements Spack's configuration file handling.
  
  This implements Spack's configuration system, which handles merging
  multiple scopes with different levels of precedence.  See the
  documentation on :ref:`configuration-scopes` for details on how Spack's
  configuration system behaves.  The scopes are:
  
    #. ``default``
    #. ``system``
    #. ``site``
    #. ``user``
  
  And corresponding :ref:`per-platform scopes <platform-scopes>`. Important
  functions in this module are:
  
  * :py:func:`get_config`
  * :py:func:`update_config`
  
  ``get_config`` reads in YAML data for a particular scope and returns
  it. Callers can then modify the data and write it back with
  ``update_config``.
  
  When read in, Spack validates configurations with jsonschemas.  The
  schemas are in submodules of :py:mod:`spack.schema`.
  
  """
  
  import copy
  import os
  import re
  import sys
  import multiprocessing
  from contextlib import contextmanager
  from six import string_types
  from six import iteritems
  from ordereddict_backport import OrderedDict
  
  import ruamel.yaml as yaml
  from ruamel.yaml.error import MarkedYAMLError
  
  import llnl.util.lang
  import llnl.util.tty as tty
  from llnl.util.filesystem import mkdirp
  
  import spack.paths
  import spack.architecture
  import spack.schema.compilers
  import spack.schema.mirrors
  import spack.schema.repos
  import spack.schema.packages
  import spack.schema.modules
  import spack.schema.config
  from spack.error import SpackError
  
  # Hacked yaml for configuration files preserves line numbers.
  import spack.util.spack_yaml as syaml
  
  
  #: Dict from section names -> schema for that section
  section_schemas = {
      'compilers': spack.schema.compilers.schema,
      'mirrors': spack.schema.mirrors.schema,
      'repos': spack.schema.repos.schema,
      'packages': spack.schema.packages.schema,
      'modules': spack.schema.modules.schema,
      'config': spack.schema.config.schema,
  }
  
  #: Builtin paths to configuration files in Spack
  configuration_paths = (
      # Default configuration scope is the lowest-level scope. These are
      # versioned with Spack and can be overridden by systems, sites or users
      ('defaults', os.path.join(spack.paths.etc_path, 'spack', 'defaults')),
  
      # System configuration is per machine.
      # No system-level configs should be checked into spack by default
      ('system', os.path.join(spack.paths.system_etc_path, 'spack')),
  
      # Site configuration is per spack instance, for sites or projects
      # No site-level configs should be checked into spack by default.
      ('site', os.path.join(spack.paths.etc_path, 'spack')),
  
      # User configuration can override both spack defaults and site config
      ('user', spack.paths.user_config_path)
  )
  
  #: Hard-coded default values for some key configuration options.
  #: This ensures that Spack will still work even if config.yaml in
  #: the defaults scope is removed.
  config_defaults = {
      'config': {
          'debug': False,
          'verify_ssl': True,
          'checksum': True,
          'dirty': False,
          'build_jobs': multiprocessing.cpu_count(),
      }
  }
  
  #: metavar to use for commands that accept scopes
  #: this is shorter and more readable than listing all choices
  scopes_metavar = '{defaults,system,site,user}[/PLATFORM]'
  
  
  def first_existing(dictionary, keys):
      """Get the value of the first key in keys that is in the dictionary."""
      try:
          return next(k for k in keys if k in dictionary)
      except StopIteration:
          raise KeyError("None of %s is in dict!" % keys)
  
  
  def _extend_with_default(validator_class):
      """Add support for the 'default' attr for properties and patternProperties.
  
         jsonschema does not handle this out of the box -- it only
         validates.  This allows us to set default values for configs
         where certain fields are `None` b/c they're deleted or
         commented out.
  
