text: #  Author:      Fred L. Drake, Jr.
  #               fdrake@acm.org
  #
  #  This is a simple little module I wrote to make life easier.  I didn't
  #  see anything quite like it in the library, though I may have overlooked
  #  something.  I wrote this when I was trying to read some heavily nested
  #  tuples with fairly non-descriptive content.  This is modeled very much
  #  after Lisp/Scheme - style pretty-printing of lists.  If you find it
  #  useful, thank small children who sleep at night.
  
  """Support to pretty-print lists, tuples, & dictionaries recursively.
  
  Very simple, but useful, especially in debugging data structures.
  
  Classes
  -------
  
  PrettyPrinter()
      Handle pretty-printing operations onto a stream using a configured
      set of formatting parameters.
  
  Functions
  ---------
  
  pformat()
      Format a Python object into a pretty-printed representation.
  
  pprint()
      Pretty-print a Python object to a stream [default is sys.stdout].
  
  saferepr()
      Generate a 'standard' repr()-like value, but protect against recursive
      data structures.
  
  """
  
  import re
  import sys as _sys
  from collections import OrderedDict as _OrderedDict
  from io import StringIO as _StringIO
  
  __all__ = ["pprint","pformat","isreadable","isrecursive","saferepr",
             "PrettyPrinter"]
  
  
  def pprint(object, stream=None, indent=1, width=80, depth=None, *,
             compact=False):
      """Pretty-print a Python object to a stream [default is sys.stdout]."""
      printer = PrettyPrinter(
          stream=stream, indent=indent, width=width, depth=depth,
          compact=compact)
      printer.pprint(object)
  
  def pformat(object, indent=1, width=80, depth=None, *, compact=False):
      """Format a Python object into a pretty-printed representation."""
      return PrettyPrinter(indent=indent, width=width, depth=depth,
                           compact=compact).pformat(object)
  
  def saferepr(object):
      """Version of repr() which can handle recursive data structures."""
      return _safe_repr(object, {}, None, 0)[0]
  
  def isreadable(object):
      """Determine if saferepr(object) is readable by eval()."""
      return _safe_repr(object, {}, None, 0)[1]
  
  def isrecursive(object):
      """Determine if object requires a recursive representation."""
      return _safe_repr(object, {}, None, 0)[2]
  
  class _safe_key:
      """Helper function for key functions when sorting unorderable objects.
  
      The wrapped-object will fallback to an Py2.x style comparison for
      unorderable types (sorting first comparing the type name and then by
      the obj ids).  Does not work recursively, so dict.items() must have
      _safe_key applied to both the key and the value.
  
      """
  
      __slots__ = ['obj']
  
      def __init__(self, obj):
          self.obj = obj
  
      def __lt__(self, other):
          try:
              rv = self.obj.__lt__(other.obj)
          except TypeError:
              rv = NotImplemented
  
          if rv is NotImplemented:
              rv = (str(type(self.obj)), id(self.obj)) < \
                   (str(type(other.obj)), id(other.obj))
          return rv
  
  def _safe_tuple(t):
      "Helper function for comparing 2-tuples"
      return _safe_key(t[0]), _safe_key(t[1])
  
  class PrettyPrinter:
      def __init__(self, indent=1, width=80, depth=None, stream=None, *,
                   compact=False):
          """Handle pretty printing operations onto a stream using a set of
          configured parameters.
  
          indent
              Number of spaces to indent for each level of nesting.
  
          width
              Attempted maximum number of columns in the output.
  
          depth
              The maximum depth to print out nested structures.
  
          stream
              The desired output stream.  If omitted (or false), the standard
              output stream available at construction will be used.
  
          compact
              If true, several items will be combined in one line.
  
