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# A part of pdfrw (https://github.com/pmaupin/pdfrw)
# Copyright (C) 2006-2015 Patrick Maupin, Austin, Texas
# MIT license -- See LICENSE.txt for details
from .pdfname import PdfName, BasePdfName
from .pdfindirect import PdfIndirect
from .pdfobject import PdfObject
from ..py23_diffs import iteritems
from ..errors import PdfParseError
class _DictSearch(object):
''' Used to search for inheritable attributes.
'''
def __init__(self, basedict):
self.basedict = basedict
def __getattr__(self, name, PdfName=PdfName):
return self[PdfName(name)]
def __getitem__(self, name, set=set, getattr=getattr, id=id):
visited = set()
mydict = self.basedict
while 1:
value = mydict[name]
if value is not None:
return value
myid = id(mydict)
assert myid not in visited
visited.add(myid)
mydict = mydict.Parent
if mydict is None:
return
class _Private(object):
''' Used to store private attributes (not output to PDF files)
on PdfDict classes
'''
def __init__(self, pdfdict):
vars(self)['pdfdict'] = pdfdict
def __setattr__(self, name, value):
vars(self.pdfdict)[name] = value
class PdfDict(dict):
''' PdfDict objects are subclassed dictionaries
with the following features:
- Every key in the dictionary starts with "/"
- A dictionary item can be deleted by assigning it to None
- Keys that (after the initial "/") conform to Python
naming conventions can also be accessed (set and retrieved)
as attributes of the dictionary. E.g. mydict.Page is the
same thing as mydict['/Page']
- Private attributes (not in the PDF space) can be set
on the dictionary object attribute dictionary by using
the private attribute:
mydict.private.foo = 3
mydict.foo = 5
x = mydict.foo # x will now contain 3
y = mydict['/foo'] # y will now contain 5
Most standard adobe dictionary keys start with an upper case letter,
so to avoid conflicts, it is best to start private attributes with
lower case letters.
- PdfDicts have the following read-only properties:
- private -- as discussed above, provides write access to
dictionary's attributes
- inheritable -- this creates and returns a "view" attribute
that will search through the object hierarchy for
any desired attribute, such as /Rotate or /MediaBox
- PdfDicts also have the following special attributes:
- indirect is not stored in the PDF dictionary, but in the object's
attribute dictionary
- stream is also stored in the object's attribute dictionary
and will also update the stream length.
- _stream will store in the object's attribute dictionary without
updating the stream length.
It is possible, for example, to have a PDF name such as "/indirect"
or "/stream", but you cannot access such a name as an attribute:
mydict.indirect -- accesses object's attribute dictionary
mydict["/indirect"] -- accesses actual PDF dictionary
'''
indirect = False
stream = None
_special = dict(indirect=('indirect', False),
stream=('stream', True),
_stream=('stream', False),
)
def __setitem__(self, name, value, setter=dict.__setitem__,
BasePdfName=BasePdfName, isinstance=isinstance):
if not isinstance(name, BasePdfName):
raise PdfParseError('Dict key %s is not a PdfName' % repr(name))
if value is not None:
setter(self, name, value)
elif name in self:
del self[name]
def __init__(self, *args, **kw):
if args:
if len(args) == 1:
args = args[0]
self.update(args)
if isinstance(args, PdfDict):
self.indirect = args.indirect
self._stream = args.stream
for key, value in iteritems(kw):
setattr(self, key, value)
def __getattr__(self, name, PdfName=PdfName):
''' If the attribute doesn't exist on the dictionary object,
try to slap a '/' in front of it and get it out
of the actual dictionary itself.
'''
return self.get(PdfName(name))
def get(self, key, dictget=dict.get, isinstance=isinstance,
PdfIndirect=PdfIndirect):
''' Get a value out of the dictionary,
after resolving any indirect objects.
'''
value = dictget(self, key)
if isinstance(value, PdfIndirect):
self[key] = value = value.real_value()
return value
def __getitem__(self, key):
return self.get(key)
def __setattr__(self, name, value, special=_special.get,
PdfName=PdfName, vars=vars):
''' Set an attribute on the dictionary. Handle the keywords
indirect, stream, and _stream specially (for content objects)
'''
info = special(name)
if info is None:
self[PdfName(name)] = value
else:
name, setlen = info
vars(self)[name] = value
if setlen:
notnone = value is not None
self.Length = notnone and PdfObject(len(value)) or None
def iteritems(self, dictiter=iteritems,
isinstance=isinstance, PdfIndirect=PdfIndirect,
BasePdfName=BasePdfName):
''' Iterate over the dictionary, resolving any unresolved objects
'''
for key, value in list(dictiter(self)):
if isinstance(value, PdfIndirect):
self[key] = value = value.real_value()
if value is not None:
if not isinstance(key, BasePdfName):
raise PdfParseError('Dict key %s is not a PdfName' %
repr(key))
yield key, value
def items(self):
return list(self.iteritems())
def itervalues(self):
for key, value in self.iteritems():
yield value
def values(self):
return list((value for key, value in self.iteritems()))
def keys(self):
return list((key for key, value in self.iteritems()))
def __iter__(self):
for key, value in self.iteritems():
yield key
def iterkeys(self):
return iter(self)
def copy(self):
return type(self)(self)
def pop(self, key):
value = self.get(key)
del self[key]
return value
def popitem(self):
key, value = dict.pop(self)
if isinstance(value, PdfIndirect):
value = value.real_value()
return value
def inheritable(self):
''' Search through ancestors as needed for inheritable
dictionary items.
NOTE: You might think it would be a good idea
to cache this class, but then you'd have to worry
about it pointing to the wrong dictionary if you
made a copy of the object...
'''
return _DictSearch(self)
inheritable = property(inheritable)
def private(self):
''' Allows setting private metadata for use in
processing (not sent to PDF file).
See note on inheritable
'''
return _Private(self)
private = property(private)
class IndirectPdfDict(PdfDict):
''' IndirectPdfDict is a convenience class. You could
create a direct PdfDict and then set indirect = True on it,
or you could just create an IndirectPdfDict.
'''
indirect = True
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