      """
      import jsonschema
      validate_properties = validator_class.VALIDATORS["properties"]
      validate_pattern_properties = validator_class.VALIDATORS[
          "patternProperties"]
  
      def set_defaults(validator, properties, instance, schema):
          for property, subschema in iteritems(properties):
              if "default" in subschema:
                  instance.setdefault(
                      property, copy.deepcopy(subschema["default"]))
          for err in validate_properties(
                  validator, properties, instance, schema):
              yield err
  
      def set_pp_defaults(validator, properties, instance, schema):
          for property, subschema in iteritems(properties):
              if "default" in subschema:
                  if isinstance(instance, dict):
                      for key, val in iteritems(instance):
                          if re.match(property, key) and val is None:
                              instance[key] = copy.deepcopy(subschema["default"])
  
          for err in validate_pattern_properties(
                  validator, properties, instance, schema):
              yield err
  
      return jsonschema.validators.extend(validator_class, {
          "properties": set_defaults,
          "patternProperties": set_pp_defaults
      })
  
  
  class ConfigScope(object):
      """This class represents a configuration scope.
  
         A scope is one directory containing named configuration files.
         Each file is a config "section" (e.g., mirrors, compilers, etc).
      """
  
      def __init__(self, name, path):
          self.name = name           # scope name.
          self.path = path           # path to directory containing configs.
          self.sections = syaml.syaml_dict()  # sections read from config files.
  
      def get_section_filename(self, section):
          _validate_section_name(section)
          return os.path.join(self.path, "%s.yaml" % section)
  
      def get_section(self, section):
          if section not in self.sections:
              path   = self.get_section_filename(section)
              schema = section_schemas[section]
              data   = _read_config_file(path, schema)
              self.sections[section] = data
          return self.sections[section]
  
      def write_section(self, section):
          filename = self.get_section_filename(section)
          data = self.get_section(section)
          _validate(data, section_schemas[section])
  
          try:
              mkdirp(self.path)
              with open(filename, 'w') as f:
                  _validate(data, section_schemas[section])
                  syaml.dump(data, stream=f, default_flow_style=False)
          except (yaml.YAMLError, IOError) as e:
              raise ConfigFileError(
                  "Error writing to config file: '%s'" % str(e))
  
      def clear(self):
          """Empty cached config information."""
          self.sections = syaml.syaml_dict()
  
      def __repr__(self):
          return '<ConfigScope: %s: %s>' % (self.name, self.path)
  
  
  class SingleFileScope(ConfigScope):
      """This class represents a configuration scope in a single YAML file."""
      def __init__(self, name, path, schema, yaml_path=None):
          """Similar to ``ConfigScope`` but can be embedded in another schema.
  
          Arguments:
              schema (dict): jsonschema for the file to read
              yaml_path (list): list of dict keys in the schema where
                  config data can be found;
  
          Elements of ``yaml_path`` can be tuples or lists to represent an
          "or" of keys (e.g. "env" or "spack" is ``('env', 'spack')``)
  
          """
          super(SingleFileScope, self).__init__(name, path)
          self._raw_data = None
          self.schema = schema
          self.yaml_path = yaml_path or []
  
      def get_section_filename(self, section):
          return self.path
  
      def get_section(self, section):
          # read raw data from the file, which looks like:
          # {
          #   'config': {
          #      ... data ...
          #   },
          #   'packages': {
          #      ... data ...
          #   },
          # }
          if self._raw_data is None:
              self._raw_data = _read_config_file(self.path, self.schema)
              if self._raw_data is None:
                  return None
  
              for key in self.yaml_path:
                  if self._raw_data is None:
                      return None
  
                  # support tuples as "or" in the yaml path
                  if isinstance(key, (list, tuple)):
                      key = first_existing(self._raw_data, key)
  
                  self._raw_data = self._raw_data[key]
  
