text: # -*- coding: utf-8 -*-
  """
      ast
      ~~~
  
      The `ast` module helps Python applications to process trees of the Python
      abstract syntax grammar.  The abstract syntax itself might change with
      each Python release; this module helps to find out programmatically what
      the current grammar looks like and allows modifications of it.
  
      An abstract syntax tree can be generated by passing `ast.PyCF_ONLY_AST` as
      a flag to the `compile()` builtin function or by using the `parse()`
      function from this module.  The result will be a tree of objects whose
      classes all inherit from `ast.AST`.
  
      A modified abstract syntax tree can be compiled into a Python code object
      using the built-in `compile()` function.
  
      Additionally various helper functions are provided that make working with
      the trees simpler.  The main intention of the helper functions and this
      module in general is to provide an easy to use interface for libraries
      that work tightly with the python syntax (template engines for example).
  
  
      :copyright: Copyright 2008 by Armin Ronacher.
                  Modified 2013 by Roger Lew for undaqTools
                  
      :license: Python License.
  """
  from _ast import *
  
  from six import string_types
  
  try:
      from _ast import __version__
  except:
      __version = None
      
  from undaqTools.element import FrameSlice, FrameIndex
  
  
  def parse(source, filename='<unknown>', mode='exec'):
      """
      Parse the source into an AST node.
      Equivalent to compile(source, filename, mode, PyCF_ONLY_AST).
      """
      return compile(source, filename, mode, PyCF_ONLY_AST)
  
  
  ### Added for undaqTools ####
  def _literal_repr(strng):
      """
      returns a repr string for exporting etc values to hdf5.
  
      essential makes something like:
          FrameSlice(start=300, stop=800, step=None)
      into:
          ('fslice', 300, 800, None)
  
      and something like:
          FrameIndex(frame=300)
      into:
          ('findex', 300)
  
      since the resulting strings are evaluataed as tuples it makes
      undaqtools.ast._literal_eval happy.
  
      In _literal_eval when we find a tuple we check to see if it should
      be recast as a FrameSlice or FrameIndex.
  
      voila!
      A safe pseudo _literal_eval with with strictly specified non-literal types
      """
      return repr(strng).replace('FrameSlice(start=', '("fslice", ') \
                        .replace('stop=', '') \
                        .replace('step=','') \
                        .replace('FrameIndex(frame=', '("findex", ')
  
  ### modified for undaqTools ###
  def _literal_eval(node_or_string):
      """
      Safely evaluate an expression node or a string containing a Python
      expression.  The string or node provided may only consist of the following
      Python literal structures (strings, numbers, tuples, lists, dicts, booleans,
      and None) and undaqTools FrameSlice and FrameIndex objects.
      """
      _safe_names = {'None': None, 'True': True, 'False': False}
      if isinstance(node_or_string, string_types):
          node_or_string = parse(node_or_string, mode='eval')
      if isinstance(node_or_string, Expression):
          node_or_string = node_or_string.body
      def _convert(node):
          if isinstance(node, Str):
              return node.s
          elif isinstance(node, Num):
              return node.n
          elif isinstance(node, Tuple):
              ### lines added to handle FrameSlice and FrameIndex objects ###
              obj = tuple(map(_convert, node.elts))
              if obj[0] == 'fslice':
                  obj = FrameSlice(*obj[1:])
              elif obj[0] == 'findex':
                  obj = FrameIndex(obj[1])
              return obj
              ###############################################################
          elif isinstance(node, List):
              return list(map(_convert, node.elts))
          elif isinstance(node, Dict):
              return dict((_convert(k), _convert(v)) for k, v
                          in zip(node.keys, node.values))
          elif isinstance(node, Name):
              if node.id in _safe_names:
                  return _safe_names[node.id]
          elif isinstance(node, BinOp) and \
               isinstance(node.op, (Add, Sub)) and \
               isinstance(node.right, Num) and \
               isinstance(node.right.n, complex) and \
               isinstance(node.left, Num) and \
               isinstance(node.left.n, (int, long, float)):
              left = node.left.n
              right = node.right.n
              if isinstance(node.op, Add):
                  return left + right
              else:
                  return left - right
          raise ValueError('malformed string')
      return _convert(node_or_string)
  
