/
parser.py
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/
parser.py
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# -*- coding: utf-8 -*-
from __future__ import absolute_import
from datetime import datetime
from dateutil import tz
import calendar
import re
from arrow import locales
class ParserError(RuntimeError):
pass
class DateTimeParser(object):
_FORMAT_RE = re.compile('(YYY?Y?|MM?M?M?|DD?D?D?|HH?|hh?|mm?|ss?|SS?S?S?S?S?|ZZ?|a|A|X)')
_ONE_THROUGH_SIX_DIGIT_RE = re.compile('\d{1,6}')
_ONE_THROUGH_FIVE_DIGIT_RE = re.compile('\d{1,5}')
_ONE_THROUGH_FOUR_DIGIT_RE = re.compile('\d{1,4}')
_ONE_TWO_OR_THREE_DIGIT_RE = re.compile('\d{1,3}')
_ONE_OR_TWO_DIGIT_RE = re.compile('\d{1,2}')
_FOUR_DIGIT_RE = re.compile('\d{4}')
_TWO_DIGIT_RE = re.compile('\d{2}')
_TZ_RE = re.compile('[+\-]?\d{2}:?\d{2}')
_INPUT_RE_MAP = {
'YYYY': _FOUR_DIGIT_RE,
'YY': _TWO_DIGIT_RE,
'MMMM': re.compile('({0})'.format('|'.join(calendar.month_name[1:]))),
'MMM': re.compile('({0})'.format('|'.join(calendar.month_abbr[1:]))),
'MM': _TWO_DIGIT_RE,
'M': _ONE_OR_TWO_DIGIT_RE,
'DD': _TWO_DIGIT_RE,
'D': _ONE_OR_TWO_DIGIT_RE,
'HH': _TWO_DIGIT_RE,
'H': _ONE_OR_TWO_DIGIT_RE,
'hh': _TWO_DIGIT_RE,
'h': _ONE_OR_TWO_DIGIT_RE,
'mm': _TWO_DIGIT_RE,
'm': _ONE_OR_TWO_DIGIT_RE,
'ss': _TWO_DIGIT_RE,
's': _ONE_OR_TWO_DIGIT_RE,
'a': re.compile('(a|A|p|P)'),
'A': re.compile('(am|AM|pm|PM)'),
'X': re.compile('\d+'),
'ZZ': _TZ_RE,
'Z': _TZ_RE,
'SSSSSS': _ONE_THROUGH_SIX_DIGIT_RE,
'SSSSS': _ONE_THROUGH_FIVE_DIGIT_RE,
'SSSS': _ONE_THROUGH_FOUR_DIGIT_RE,
'SSS': _ONE_TWO_OR_THREE_DIGIT_RE,
'SS': _ONE_OR_TWO_DIGIT_RE,
'S': re.compile('\d'),
}
def __init__(self, locale='en_us'):
self.locale = locales.get_locale(locale)
def parse_iso(self, string):
has_time = 'T' in string or ' ' in string.strip()
space_divider = ' ' in string.strip()
if has_time:
if space_divider:
date_string, time_string = string.split(' ', 1)
else:
date_string, time_string = string.split('T', 1)
time_parts = re.split('[+-]', time_string, 1)
has_tz = len(time_parts) > 1
has_seconds = time_parts[0].count(':') > 1
has_subseconds = '.' in time_parts[0]
else:
has_tz = has_seconds = has_subseconds = False
if has_time:
if has_subseconds:
formats = ['YYYY-MM-DDTHH:mm:ss.SSSSSS']
elif has_seconds:
formats = ['YYYY-MM-DDTHH:mm:ss']
else:
formats = ['YYYY-MM-DDTHH:mm']
else:
formats = [
'YYYY-MM-DD',
'YYYY-MM',
'YYYY',
]
if has_time and has_tz:
formats = [f + 'Z' for f in formats]
if space_divider:
formats = [item.replace('T', ' ', 1) for item in formats]
return self._parse_multiformat(string, formats)
def parse(self, string, fmt):
if isinstance(fmt, list):
return self._parse_multiformat(string, fmt)
original_string = string
tokens = self._FORMAT_RE.findall(fmt)
token_values = []
separators = self._parse_separators(fmt, tokens)
parts = {}
for token in tokens:
try:
input_re = self._INPUT_RE_MAP[token]
except KeyError:
raise ParserError('Unrecognized token \'{0}\''.format(token))
match = input_re.search(string)
if match:
token_values.append(match.group(0))
self._parse_token(token, match.group(0), parts)
index = match.span(0)[1]
string = string[index:]
else:
raise ParserError('Failed to match token \'{0}\' when parsing \'{1}\''.format(token, original_string))
parsed = ''.join(self._interleave_lists(token_values, separators))
if parsed not in original_string:
raise ParserError('Failed to match format \'{0}\' when parsing \'{1}\''.format(fmt, original_string))
return self._build_datetime(parts)
def _interleave_lists(self, tokens, separators):
joined = tokens + separators
joined[::2] = tokens
joined[1::2] = separators
return joined
def _parse_separators(self, fmt, tokens):
separators = []
for i in range(len(tokens) - 1):
start_index = fmt.find(tokens[i]) + len(tokens[i])
end_index = fmt.find(tokens[i + 1])
separators.append(fmt[start_index:end_index])
return separators
def _parse_token(self, token, value, parts):
if token == 'YYYY':
parts['year'] = int(value)
elif token == 'YY':
value = int(value)
parts['year'] = 1900 + value if value > 68 else 2000 + value
elif token in ['MMMM', 'MMM']:
parts['month'] = self.locale.month_number(value)
elif token in ['MM', 'M']:
parts['month'] = int(value)
elif token in ['DD', 'D']:
parts['day'] = int(value)
elif token in ['HH', 'H']:
parts['hour'] = int(value)
elif token in ['mm', 'm']:
parts['minute'] = int(value)
elif token in ['ss', 's']:
parts['second'] = int(value)
elif token == 'SSSSSS':
parts['microsecond'] = int(value)
elif token == 'SSSSS':
parts['microsecond'] = int(value) * 10
elif token == 'SSSS':
parts['microsecond'] = int(value) * 100
elif token == 'SSS':
parts['microsecond'] = int(value) * 1000
elif token == 'SS':
parts['microsecond'] = int(value) * 10000
elif token == 'S':
parts['microsecond'] = int(value) * 100000
elif token == 'X':
parts['timestamp'] = int(value)
elif token in ['ZZ', 'Z']:
parts['tzinfo'] = TzinfoParser.parse(value)
elif token in ['a', 'A']:
if value in ['a', 'A', 'am', 'AM']:
parts['am_pm'] = 'am'
elif value in ['p', 'P', 'pm', 'PM']:
parts['am_pm'] = 'pm'
@classmethod
def _build_datetime(cls, parts):
timestamp = parts.get('timestamp')
if timestamp:
tz_utc = tz.tzutc()
return datetime.fromtimestamp(timestamp, tz=tz_utc)
am_pm = parts.get('am_pm')
hour = parts.get('hour', 0)
if am_pm == 'pm' and hour < 12:
hour += 12
elif am_pm == 'am' and hour == 12:
hour = 0
return datetime(year=parts.get('year', 1), month=parts.get('month', 1),
day=parts.get('day', 1), hour=hour, minute=parts.get('minute', 0),
second=parts.get('second', 0), microsecond=parts.get('microsecond', 0),
tzinfo=parts.get('tzinfo'))
def _parse_multiformat(self, string, formats):
_datetime = None
for fmt in formats:
try:
_datetime = self.parse(string, fmt)
break
except:
pass
if _datetime is None:
raise ParserError('Could not match input to any of {0} on \'{1}\''.format(formats, string))
return _datetime
@classmethod
def _map_lookup(cls, input_map, key):
try:
return input_map[key]
except KeyError:
raise ParserError('Could not match "{0}" to {1}'.format(key, input_map))
@classmethod
def _try_timestamp(cls, string):
try:
return float(string)
except:
return None
class TzinfoParser(object):
_TZINFO_RE = re.compile('([+\-])?(\d\d):?(\d\d)')
@classmethod
def parse(cls, string):
tzinfo = None
if string == 'local':
tzinfo = tz.tzlocal()
elif string in ['utc', 'UTC']:
tzinfo = tz.tzutc()
else:
iso_match = cls._TZINFO_RE.match(string)
if iso_match:
sign, hours, minutes = iso_match.groups()
seconds = int(hours) * 3600 + int(minutes) * 60
if sign == '-':
seconds *= -1
tzinfo = tz.tzoffset(None, seconds)
else:
tzinfo = tz.gettz(string)
if tzinfo is None:
raise ParserError('Could not parse timezone expression "{0}"', string)
return tzinfo