          # data in self.sections looks (awkwardly) like this:
          # {
          #   'config': {
          #      'config': {
          #         ... data ...
          #       }
          #   },
          #   'packages': {
          #      'packages': {
          #         ... data ...
          #      }
          #   }
          # }
          #
          # UNLESS there is no section, in which case it is stored as:
          # {
          #   'config': None,
          #   ...
          # }
          value = self._raw_data.get(section)
          self.sections.setdefault(
              section, None if value is None else {section: value})
          return self.sections[section]
  
      def write_section(self, section):
          _validate(self.sections, self.schema)
          try:
              parent = os.path.dirname(self.path)
              mkdirp(parent)
  
              tmp = os.path.join(parent, '.%s.tmp' % self.path)
              with open(tmp, 'w') as f:
                  syaml.dump(self.sections, stream=f, default_flow_style=False)
              os.path.move(tmp, self.path)
          except (yaml.YAMLError, IOError) as e:
              raise ConfigFileError(
                  "Error writing to config file: '%s'" % str(e))
  
      def __repr__(self):
          return '<SingleFileScope: %s: %s>' % (self.name, self.path)
  
  
  class ImmutableConfigScope(ConfigScope):
      """A configuration scope that cannot be written to.
  
      This is used for ConfigScopes passed on the command line.
      """
  
      def write_section(self, section):
          raise ConfigError("Cannot write to immutable scope %s" % self)
  
      def __repr__(self):
          return '<ImmutableConfigScope: %s: %s>' % (self.name, self.path)
  
  
  class InternalConfigScope(ConfigScope):
      """An internal configuration scope that is not persisted to a file.
  
      This is for spack internal use so that command-line options and
      config file settings are accessed the same way, and Spack can easily
      override settings from files.
      """
      def __init__(self, name, data=None):
          super(InternalConfigScope, self).__init__(name, None)
          self.sections = syaml.syaml_dict()
  
          if data:
              for section in data:
                  dsec = data[section]
                  _validate({section: dsec}, section_schemas[section])
                  self.sections[section] = _mark_internal(
                      syaml.syaml_dict({section: dsec}), name)
  
      def get_section_filename(self, section):
          raise NotImplementedError(
              "Cannot get filename for InternalConfigScope.")
  
      def get_section(self, section):
          """Just reads from an internal dictionary."""
          if section not in self.sections:
              self.sections[section] = None
          return self.sections[section]
  
      def write_section(self, section):
          """This only validates, as the data is already in memory."""
          data = self.get_section(section)
          if data is not None:
              _validate(data, section_schemas[section])
          self.sections[section] = _mark_internal(data, self.name)
  
      def __repr__(self):
          return '<InternalConfigScope: %s>' % self.name
  
  
  class Configuration(object):
      """A full Spack configuration, from a hierarchy of config files.
  
      This class makes it easy to add a new scope on top of an existing one.
      """
  
      def __init__(self, *scopes):
          """Initialize a configuration with an initial list of scopes.
  
          Args:
              scopes (list of ConfigScope): list of scopes to add to this
                  Configuration, ordered from lowest to highest precedence
  
          """
          self.scopes = OrderedDict()
          for scope in scopes:
              self.push_scope(scope)
  
      def push_scope(self, scope):
          """Add a higher precedence scope to the Configuration."""
          cmd_line_scope = None
          if self.scopes:
              highest_precedence_scope = list(self.scopes.values())[-1]
              if highest_precedence_scope.name == 'command_line':
                  # If the command-line scope is present, it should always
                  # be the scope of highest precedence
                  cmd_line_scope = self.pop_scope()
  
          self.scopes[scope.name] = scope
          if cmd_line_scope:
              self.scopes['command_line'] = cmd_line_scope
  
      def pop_scope(self):
          """Remove the highest precedence scope and return it."""
          name, scope = self.scopes.popitem(last=True)
          return scope
  
      def remove_scope(self, scope_name):
          return self.scopes.pop(scope_name)
  
      @property
      def file_scopes(self):
          """List of writable scopes with an associated file."""
          return [s for s in self.scopes.values() if type(s) == ConfigScope]
  
      def highest_precedence_scope(self):
          """Non-internal scope with highest precedence."""
          return next(reversed(self.file_scopes), None)
  
      def _validate_scope(self, scope):
          """Ensure that scope is valid in this configuration.
  
