path: root/contrib/python/ipython/py2/IPython/lib/pretty.py

# -*- coding: utf-8 -*- 
""" 
Python advanced pretty printer.  This pretty printer is intended to 
replace the old `pprint` python module which does not allow developers 
to provide their own pretty print callbacks. 
 
This module is based on ruby's `prettyprint.rb` library by `Tanaka Akira`. 
 
 
Example Usage 
------------- 
 
To directly print the representation of an object use `pprint`:: 
 
    from pretty import pprint 
    pprint(complex_object) 
 
To get a string of the output use `pretty`:: 
 
    from pretty import pretty 
    string = pretty(complex_object) 
 
 
Extending 
--------- 
 
The pretty library allows developers to add pretty printing rules for their 
own objects.  This process is straightforward.  All you have to do is to 
add a `_repr_pretty_` method to your object and call the methods on the 
pretty printer passed:: 
 
    class MyObject(object): 
 
        def _repr_pretty_(self, p, cycle): 
            ... 
 
Here is an example implementation of a `_repr_pretty_` method for a list 
subclass:: 
 
    class MyList(list): 
 
        def _repr_pretty_(self, p, cycle): 
            if cycle: 
                p.text('MyList(...)') 
            else: 
                with p.group(8, 'MyList([', '])'): 
                    for idx, item in enumerate(self): 
                        if idx: 
                            p.text(',') 
                            p.breakable() 
                        p.pretty(item) 
 
The `cycle` parameter is `True` if pretty detected a cycle.  You *have* to 
react to that or the result is an infinite loop.  `p.text()` just adds 
non breaking text to the output, `p.breakable()` either adds a whitespace 
or breaks here.  If you pass it an argument it's used instead of the 
default space.  `p.pretty` prettyprints another object using the pretty print 
method. 
 
The first parameter to the `group` function specifies the extra indentation 
of the next line.  In this example the next item will either be on the same 
line (if the items are short enough) or aligned with the right edge of the 
opening bracket of `MyList`. 
 
If you just want to indent something you can use the group function 
without open / close parameters.  You can also use this code:: 
 
    with p.indent(2): 
        ... 
 
Inheritance diagram: 
 
.. inheritance-diagram:: IPython.lib.pretty 
   :parts: 3 
 
:copyright: 2007 by Armin Ronacher. 
            Portions (c) 2009 by Robert Kern. 
:license: BSD License. 
""" 
from __future__ import print_function 
from contextlib import contextmanager 
import sys 
import types 
import re 
import datetime 
from collections import deque 
 
from IPython.utils.py3compat import PY3, PYPY, cast_unicode, string_types
from IPython.utils.encoding import get_stream_enc 
 
from io import StringIO 
 
 
__all__ = ['pretty', 'pprint', 'PrettyPrinter', 'RepresentationPrinter', 
    'for_type', 'for_type_by_name'] 
 
 
MAX_SEQ_LENGTH = 1000 
# The language spec says that dicts preserve order from 3.7, but CPython
# does so from 3.6, so it seems likely that people will expect that.
DICT_IS_ORDERED = sys.version_info >= (3, 6)
_re_pattern_type = type(re.compile('')) 
 
def _safe_getattr(obj, attr, default=None): 
    """Safe version of getattr. 
     
    Same as getattr, but will return ``default`` on any Exception, 
    rather than raising. 
    """ 
    try: 
        return getattr(obj, attr, default) 
    except Exception: 
        return default 
 
if PY3: 
    CUnicodeIO = StringIO 
else: 
    class CUnicodeIO(StringIO): 
        """StringIO that casts str to unicode on Python 2""" 
        def write(self, text): 
            return super(CUnicodeIO, self).write( 
                cast_unicode(text, encoding=get_stream_enc(sys.stdout))) 
 
 
def _sorted_for_pprint(items):
    """
    Sort the given items for pretty printing. Since some predictable
    sorting is better than no sorting at all, we sort on the string
    representation if normal sorting fails.
    """
    items = list(items)
    try:
        return sorted(items)
    except Exception:
        try:
            return sorted(items, key=str)
        except Exception:
            return items

