cpython/Lib/csv/csv.py

139 lines
4.8 KiB
Python

from _csv import Error, __version__, writer, reader, register_dialect, \
unregister_dialect, get_dialect, list_dialects, \
QUOTE_MINIMAL, QUOTE_ALL, QUOTE_NONNUMERIC, QUOTE_NONE, \
__doc__
__all__ = [ "QUOTE_MINIMAL", "QUOTE_ALL", "QUOTE_NONNUMERIC", "QUOTE_NONE",
"Error", "Dialect", "excel", "excel_tab", "reader", "writer",
"register_dialect", "get_dialect", "list_dialects",
"unregister_dialect", "__version__", "DictReader", "DictWriter" ]
class Dialect:
_name = ""
_valid = False
# placeholders
delimiter = None
quotechar = None
escapechar = None
doublequote = None
skipinitialspace = None
lineterminator = None
quoting = None
def __init__(self):
if self.__class__ != Dialect:
self._valid = True
errors = self._validate()
if errors != []:
raise Error, "Dialect did not validate: %s" % ", ".join(errors)
def _validate(self):
errors = []
if not self._valid:
errors.append("can't directly instantiate Dialect class")
if self.delimiter is None:
errors.append("delimiter character not set")
elif (not isinstance(self.delimiter, str) or
len(self.delimiter) > 1):
errors.append("delimiter must be one-character string")
if self.quotechar is None:
if self.quoting != QUOTE_NONE:
errors.append("quotechar not set")
elif (not isinstance(self.quotechar, str) or
len(self.quotechar) > 1):
errors.append("quotechar must be one-character string")
if self.lineterminator is None:
errors.append("lineterminator not set")
elif not isinstance(self.lineterminator, str):
errors.append("lineterminator must be a string")
if self.doublequote not in (True, False):
errors.append("doublequote parameter must be True or False")
if self.skipinitialspace not in (True, False):
errors.append("skipinitialspace parameter must be True or False")
if self.quoting is None:
errors.append("quoting parameter not set")
if self.quoting is QUOTE_NONE:
if (not isinstance(self.escapechar, (unicode, str)) or
len(self.escapechar) > 1):
errors.append("escapechar must be a one-character string or unicode object")
return errors
class excel(Dialect):
delimiter = ','
quotechar = '"'
doublequote = True
skipinitialspace = False
lineterminator = '\r\n'
quoting = QUOTE_MINIMAL
register_dialect("excel", excel)
class excel_tab(excel):
delimiter = '\t'
register_dialect("excel-tab", excel_tab)
class DictReader:
def __init__(self, f, fieldnames, restkey=None, restval=None,
dialect="excel", *args):
self.fieldnames = fieldnames # list of keys for the dict
self.restkey = restkey # key to catch long rows
self.restval = restval # default value for short rows
self.reader = reader(f, dialect, *args)
def __iter__(self):
return self
def next(self):
row = self.reader.next()
# unlike the basic reader, we prefer not to return blanks,
# because we will typically wind up with a dict full of None
# values
while row == []:
row = self.reader.next()
d = dict(zip(self.fieldnames, row))
lf = len(self.fieldnames)
lr = len(row)
if lf < lr:
d[self.restkey] = row[lf:]
elif lf > lr:
for key in self.fieldnames[lr:]:
d[key] = self.restval
return d
class DictWriter:
def __init__(self, f, fieldnames, restval="", extrasaction="raise",
dialect="excel", *args):
self.fieldnames = fieldnames # list of keys for the dict
self.restval = restval # for writing short dicts
if extrasaction.lower() not in ("raise", "ignore"):
raise ValueError, \
("extrasaction (%s) must be 'raise' or 'ignore'" %
extrasaction)
self.extrasaction = extrasaction
self.writer = writer(f, dialect, *args)
def _dict_to_list(self, rowdict):
if self.extrasaction == "raise":
for k in rowdict.keys():
if k not in self.fieldnames:
raise ValueError, "dict contains fields not in fieldnames"
return [rowdict.get(key, self.restval) for key in self.fieldnames]
def writerow(self, rowdict):
return self.writer.writerow(self._dict_to_list(rowdict))
def writerows(self, rowdicts):
rows = []
for rowdict in rowdicts:
rows.append(self._dict_to_list(rowdict))
return self.writer.writerows(rows)