A perl Data.Dumper clone for Python

Dumper.py

"""
A perl Data.Dumper clone for Python
Author: simon@log4think.com
2011-07-08

Copyright 2011 Jinyu LIU

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 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.
"""
#!/bin/env python

import sys
from types import *

def DEBUG(msg, level=None):
    pass

magin_space = '    '
break_base = False
break_string = False

break_before_list_item = True
break_before_list_begin = False
break_after_list_begin = False
break_before_list_end = True
break_after_list_end = False

break_before_tuple_item = True
break_before_tuple_begin = False
break_after_tuple_begin = False
break_before_tuple_end = True
break_after_tuple_end = False

break_before_dict_key = True
break_before_dict_value = False
break_before_dict_begin = False
break_after_dict_begin = False
break_before_dict_end = True
break_after_dict_end = False

DICT_TYPES = {DictionaryType: 1}

def atomic_type (t):
    return t in (NoneType, StringType, IntType, LongType, FloatType, ComplexType)

def simple_value (val):
    t = type(val)

    if atomic_type (val):
        return True

    if (not DICT_TYPES.has_key(t) and t not in (ListType, TupleType) and
            not is_instance(val)):
        return True

    elif t in (ListType, TupleType) and len (val) <= 10:
        for x in val:
            if not atomic_type (type (x)):
                return False
        return True

    elif DICT_TYPES.has_key(t) and len (val) <= 5:
        for (k,v) in val.items():
            if not (atomic_type (type (k)) and atomic_type (type (v))):
                return False
        return True

    else:
        return False

def is_instance (val):
    if type(val) is InstanceType:
        return True
    # instance of extension class, but not an actual extension class
    elif (hasattr(val, '__class__') and
          hasattr(val, '__dict__') and
          not hasattr(val, '__bases__')):
        return True
    else:
        return False

def is_class (val):
    return hasattr(val, '__bases__')

def indent(level=0, nextline=True):
    if nextline:
        return "\n" + magin_space*level
    else:
        return ""

class Dumper():
    def __init__(self, max_depth=999):
        self.max_depth = max_depth
        self.seen = {}

    def reset(self):
        self.seen = {}

    def dump_default(self, obj, level=0, nextline=True):
        DEBUG('; dump_default')
        if level + 1 > self.max_depth:
            return " <%s...>" % type(obj).__class__
        else:
            result = "%s::%s <<" % (type(obj).__name__, obj.__class__)
            if hasattr(obj, '__dict__'):
                result = "%s%s__dict__ :: %s" % (
                    result,
                    indent(level+1),
                    self.dump_dict(obj.__dict__, level+1)
                )

            if isinstance(obj, dict):
                result = "%s%sas_dict :: %s" % (
                    result,
                    indent(level+1),
                    self.dump_dict(obj, level+1)
                )
            elif isinstance(obj, list):
                result = "%s%sas_list :: %s" % (
                    result,
                    indent(level+1),
                    self.dump_list(obj, level+1)
                )

            result = result = "%s%s>>" % (result, indent(level))

        return result

    def dump_base(self, obj, level=0, nextline=True):
        DEBUG("; dump_%s", type(obj).__name__)
        return  "%s%s" % (indent(level, break_base), obj)

    dump_NoneType = dump_base
    dump_int = dump_base
    dump_long = dump_base
    dump_float = dump_base

    def dump_str(self, obj, level=0, nextline=True):
        DEBUG('; dump_str')
        return  "%s'%s'" % (indent(level, break_string), obj)

    def dump_tuple(self, obj, level=0, nextline=True):
        DEBUG('; dump_tuple')
        if level + 1 > self.max_depth:
            return "%s(...)%s" % (
                indent(level, break_before_tuple_begin),
                indent(level, break_after_tuple_end)
            )
        else:
            items = ["%s%s" % (
                    indent(level + 1, break_before_tuple_item),
                    self.dump(x, level + 1)
                ) for x in obj
            ]
            return  "%s(%s%s%s)%s" % (
                indent(level, nextline and break_before_tuple_begin),
                indent(level + 1, break_after_tuple_begin), ' '.join(items),
                indent(level, break_before_tuple_end),
                indent(level, break_after_tuple_end)
            )

