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Commit 63c4ca54 authored by Marek Gumiński's avatar Marek Gumiński
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Added parse.py to the repository. 

It is a python library, but sometimes it's difficult to find.
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r'''Parse strings using a specification based on the Python format() syntax.
``parse()`` is the opposite of ``format()``
The module is set up to only export ``parse()``, ``search()``, ``findall()``,
and ``with_pattern()`` when ``import \*`` is used:
>>> from parse import *
From there it's a simple thing to parse a string:
.. code-block:: pycon
>>> parse("It's {}, I love it!", "It's spam, I love it!")
<Result ('spam',) {}>
>>> _[0]
'spam'
Or to search a string for some pattern:
.. code-block:: pycon
>>> search('Age: {:d}\n', 'Name: Rufus\nAge: 42\nColor: red\n')
<Result (42,) {}>
Or find all the occurrences of some pattern in a string:
.. code-block:: pycon
>>> ''.join(r[0] for r in findall(">{}<", "<p>the <b>bold</b> text</p>"))
'the bold text'
If you're going to use the same pattern to match lots of strings you can
compile it once:
.. code-block:: pycon
>>> from parse import compile
>>> p = compile("It's {}, I love it!")
>>> print(p)
<Parser "It's {}, I love it!">
>>> p.parse("It's spam, I love it!")
<Result ('spam',) {}>
("compile" is not exported for ``import *`` usage as it would override the
built-in ``compile()`` function)
The default behaviour is to match strings case insensitively. You may match with
case by specifying `case_sensitive=True`:
.. code-block:: pycon
>>> parse('SPAM', 'spam', case_sensitive=True) is None
True
Format Syntax
-------------
A basic version of the `Format String Syntax`_ is supported with anonymous
(fixed-position), named and formatted fields::
{[field name]:[format spec]}
Field names must be a valid Python identifiers, including dotted names;
element indexes imply dictionaries (see below for example).
Numbered fields are also not supported: the result of parsing will include
the parsed fields in the order they are parsed.
The conversion of fields to types other than strings is done based on the
type in the format specification, which mirrors the ``format()`` behaviour.
There are no "!" field conversions like ``format()`` has.
Some simple parse() format string examples:
.. code-block:: pycon
>>> parse("Bring me a {}", "Bring me a shrubbery")
<Result ('shrubbery',) {}>
>>> r = parse("The {} who {} {}", "The knights who say Ni!")
>>> print(r)
<Result ('knights', 'say', 'Ni!') {}>
>>> print(r.fixed)
('knights', 'say', 'Ni!')
>>> print(r[0])
knights
>>> print(r[1:])
('say', 'Ni!')
>>> r = parse("Bring out the holy {item}", "Bring out the holy hand grenade")
>>> print(r)
<Result () {'item': 'hand grenade'}>
>>> print(r.named)
{'item': 'hand grenade'}
>>> print(r['item'])
hand grenade
>>> 'item' in r
True
Note that `in` only works if you have named fields.
Dotted names and indexes are possible with some limits. Only word identifiers
are supported (ie. no numeric indexes) and the application must make additional
sense of the result:
.. code-block:: pycon
>>> r = parse("Mmm, {food.type}, I love it!", "Mmm, spam, I love it!")
>>> print(r)
<Result () {'food.type': 'spam'}>
>>> print(r.named)
{'food.type': 'spam'}
>>> print(r['food.type'])
spam
>>> r = parse("My quest is {quest[name]}", "My quest is to seek the holy grail!")
>>> print(r)
<Result () {'quest': {'name': 'to seek the holy grail!'}}>
>>> print(r['quest'])
{'name': 'to seek the holy grail!'}
>>> print(r['quest']['name'])
to seek the holy grail!
If the text you're matching has braces in it you can match those by including
a double-brace ``{{`` or ``}}`` in your format string, just like format() does.
Format Specification
--------------------
Most often a straight format-less ``{}`` will suffice where a more complex
format specification might have been used.
Most of `format()`'s `Format Specification Mini-Language`_ is supported:
[[fill]align][0][width][.precision][type]
The differences between `parse()` and `format()` are:
- The align operators will cause spaces (or specified fill character) to be
stripped from the parsed value. The width is not enforced; it just indicates
there may be whitespace or "0"s to strip.
- Numeric parsing will automatically handle a "0b", "0o" or "0x" prefix.
That is, the "#" format character is handled automatically by d, b, o
and x formats. For "d" any will be accepted, but for the others the correct
prefix must be present if at all.
- Numeric sign is handled automatically.
- The thousands separator is handled automatically if the "n" type is used.
- The types supported are a slightly different mix to the format() types. Some
format() types come directly over: "d", "n", "%", "f", "e", "b", "o" and "x".
In addition some regular expression character group types "D", "w", "W", "s"
and "S" are also available.
- The "e" and "g" types are case-insensitive so there is not need for
the "E" or "G" types. The "e" type handles Fortran formatted numbers (no
leading 0 before the decimal point).