          This should be used by routines in ``config.py`` to validate
          scope name arguments, and to determine a default scope where no
          scope is specified.
  
          Raises:
              ValueError: if ``scope`` is not valid
  
          Returns:
              ConfigScope: a valid ConfigScope if ``scope`` is ``None`` or valid
          """
          if scope is None:
              # default to the scope with highest precedence.
              return self.highest_precedence_scope()
  
          elif scope in self.scopes:
              return self.scopes[scope]
  
          else:
              raise ValueError("Invalid config scope: '%s'.  Must be one of %s"
                               % (scope, self.scopes.keys()))
  
      def get_config_filename(self, scope, section):
          """For some scope and section, get the name of the configuration file.
          """
          scope = self._validate_scope(scope)
          return scope.get_section_filename(section)
  
      def clear_caches(self):
          """Clears the caches for configuration files,
  
          This will cause files to be re-read upon the next request."""
          for scope in self.scopes.values():
              scope.clear()
  
      def update_config(self, section, update_data, scope=None):
          """Update the configuration file for a particular scope.
  
          Overwrites contents of a section in a scope with update_data,
          then writes out the config file.
  
          update_data should have the top-level section name stripped off
          (it will be re-added).  Data itself can be a list, dict, or any
          other yaml-ish structure.
          """
          _validate_section_name(section)  # validate section name
          scope = self._validate_scope(scope)  # get ConfigScope object
  
          # read only the requested section's data.
          scope.sections[section] = {section: update_data}
          scope.write_section(section)
  
      def get_config(self, section, scope=None):
          """Get configuration settings for a section.
  
          If ``scope`` is ``None`` or not provided, return the merged contents
          of all of Spack's configuration scopes.  If ``scope`` is provided,
          return only the confiugration as specified in that scope.
  
          This off the top-level name from the YAML section.  That is, for a
          YAML config file that looks like this::
  
             config:
               install_tree: $spack/opt/spack
               module_roots:
                 lmod:   $spack/share/spack/lmod
  
          ``get_config('config')`` will return::
  
             { 'install_tree': '$spack/opt/spack',
               'module_roots: {
                   'lmod': '$spack/share/spack/lmod'
               }
             }
  
          """
          _validate_section_name(section)
  
          if scope is None:
              scopes = self.scopes.values()
          else:
              scopes = [self._validate_scope(scope)]
  
          merged_section = syaml.syaml_dict()
          for scope in scopes:
              # read potentially cached data from the scope.
  
              data = scope.get_section(section)
  
              # Skip empty configs
              if not data or not isinstance(data, dict):
                  continue
  
              if section not in data:
                  continue
  
              merged_section = _merge_yaml(merged_section, data)
  
          # no config files -- empty config.
          if section not in merged_section:
              return {}
  
          # take the top key off before returning.
          return merged_section[section]
  
      def get(self, path, default=None, scope=None):
          """Get a config section or a single value from one.
  
          Accepts a path syntax that allows us to grab nested config map
          entries.  Getting the 'config' section would look like::
  
              spack.config.get('config')
  
          and the ``dirty`` section in the ``config`` scope would be::
  
              spack.config.get('config:dirty')
  
          We use ``:`` as the separator, like YAML objects.
      """
          # TODO: Currently only handles maps. Think about lists if neded.
          section, _, rest = path.partition(':')
  
          value = self.get_config(section, scope=scope)
          if not rest:
              return value
  
          parts = rest.split(':')
          while parts:
              key = parts.pop(0)
              value = value.get(key, default)
  
          return value
  
      def set(self, path, value, scope=None):
          """Convenience function for setting single values in config files.
  