def pretty(obj, verbose=False, max_width=79, newline='\n', max_seq_length=MAX_SEQ_LENGTH): 
    """ 
    Pretty print the object's representation. 
    """ 
    stream = CUnicodeIO() 
    printer = RepresentationPrinter(stream, verbose, max_width, newline, max_seq_length=max_seq_length) 
    printer.pretty(obj) 
    printer.flush() 
    return stream.getvalue() 
 
 
def pprint(obj, verbose=False, max_width=79, newline='\n', max_seq_length=MAX_SEQ_LENGTH): 
    """ 
    Like `pretty` but print to stdout. 
    """ 
    printer = RepresentationPrinter(sys.stdout, verbose, max_width, newline, max_seq_length=max_seq_length) 
    printer.pretty(obj) 
    printer.flush() 
    sys.stdout.write(newline) 
    sys.stdout.flush() 
 
class _PrettyPrinterBase(object): 
 
    @contextmanager 
    def indent(self, indent): 
        """with statement support for indenting/dedenting.""" 
        self.indentation += indent 
        try: 
            yield 
        finally: 
            self.indentation -= indent 
 
    @contextmanager 
    def group(self, indent=0, open='', close=''): 
        """like begin_group / end_group but for the with statement.""" 
        self.begin_group(indent, open) 
        try: 
            yield 
        finally: 
            self.end_group(indent, close) 
 
class PrettyPrinter(_PrettyPrinterBase): 
    """ 
    Baseclass for the `RepresentationPrinter` prettyprinter that is used to 
    generate pretty reprs of objects.  Contrary to the `RepresentationPrinter` 
    this printer knows nothing about the default pprinters or the `_repr_pretty_` 
    callback method. 
    """ 
 
    def __init__(self, output, max_width=79, newline='\n', max_seq_length=MAX_SEQ_LENGTH): 
        self.output = output 
        self.max_width = max_width 
        self.newline = newline 
        self.max_seq_length = max_seq_length 
        self.output_width = 0 
        self.buffer_width = 0 
        self.buffer = deque() 
 
        root_group = Group(0) 
        self.group_stack = [root_group] 
        self.group_queue = GroupQueue(root_group) 
        self.indentation = 0 
 
    def _break_outer_groups(self): 
        while self.max_width < self.output_width + self.buffer_width: 
            group = self.group_queue.deq() 
            if not group: 
                return 
            while group.breakables: 
                x = self.buffer.popleft() 
                self.output_width = x.output(self.output, self.output_width) 
                self.buffer_width -= x.width 
            while self.buffer and isinstance(self.buffer[0], Text): 
                x = self.buffer.popleft() 
                self.output_width = x.output(self.output, self.output_width) 
                self.buffer_width -= x.width 
 
    def text(self, obj): 
        """Add literal text to the output.""" 
        width = len(obj) 
        if self.buffer: 
            text = self.buffer[-1] 
            if not isinstance(text, Text): 
                text = Text() 
                self.buffer.append(text) 
            text.add(obj, width) 
            self.buffer_width += width 
            self._break_outer_groups() 
        else: 
            self.output.write(obj) 
            self.output_width += width 
 
    def breakable(self, sep=' '): 
        """ 
        Add a breakable separator to the output.  This does not mean that it 
        will automatically break here.  If no breaking on this position takes 
        place the `sep` is inserted which default to one space. 
        """ 
        width = len(sep) 
        group = self.group_stack[-1] 
        if group.want_break: 
            self.flush() 
            self.output.write(self.newline) 
            self.output.write(' ' * self.indentation) 
            self.output_width = self.indentation 
            self.buffer_width = 0 
        else: 
            self.buffer.append(Breakable(sep, width, self)) 
            self.buffer_width += width 
            self._break_outer_groups() 
             
    def break_(self): 
        """ 
        Explicitly insert a newline into the output, maintaining correct indentation. 
        """ 
        self.flush() 
        self.output.write(self.newline) 
        self.output.write(' ' * self.indentation) 
        self.output_width = self.indentation 
        self.buffer_width = 0 
         
 
    def begin_group(self, indent=0, open=''): 
        """ 
        Begin a group.  If you want support for python < 2.5 which doesn't has 
        the with statement this is the preferred way: 
 
            p.begin_group(1, '{') 
            ... 
            p.end_group(1, '}') 
 
        The python 2.5 expression would be this: 
 
            with p.group(1, '{', '}'): 
                ... 
 