===== =========================================== ========
Type Characters Matched Output
===== =========================================== ========
l Letters (ASCII) str
w Letters, numbers and underscore str
W Not letters, numbers and underscore str
s Whitespace str
S Non-whitespace str
d Digits (effectively integer numbers) int
D Non-digit str
n Numbers with thousands separators (, or .) int
% Percentage (converted to value/100.0) float
f Fixed-point numbers float
F Decimal numbers Decimal
e Floating-point numbers with exponent float
e.g. 1.1e-10, NAN (all case insensitive)
g General number format (either d, f or e) float
b Binary numbers int
o Octal numbers int
x Hexadecimal numbers (lower and upper case) int
ti ISO 8601 format date/time datetime
e.g. 1972-01-20T10:21:36Z ("T" and "Z"
optional)
te RFC2822 e-mail format date/time datetime
e.g. Mon, 20 Jan 1972 10:21:36 +1000
tg Global (day/month) format date/time datetime
e.g. 20/1/1972 10:21:36 AM +1:00
ta US (month/day) format date/time datetime
e.g. 1/20/1972 10:21:36 PM +10:30
tc ctime() format date/time datetime
e.g. Sun Sep 16 01:03:52 1973
th HTTP log format date/time datetime
e.g. 21/Nov/2011:00:07:11 +0000
ts Linux system log format date/time datetime
e.g. Nov 9 03:37:44
tt Time time
e.g. 10:21:36 PM -5:30
===== =========================================== ========
Some examples of typed parsing with ``None`` returned if the typing
does not match:
.. code-block:: pycon
>>> parse('Our {:d} {:w} are...', 'Our 3 weapons are...')
<Result (3, 'weapons') {}>
>>> parse('Our {:d} {:w} are...', 'Our three weapons are...')
>>> parse('Meet at {:tg}', 'Meet at 1/2/2011 11:00 PM')
<Result (datetime.datetime(2011, 2, 1, 23, 0),) {}>
And messing about with alignment:
.. code-block:: pycon
>>> parse('with {:>} herring', 'with a herring')
<Result ('a',) {}>
>>> parse('spam {:^} spam', 'spam lovely spam')
<Result ('lovely',) {}>
Note that the "center" alignment does not test to make sure the value is
centered - it just strips leading and trailing whitespace.
Width and precision may be used to restrict the size of matched text
from the input. Width specifies a minimum size and precision specifies
a maximum. For example:
.. code-block:: pycon
>>> parse('{:.2}{:.2}', 'look') # specifying precision
<Result ('lo', 'ok') {}>
>>> parse('{:4}{:4}', 'look at that') # specifying width
<Result ('look', 'at that') {}>
>>> parse('{:4}{:.4}', 'look at that') # specifying both
<Result ('look at ', 'that') {}>
>>> parse('{:2d}{:2d}', '0440') # parsing two contiguous numbers
<Result (4, 40) {}>
Some notes for the date and time types:
- the presence of the time part is optional (including ISO 8601, starting
at the "T"). A full datetime object will always be returned; the time
will be set to 00:00:00. You may also specify a time without seconds.
- when a seconds amount is present in the input fractions will be parsed
to give microseconds.
- except in ISO 8601 the day and month digits may be 0-padded.
- the date separator for the tg and ta formats may be "-" or "/".
- named months (abbreviations or full names) may be used in the ta and tg
formats in place of numeric months.
- as per RFC 2822 the e-mail format may omit the day (and comma), and the
seconds but nothing else.
- hours greater than 12 will be happily accepted.
- the AM/PM are optional, and if PM is found then 12 hours will be added
to the datetime object's hours amount - even if the hour is greater
than 12 (for consistency.)
- in ISO 8601 the "Z" (UTC) timezone part may be a numeric offset
- timezones are specified as "+HH:MM" or "-HH:MM". The hour may be one or two
digits (0-padded is OK.) Also, the ":" is optional.
- the timezone is optional in all except the e-mail format (it defaults to
UTC.)
- named timezones are not handled yet.
Note: attempting to match too many datetime fields in a single parse() will
currently result in a resource allocation issue. A TooManyFields exception
will be raised in this instance. The current limit is about 15. It is hoped
that this limit will be removed one day.
.. _`Format String Syntax`:
http://docs.python.org/library/string.html#format-string-syntax
.. _`Format Specification Mini-Language`:
http://docs.python.org/library/string.html#format-specification-mini-language
Result and Match Objects
------------------------
The result of a ``parse()`` and ``search()`` operation is either ``None`` (no match), a
``Result`` instance or a ``Match`` instance if ``evaluate_result`` is False.
The ``Result`` instance has three attributes:
``fixed``
A tuple of the fixed-position, anonymous fields extracted from the input.
``named``
A dictionary of the named fields extracted from the input.
``spans``
A dictionary mapping the names and fixed position indices matched to a
2-tuple slice range of where the match occurred in the input.
The span does not include any stripped padding (alignment or width).
The ``Match`` instance has one method:
``evaluate_result()``
Generates and returns a ``Result`` instance for this ``Match`` object.
Custom Type Conversions
-----------------------
If you wish to have matched fields automatically converted to your own type you
may pass in a dictionary of type conversion information to ``parse()`` and
``compile()``.