          """
          indent = int(indent)
          width = int(width)
          assert indent >= 0, "indent must be >= 0"
          assert depth is None or depth > 0, "depth must be > 0"
          assert width, "width must be != 0"
          self._depth = depth
          self._indent_per_level = indent
          self._width = width
          if stream is not None:
              self._stream = stream
          else:
              self._stream = _sys.stdout
          self._compact = bool(compact)
  
      def pprint(self, object):
          self._format(object, self._stream, 0, 0, {}, 0)
          self._stream.write("\n")
  
      def pformat(self, object):
          sio = _StringIO()
          self._format(object, sio, 0, 0, {}, 0)
          return sio.getvalue()
  
      def isrecursive(self, object):
          return self.format(object, {}, 0, 0)[2]
  
      def isreadable(self, object):
          s, readable, recursive = self.format(object, {}, 0, 0)
          return readable and not recursive
  
      def _format(self, object, stream, indent, allowance, context, level):
          level = level + 1
          objid = id(object)
          if objid in context:
              stream.write(_recursion(object))
              self._recursive = True
              self._readable = False
              return
          rep = self._repr(object, context, level - 1)
          typ = type(object)
          max_width = self._width - 1 - indent - allowance
          sepLines = len(rep) > max_width
          write = stream.write
  
          if sepLines:
              r = getattr(typ, "__repr__", None)
              if issubclass(typ, dict):
                  write('{')
                  if self._indent_per_level > 1:
                      write((self._indent_per_level - 1) * ' ')
                  length = len(object)
                  if length:
                      context[objid] = 1
                      indent = indent + self._indent_per_level
                      if issubclass(typ, _OrderedDict):
                          items = list(object.items())
                      else:
                          items = sorted(object.items(), key=_safe_tuple)
                      key, ent = items[0]
                      rep = self._repr(key, context, level)
                      write(rep)
                      write(': ')
                      self._format(ent, stream, indent + len(rep) + 2,
                                    allowance + 1, context, level)
                      if length > 1:
                          for key, ent in items[1:]:
                              rep = self._repr(key, context, level)
                              write(',\n%s%s: ' % (' '*indent, rep))
                              self._format(ent, stream, indent + len(rep) + 2,
                                            allowance + 1, context, level)
                      indent = indent - self._indent_per_level
                      del context[objid]
                  write('}')
                  return
  
              if ((issubclass(typ, list) and r is list.__repr__) or
                  (issubclass(typ, tuple) and r is tuple.__repr__) or
                  (issubclass(typ, set) and r is set.__repr__) or
                  (issubclass(typ, frozenset) and r is frozenset.__repr__)
                 ):
                  length = len(object)
                  if issubclass(typ, list):
                      write('[')
                      endchar = ']'
                  elif issubclass(typ, tuple):
                      write('(')
                      endchar = ')'
                  else:
                      if not length:
                          write(rep)
                          return
                      if typ is set:
                          write('{')
                          endchar = '}'
                      else:
                          write(typ.__name__)
                          write('({')
                          endchar = '})'
                          indent += len(typ.__name__) + 1
                      object = sorted(object, key=_safe_key)
                  if self._indent_per_level > 1:
                      write((self._indent_per_level - 1) * ' ')
                  if length:
                      context[objid] = 1
                      self._format_items(object, stream,
                                         indent + self._indent_per_level,
                                         allowance + 1, context, level)
                      del context[objid]
                  if issubclass(typ, tuple) and length == 1:
                      write(',')
                  write(endchar)
                  return
  
              if issubclass(typ, str) and len(object) > 0 and r is str.__repr__:
                  def _str_parts(s):
                      """
                      Return a list of string literals comprising the repr()
                      of the given string using literal concatenation.
                      """
                      lines = s.splitlines(True)
                      for i, line in enumerate(lines):
                          rep = repr(line)
                          if len(rep) <= max_width:
                              yield rep
                          else:
                              # A list of alternating (non-space, space) strings
                              parts = re.split(r'(\s+)', line) + ['']
                              current = ''
                              for i in range(0, len(parts), 2):
                                  part = parts[i] + parts[i+1]
                                  candidate = current + part
                                  if len(repr(candidate)) > max_width:
                                      if current:
                                          yield repr(current)
                                      current = part
                                  else:
                                      current = candidate
                              if current:
                                  yield repr(current)
                  for i, rep in enumerate(_str_parts(object)):
                      if i > 0:
                          write('\n' + ' '*indent)
                      write(rep)
                  return
          write(rep)
  
