bibfield_utils.py
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bibfield_utils.py
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	# -- coding: utf-8 --
	##
	## This file is part of Invenio.
	## Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010, 2011, 2013 CERN.
	##
	## Invenio is free software; you can redistribute it and/or
	## modify it under the terms of the GNU General Public License as
	## published by the Free Software Foundation; either version 2 of the
	## License, or (at your option) any later version.
	##
	## Invenio is distributed in the hope that it will be useful, but
	## WITHOUT ANY WARRANTY; without even the implied warranty of
	## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	## General Public License for more details.
	##
	## You should have received a copy of the GNU General Public License
	## along with Invenio; if not, write to the Free Software Foundation, Inc.,
	## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.

	"""
	BibField Utils

	Helper classes and functions to work with BibField
	"""

	import re

	__revision__ = "$Id$"

	import os
	import datetime

	from invenio.config import CFG_PYLIBDIR
	from invenio.pluginutils import PluginContainer

	CFG_BIBFIELD_FUNCTIONS = PluginContainer(os.path.join(CFG_PYLIBDIR, 'invenio', 'bibfield_functions', '*.py'))


	class BibFieldException(Exception):
	"""
	General exception to use within BibField
	"""
	pass


	class BibFieldCheckerException(Exception):
	"""
	Exception raised when some error happens during checking
	"""
	pass


	class BibFieldDict(object):
	"""
	This class implements a I{dict} mostly and uses special key naming for
	accessing as describe in __getitem__

	>>> #Creating a dictionary
	>>> d = BibFieldDict()

	>>> #Filling up the dictionary
	>>> d['foo'] = {'a': 'world', 'b':'hello'}
	>>> d['a'] = [ {'b':1}, {'b':2}, {'b':3} ]
	>>> d['_c'] = "random.randint(1,100)"

	>>> #Accessing data inside the dictionary
	>>> d['a']
	>>> d['a[0]']
	>>> d['a.b']
	>>> d['a[1:]']
	>>> d['_c'] #this value will be calculated on the fly
	"""

	def __init__(self):
	self.rec_json = {}
	self._aliases = {}
	self._do_not_cache = []
	self._init_fase = True

	def __getitem__(self, key):
	"""
	As in C{dict.__getitem__} but using BibField name convention.

	@param key: String containing the name of the field and subfield.
	For e.g. lest work with:
	{'a': [ {'b':1}, {'b':2}, {'b':3} ], '_c': [42, random.randint(1,100)"] }
	- 'a' -> All the 'a' field info
	[{'b': 1}, {'b': 2}, {'b': 3}]
	- 'a[0]' -> All the info of the first element inside 'a'
	{'b': 1}
	- 'a[0].b' -> Field 'b' for the first element in 'a'
	1
	- 'a[1:]' -> All the 'a' field info but the first
	[{'b': 2}, {'b': 3}]
	- 'a.b' -> All the 'b' inside 'b'
	[1, 2, 3]
	- '_c- -> will give us the random number that is cached
	42
	- ... any other combination ...
	- ... as deep as the dictionary is ...

	NOTE: accessing one value in a normal way, meaning d['a'], is almost as
	fast as accessing a regular dictionary. But using the special name
	convention is a bit slower than using the regular access.
	d['a[0].b'] -> 10000 loops, best of 3: 18.4 us per loop
	d['a'][0]['b'] -> 1000000 loops, best of 3: 591 ns per loop

	@return: The value of the field, this might be, a dictionary, a list,
	a string, or any combination of the three depending on the value of
	field
	"""
	try:
	if '.' not in key and '[' not in key:
	dict_part = self.rec_json[key]
	else:
	dict_part = self.rec_json
	for group in prepare_field_keys(key):
	dict_part = self._get_intermediate_value(dict_part, group)
	except KeyError, err:
	return self[key.replace(err.message, self._aliases[err.message].replace('[n]', '[1:]'), 1)]

	if re.search('^_[a-zA-Z0-9]', key):
	if key in self._do_not_cache:
	self.update_field_cache(key)
	dict_part = dict_part[0]

	return dict_part

	def __setitem__(self, key, value):
	"""
	As in C{dict.__setitem__} but using BibField name convention.

	@note: at creation time dict['a[-1]'] = 'something' will mean
	dict['a'].append('something') and if the field already exists and is
	not a list, then this method will create a list with the existing value
	and append the new one,
	dict['a'] = 'first value' -> {'a':'first value'}
	dict['a'] = 'second value' -> {'a':['first value', 'second value']}
	There is one class variable self._init_fase for that matter.