The converter will be passed the field string matched. Whatever it returns
will be substituted in the ``Result`` instance for that field.
Your custom type conversions may override the builtin types if you supply one
with the same identifier:
.. code-block:: pycon
>>> def shouty(string):
... return string.upper()
...
>>> parse('{:shouty} world', 'hello world', dict(shouty=shouty))
<Result ('HELLO',) {}>
If the type converter has the optional ``pattern`` attribute, it is used as
regular expression for better pattern matching (instead of the default one):
.. code-block:: pycon
>>> def parse_number(text):
... return int(text)
>>> parse_number.pattern = r'\d+'
>>> parse('Answer: {number:Number}', 'Answer: 42', dict(Number=parse_number))
<Result () {'number': 42}>
>>> _ = parse('Answer: {:Number}', 'Answer: Alice', dict(Number=parse_number))
>>> assert _ is None, "MISMATCH"
You can also use the ``with_pattern(pattern)`` decorator to add this
information to a type converter function:
.. code-block:: pycon
>>> from parse import with_pattern
>>> @with_pattern(r'\d+')
... def parse_number(text):
... return int(text)
>>> parse('Answer: {number:Number}', 'Answer: 42', dict(Number=parse_number))
<Result () {'number': 42}>
A more complete example of a custom type might be:
.. code-block:: pycon
>>> yesno_mapping = {
... "yes": True, "no": False,
... "on": True, "off": False,
... "true": True, "false": False,
... }
>>> @with_pattern(r"|".join(yesno_mapping))
... def parse_yesno(text):
... return yesno_mapping[text.lower()]
If the type converter ``pattern`` uses regex-grouping (with parenthesis),
you should indicate this by using the optional ``regex_group_count`` parameter
in the ``with_pattern()`` decorator:
.. code-block:: pycon
>>> @with_pattern(r'((\d+))', regex_group_count=2)
... def parse_number2(text):
... return int(text)
>>> parse('Answer: {:Number2} {:Number2}', 'Answer: 42 43', dict(Number2=parse_number2))
<Result (42, 43) {}>
Otherwise, this may cause parsing problems with unnamed/fixed parameters.
Potential Gotchas
-----------------
``parse()`` will always match the shortest text necessary (from left to right)
to fulfil the parse pattern, so for example:
.. code-block:: pycon
>>> pattern = '{dir1}/{dir2}'
>>> data = 'root/parent/subdir'
>>> sorted(parse(pattern, data).named.items())
[('dir1', 'root'), ('dir2', 'parent/subdir')]
So, even though `{'dir1': 'root/parent', 'dir2': 'subdir'}` would also fit
the pattern, the actual match represents the shortest successful match for
``dir1``.
----
- 1.19.0 Added slice access to fixed results (thanks @jonathangjertsen).
Also corrected matching of *full string* vs. *full line* (thanks @giladreti)
Fix issue with using digit field numbering and types
- 1.18.0 Correct bug in int parsing introduced in 1.16.0 (thanks @maxxk)
- 1.17.0 Make left- and center-aligned search consume up to next space
- 1.16.0 Make compiled parse objects pickleable (thanks @martinResearch)
- 1.15.0 Several fixes for parsing non-base 10 numbers (thanks @vladikcomper)
- 1.14.0 More broad acceptance of Fortran number format (thanks @purpleskyfall)
- 1.13.1 Project metadata correction.
- 1.13.0 Handle Fortran formatted numbers with no leading 0 before decimal
point (thanks @purpleskyfall).
Handle comparison of FixedTzOffset with other types of object.
- 1.12.1 Actually use the `case_sensitive` arg in compile (thanks @jacquev6)
- 1.12.0 Do not assume closing brace when an opening one is found (thanks @mattsep)
- 1.11.1 Revert having unicode char in docstring, it breaks Bamboo builds(?!)
- 1.11.0 Implement `__contains__` for Result instances.
- 1.10.0 Introduce a "letters" matcher, since "w" matches numbers
also.
- 1.9.1 Fix deprecation warnings around backslashes in regex strings
(thanks Mickael Schoentgen). Also fix some documentation formatting
issues.
- 1.9.0 We now honor precision and width specifiers when parsing numbers
and strings, allowing parsing of concatenated elements of fixed width
(thanks Julia Signell)
- 1.8.4 Add LICENSE file at request of packagers.
Correct handling of AM/PM to follow most common interpretation.
Correct parsing of hexadecimal that looks like a binary prefix.
Add ability to parse case sensitively.