    def dump_list(self, obj, level=0, nextline=True):
        DEBUG('; dump_list')
        if level + 1 > self.max_depth:
            return "%s[...]%s" % (
                indent(level, break_before_list_begin),
                indent(level, break_after_list_end)
            )
        else:
            items = ["%s%s" % (
                    indent(level + 1, break_before_list_item),
                    self.dump(x, level + 1)
                ) for x in obj
            ]
            return  "%s[%s%s%s]%s" % (
                indent(level, nextline and break_before_list_begin),
                indent(level + 1, break_after_list_begin), ' '.join(items),
                indent(level, break_before_list_end),
                indent(level, break_after_list_end)
            )

    def dump_dict(self, obj, level=0, nextline=True):
        DEBUG('; dump_dict')
        if level + 1 > self.max_depth:
            return "%s{...}%s" % (
                indent(level, break_before_dict_begin),
                indent(level, break_after_dict_end)
            )
        else:
            items = ["%s%s: %s%s" % (
                    indent(level + 1, break_before_dict_key),
                    self.dump(k, level + 1),
                    indent(level + 2, break_before_dict_value),
                    self.dump(v, level + 1)
                ) for k, v in obj.items()
            ]
            return  "%s{%s%s%s}%s" % (
                indent(level, nextline and break_before_dict_begin),
                indent(level + 1, break_after_dict_begin), ' '.join(items),
                indent(level, break_before_dict_end),
                indent(level, break_after_dict_end)
            )

    def dump(self, obj, level=0, nextline=True):
        DEBUG('; dump')
        if not simple_value(obj):
            if self.seen.has_key(id(obj)):
                return "%s::%s <<...>>" % (type(obj).__name__, obj.__class__)
            else:
                self.seen[id(obj)] = 1

        name = type(obj).__name__
        dump_func = getattr(self, "dump_%s" % name, self.dump_default)
        return dump_func(obj, level, nextline)

def dump(obj, max_depth=999):
    d = Dumper(max_depth)
    return d.dump(obj)

if __name__ == '__main__':

    l1 = [3, 5, 'hello']
    t1 = ('uh', 'oh')
    l2 = ['foo', t1]
    d1 = {'k1': 'val1',
          'k2': l1,
          'k2': l2}

    print dump (l1)
    print dump (t1)
    print dump (l2)
    print dump (d1)

    dumper = Dumper (max_depth=1)
    l = { 'author': 'joe',
          'created' : '03/28/2009',
          'title' : 'Yet another blog post',
          'text' : 'Here is the text...',
          'tags' : [ 'example', 'joe' ],
          'comments' : [ { 'author': 'jim', 'comment': 'I disagree' },
                      { 'author': 'nancy', 'comment': 'Good post' }
          ],
        }
    print dumper.dump (l)

    dumper.reset()
    dumper.max_depth = 2
    print dumper.dump (l)
    
    dumper.reset()
    dumper.max_depth = None
    print "max_depth: %s" % dumper.max_depth

    class Foo(list): pass
    class Bar(dict): pass

    f = Foo ()
    b = Bar ()

    f.a1 = 35
    f.a2 = l1
    f.a3 = 'foo'
    f.b = b
    f.a4 = l2
    b.a1 = f
    b.a2 = None
    b.a3 = 'bar'

    print dump (f)

    print dump (Dumper())

Might add these::

def dump_unicode(self, obj, level=0, nextline=True):
    DEBUG('; dump_unicode')
    return  "%s'%s'" % (indent(level, break_string), obj)

def dump_bool(self, obj, level=0, nextline=True):
    DEBUG('; dump_bool')
    return  "%s%s" % (indent(level, break_string), obj)