        The first parameter specifies the indentation for the next line (usually 
        the width of the opening text), the second the opening text.  All 
        parameters are optional. 
        """ 
        if open: 
            self.text(open) 
        group = Group(self.group_stack[-1].depth + 1) 
        self.group_stack.append(group) 
        self.group_queue.enq(group) 
        self.indentation += indent 
     
    def _enumerate(self, seq): 
        """like enumerate, but with an upper limit on the number of items""" 
        for idx, x in enumerate(seq): 
            if self.max_seq_length and idx >= self.max_seq_length: 
                self.text(',') 
                self.breakable() 
                self.text('...') 
                return 
            yield idx, x 
     
    def end_group(self, dedent=0, close=''): 
        """End a group. See `begin_group` for more details.""" 
        self.indentation -= dedent 
        group = self.group_stack.pop() 
        if not group.breakables: 
            self.group_queue.remove(group) 
        if close: 
            self.text(close) 
 
    def flush(self): 
        """Flush data that is left in the buffer.""" 
        for data in self.buffer: 
            self.output_width += data.output(self.output, self.output_width) 
        self.buffer.clear() 
        self.buffer_width = 0 
 
 
def _get_mro(obj_class): 
    """ Get a reasonable method resolution order of a class and its superclasses 
    for both old-style and new-style classes. 
    """ 
    if not hasattr(obj_class, '__mro__'): 
        # Old-style class. Mix in object to make a fake new-style class. 
        try: 
            obj_class = type(obj_class.__name__, (obj_class, object), {}) 
        except TypeError: 
            # Old-style extension type that does not descend from object. 
            # FIXME: try to construct a more thorough MRO. 
            mro = [obj_class] 
        else: 
            mro = obj_class.__mro__[1:-1] 
    else: 
        mro = obj_class.__mro__ 
    return mro 
 
 
class RepresentationPrinter(PrettyPrinter): 
    """ 
    Special pretty printer that has a `pretty` method that calls the pretty 
    printer for a python object. 
 
    This class stores processing data on `self` so you must *never* use 
    this class in a threaded environment.  Always lock it or reinstanciate 
    it. 
 
    Instances also have a verbose flag callbacks can access to control their 
    output.  For example the default instance repr prints all attributes and 
    methods that are not prefixed by an underscore if the printer is in 
    verbose mode. 
    """ 
 
    def __init__(self, output, verbose=False, max_width=79, newline='\n', 
        singleton_pprinters=None, type_pprinters=None, deferred_pprinters=None, 
        max_seq_length=MAX_SEQ_LENGTH): 
 
        PrettyPrinter.__init__(self, output, max_width, newline, max_seq_length=max_seq_length) 
        self.verbose = verbose 
        self.stack = [] 
        if singleton_pprinters is None: 
            singleton_pprinters = _singleton_pprinters.copy() 
        self.singleton_pprinters = singleton_pprinters 
        if type_pprinters is None: 
            type_pprinters = _type_pprinters.copy() 
        self.type_pprinters = type_pprinters 
        if deferred_pprinters is None: 
            deferred_pprinters = _deferred_type_pprinters.copy() 
        self.deferred_pprinters = deferred_pprinters 
 