Add parsing of numbers to Decimal with "F" (thanks John Vandenberg)
- 1.8.3 Add regex_group_count to with_pattern() decorator to support
user-defined types that contain brackets/parenthesis (thanks Jens Engel)
- 1.8.2 add documentation for including braces in format string
- 1.8.1 ensure bare hexadecimal digits are not matched
- 1.8.0 support manual control over result evaluation (thanks Timo Furrer)
- 1.7.0 parse dict fields (thanks Mark Visser) and adapted to allow
more than 100 re groups in Python 3.5+ (thanks David King)
- 1.6.6 parse Linux system log dates (thanks Alex Cowan)
- 1.6.5 handle precision in float format (thanks Levi Kilcher)
- 1.6.4 handle pipe "|" characters in parse string (thanks Martijn Pieters)
- 1.6.3 handle repeated instances of named fields, fix bug in PM time
overflow
- 1.6.2 fix logging to use local, not root logger (thanks Necku)
- 1.6.1 be more flexible regarding matched ISO datetimes and timezones in
general, fix bug in timezones without ":" and improve docs
- 1.6.0 add support for optional ``pattern`` attribute in user-defined types
(thanks Jens Engel)
- 1.5.3 fix handling of question marks
- 1.5.2 fix type conversion error with dotted names (thanks Sebastian Thiel)
- 1.5.1 implement handling of named datetime fields
- 1.5 add handling of dotted field names (thanks Sebastian Thiel)
- 1.4.1 fix parsing of "0" in int conversion (thanks James Rowe)
- 1.4 add __getitem__ convenience access on Result.
- 1.3.3 fix Python 2.5 setup.py issue.
- 1.3.2 fix Python 3.2 setup.py issue.
- 1.3.1 fix a couple of Python 3.2 compatibility issues.
- 1.3 added search() and findall(); removed compile() from ``import *``
export as it overwrites builtin.
- 1.2 added ability for custom and override type conversions to be
provided; some cleanup
- 1.1.9 to keep things simpler number sign is handled automatically;
significant robustification in the face of edge-case input.
- 1.1.8 allow "d" fields to have number base "0x" etc. prefixes;
fix up some field type interactions after stress-testing the parser;
implement "%" type.
- 1.1.7 Python 3 compatibility tweaks (2.5 to 2.7 and 3.2 are supported).
- 1.1.6 add "e" and "g" field types; removed redundant "h" and "X";
removed need for explicit "#".
- 1.1.5 accept textual dates in more places; Result now holds match span
positions.
- 1.1.4 fixes to some int type conversion; implemented "=" alignment; added
date/time parsing with a variety of formats handled.
- 1.1.3 type conversion is automatic based on specified field types. Also added
"f" and "n" types.
- 1.1.2 refactored, added compile() and limited ``from parse import *``
- 1.1.1 documentation improvements
- 1.1.0 implemented more of the `Format Specification Mini-Language`_
and removed the restriction on mixing fixed-position and named fields
- 1.0.0 initial release
This code is copyright 2012-2021 Richard Jones <richard@python.org>
See the end of the source file for the license of use.
'''
from __future__ import absolute_import
__version__ = '1.19.0'
# yes, I now have two problems
import re
import sys
from datetime import datetime, time, tzinfo, timedelta
from decimal import Decimal
from functools import partial
import logging
__all__ = 'parse search findall with_pattern'.split()
log = logging.getLogger(__name__)
def with_pattern(pattern, regex_group_count=None):
r"""Attach a regular expression pattern matcher to a custom type converter
function.
This annotates the type converter with the :attr:`pattern` attribute.
EXAMPLE:
>>> import parse
>>> @parse.with_pattern(r"\d+")
... def parse_number(text):
... return int(text)
is equivalent to:
>>> def parse_number(text):
... return int(text)
>>> parse_number.pattern = r"\d+"
:param pattern: regular expression pattern (as text)
:param regex_group_count: Indicates how many regex-groups are in pattern.
:return: wrapped function
"""
def decorator(func):
func.pattern = pattern
func.regex_group_count = regex_group_count
return func
return decorator
class int_convert:
"""Convert a string to an integer.
The string may start with a sign.
It may be of a base other than 2, 8, 10 or 16.
If base isn't specified, it will be detected automatically based
on a string format. When string starts with a base indicator, 0#nnnn,
it overrides the default base of 10.
It may also have other non-numeric characters that we can ignore.
"""
CHARS = '0123456789abcdefghijklmnopqrstuvwxyz'
def __init__(self, base=None):
self.base = base
def __call__(self, string, match):
if string[0] == '-':
sign = -1
number_start = 1
elif string[0] == '+':
sign = 1
number_start = 1
else:
sign = 1
number_start = 0
base = self.base
# If base wasn't specified, detect it automatically
if base is None:
# Assume decimal number, unless different base is detected
base = 10
# For number formats starting with 0b, 0o, 0x, use corresponding base ...
if string[number_start] == '0' and len(string) - number_start > 2:
if string[number_start + 1] in 'bB':
base = 2
elif string[number_start + 1] in 'oO':
base = 8
elif string[number_start + 1] in 'xX':
base = 16
chars = int_convert.CHARS[:base]
string = re.sub('[^%s]' % chars, '', string.lower())
return sign * int(string, base)
class convert_first:
"""Convert the first element of a pair.
This equivalent to lambda s,m: converter(s). But unlike a lambda function, it can be pickled
"""
def __init__(self, converter):
self.converter = converter
def __call__(self, string, match):
return self.converter(string)
def percentage(string, match):
return float(string[:-1]) / 100.0
class FixedTzOffset(tzinfo):
"""Fixed offset in minutes east from UTC."""