          Accepts the path syntax described in ``get()``.
          """
          section, _, rest = path.partition(':')
  
          if not rest:
              self.update_config(section, value, scope=scope)
          else:
              section_data = self.get_config(section, scope=scope)
  
              parts = rest.split(':')
              data = section_data
              while len(parts) > 1:
                  key = parts.pop(0)
                  data = data[key]
              data[parts[0]] = value
  
              self.update_config(section, section_data, scope=scope)
  
      def __iter__(self):
          """Iterate over scopes in this configuration."""
          for scope in self.scopes.values():
              yield scope
  
      def print_section(self, section, blame=False):
          """Print a configuration to stdout."""
          try:
              data = syaml.syaml_dict()
              data[section] = self.get_config(section)
              syaml.dump(
                  data, stream=sys.stdout, default_flow_style=False, blame=blame)
          except (yaml.YAMLError, IOError):
              raise ConfigError("Error reading configuration: %s" % section)
  
  
  @contextmanager
  def override(path_or_scope, value=None):
      """Simple way to override config settings within a context.
  
      Arguments:
          path_or_scope (ConfigScope or str): scope or single option to override
          value (object, optional): value for the single option
  
      Temporarily push a scope on the current configuration, then remove it
      after the context completes. If a single option is provided, create
      an internal config scope for it and push/pop that scope.
  
      """
      if isinstance(path_or_scope, ConfigScope):
          overrides = path_or_scope
          config.push_scope(path_or_scope)
      else:
          overrides = InternalConfigScope('overrides')
          config.push_scope(overrides)
          config.set(path_or_scope, value, scope='overrides')
  
      yield config
  
      scope = config.remove_scope(overrides.name)
      assert scope is overrides
  
  
  #: configuration scopes added on the command line
  #: set by ``spack.main.main()``.
  command_line_scopes = []
  
  
  def _add_platform_scope(cfg, scope_type, name, path):
      """Add a platform-specific subdirectory for the current platform."""
      platform = spack.architecture.platform().name
      plat_name = '%s/%s' % (name, platform)
      plat_path = os.path.join(path, platform)
      cfg.push_scope(scope_type(plat_name, plat_path))
  
  
  def _add_command_line_scopes(cfg, command_line_scopes):
      """Add additional scopes from the --config-scope argument.
  
      Command line scopes are named after their position in the arg list.
      """
      for i, path in enumerate(command_line_scopes):
          # We ensure that these scopes exist and are readable, as they are
          # provided on the command line by the user.
          if not os.path.isdir(path):
              raise ConfigError("config scope is not a directory: '%s'" % path)
          elif not os.access(path, os.R_OK):
              raise ConfigError("config scope is not readable: '%s'" % path)
  
          # name based on order on the command line
          name = 'cmd_scope_%d' % i
          cfg.push_scope(ImmutableConfigScope(name, path))
          _add_platform_scope(cfg, ImmutableConfigScope, name, path)
  
  
  def _config():
      """Singleton Configuration instance.
  
      This constructs one instance associated with this module and returns
      it. It is bundled inside a function so that configuratoin can be
      initialized lazily.
  
      Return:
          (Configuration): object for accessing spack configuration
  
      """
      cfg = Configuration()
  
      # first do the builtin, hardcoded defaults
      defaults = InternalConfigScope('_builtin', config_defaults)
      cfg.push_scope(defaults)
  
      # add each scope and its platform-specific directory
      for name, path in configuration_paths:
          cfg.push_scope(ConfigScope(name, path))
  
          # Each scope can have per-platfom overrides in subdirectories
          _add_platform_scope(cfg, ConfigScope, name, path)
  
      # add command-line scopes
      _add_command_line_scopes(cfg, command_line_scopes)
  
      # we make a special scope for spack commands so that they can
      # override configuration options.
      cfg.push_scope(InternalConfigScope('command_line'))
  
      return cfg
  
  
  #: This is the singleton configuration instance for Spack.
  config = llnl.util.lang.Singleton(_config)
  
  
  def get(path, default=None, scope=None):
      """Module-level wrapper for ``Configuration.get()``."""
      return config.get(path, default, scope)
  
  
  def set(path, value, scope=None):
      """Convenience function for getting single values in config files.
  