    def pretty(self, obj): 
        """Pretty print the given object.""" 
        obj_id = id(obj) 
        cycle = obj_id in self.stack 
        self.stack.append(obj_id) 
        self.begin_group() 
        try: 
            obj_class = _safe_getattr(obj, '__class__', None) or type(obj) 
            # First try to find registered singleton printers for the type. 
            try: 
                printer = self.singleton_pprinters[obj_id] 
            except (TypeError, KeyError): 
                pass 
            else: 
                return printer(obj, self, cycle) 
            # Next walk the mro and check for either: 
            #   1) a registered printer 
            #   2) a _repr_pretty_ method 
            for cls in _get_mro(obj_class): 
                if cls in self.type_pprinters: 
                    # printer registered in self.type_pprinters 
                    return self.type_pprinters[cls](obj, self, cycle) 
                else: 
                    # deferred printer 
                    printer = self._in_deferred_types(cls) 
                    if printer is not None: 
                        return printer(obj, self, cycle) 
                    else: 
                        # Finally look for special method names. 
                        # Some objects automatically create any requested 
                        # attribute. Try to ignore most of them by checking for 
                        # callability. 
                        if '_repr_pretty_' in cls.__dict__: 
                            meth = cls._repr_pretty_ 
                            if callable(meth): 
                                return meth(obj, self, cycle) 
                        if cls is not object \
                                and callable(cls.__dict__.get('__repr__')):
                            return _repr_pprint(obj, self, cycle)

            return _default_pprint(obj, self, cycle) 
        finally: 
            self.end_group() 
            self.stack.pop() 
 
    def _in_deferred_types(self, cls): 
        """ 
        Check if the given class is specified in the deferred type registry. 
 
        Returns the printer from the registry if it exists, and None if the 
        class is not in the registry. Successful matches will be moved to the 
        regular type registry for future use. 
        """ 
        mod = _safe_getattr(cls, '__module__', None) 
        name = _safe_getattr(cls, '__name__', None) 
        key = (mod, name) 
        printer = None 
        if key in self.deferred_pprinters: 
            # Move the printer over to the regular registry. 
            printer = self.deferred_pprinters.pop(key) 
            self.type_pprinters[cls] = printer 
        return printer 
 
 
class Printable(object): 
 
    def output(self, stream, output_width): 
        return output_width 
 
 
class Text(Printable): 
 
    def __init__(self): 
        self.objs = [] 
        self.width = 0 
 
    def output(self, stream, output_width): 
        for obj in self.objs: 
            stream.write(obj) 
        return output_width + self.width 
 
    def add(self, obj, width): 
        self.objs.append(obj) 
        self.width += width 
 
 
class Breakable(Printable): 
 
    def __init__(self, seq, width, pretty): 
        self.obj = seq 
        self.width = width 
        self.pretty = pretty 
        self.indentation = pretty.indentation 
        self.group = pretty.group_stack[-1] 
        self.group.breakables.append(self) 
 
    def output(self, stream, output_width): 
        self.group.breakables.popleft() 
        if self.group.want_break: 
            stream.write(self.pretty.newline) 
            stream.write(' ' * self.indentation) 
            return self.indentation 
        if not self.group.breakables: 
            self.pretty.group_queue.remove(self.group) 
        stream.write(self.obj) 
        return output_width + self.width 
 
 
class Group(Printable): 
 
    def __init__(self, depth): 
        self.depth = depth 
        self.breakables = deque() 
        self.want_break = False 
 
 
class GroupQueue(object): 
 
    def __init__(self, *groups): 
        self.queue = [] 
        for group in groups: 
            self.enq(group) 
 
    def enq(self, group): 
        depth = group.depth 
        while depth > len(self.queue) - 1: 
            self.queue.append([]) 
        self.queue[depth].append(group) 
 
    def deq(self): 
        for stack in self.queue: 
            for idx, group in enumerate(reversed(stack)): 
                if group.breakables: 
                    del stack[idx] 
                    group.want_break = True 
                    return group 
            for group in stack: 
                group.want_break = True 
            del stack[:] 
 
    def remove(self, group): 
        try: 
            self.queue[group.depth].remove(group) 
        except ValueError: 
            pass 
 
try: 
    _baseclass_reprs = (object.__repr__, types.InstanceType.__repr__) 
except AttributeError:  # Python 3 
    _baseclass_reprs = (object.__repr__,) 
 