ZERO = timedelta(0)
def __init__(self, offset, name):
self._offset = timedelta(minutes=offset)
self._name = name
def __repr__(self):
return '<%s %s %s>' % (self.__class__.__name__, self._name, self._offset)
def utcoffset(self, dt):
return self._offset
def tzname(self, dt):
return self._name
def dst(self, dt):
return self.ZERO
def __eq__(self, other):
if not isinstance(other, FixedTzOffset):
return False
return self._name == other._name and self._offset == other._offset
MONTHS_MAP = dict(
Jan=1,
January=1,
Feb=2,
February=2,
Mar=3,
March=3,
Apr=4,
April=4,
May=5,
Jun=6,
June=6,
Jul=7,
July=7,
Aug=8,
August=8,
Sep=9,
September=9,
Oct=10,
October=10,
Nov=11,
November=11,
Dec=12,
December=12,
)
DAYS_PAT = r'(Mon|Tue|Wed|Thu|Fri|Sat|Sun)'
MONTHS_PAT = r'(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)'
ALL_MONTHS_PAT = r'(%s)' % '|'.join(MONTHS_MAP)
TIME_PAT = r'(\d{1,2}:\d{1,2}(:\d{1,2}(\.\d+)?)?)'
AM_PAT = r'(\s+[AP]M)'
TZ_PAT = r'(\s+[-+]\d\d?:?\d\d)'
def date_convert(
string,
match,
ymd=None,
mdy=None,
dmy=None,
d_m_y=None,
hms=None,
am=None,
tz=None,
mm=None,
dd=None,
):
"""Convert the incoming string containing some date / time info into a
datetime instance.
"""
groups = match.groups()
time_only = False
if mm and dd:
y = datetime.today().year
m = groups[mm]
d = groups[dd]
elif ymd is not None:
y, m, d = re.split(r'[-/\s]', groups[ymd])
elif mdy is not None:
m, d, y = re.split(r'[-/\s]', groups[mdy])
elif dmy is not None:
d, m, y = re.split(r'[-/\s]', groups[dmy])
elif d_m_y is not None:
d, m, y = d_m_y
d = groups[d]
m = groups[m]
y = groups[y]
else:
time_only = True
H = M = S = u = 0
if hms is not None and groups[hms]:
t = groups[hms].split(':')
if len(t) == 2:
H, M = t
else:
H, M, S = t
if '.' in S:
S, u = S.split('.')
u = int(float('.' + u) * 1000000)
S = int(S)
H = int(H)
M = int(M)
if am is not None:
am = groups[am]
if am:
am = am.strip()
if am == 'AM' and H == 12:
# correction for "12" hour functioning as "0" hour: 12:15 AM = 00:15 by 24 hr clock
H -= 12
elif am == 'PM' and H == 12:
# no correction needed: 12PM is midday, 12:00 by 24 hour clock
pass
elif am == 'PM':
H += 12
if tz is not None:
tz = groups[tz]
if tz == 'Z':
tz = FixedTzOffset(0, 'UTC')
elif tz:
tz = tz.strip()
if tz.isupper():
# TODO use the awesome python TZ module?
pass
else:
sign = tz[0]
if ':' in tz:
tzh, tzm = tz[1:].split(':')
elif len(tz) == 4: # 'snnn'
tzh, tzm = tz[1], tz[2:4]
else:
tzh, tzm = tz[1:3], tz[3:5]
offset = int(tzm) + int(tzh) * 60
if sign == '-':
offset = -offset
tz = FixedTzOffset(offset, tz)
if time_only:
d = time(H, M, S, u, tzinfo=tz)
else:
y = int(y)
if m.isdigit():
m = int(m)
else:
m = MONTHS_MAP[m]
d = int(d)
d = datetime(y, m, d, H, M, S, u, tzinfo=tz)
return d
class TooManyFields(ValueError):
pass
class RepeatedNameError(ValueError):
pass
# note: {} are handled separately
# note: I don't use r'' here because Sublime Text 2 syntax highlight has a fit
REGEX_SAFETY = re.compile(r'([?\\\\.[\]()*+\^$!\|])')
# allowed field types
ALLOWED_TYPES = set(list('nbox%fFegwWdDsSl') + ['t' + c for c in 'ieahgcts'])
def extract_format(format, extra_types):
"""Pull apart the format [[fill]align][0][width][.precision][type]"""
fill = align = None
if format[0] in '<>=^':
align = format[0]
format = format[1:]
elif len(format) > 1 and format[1] in '<>=^':
fill = format[0]
align = format[1]
format = format[2:]
zero = False
if format and format[0] == '0':
zero = True
format = format[1:]
width = ''
while format:
if not format[0].isdigit():
break
width += format[0]
format = format[1:]
if format.startswith('.'):
# Precision isn't needed but we need to capture it so that
# the ValueError isn't raised.
format = format[1:] # drop the '.'
