text: """SCons.Scanner
  
  The Scanner package for the SCons software construction utility.
  
  """
  
  #
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  # a copy of this software and associated documentation files (the
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  # permit persons to whom the Software is furnished to do so, subject to
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  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
  # KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
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  # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  # LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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  __revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"
  
  import re
  
  import SCons.Node.FS
  import SCons.Util
  
  
  class _Null(object):
      pass
  
  # This is used instead of None as a default argument value so None can be
  # used as an actual argument value.
  _null = _Null
  
  def Scanner(function, *args, **kw):
      """
      Public interface factory function for creating different types
      of Scanners based on the different types of "functions" that may
      be supplied.
  
      TODO:  Deprecate this some day.  We've moved the functionality
      inside the Base class and really don't need this factory function
      any more.  It was, however, used by some of our Tool modules, so
      the call probably ended up in various people's custom modules
      patterned on SCons code.
      """
      if SCons.Util.is_Dict(function):
          return Selector(function, *args, **kw)
      else:
          return Base(function, *args, **kw)
  
  
  
  class FindPathDirs(object):
      """A class to bind a specific *PATH variable name to a function that
      will return all of the *path directories."""
      def __init__(self, variable):
          self.variable = variable
      def __call__(self, env, dir=None, target=None, source=None, argument=None):
          import SCons.PathList
          try:
              path = env[self.variable]
          except KeyError:
              return ()
  
          dir = dir or env.fs._cwd
          path = SCons.PathList.PathList(path).subst_path(env, target, source)
          return tuple(dir.Rfindalldirs(path))
  
  
  
  class Base(object):
      """
      The base class for dependency scanners.  This implements
      straightforward, single-pass scanning of a single file.
      """
  
      def __init__(self,
                   function,
                   name = "NONE",
                   argument = _null,
                   skeys = _null,
                   path_function = None,
                   # Node.FS.Base so that, by default, it's okay for a
                   # scanner to return a Dir, File or Entry.
                   node_class = SCons.Node.FS.Base,
                   node_factory = None,
                   scan_check = None,
                   recursive = None):
          """
          Construct a new scanner object given a scanner function.
  
          'function' - a scanner function taking two or three
          arguments and returning a list of strings.
  
          'name' - a name for identifying this scanner object.
  
          'argument' - an optional argument that, if specified, will be
          passed to both the scanner function and the path_function.
  
          'skeys' - an optional list argument that can be used to determine
          which scanner should be used for a given Node. In the case of File
          nodes, for example, the 'skeys' would be file suffixes.
  
          'path_function' - a function that takes four or five arguments
          (a construction environment, Node for the directory containing
          the SConscript file that defined the primary target, list of
          target nodes, list of source nodes, and optional argument for
          this instance) and returns a tuple of the directories that can
          be searched for implicit dependency files.  May also return a
          callable() which is called with no args and returns the tuple
          (supporting Bindable class).
  
          'node_class' - the class of Nodes which this scan will return.
          If node_class is None, then this scanner will not enforce any
          Node conversion and will return the raw results from the
          underlying scanner function.
  
          'node_factory' - the factory function to be called to translate
          the raw results returned by the scanner function into the
          expected node_class objects.
  
          'scan_check' - a function to be called to first check whether
          this node really needs to be scanned.
  
          'recursive' - specifies that this scanner should be invoked
          recursively on all of the implicit dependencies it returns
          (the canonical example being #include lines in C source files).
          May be a callable, which will be called to filter the list
          of nodes found to select a subset for recursive scanning
          (the canonical example being only recursively scanning
          subdirectories within a directory).
  
          The scanner function's first argument will be a Node that should
          be scanned for dependencies, the second argument will be an
          Environment object, the third argument will be the tuple of paths
          returned by the path_function, and the fourth argument will be
          the value passed into 'argument', and the returned list should
          contain the Nodes for all the direct dependencies of the file.
  
          Examples:
  
          s = Scanner(my_scanner_function)
  
          s = Scanner(function = my_scanner_function)
  
          s = Scanner(function = my_scanner_function, argument = 'foo')
  
          """
  
          # Note: this class could easily work with scanner functions that take
          # something other than a filename as an argument (e.g. a database
          # node) and a dependencies list that aren't file names. All that
          # would need to be changed is the documentation.
  
          self.function = function
          self.path_function = path_function
          self.name = name
          self.argument = argument
  
          if skeys is _null:
              if SCons.Util.is_Dict(function):
                  skeys = list(function.keys())
              else:
                  skeys = []
          self.skeys = skeys
  
          self.node_class = node_class
          self.node_factory = node_factory
          self.scan_check = scan_check
          if callable(recursive):
              self.recurse_nodes = recursive
          elif recursive:
              self.recurse_nodes = self._recurse_all_nodes
          else:
              self.recurse_nodes = self._recurse_no_nodes
  
      def path(self, env, dir=None, target=None, source=None):
          if not self.path_function:
              return ()
          if not self.argument is _null:
              return self.path_function(env, dir, target, source, self.argument)
          else:
              return self.path_function(env, dir, target, source)
  
      def __call__(self, node, env, path = ()):
          """
          This method scans a single object. 'node' is the node
          that will be passed to the scanner function, and 'env' is the
          environment that will be passed to the scanner function. A list of
          direct dependency nodes for the specified node will be returned.
          """
          if self.scan_check and not self.scan_check(node, env):
              return []
  
          self = self.select(node)
  
          if not self.argument is _null:
              list = self.function(node, env, path, self.argument)
          else:
              list = self.function(node, env, path)
  
          kw = {}
          if hasattr(node, 'dir'):
              kw['directory'] = node.dir
          node_factory = env.get_factory(self.node_factory)
          nodes = []
          for l in list:
              if self.node_class and not isinstance(l, self.node_class):
                  l = node_factory(l, **kw)
              nodes.append(l)
          return nodes
  