      Accepts the path syntax described in ``get()``.
      """
      return config.set(path, value, scope)
  
  
  def scopes():
      """Convenience function to get list of configuration scopes."""
      return config.scopes
  
  
  def _validate_section_name(section):
      """Exit if the section is not a valid section."""
      if section not in section_schemas:
          raise ConfigSectionError(
              "Invalid config section: '%s'. Options are: %s"
              % (section, " ".join(section_schemas.keys())))
  
  
  def _validate(data, schema, set_defaults=True):
      """Validate data read in from a Spack YAML file.
  
      Arguments:
          data (dict or list): data read from a Spack YAML file
          schema (dict or list): jsonschema to validate data
          set_defaults (bool): whether to set defaults based on the schema
  
      This leverages the line information (start_mark, end_mark) stored
      on Spack YAML structures.
  
      """
      import jsonschema
  
      if not hasattr(_validate, 'validator'):
          default_setting_validator = _extend_with_default(
              jsonschema.Draft4Validator)
          _validate.validator = default_setting_validator
  
      try:
          _validate.validator(schema).validate(data)
      except jsonschema.ValidationError as e:
          raise ConfigFormatError(e, data)
  
  
  def _read_config_file(filename, schema):
      """Read a YAML configuration file."""
      # Ignore nonexisting files.
      if not os.path.exists(filename):
          return None
  
      elif not os.path.isfile(filename):
          raise ConfigFileError(
              "Invalid configuration. %s exists but is not a file." % filename)
  
      elif not os.access(filename, os.R_OK):
          raise ConfigFileError("Config file is not readable: %s" % filename)
  
      try:
          tty.debug("Reading config file %s" % filename)
          with open(filename) as f:
              data = _mark_overrides(syaml.load(f))
  
          if data:
              _validate(data, schema)
          return data
  
      except MarkedYAMLError as e:
          raise ConfigFileError(
              "Error parsing yaml%s: %s" % (str(e.context_mark), e.problem))
  
      except IOError as e:
          raise ConfigFileError(
              "Error reading configuration file %s: %s" % (filename, str(e)))
  
  
  def _override(string):
      """Test if a spack YAML string is an override.
  
      See ``spack_yaml`` for details.  Keys in Spack YAML can end in `::`,
      and if they do, their values completely replace lower-precedence
      configs instead of merging into them.
  
      """
      return hasattr(string, 'override') and string.override
  
  
  def _mark_overrides(data):
      if isinstance(data, list):
          return syaml.syaml_list(_mark_overrides(elt) for elt in data)
  
      elif isinstance(data, dict):
          marked = syaml.syaml_dict()
          for key, val in iteritems(data):
              if isinstance(key, string_types) and key.endswith(':'):
                  key = syaml.syaml_str(key[:-1])
                  key.override = True
              marked[key] = _mark_overrides(val)
          return marked
  
      else:
          return data
  
  
  def _mark_internal(data, name):
      """Add a simple name mark to raw YAML/JSON data.
  
      This is used by `spack config blame` to show where config lines came from.
      """
      if isinstance(data, dict):
          d = syaml.syaml_dict((_mark_internal(k, name), _mark_internal(v, name))
                               for k, v in data.items())
      elif isinstance(data, list):
          d = syaml.syaml_list(_mark_internal(e, name) for e in data)
      else:
          d = syaml.syaml_type(data)
  
      if syaml.markable(d):
          d._start_mark = yaml.Mark(name, None, None, None, None, None)
          d._end_mark = yaml.Mark(name, None, None, None, None, None)
  
      return d
  
  
  def _merge_yaml(dest, source):
      """Merges source into dest; entries in source take precedence over dest.
  
      This routine may modify dest and should be assigned to dest, in
      case dest was None to begin with, e.g.:
  
         dest = _merge_yaml(dest, source)
  
      Config file authors can optionally end any attribute in a dict
      with `::` instead of `:`, and the key will override that of the
      parent instead of merging.
  