 
def _default_pprint(obj, p, cycle): 
    """ 
    The default print function.  Used if an object does not provide one and 
    it's none of the builtin objects. 
    """ 
    klass = _safe_getattr(obj, '__class__', None) or type(obj) 
    if _safe_getattr(klass, '__repr__', None) not in _baseclass_reprs: 
        # A user-provided repr. Find newlines and replace them with p.break_() 
        _repr_pprint(obj, p, cycle) 
        return 
    p.begin_group(1, '<') 
    p.pretty(klass) 
    p.text(' at 0x%x' % id(obj)) 
    if cycle: 
        p.text(' ...') 
    elif p.verbose: 
        first = True 
        for key in dir(obj): 
            if not key.startswith('_'): 
                try: 
                    value = getattr(obj, key) 
                except AttributeError: 
                    continue 
                if isinstance(value, types.MethodType): 
                    continue 
                if not first: 
                    p.text(',') 
                p.breakable() 
                p.text(key) 
                p.text('=') 
                step = len(key) + 1 
                p.indentation += step 
                p.pretty(value) 
                p.indentation -= step 
                first = False 
    p.end_group(1, '>') 
 
 
def _seq_pprinter_factory(start, end):
    """ 
    Factory that returns a pprint function useful for sequences.  Used by 
    the default pprint for tuples, dicts, and lists. 
    """ 
    def inner(obj, p, cycle): 
        if cycle: 
            return p.text(start + '...' + end) 
        step = len(start) 
        p.begin_group(step, start) 
        for idx, x in p._enumerate(obj): 
            if idx: 
                p.text(',') 
                p.breakable() 
            p.pretty(x) 
        if len(obj) == 1 and type(obj) is tuple: 
            # Special case for 1-item tuples. 
            p.text(',') 
        p.end_group(step, end) 
    return inner 
 
 
def _set_pprinter_factory(start, end):
    """ 
    Factory that returns a pprint function useful for sets and frozensets. 
    """ 
    def inner(obj, p, cycle): 
        if cycle: 
            return p.text(start + '...' + end) 
        if len(obj) == 0: 
            # Special case. 
            p.text(type(obj).__name__ + '()')
        else: 
            step = len(start) 
            p.begin_group(step, start) 
            # Like dictionary keys, we will try to sort the items if there aren't too many 
            if not (p.max_seq_length and len(obj) >= p.max_seq_length): 
                items = _sorted_for_pprint(obj)
            else:
                items = obj
            for idx, x in p._enumerate(items): 
                if idx: 
                    p.text(',') 
                    p.breakable() 
                p.pretty(x) 
            p.end_group(step, end) 
    return inner 
 
 
def _dict_pprinter_factory(start, end):
    """ 
    Factory that returns a pprint function used by the default pprint of 
    dicts and dict proxies. 
    """ 
    def inner(obj, p, cycle): 
        if cycle: 
            return p.text('{...}') 
        step = len(start)
        p.begin_group(step, start)
        keys = obj.keys() 
        # if dict isn't large enough to be truncated, sort keys before displaying 
        # From Python 3.7, dicts preserve order by definition, so we don't sort.
        if not DICT_IS_ORDERED \
                and not (p.max_seq_length and len(obj) >= p.max_seq_length):
            keys = _sorted_for_pprint(keys)
        for idx, key in p._enumerate(keys): 
            if idx: 
                p.text(',') 
                p.breakable() 
            p.pretty(key) 
            p.text(': ') 
            p.pretty(obj[key]) 
        p.end_group(step, end)
    return inner 
 
 
def _super_pprint(obj, p, cycle): 
    """The pprint for the super type.""" 
    p.begin_group(8, '<super: ') 
    p.pretty(obj.__thisclass__) 
    p.text(',') 
    p.breakable() 
    if PYPY: # In PyPy, super() objects don't have __self__ attributes
        dself = obj.__repr__.__self__
        p.pretty(None if dself is obj else dself)
    else:
        p.pretty(obj.__self__)
    p.end_group(8, '>') 
 