      def __cmp__(self, other):
          try:
              return cmp(self.__dict__, other.__dict__)
          except AttributeError:
              # other probably doesn't have a __dict__
              return cmp(self.__dict__, other)
  
      def __hash__(self):
          return id(self)
  
      def __str__(self):
          return self.name
  
      def add_skey(self, skey):
          """Add a skey to the list of skeys"""
          self.skeys.append(skey)
  
      def get_skeys(self, env=None):
          if env and SCons.Util.is_String(self.skeys):
              return env.subst_list(self.skeys)[0]
          return self.skeys
  
      def select(self, node):
          if SCons.Util.is_Dict(self.function):
              key = node.scanner_key()
              try:
                  return self.function[key]
              except KeyError:
                  return None
          else:
              return self
  
      def _recurse_all_nodes(self, nodes):
          return nodes
  
      def _recurse_no_nodes(self, nodes):
          return []
  
      recurse_nodes = _recurse_no_nodes
  
      def add_scanner(self, skey, scanner):
          self.function[skey] = scanner
          self.add_skey(skey)
  
  
  class Selector(Base):
      """
      A class for selecting a more specific scanner based on the
      scanner_key() (suffix) for a specific Node.
  
      TODO:  This functionality has been moved into the inner workings of
      the Base class, and this class will be deprecated at some point.
      (It was never exposed directly as part of the public interface,
      although it is used by the Scanner() factory function that was
      used by various Tool modules and therefore was likely a template
      for custom modules that may be out there.)
      """
      def __init__(self, dict, *args, **kw):
          Base.__init__(self, None, *args, **kw)
          self.dict = dict
          self.skeys = list(dict.keys())
  
      def __call__(self, node, env, path = ()):
          return self.select(node)(node, env, path)
  
      def select(self, node):
          try:
              return self.dict[node.scanner_key()]
          except KeyError:
              return None
  
      def add_scanner(self, skey, scanner):
          self.dict[skey] = scanner
          self.add_skey(skey)
  
  
  class Current(Base):
      """
      A class for scanning files that are source files (have no builder)
      or are derived files and are current (which implies that they exist,
      either locally or in a repository).
      """
  
      def __init__(self, *args, **kw):
          def current_check(node, env):
              return not node.has_builder() or node.is_up_to_date()
          kw['scan_check'] = current_check
          Base.__init__(self, *args, **kw)
  
  class Classic(Current):
      """
      A Scanner subclass to contain the common logic for classic CPP-style
      include scanning, but which can be customized to use different
      regular expressions to find the includes.
  
      Note that in order for this to work "out of the box" (without
      overriding the find_include() and sort_key() methods), the regular
      expression passed to the constructor must return the name of the
      include file in group 0.
      """
  
      def __init__(self, name, suffixes, path_variable, regex, *args, **kw):
  
          self.cre = re.compile(regex, re.M)
  
          def _scan(node, env, path=(), self=self):
              node = node.rfile()
              if not node.exists():
                  return []
              return self.scan(node, path)
  
          kw['function'] = _scan
          kw['path_function'] = FindPathDirs(path_variable)
          kw['recursive'] = 1
          kw['skeys'] = suffixes
          kw['name'] = name
  
          Current.__init__(self, *args, **kw)
  
      def find_include(self, include, source_dir, path):
          n = SCons.Node.FS.find_file(include, (source_dir,) + tuple(path))
          return n, include
  
      def sort_key(self, include):
          return SCons.Node.FS._my_normcase(include)
  
      def find_include_names(self, node):
          return self.cre.findall(node.get_text_contents())
  
      def scan(self, node, path=()):
  
          # cache the includes list in node so we only scan it once:
          if node.includes is not None:
              includes = node.includes
          else:
              includes = self.find_include_names (node)
              # Intern the names of the include files. Saves some memory
              # if the same header is included many times.
              node.includes = list(map(SCons.Util.silent_intern, includes))
  
          # This is a hand-coded DSU (decorate-sort-undecorate, or
          # Schwartzian transform) pattern.  The sort key is the raw name
          # of the file as specifed on the #include line (including the
          # " or <, since that may affect what file is found), which lets
          # us keep the sort order constant regardless of whether the file
          # is actually found in a Repository or locally.
          nodes = []
          source_dir = node.get_dir()
          if callable(path):
              path = path()
          for include in includes:
              n, i = self.find_include(include, source_dir, path)
  
              if n is None:
                  SCons.Warnings.warn(SCons.Warnings.DependencyWarning,
                                      "No dependency generated for file: %s (included from: %s) -- file not found" % (i, node))
              else:
                  nodes.append((self.sort_key(include), n))
  
          return [pair[1] for pair in sorted(nodes)]
  
  class ClassicCPP(Classic):
      """
      A Classic Scanner subclass which takes into account the type of
      bracketing used to include the file, and uses classic CPP rules
      for searching for the files based on the bracketing.
  
      Note that in order for this to work, the regular expression passed
      to the constructor must return the leading bracket in group 0, and
      the contained filename in group 1.
      """
      def find_include(self, include, source_dir, path):
          if include[0] == '"':
              paths = (source_dir,) + tuple(path)
          else:
              paths = tuple(path) + (source_dir,)
  
          n = SCons.Node.FS.find_file(include[1], paths)
  
          i = SCons.Util.silent_intern(include[1])
          return n, i
  
      def sort_key(self, include):
          return SCons.Node.FS._my_normcase(' '.join(include))
  
  # Local Variables:
  # tab-width:4
  # indent-tabs-mode:nil
  # End:
  # vim: set expandtab tabstop=4 shiftwidth=4:
  