	@param key: String containing the name of the field and subfield.
	@param value: The new value
	"""
	if self._init_fase:
	if '.' not in key and '[' not in key:
	if not key in self.rec_json:
	self.rec_json[key] = value
	return
	tmp = self.rec_json[key]
	if tmp is None:
	self.rec_json[key] = value
	else:
	if not isinstance(tmp, list):
	self.rec_json[key] = [tmp]
	self.rec_json[key].append(value)
	else:
	try:
	dict_part = eval("self.rec_json%s" % (''.join(prepare_field_keys(key)),)) # kwalitee: disable=eval
	except:
	build_data_structure(self.rec_json, key)
	dict_part = eval("self.rec_json%s" % (''.join(prepare_field_keys(key)),))
	if dict_part:
	exec("self.rec_json%s.append(value)" % (''.join(prepare_field_keys(key, write=True)[:-1]),))
	else:
	exec("self.rec_json%s = value" % (''.join(prepare_field_keys(key)),))
	else:
	if '.' not in key and '[' not in key:
	self.rec_json[key] = value
	else:
	try:
	exec("self.rec_json%s = value" % (''.join(prepare_field_keys(key)),))
	except:
	build_data_structure(self.rec_json, key)
	exec("self.rec_json%s = value" % (''.join(prepare_field_keys(key)),))

	def __delitem__(self, key):
	"""
	As in C{dict.__delitem__}.

	@note: It only works with first keys
	"""
	del self.rec_json[key]

	def __contains__(self, key):
	"""
	As in C{dict.__contains__} but using BibField name convention.

	@param key: Name of the key
	@return: True if the dictionary contains the special key
	"""
	if '.' not in key and '[' not in key:
	return key in self.rec_json
	try:
	self[key]
	except:
	return False
	return True

	def __eq__(self, other):
	"""@see C{dict.__eq__}"""
	try:
	return dict.__eq__(self.rec_json, other.rec_json)
	except:
	return False

	def __repr__(self):
	"""@see C{dict.__repr__}"""
	return repr(self.rec_json)

	def __iter__(self):
	"""@see C{dict.__iter__}"""
	return iter(self.rec_json)

	def __len__(self):
	"""@see C{dict.__len__}"""
	return len(self.rec_json)

	def keys(self):
	"""@see C{dict.keys}"""
	return self.rec_json.keys()

	def iteritems(self):
	"""@see C{dict.iteritems}"""
	return self.rec_json.iteritems()

	def iterkeys(self):
	"""@see C{dict.iterkeys}"""
	return self.rec_json.iterkeys()

	def itervalues(self):
	"""@see C{dict.itervalues}"""
	return self.rec_json.itervalues()

	def has_key(self, key):
	"""
	As in C{dict.has_key} but using BibField name convention.
	@see __contains__(self, key)
	"""
	return self.__contains__(key)

	def get(self, field=None, default=None, reset_cache=False, formatstring=None, formatfunction=None):
	"""
	As in C{dict.get} it Retrieves the value of field from the json structure
	but using BibField name convention and also applies some formating if
	present.

	@see __getitem__(self, key)

	@param field: Name of the field/s to retrieve. If it is None then it
	will return the entire dictionary.
	@param default: in case of error this value will be returned
	@param formatstring: Optional parameter to format the output value.
	This could be a format string, like this example:
	>>> d['foo'] = {'a': 'world', 'b':'hello'}
	>>> get('foo', formatstring="{0[b]} {0[a]}!")
	>>> 'hello world!'

	@param formatfunction: Optional parameter to format the output value.
	This parameter must be function and must handle all the possible
	parameter types (strin, dict or list)

	@return: The value of the field, this might be, a dictionary, a list,
	a string, or any combination of the three depending on the value of
	field. If any formating parameter is present, then the return value
	will be the formated value.
	"""
	if field.startswith('_') and reset_cache:
	self.update_field_cache(field)

	value = self.rec_json
	if field:
	try:
	value = self.__getitem__(field)
	except:
	return default

	if not value:
	return default

	if formatstring:
	value = self._apply_formatstring(value, formatstring)

	if formatfunction:
	value = formatfunction(value)

	return value

	def update_field_cache(self, field):
	"""
	Updates the value of the cache for the given calculated field
	"""
	calculated_field = self.rec_json.get(field)

	if calculated_field and field.startswith('_'):
	calculated_field[0] = self._try_to_eval(calculated_field[1])

	def update_all_fields_cache(self):
	"""
	Update the cache of all the calculated fields
	@see: update_field_cache()
	"""
	for field in [key for key in self.keys() if key.startswith('_')]:
	self.update_field_cache(field)

	def _try_to_eval(self, string, bibfield_functions_only=False, **context):
	"""
	This method takes care of evaluating the python expression, and, if an
	exception happens, it tries to import the needed module from bibfield_functions
	or from the python path using plugin utils