precision = ''
while format:
if not format[0].isdigit():
break
precision += format[0]
format = format[1:]
# the rest is the type, if present
type = format
if type and type not in ALLOWED_TYPES and type not in extra_types:
raise ValueError('format spec %r not recognised' % type)
return locals()
PARSE_RE = re.compile(r"""({{|}}|{\w*(?:(?:\.\w+)|(?:\[[^\]]+\]))*(?::[^}]+)?})""")
class Parser(object):
"""Encapsulate a format string that may be used to parse other strings."""
def __init__(self, format, extra_types=None, case_sensitive=False):
# a mapping of a name as in {hello.world} to a regex-group compatible
# name, like hello__world Its used to prevent the transformation of
# name-to-group and group to name to fail subtly, such as in:
# hello_.world-> hello___world->hello._world
self._group_to_name_map = {}
# also store the original field name to group name mapping to allow
# multiple instances of a name in the format string
self._name_to_group_map = {}
# and to sanity check the repeated instances store away the first
# field type specification for the named field
self._name_types = {}
self._format = format
if extra_types is None:
extra_types = {}
self._extra_types = extra_types
if case_sensitive:
self._re_flags = re.DOTALL
else:
self._re_flags = re.IGNORECASE | re.DOTALL
self._fixed_fields = []
self._named_fields = []
self._group_index = 0
self._type_conversions = {}
self._expression = self._generate_expression()
self.__search_re = None
self.__match_re = None
log.debug('format %r -> %r', format, self._expression)
def __repr__(self):
if len(self._format) > 20:
return '<%s %r>' % (self.__class__.__name__, self._format[:17] + '...')
return '<%s %r>' % (self.__class__.__name__, self._format)
@property
def _search_re(self):
if self.__search_re is None:
try:
self.__search_re = re.compile(self._expression, self._re_flags)
except AssertionError:
# access error through sys to keep py3k and backward compat
e = str(sys.exc_info()[1])
if e.endswith('this version only supports 100 named groups'):
raise TooManyFields(
'sorry, you are attempting to parse ' 'too many complex fields'
)
return self.__search_re
@property
def _match_re(self):
if self.__match_re is None:
expression = r'\A%s\Z' % self._expression
try:
self.__match_re = re.compile(expression, self._re_flags)
except AssertionError:
# access error through sys to keep py3k and backward compat
e = str(sys.exc_info()[1])
if e.endswith('this version only supports 100 named groups'):
raise TooManyFields(
'sorry, you are attempting to parse ' 'too many complex fields'
)
except re.error:
raise NotImplementedError(
"Group names (e.g. (?P<name>) can "
"cause failure, as they are not escaped properly: '%s'" % expression
)
return self.__match_re
@property
def named_fields(self):
return self._named_fields.copy()
@property
def fixed_fields(self):
return self._fixed_fields.copy()
def parse(self, string, evaluate_result=True):
"""Match my format to the string exactly.
Return a Result or Match instance or None if there's no match.
"""
m = self._match_re.match(string)
if m is None:
return None
if evaluate_result:
return self.evaluate_result(m)
else:
return Match(self, m)
def search(self, string, pos=0, endpos=None, evaluate_result=True):
"""Search the string for my format.
Optionally start the search at "pos" character index and limit the
search to a maximum index of endpos - equivalent to
search(string[:endpos]).
If the ``evaluate_result`` argument is set to ``False`` a
Match instance is returned instead of the actual Result instance.
Return either a Result instance or None if there's no match.
"""
if endpos is None:
endpos = len(string)
m = self._search_re.search(string, pos, endpos)
if m is None:
return None
if evaluate_result:
return self.evaluate_result(m)
else:
return Match(self, m)
def findall(
self, string, pos=0, endpos=None, extra_types=None, evaluate_result=True
):
"""Search "string" for all occurrences of "format".
Optionally start the search at "pos" character index and limit the
search to a maximum index of endpos - equivalent to
search(string[:endpos]).
Returns an iterator that holds Result or Match instances for each format match
found.
"""
if endpos is None:
endpos = len(string)
return ResultIterator(
self, string, pos, endpos, evaluate_result=evaluate_result
)
def _expand_named_fields(self, named_fields):
result = {}
for field, value in named_fields.items():