  
  def dump(node, annotate_fields=True, include_attributes=False):
      """
      Return a formatted dump of the tree in *node*.  This is mainly useful for
      debugging purposes.  The returned string will show the names and the values
      for fields.  This makes the code impossible to evaluate, so if evaluation is
      wanted *annotate_fields* must be set to False.  Attributes such as line
      numbers and column offsets are not dumped by default.  If this is wanted,
      *include_attributes* can be set to True.
      """
      def _format(node):
          if isinstance(node, AST):
              fields = [(a, _format(b)) for a, b in iter_fields(node)]
              rv = '%s(%s' % (node.__class__.__name__, ', '.join(
                  ('%s=%s' % field for field in fields)
                  if annotate_fields else
                  (b for a, b in fields)
              ))
              if include_attributes and node._attributes:
                  rv += fields and ', ' or ' '
                  rv += ', '.join('%s=%s' % (a, _format(getattr(node, a)))
                                  for a in node._attributes)
              return rv + ')'
          elif isinstance(node, list):
              return '[%s]' % ', '.join(_format(x) for x in node)
          return repr(node)
      if not isinstance(node, AST):
          raise TypeError('expected AST, got %r' % node.__class__.__name__)
      return _format(node)
  
  
  def copy_location(new_node, old_node):
      """
      Copy source location (`lineno` and `col_offset` attributes) from
      *old_node* to *new_node* if possible, and return *new_node*.
      """
      for attr in 'lineno', 'col_offset':
          if attr in old_node._attributes and attr in new_node._attributes \
             and hasattr(old_node, attr):
              setattr(new_node, attr, getattr(old_node, attr))
      return new_node
  
  
  def fix_missing_locations(node):
      """
      When you compile a node tree with compile(), the compiler expects lineno and
      col_offset attributes for every node that supports them.  This is rather
      tedious to fill in for generated nodes, so this helper adds these attributes
      recursively where not already set, by setting them to the values of the
      parent node.  It works recursively starting at *node*.
      """
      def _fix(node, lineno, col_offset):
          if 'lineno' in node._attributes:
              if not hasattr(node, 'lineno'):
                  node.lineno = lineno
              else:
                  lineno = node.lineno
          if 'col_offset' in node._attributes:
              if not hasattr(node, 'col_offset'):
                  node.col_offset = col_offset
              else:
                  col_offset = node.col_offset
          for child in iter_child_nodes(node):
              _fix(child, lineno, col_offset)
      _fix(node, 1, 0)
      return node
  
  
  def increment_lineno(node, n=1):
      """
      Increment the line number of each node in the tree starting at *node* by *n*.
      This is useful to "move code" to a different location in a file.
      """
      for child in walk(node):
          if 'lineno' in child._attributes:
              child.lineno = getattr(child, 'lineno', 0) + n
      return node
  
  
  def iter_fields(node):
      """
      Yield a tuple of ``(fieldname, value)`` for each field in ``node._fields``
      that is present on *node*.
      """
      for field in node._fields:
          try:
              yield field, getattr(node, field)
          except AttributeError:
              pass
  
  
  def iter_child_nodes(node):
      """
      Yield all direct child nodes of *node*, that is, all fields that are nodes
      and all items of fields that are lists of nodes.
      """
      for name, field in iter_fields(node):
          if isinstance(field, AST):
              yield field
          elif isinstance(field, list):
              for item in field:
                  if isinstance(item, AST):
                      yield item
  