      def _format_items(self, items, stream, indent, allowance, context, level):
          write = stream.write
          delimnl = ',\n' + ' ' * indent
          delim = ''
          width = max_width = self._width - indent - allowance + 2
          for ent in items:
              if self._compact:
                  rep = self._repr(ent, context, level)
                  w = len(rep) + 2
                  if width < w:
                      width = max_width
                      if delim:
                          delim = delimnl
                  if width >= w:
                      width -= w
                      write(delim)
                      delim = ', '
                      write(rep)
                      continue
              write(delim)
              delim = delimnl
              self._format(ent, stream, indent, allowance, context, level)
  
      def _repr(self, object, context, level):
          repr, readable, recursive = self.format(object, context.copy(),
                                                  self._depth, level)
          if not readable:
              self._readable = False
          if recursive:
              self._recursive = True
          return repr
  
      def format(self, object, context, maxlevels, level):
          """Format object for a specific context, returning a string
          and flags indicating whether the representation is 'readable'
          and whether the object represents a recursive construct.
          """
          return _safe_repr(object, context, maxlevels, level)
  
  
  # Return triple (repr_string, isreadable, isrecursive).
  
  def _safe_repr(object, context, maxlevels, level):
      typ = type(object)
      if typ is str:
          if 'locale' not in _sys.modules:
              return repr(object), True, False
          if "'" in object and '"' not in object:
              closure = '"'
              quotes = {'"': '\\"'}
          else:
              closure = "'"
              quotes = {"'": "\\'"}
          qget = quotes.get
          sio = _StringIO()
          write = sio.write
          for char in object:
              if char.isalpha():
                  write(char)
              else:
                  write(qget(char, repr(char)[1:-1]))
          return ("%s%s%s" % (closure, sio.getvalue(), closure)), True, False
  
      r = getattr(typ, "__repr__", None)
      if issubclass(typ, dict) and r is dict.__repr__:
          if not object:
              return "{}", True, False
          objid = id(object)
          if maxlevels and level >= maxlevels:
              return "{...}", False, objid in context
          if objid in context:
              return _recursion(object), False, True
          context[objid] = 1
          readable = True
          recursive = False
          components = []
          append = components.append
          level += 1
          saferepr = _safe_repr
          items = sorted(object.items(), key=_safe_tuple)
          for k, v in items:
              krepr, kreadable, krecur = saferepr(k, context, maxlevels, level)
              vrepr, vreadable, vrecur = saferepr(v, context, maxlevels, level)
              append("%s: %s" % (krepr, vrepr))
              readable = readable and kreadable and vreadable
              if krecur or vrecur:
                  recursive = True
          del context[objid]
          return "{%s}" % ", ".join(components), readable, recursive
  
      if (issubclass(typ, list) and r is list.__repr__) or \
         (issubclass(typ, tuple) and r is tuple.__repr__):
          if issubclass(typ, list):
              if not object:
                  return "[]", True, False
              format = "[%s]"
          elif len(object) == 1:
              format = "(%s,)"
          else:
              if not object:
                  return "()", True, False
              format = "(%s)"
          objid = id(object)
          if maxlevels and level >= maxlevels:
              return format % "...", False, objid in context
          if objid in context:
              return _recursion(object), False, True
          context[objid] = 1
          readable = True
          recursive = False
          components = []
          append = components.append
          level += 1
          for o in object:
              orepr, oreadable, orecur = _safe_repr(o, context, maxlevels, level)
              append(orepr)
              if not oreadable:
                  readable = False
              if orecur:
                  recursive = True
          del context[objid]
          return format % ", ".join(components), readable, recursive
  
      rep = repr(object)
      return rep, (rep and not rep.startswith('<')), False
  
  
  def _recursion(object):
      return ("<Recursion on %s with id=%s>"
              % (type(object).__name__, id(object)))
  
  
  def _perfcheck(object=None):
      import time
      if object is None:
          object = [("string", (1, 2), [3, 4], {5: 6, 7: 8})] * 100000
      p = PrettyPrinter()
      t1 = time.time()
      _safe_repr(object, {}, None, 0)
      t2 = time.time()
      p.pformat(object)
      t3 = time.time()
      print("_safe_repr:", t2 - t1)
      print("pformat:", t3 - t2)
  
  if __name__ == "__main__":
      _perfcheck()
  