# split 'aaa[bbb][ccc]...' into 'aaa' and '[bbb][ccc]...'
basename, subkeys = re.match(r'([^\[]+)(.*)', field).groups()
# create nested dictionaries {'aaa': {'bbb': {'ccc': ...}}}
d = result
k = basename
if subkeys:
for subkey in re.findall(r'\[[^\]]+\]', subkeys):
d = d.setdefault(k, {})
k = subkey[1:-1]
# assign the value to the last key
d[k] = value
return result
def evaluate_result(self, m):
'''Generate a Result instance for the given regex match object'''
# ok, figure the fixed fields we've pulled out and type convert them
fixed_fields = list(m.groups())
for n in self._fixed_fields:
if n in self._type_conversions:
fixed_fields[n] = self._type_conversions[n](fixed_fields[n], m)
fixed_fields = tuple(fixed_fields[n] for n in self._fixed_fields)
# grab the named fields, converting where requested
groupdict = m.groupdict()
named_fields = {}
name_map = {}
for k in self._named_fields:
korig = self._group_to_name_map[k]
name_map[korig] = k
if k in self._type_conversions:
value = self._type_conversions[k](groupdict[k], m)
else:
value = groupdict[k]
named_fields[korig] = value
# now figure the match spans
spans = dict((n, m.span(name_map[n])) for n in named_fields)
spans.update((i, m.span(n + 1)) for i, n in enumerate(self._fixed_fields))
# and that's our result
return Result(fixed_fields, self._expand_named_fields(named_fields), spans)
def _regex_replace(self, match):
return '\\' + match.group(1)
def _generate_expression(self):
# turn my _format attribute into the _expression attribute
e = []
for part in PARSE_RE.split(self._format):
if not part:
continue
elif part == '{{':
e.append(r'\{')
elif part == '}}':
e.append(r'\}')
elif part[0] == '{' and part[-1] == '}':
# this will be a braces-delimited field to handle
e.append(self._handle_field(part))
else:
# just some text to match
e.append(REGEX_SAFETY.sub(self._regex_replace, part))
return ''.join(e)
def _to_group_name(self, field):
# return a version of field which can be used as capture group, even
# though it might contain '.'
group = field.replace('.', '_').replace('[', '_').replace(']', '_')
# make sure we don't collide ("a.b" colliding with "a_b")
n = 1
while group in self._group_to_name_map:
n += 1
if '.' in field:
group = field.replace('.', '_' * n)
elif '_' in field:
group = field.replace('_', '_' * n)
else:
raise KeyError('duplicated group name %r' % (field,))
# save off the mapping
self._group_to_name_map[group] = field
self._name_to_group_map[field] = group
return group
def _handle_field(self, field):
# first: lose the braces
field = field[1:-1]
# now figure whether this is an anonymous or named field, and whether
# there's any format specification
format = ''
if ':' in field:
name, format = field.split(':')
else:
name = field
# This *should* be more flexible, but parsing complicated structures
# out of the string is hard (and not necessarily useful) ... and I'm
# being lazy. So for now `identifier` is "anything starting with a
# letter" and digit args don't get attribute or element stuff.
if name and name[0].isalpha():
if name in self._name_to_group_map:
if self._name_types[name] != format:
raise RepeatedNameError(
'field type %r for field "%s" '
'does not match previous seen type %r'
% (format, name, self._name_types[name])
)
group = self._name_to_group_map[name]
# match previously-seen value
return r'(?P=%s)' % group
else:
group = self._to_group_name(name)
self._name_types[name] = format
self._named_fields.append(group)
# this will become a group, which must not contain dots
wrap = r'(?P<%s>%%s)' % group
else:
self._fixed_fields.append(self._group_index)
wrap = r'(%s)'
group = self._group_index
# simplest case: no type specifier ({} or {name})
if not format:
self._group_index += 1
return wrap % r'.+?'
# decode the format specification
format = extract_format(format, self._extra_types)
# figure type conversions, if any
type = format['type']
is_numeric = type and type in 'n%fegdobx'
if type in self._extra_types:
type_converter = self._extra_types[type]
s = getattr(type_converter, 'pattern', r'.+?')
regex_group_count = getattr(type_converter, 'regex_group_count', 0)
if regex_group_count is None:
regex_group_count = 0
self._group_index += regex_group_count
self._type_conversions[group] = convert_first(type_converter)
elif type == 'n':
s = r'\d{1,3}([,.]\d{3})*'
self._group_index += 1
self._type_conversions[group] = int_convert(10)
elif type == 'b':
s = r'(0[bB])?[01]+'
self._type_conversions[group] = int_convert(2)
self._group_index += 1
elif type == 'o':
s = r'(0[oO])?[0-7]+'
self._type_conversions[group] = int_convert(8)
self._group_index += 1
elif type == 'x':
s = r'(0[xX])?[0-9a-fA-F]+'
self._type_conversions[group] = int_convert(16)
self._group_index += 1
elif type == '%':
s = r'\d+(\.\d+)?%'
self._group_index += 1
self._type_conversions[group] = percentage