  
  def get_docstring(node, clean=True):
      """
      Return the docstring for the given node or None if no docstring can
      be found.  If the node provided does not have docstrings a TypeError
      will be raised.
      """
      if not isinstance(node, (FunctionDef, ClassDef, Module)):
          raise TypeError("%r can't have docstrings" % node.__class__.__name__)
      if node.body and isinstance(node.body[0], Expr) and \
         isinstance(node.body[0].value, Str):
          if clean:
              import inspect
              return inspect.cleandoc(node.body[0].value.s)
          return node.body[0].value.s
  
  
  def walk(node):
      """
      Recursively yield all descendant nodes in the tree starting at *node*
      (including *node* itself), in no specified order.  This is useful if you
      only want to modify nodes in place and don't care about the context.
      """
      from collections import deque
      todo = deque([node])
      while todo:
          node = todo.popleft()
          todo.extend(iter_child_nodes(node))
          yield node
  
  
  class NodeVisitor(object):
      """
      A node visitor base class that walks the abstract syntax tree and calls a
      visitor function for every node found.  This function may return a value
      which is forwarded by the `visit` method.
  
      This class is meant to be subclassed, with the subclass adding visitor
      methods.
  
      Per default the visitor functions for the nodes are ``'visit_'`` +
      class name of the node.  So a `TryFinally` node visit function would
      be `visit_TryFinally`.  This behavior can be changed by overriding
      the `visit` method.  If no visitor function exists for a node
      (return value `None`) the `generic_visit` visitor is used instead.
  
      Don't use the `NodeVisitor` if you want to apply changes to nodes during
      traversing.  For this a special visitor exists (`NodeTransformer`) that
      allows modifications.
      """
  
      def visit(self, node):
          """Visit a node."""
          method = 'visit_' + node.__class__.__name__
          visitor = getattr(self, method, self.generic_visit)
          return visitor(node)
  
      def generic_visit(self, node):
          """Called if no explicit visitor function exists for a node."""
          for field, value in iter_fields(node):
              if isinstance(value, list):
                  for item in value:
                      if isinstance(item, AST):
                          self.visit(item)
              elif isinstance(value, AST):
                  self.visit(value)
  
  
  class NodeTransformer(NodeVisitor):
      """
      A :class:`NodeVisitor` subclass that walks the abstract syntax tree and
      allows modification of nodes.
  
      The `NodeTransformer` will walk the AST and use the return value of the
      visitor methods to replace or remove the old node.  If the return value of
      the visitor method is ``None``, the node will be removed from its location,
      otherwise it is replaced with the return value.  The return value may be the
      original node in which case no replacement takes place.
  
      Here is an example transformer that rewrites all occurrences of name lookups
      (``foo``) to ``data['foo']``::
  
         class RewriteName(NodeTransformer):
  
             def visit_Name(self, node):
                 return copy_location(Subscript(
                     value=Name(id='data', ctx=Load()),
                     slice=Index(value=Str(s=node.id)),
                     ctx=node.ctx
                 ), node)
  
      Keep in mind that if the node you're operating on has child nodes you must
      either transform the child nodes yourself or call the :meth:`generic_visit`
      method for the node first.
  
      For nodes that were part of a collection of statements (that applies to all
      statement nodes), the visitor may also return a list of nodes rather than
      just a single node.
  
      Usually you use the transformer like this::
  
         node = YourTransformer().visit(node)
      """
  
      def generic_visit(self, node):
          for field, old_value in iter_fields(node):
              old_value = getattr(node, field, None)
              if isinstance(old_value, list):
                  new_values = []
                  for value in old_value:
                      if isinstance(value, AST):
                          value = self.visit(value)
                          if value is None:
                              continue
                          elif not isinstance(value, AST):
                              new_values.extend(value)
                              continue
                      new_values.append(value)
                  old_value[:] = new_values
              elif isinstance(old_value, AST):
                  new_node = self.visit(old_value)
                  if new_node is None:
                      delattr(node, field)
                  else:
                      setattr(node, field, new_node)
          return node
  