 
def _re_pattern_pprint(obj, p, cycle): 
    """The pprint function for regular expression patterns.""" 
    p.text('re.compile(') 
    pattern = repr(obj.pattern) 
    if pattern[:1] in 'uU': 
        pattern = pattern[1:] 
        prefix = 'ur' 
    else: 
        prefix = 'r' 
    pattern = prefix + pattern.replace('\\\\', '\\') 
    p.text(pattern) 
    if obj.flags: 
        p.text(',') 
        p.breakable() 
        done_one = False 
        for flag in ('TEMPLATE', 'IGNORECASE', 'LOCALE', 'MULTILINE', 'DOTALL', 
            'UNICODE', 'VERBOSE', 'DEBUG'): 
            if obj.flags & getattr(re, flag): 
                if done_one: 
                    p.text('|') 
                p.text('re.' + flag) 
                done_one = True 
    p.text(')') 
 
 
def _type_pprint(obj, p, cycle): 
    """The pprint for classes and types.""" 
    # Heap allocated types might not have the module attribute, 
    # and others may set it to None. 
 
    # Checks for a __repr__ override in the metaclass. Can't compare the
    # type(obj).__repr__ directly because in PyPy the representation function
    # inherited from type isn't the same type.__repr__
    if [m for m in _get_mro(type(obj)) if "__repr__" in vars(m)][:1] != [type]:
        _repr_pprint(obj, p, cycle) 
        return 
 
    mod = _safe_getattr(obj, '__module__', None) 
    try: 
        name = obj.__qualname__ 
        if not isinstance(name, string_types): 
            # This can happen if the type implements __qualname__ as a property 
            # or other descriptor in Python 2. 
            raise Exception("Try __name__") 
    except Exception: 
        name = obj.__name__ 
        if not isinstance(name, string_types): 
            name = '<unknown type>' 
 
    if mod in (None, '__builtin__', 'builtins', 'exceptions'): 
        p.text(name) 
    else: 
        p.text(mod + '.' + name) 
 
 
def _repr_pprint(obj, p, cycle): 
    """A pprint that just redirects to the normal repr function.""" 
    # Find newlines and replace them with p.break_() 
    output = repr(obj) 
    for idx,output_line in enumerate(output.splitlines()): 
        if idx: 
            p.break_() 
        p.text(output_line) 
 
 
def _function_pprint(obj, p, cycle): 
    """Base pprint for all functions and builtin functions.""" 
    name = _safe_getattr(obj, '__qualname__', obj.__name__) 
    mod = obj.__module__ 
    if mod and mod not in ('__builtin__', 'builtins', 'exceptions'): 
        name = mod + '.' + name 
    p.text('<function %s>' % name) 
 
 
def _exception_pprint(obj, p, cycle): 
    """Base pprint for all exceptions.""" 
    name = getattr(obj.__class__, '__qualname__', obj.__class__.__name__) 
    if obj.__class__.__module__ not in ('exceptions', 'builtins'): 
        name = '%s.%s' % (obj.__class__.__module__, name) 
    step = len(name) + 1 
    p.begin_group(step, name + '(') 
    for idx, arg in enumerate(getattr(obj, 'args', ())): 
        if idx: 
            p.text(',') 
            p.breakable() 
        p.pretty(arg) 
    p.end_group(step, ')') 
 
 
#: the exception base 
try: 
    _exception_base = BaseException 
except NameError: 
    _exception_base = Exception 
 
 
#: printers for builtin types 
_type_pprinters = { 
    int:                        _repr_pprint, 
    float:                      _repr_pprint, 
    str:                        _repr_pprint, 
    tuple:                      _seq_pprinter_factory('(', ')'),
    list:                       _seq_pprinter_factory('[', ']'),
    dict:                       _dict_pprinter_factory('{', '}'),
     
    set:                        _set_pprinter_factory('{', '}'),
    frozenset:                  _set_pprinter_factory('frozenset({', '})'),
    super:                      _super_pprint, 
    _re_pattern_type:           _re_pattern_pprint, 
    type:                       _type_pprint, 
    types.FunctionType:         _function_pprint, 
    types.BuiltinFunctionType:  _function_pprint, 
    types.MethodType:           _repr_pprint, 
     