	@param string: String to evaluate
	@param context: Context needed, in some cases, to evaluate the string

	@return: The value of the expression inside string
	"""
	if not string:
	return None

	res = None
	imports = []

	while (True):
	try:
	res = eval(string, globals().update(context), locals()) # kwalitee: disable=eval
	except NameError, err:
	import_name = err.message.split("'")[1]
	if not import_name in imports:
	if import_name in CFG_BIBFIELD_FUNCTIONS:
	globals()[import_name] = CFG_BIBFIELD_FUNCTIONS[import_name]
	elif not bibfield_functions_only:
	globals()[import_name] = __import__(import_name)
	imports.append(import_name)
	continue
	assert False, 'Error not expected when trying to import bibfield function module'
	return res

	def _apply_formatstring(self, value, formatstring):
	"""
	Helper function that simply formats the result of get() using a
	format string

	If the value is of type datetime it tries to apply the format using
	strftime(formatstring).

	@see: get(self, field=None, formatstring=None, formatfunction=None)

	@param value: String, dict or list to apply the format string
	@param formatstring: formatstring

	@return: Formated value of "value"
	"""
	if not value:
	return ''
	if isinstance(value, datetime.datetime):
	if formatstring == value.strftime(formatstring):
	value = value.isoformat()
	else:
	return value.strftime(formatstring)
	if isinstance(value, list):
	tmp = ''
	for element in value:
	tmp += self._apply_formatstring(element, formatstring)
	return tmp
	elif isinstance(value, dict) or isinstance(value, basestring):
	return formatstring.format(value)
	else:
	assert False, 'String, Dictionay or List expected'

	def _get_intermediate_value(self, dict_part, field):
	"""
	Helper function that fetch the value of some field from dict_part

	@see: get(self, field=None, formatstring=None, formatfunction=None)

	@param dict_part: Dictionary or list containing all the information from
	this method will fetch field.
	@param field: Name or index of the field to fetch from dict_part

	@return: The value of the field, this might be, a dictionary, a list,
	a string, or any combination of the three depending on the value of
	field
	"""
	if isinstance(dict_part, dict):
	return eval('dict_part%s' % field) # kwalitee: disable=eval
	elif isinstance(dict_part, list):
	tmp = []
	for element in dict_part:
	tmp.append(self._get_intermediate_value(element, field))
	return tmp
	else:
	assert False, 'Dictionay or List expected get %s' % (type(dict_part),)


	class BlobWrapper(object):
	"""
	Wrapper class to work easily with the blob and the information related to it
	inside the *Reader
	"""
	def __init__(self, blob, **kw):
	self.__info = kw
	self.blob = blob

	def __getattr__(self, name):
	"""Trick to access the information inside self.__info using dot syntax"""
	try:
	return self.__info[name]
	except KeyError:
	raise AttributeError("%r object has no attribute %r" % (type(self).__name__, name))


	class CoolDict(dict):
	"""
	C{dict} but it keeps track of which elements has been consumed/accessed
	and which not
	"""

	def __init__(self, args, *kwargs):
	dict.__init__(self, args, *kwargs)
	self._consumed = {}
	if self:
	for key, value in dict.iteritems(self):
	self[key] = value

	def __getitem__(self, key):
	"""
	As in C{dict} but in this case the key could be a compiled regular expression.

	Also update the consumed list in case the item is not a list or other
	dictionary.

	@return: Like in C{dict.__getitem__} or, if a regular expression is used,
	a list containing all the items inside the dictionary which key matches
	the regular expression ([] if none)
	"""
	if isinstance(key, re._pattern_type):
	keys = filter(key.match, self.keys())
	values = []
	for key in keys:
	value = dict.get(self, key)
	values.append(dict.get(self, key))
	if not isinstance(value, dict) and not isinstance(value, list):
	self._consumed[key] = True
	return values
	else:
	try:
	value = dict.get(self, key)
	if not isinstance(value, dict) and not isinstance(value, list):
	self._consumed[key] = True
	return value
	except:
	return None

	def __setitem__(self, key, value):
	"""
	As in C{dict} but in this case it takes care of updating the consumed
	value for each element inside value depending on its type.
	"""
	if isinstance(value, dict):
	dict.__setitem__(self, key, CoolDict(value))
	self._consumed[key] = self[key]._consumed
	elif isinstance(value, list):
	dict.__setitem__(self, key, CoolList(value))
	self._consumed[key] = self[key]._consumed
	else:
	dict.__setitem__(self, key, value)
	self._consumed[key] = False