      """
      def they_are(t):
          return isinstance(dest, t) and isinstance(source, t)
  
      # If both are None, handle specially and return None.
      if source is None and dest is None:
          return None
  
      # If source is None, overwrite with source.
      elif source is None:
          return None
  
      # Source list is prepended (for precedence)
      if they_are(list):
          dest[:] = source + [x for x in dest if x not in source]
          return dest
  
      # Source dict is merged into dest.
      elif they_are(dict):
          # track keys for marking
          key_marks = {}
  
          for sk, sv in iteritems(source):
              if _override(sk) or sk not in dest:
                  # if sk ended with ::, or if it's new, completely override
                  dest[sk] = copy.copy(sv)
              else:
                  # otherwise, merge the YAML
                  dest[sk] = _merge_yaml(dest[sk], source[sk])
  
              # this seems unintuitive, but see below. We need this because
              # Python dicts do not overwrite keys on insert, and we want
              # to copy mark information on source keys to dest.
              key_marks[sk] = sk
  
          # ensure that keys are marked in the destination.  the key_marks dict
          # ensures we can get the actual source key objects from dest keys
          for dk in dest.keys():
              if dk in key_marks:
                  syaml.mark(dk, key_marks[dk])
  
          return dest
  
      # In any other case, overwrite with a copy of the source value.
      else:
          return copy.copy(source)
  
  
  #
  # Settings for commands that modify configuration
  #
  def default_modify_scope():
      """Return the config scope that commands should modify by default.
  
      Commands that modify configuration by default modify the *highest*
      priority scope.
      """
      return spack.config.config.highest_precedence_scope().name
  
  
  def default_list_scope():
      """Return the config scope that is listed by default.
  
      Commands that list configuration list *all* scopes (merged) by default.
      """
      return None
  
  
  class ConfigError(SpackError):
      """Superclass for all Spack config related errors."""
  
  
  class ConfigSectionError(ConfigError):
      """Error for referring to a bad config section name in a configuration."""
  
  
  class ConfigFileError(ConfigError):
      """Issue reading or accessing a configuration file."""
  
  
  class ConfigFormatError(ConfigError):
      """Raised when a configuration format does not match its schema."""
  
      def __init__(self, validation_error, data, filename=None, line=None):
          self.filename = filename  # record this for ruamel.yaml
  
          location = '<unknown file>'
  
          # spack yaml has its own file/line marks -- try to find them
          if not filename and not line:
              mark = self._get_mark(validation_error, data)
              if mark:
                  filename = mark.name
                  line = mark.line + 1
  
          if filename:
              location = '%s' % filename
          if line is not None:
              location += ':%d' % line
  
          message = '%s: %s' % (location, validation_error.message)
          super(ConfigError, self).__init__(message)
  
      def _get_mark(self, validation_error, data):
          """Get the file/line mark fo a validation error from a Spack YAML file.
          """
          def _get_mark_or_first_member_mark(obj):
              # mark of object itelf
              mark = getattr(obj, '_start_mark', None)
              if mark:
                  return mark
  
              # mark of first member if it is a container
              if isinstance(obj, (list, dict)):
                  first_member = next(iter(obj), None)
                  if first_member:
                      mark = getattr(first_member, '_start_mark', None)
                      if mark:
                          return mark
  
          # Try various places, starting with instance and parent
          for obj in (validation_error.instance, validation_error.parent):
              mark = _get_mark_or_first_member_mark(obj)
              if mark:
                  return mark
  
          def get_path(path, data):
              if path:
                  return get_path(path[1:], data[path[0]])
              else:
                  return data
  
          # Try really hard to get the parent (which sometimes is not
          # set) This digs it out of the validated structure if it's not
          # on the validation_error.
          path = validation_error.path
          if path:
              parent = get_path(list(path)[:-1], data)
              if path[-1] in parent:
                  if isinstance(parent, dict):
                      keylist = list(parent.keys())
                  elif isinstance(parent, list):
                      keylist = parent
                  idx = keylist.index(path[-1])
                  mark = getattr(keylist[idx], '_start_mark', None)
                  if mark:
                      return mark
  
          # give up and return None if nothing worked
          return None
  