    datetime.datetime:          _repr_pprint, 
    datetime.timedelta:         _repr_pprint, 
    _exception_base:            _exception_pprint 
} 
 
try: 
    # In PyPy, types.DictProxyType is dict, setting the dictproxy printer
    # using dict.setdefault avoids overwritting the dict printer
    _type_pprinters.setdefault(types.DictProxyType,
                               _dict_pprinter_factory('dict_proxy({', '})'))
    _type_pprinters[types.ClassType] = _type_pprint 
    _type_pprinters[types.SliceType] = _repr_pprint 
except AttributeError: # Python 3 
    _type_pprinters[types.MappingProxyType] = \
        _dict_pprinter_factory('mappingproxy({', '})')
    _type_pprinters[slice] = _repr_pprint 
     
try: 
    _type_pprinters[xrange] = _repr_pprint 
    _type_pprinters[long] = _repr_pprint 
    _type_pprinters[unicode] = _repr_pprint 
except NameError: 
    _type_pprinters[range] = _repr_pprint 
    _type_pprinters[bytes] = _repr_pprint 
 
#: printers for types specified by name 
_deferred_type_pprinters = { 
} 
 
def for_type(typ, func): 
    """ 
    Add a pretty printer for a given type. 
    """ 
    oldfunc = _type_pprinters.get(typ, None) 
    if func is not None: 
        # To support easy restoration of old pprinters, we need to ignore Nones. 
        _type_pprinters[typ] = func 
    return oldfunc 
 
def for_type_by_name(type_module, type_name, func): 
    """ 
    Add a pretty printer for a type specified by the module and name of a type 
    rather than the type object itself. 
    """ 
    key = (type_module, type_name) 
    oldfunc = _deferred_type_pprinters.get(key, None) 
    if func is not None: 
        # To support easy restoration of old pprinters, we need to ignore Nones. 
        _deferred_type_pprinters[key] = func 
    return oldfunc 
 
 
#: printers for the default singletons 
_singleton_pprinters = dict.fromkeys(map(id, [None, True, False, Ellipsis, 
                                      NotImplemented]), _repr_pprint) 
 
 
def _defaultdict_pprint(obj, p, cycle): 
    name = obj.__class__.__name__ 
    with p.group(len(name) + 1, name + '(', ')'): 
        if cycle: 
            p.text('...') 
        else: 
            p.pretty(obj.default_factory) 
            p.text(',') 
            p.breakable() 
            p.pretty(dict(obj)) 
 
def _ordereddict_pprint(obj, p, cycle): 
    name = obj.__class__.__name__ 
    with p.group(len(name) + 1, name + '(', ')'): 
        if cycle: 
            p.text('...') 
        elif len(obj): 
            p.pretty(list(obj.items())) 
 
def _deque_pprint(obj, p, cycle): 
    name = obj.__class__.__name__ 
    with p.group(len(name) + 1, name + '(', ')'): 
        if cycle: 
            p.text('...') 
        else: 
            p.pretty(list(obj)) 
 
 
def _counter_pprint(obj, p, cycle): 
    name = obj.__class__.__name__ 
    with p.group(len(name) + 1, name + '(', ')'): 
        if cycle: 
            p.text('...') 
        elif len(obj): 
            p.pretty(dict(obj)) 
 
for_type_by_name('collections', 'defaultdict', _defaultdict_pprint) 
for_type_by_name('collections', 'OrderedDict', _ordereddict_pprint) 
for_type_by_name('collections', 'deque', _deque_pprint) 
for_type_by_name('collections', 'Counter', _counter_pprint) 
 
if __name__ == '__main__': 
    from random import randrange 
    class Foo(object): 
        def __init__(self): 
            self.foo = 1 
            self.bar = re.compile(r'\s+') 
            self.blub = dict.fromkeys(range(30), randrange(1, 40)) 
            self.hehe = 23424.234234 
            self.list = ["blub", "blah", self] 
 
        def get_foo(self): 
            print("foo") 
 
    pprint(Foo(), verbose=True)