	def extend(self, key, value):
	"""
	If the key is present inside the dictionary it creates a list (it not
	present) and extends it with the new value. Almost as in C{list.extend}
	"""
	if key in self:
	current_value = dict.get(self, key)
	if not isinstance(current_value, list):
	current_value = CoolList([current_value])
	current_value.append(value)
	value = current_value

	self[key] = value

	def iteritems(self):
	""" As in C{dict} but it updates the consumed value if needed"""
	for key, value in dict.iteritems(self):
	if not isinstance(value, dict) and not isinstance(value, list):
	self._consumed[key] = True
	yield key, value

	raise StopIteration

	@property
	def consumed(self):
	for key, value in self._consumed.iteritems():
	if not isinstance(value, dict) and not isinstance(value, list):
	if not value:
	return False
	elif not dict.get(self, key).consumed:
	return False
	return True


	class CoolList(list):
	"""
	C{list} but it keeps track of which elements has been consumed/accessed and
	which not
	"""

	def __init__(self, args, *kwargs):
	list.__init__(self, args, *kwargs)
	self._consumed = []
	if self:
	for i, value in enumerate(list.__iter__(self)):
	self._consumed.append(None)
	self[i] = value

	def __getitem__(self, index):
	"""As in C{list}, also update the consumed list in case the item is not
	a dictionary or other list.

	@return: Like in C{list.__getitem__}
	"""
	value = list.__getitem__(self, index)
	if not isinstance(value, dict) and not isinstance(value, list):
	self._consumed[index] = True
	return value

	def __setitem__(self, index, value):
	"""
	As in C{list} but in this case it takes care of updating the consumed
	value for each element inside value depending on its type
	"""

	if isinstance(value, dict):
	list.__setitem__(self, index, CoolDict(value))
	self._consumed[index] = self[index]._consumed
	elif isinstance(value, list):
	list.__setitem__(self, index, CoolList(value))
	self._consumed[index] = self[index]._consumed
	else:
	list.__setitem__(self, index, value)
	self._consumed[index] = False

	def __iter__(self, args, *kwargs):
	""" As in C{dict} but it updates the consumed value if needed"""
	for index, value in enumerate(list.__iter__(self)):
	if not isinstance(value, dict) and not isinstance(value, list):
	self._consumed[index] = True
	yield value

	raise StopIteration

	def append(self, element):
	"""@see __setitem__() """
	self += [None]
	self._consumed += [None]
	self[len(self) - 1] = element

	@property
	def consumed(self):
	for index, value in enumerate(self._consumed):
	if not isinstance(value, dict) and not isinstance(value, list):
	if not value:
	return False
	elif not list.__getitem__(self, index).consumed:
	return False
	return True


	def prepare_field_keys(field, write=False):
	"""
	Helper function to split the name of the fields and the indexes in a
	proper way to be used by eval function

	@see: bibfield.get()

	@param field: String containing all the names and indexes
	@param write: If the fields are use to write inside the record then the
	granularity is lower for convenience

	@return: List of string that can be evaluated by eval function
	"""
	parts = field.split('.')
	keys = []
	for part in parts:
	if '[' in part:
	if write:
	keys.append('["%s"]' % (part[:part.find('[')]))
	keys.append(part[part.find('['):].replace('n', '-1'))
	else:
	keys.append('["%s"]%s' % (part[:part.find('[')], part[part.find('['):].replace('n', '-1')))
	else:
	keys.append('["%s"]' % part)
	return keys


	def build_data_structure(record, field):
	"""
	Helper functions that builds the record structure

	@param record: Existing data structure
	@param field: New field to add to the structure
	"""
	eval_string = ''
	for key in prepare_field_keys(field, write=True):
	if key == '[-1]':
	try:
	eval("record%s.append(None)" % (eval_string,)) # kwalitee: disable=eval
	except AttributeError:
	exec("record%s=[None]" % (eval_string,))
	elif key == '[0]':
	try:
	eval("record%s" % (eval_string + key,)) # kwalitee: disable=eval
	rec_part = eval("record%s" % (eval_string,)) # kwalitee: disable=eval
	if not isinstance(rec_part, list):
	pass
	rec_part.insert(0, None)
	except TypeError:
	exec("record%s=list([None])" % (eval_string,))
	else:
	try:
	eval("record%s" % (eval_string + key,)) # kwalitee: disable=eval
	except KeyError:
	exec("record%s=None" % (eval_string + key,))
	except TypeError:
	exec("record%s={}" % (eval_string,))
	exec("record%s=None" % (eval_string + key,))
	eval_string += key

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