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parser.py
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parser.py
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# -*- coding: utf-8 -*-
from __future__ import absolute_import
from __future__ import unicode_literals
from datetime import datetime
from dateutil import tz
import re
try:
from functools import lru_cache
except ImportError: # pragma: no cover
from backports.functools_lru_cache import lru_cache # pragma: no cover
from arrow import locales
class ParserError(RuntimeError):
pass
class DateTimeParser(object):
_FORMAT_RE = re.compile('(YYY?Y?|MM?M?M?|Do|DD?D?D?|d?d?d?d|HH?|hh?|mm?|ss?|S+|ZZ?Z?|a|A|X)')
_ESCAPE_RE = re.compile('\[[^\[\]]*\]')
_ONE_OR_MORE_DIGIT_RE = re.compile('\d+')
_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})?')
_TZ_NAME_RE = re.compile('\w[\w+\-/]+')
_BASE_INPUT_RE_MAP = {
'YYYY': _FOUR_DIGIT_RE,
'YY': _TWO_DIGIT_RE,
'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,
'X': re.compile('\d+'),
'ZZZ': _TZ_NAME_RE,
'ZZ': _TZ_RE,
'Z': _TZ_RE,
'S': _ONE_OR_MORE_DIGIT_RE,
}
MARKERS = ['YYYY', 'MM', 'DD']
SEPARATORS = ['-', '/', '.']
def __init__(self, locale='en_us', cache_size=0):
self.locale = locales.get_locale(locale)
self._input_re_map = self._BASE_INPUT_RE_MAP.copy()
self._input_re_map.update({
'MMMM': self._choice_re(self.locale.month_names[1:], re.IGNORECASE),
'MMM': self._choice_re(self.locale.month_abbreviations[1:],
re.IGNORECASE),
'Do': re.compile(self.locale.ordinal_day_re),
'dddd': self._choice_re(self.locale.day_names[1:], re.IGNORECASE),
'ddd': self._choice_re(self.locale.day_abbreviations[1:],
re.IGNORECASE),
'd': re.compile(r"[1-7]"),
'a': self._choice_re(
(self.locale.meridians['am'], self.locale.meridians['pm'])
),
# note: 'A' token accepts both 'am/pm' and 'AM/PM' formats to
# ensure backwards compatibility of this token
'A': self._choice_re(self.locale.meridians.values())
})
if cache_size > 0:
self._generate_pattern_re =\
lru_cache(maxsize=cache_size)(self._generate_pattern_re)
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 = re.search('[.,]', time_parts[0])
if has_subseconds:
formats = ['YYYY-MM-DDTHH:mm:ss%sS' % has_subseconds.group()]
elif has_seconds:
formats = ['YYYY-MM-DDTHH:mm:ss']
else:
formats = ['YYYY-MM-DDTHH:mm']
else:
has_tz = False
# generate required formats: YYYY-MM-DD, YYYY-MM-DD, YYYY
# using various separators: -, /, .
l = len(self.MARKERS)
formats = [separator.join(self.MARKERS[:l-i])
for i in range(l)
for separator in self.SEPARATORS]
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 _generate_pattern_re(self, fmt):
# fmt is a string of tokens like 'YYYY-MM-DD'
# we construct a new string by replacing each
# token by its pattern:
# 'YYYY-MM-DD' -> '(?P<YYYY>\d{4})-(?P<MM>\d{2})-(?P<DD>\d{2})'
tokens = []
offset = 0
# Escape all special RegEx chars
escaped_fmt = re.escape(fmt)
# Extract the bracketed expressions to be reinserted later.
escaped_fmt = re.sub(self._ESCAPE_RE, "#", escaped_fmt)
# Any number of S is the same as one.
escaped_fmt = re.sub('S+', 'S', escaped_fmt)
escaped_data = re.findall(self._ESCAPE_RE, fmt)
fmt_pattern = escaped_fmt
for m in self._FORMAT_RE.finditer(escaped_fmt):
token = m.group(0)
try:
input_re = self._input_re_map[token]
except KeyError:
raise ParserError('Unrecognized token \'{}\''.format(token))
input_pattern = '(?P<{}>{})'.format(token, input_re.pattern)
tokens.append(token)
# a pattern doesn't have the same length as the token
# it replaces! We keep the difference in the offset variable.
# This works because the string is scanned left-to-right and matches
# are returned in the order found by finditer.
fmt_pattern = fmt_pattern[:m.start() + offset] + input_pattern + fmt_pattern[m.end() + offset:]
offset += len(input_pattern) - (m.end() - m.start())
final_fmt_pattern = ""
a = fmt_pattern.split("\#")
b = escaped_data
# Due to the way Python splits, 'a' will always be longer
for i in range(len(a)):
final_fmt_pattern += a[i]
if i < len(b):
final_fmt_pattern += b[i][1:-1]
return tokens, re.compile(final_fmt_pattern, flags=re.IGNORECASE)
def parse(self, string, fmt):
if isinstance(fmt, list):
return self._parse_multiformat(string, fmt)
fmt_tokens, fmt_pattern_re = self._generate_pattern_re(fmt)
match = fmt_pattern_re.search(string)
if match is None:
raise ParserError('Failed to match \'{}\' when parsing \'{}\''
.format(fmt_pattern_re.pattern, string))
if match.end() != len(string) and 'Z' not in string:
raise ParserError('BUG FIX: Failed to match \'{}\' when parsing \'{}\''
.format(fmt_pattern_re.pattern, string))
parts = {}
for token in fmt_tokens:
if token == 'Do':
value = match.group('value')
else:
value = match.group(token)
self._parse_token(token, value, parts)
return self._build_datetime(parts)
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.lower())
elif token in ['MM', 'M']:
parts['month'] = int(value)
elif token in ['DD', 'D']:
parts['day'] = int(value)
elif token in ['Do']:
parts['day'] = int(value)
elif token.upper() 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 == 'S':
# We have the *most significant* digits of an arbitrary-precision integer.
# We want the six most significant digits as an integer, rounded.
# FIXME: add nanosecond support somehow?
value = value.ljust(7, str('0'))
# floating-point (IEEE-754) defaults to half-to-even rounding
seventh_digit = int(value[6])
if seventh_digit == 5:
rounding = int(value[5]) % 2
elif seventh_digit > 5:
rounding = 1
else:
rounding = 0
parts['microsecond'] = int(value[:6]) + rounding
elif token == 'X':
parts['timestamp'] = int(value)
elif token in ['ZZZ', 'ZZ', 'Z']:
parts['tzinfo'] = TzinfoParser.parse(value)
elif token in ['a', 'A']:
if value in (
self.locale.meridians['am'],
self.locale.meridians['AM']
):
parts['am_pm'] = 'am'
elif value in (
self.locale.meridians['pm'],
self.locale.meridians['PM']
):
parts['am_pm'] = 'pm'
@staticmethod
def _build_datetime(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 ParserError:
pass
if _datetime is None:
raise ParserError('Could not match input to any of {} on \'{}\''.format(formats, string))
return _datetime
@staticmethod
def _map_lookup(input_map, key):
try:
return input_map[key]
except KeyError:
raise ParserError('Could not match "{}" to {}'.format(key, input_map))
@staticmethod
def _try_timestamp(string):
try:
return float(string)
except:
return None
@staticmethod
def _choice_re(choices, flags=0):
return re.compile('({})'.format('|'.join(choices)), flags=flags)
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()
if minutes is None:
minutes = 0
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 "{}"'.format(string))
return tzinfo