elif type == 'f':
s = r'\d*\.\d+'
self._type_conversions[group] = convert_first(float)
elif type == 'F':
s = r'\d*\.\d+'
self._type_conversions[group] = convert_first(Decimal)
elif type == 'e':
s = r'\d*\.\d+[eE][-+]?\d+|nan|NAN|[-+]?inf|[-+]?INF'
self._type_conversions[group] = convert_first(float)
elif type == 'g':
s = r'\d+(\.\d+)?([eE][-+]?\d+)?|nan|NAN|[-+]?inf|[-+]?INF'
self._group_index += 2
self._type_conversions[group] = convert_first(float)
elif type == 'd':
if format.get('width'):
width = r'{1,%s}' % int(format['width'])
else:
width = '+'
s = r'\d{w}|[-+ ]?0[xX][0-9a-fA-F]{w}|[-+ ]?0[bB][01]{w}|[-+ ]?0[oO][0-7]{w}'.format(
w=width
)
self._type_conversions[
group
] = int_convert() # do not specify number base, determine it automatically
elif type == 'ti':
s = r'(\d{4}-\d\d-\d\d)((\s+|T)%s)?(Z|\s*[-+]\d\d:?\d\d)?' % TIME_PAT
n = self._group_index
self._type_conversions[group] = partial(
date_convert, ymd=n + 1, hms=n + 4, tz=n + 7
)
self._group_index += 7
elif type == 'tg':
s = r'(\d{1,2}[-/](\d{1,2}|%s)[-/]\d{4})(\s+%s)?%s?%s?' % (
ALL_MONTHS_PAT,
TIME_PAT,
AM_PAT,
TZ_PAT,
)
n = self._group_index
self._type_conversions[group] = partial(
date_convert, dmy=n + 1, hms=n + 5, am=n + 8, tz=n + 9
)
self._group_index += 9
elif type == 'ta':
s = r'((\d{1,2}|%s)[-/]\d{1,2}[-/]\d{4})(\s+%s)?%s?%s?' % (
ALL_MONTHS_PAT,
TIME_PAT,
AM_PAT,
TZ_PAT,
)
n = self._group_index
self._type_conversions[group] = partial(
date_convert, mdy=n + 1, hms=n + 5, am=n + 8, tz=n + 9
)
self._group_index += 9
elif type == 'te':
# this will allow microseconds through if they're present, but meh
s = r'(%s,\s+)?(\d{1,2}\s+%s\s+\d{4})\s+%s%s' % (
DAYS_PAT,
MONTHS_PAT,
TIME_PAT,
TZ_PAT,
)
n = self._group_index
self._type_conversions[group] = partial(
date_convert, dmy=n + 3, hms=n + 5, tz=n + 8
)
self._group_index += 8
elif type == 'th':
# slight flexibility here from the stock Apache format
s = r'(\d{1,2}[-/]%s[-/]\d{4}):%s%s' % (MONTHS_PAT, TIME_PAT, TZ_PAT)
n = self._group_index
self._type_conversions[group] = partial(
date_convert, dmy=n + 1, hms=n + 3, tz=n + 6
)
self._group_index += 6
elif type == 'tc':
s = r'(%s)\s+%s\s+(\d{1,2})\s+%s\s+(\d{4})' % (
DAYS_PAT,
MONTHS_PAT,
TIME_PAT,
)
n = self._group_index
self._type_conversions[group] = partial(
date_convert, d_m_y=(n + 4, n + 3, n + 8), hms=n + 5
)
self._group_index += 8
elif type == 'tt':
s = r'%s?%s?%s?' % (TIME_PAT, AM_PAT, TZ_PAT)
n = self._group_index
self._type_conversions[group] = partial(
date_convert, hms=n + 1, am=n + 4, tz=n + 5
)
self._group_index += 5
elif type == 'ts':
s = r'%s(\s+)(\d+)(\s+)(\d{1,2}:\d{1,2}:\d{1,2})?' % MONTHS_PAT
n = self._group_index
self._type_conversions[group] = partial(
date_convert, mm=n + 1, dd=n + 3, hms=n + 5
)
self._group_index += 5
elif type == 'l':
s = r'[A-Za-z]+'
elif type:
s = r'\%s+' % type
elif format.get('precision'):
if format.get('width'):
s = r'.{%s,%s}?' % (format['width'], format['precision'])
else:
s = r'.{1,%s}?' % format['precision']
elif format.get('width'):
s = r'.{%s,}?' % format['width']
else:
s = r'.+?'
align = format['align']
fill = format['fill']
# handle some numeric-specific things like fill and sign
if is_numeric:
# prefix with something (align "=" trumps zero)
if align == '=':
# special case - align "=" acts like the zero above but with
# configurable fill defaulting to "0"
if not fill:
fill = '0'
s = r'%s*' % fill + s
# allow numbers to be prefixed with a sign
s = r'[-+ ]?' + s
if not fill:
fill = ' '
# Place into a group now - this captures the value we want to keep.
# Everything else from now is just padding to be stripped off
if wrap:
s = wrap % s
self._group_index += 1
if format['width']:
# all we really care about is that if the format originally
# specified a width then there will probably be padding - without
# an explicit alignment that'll mean right alignment with spaces
# padding
if not align:
align = '>'
if fill in r'.\+?*[](){}^$':
fill = '\\' + fill
# align "=" has been handled
if align == '<':
s = '%s%s+' % (s, fill)
elif align == '>':
s = '%s*%s' % (fill, s)
elif align == '^':
s = '%s*%s%s+' % (fill, s, fill)
return s
class Result(object):
"""The result of a parse() or search().
Fixed results may be looked up using `result[index]`.
Slices of fixed results may also be looked up.
Named results may be looked up using `result['name']`.
Named results may be tested for existence using `'name' in result`.
"""
def __init__(self, fixed, named, spans):
self.fixed = fixed
self.named = named
self.spans = spans
def __getitem__(self, item):
if isinstance(item, (int, slice)):
return self.fixed[item]
return self.named[item]
def __repr__(self):
return '<%s %r %r>' % (self.__class__.__name__, self.fixed, self.named)
def __contains__(self, name):
return name in self.named
class Match(object):
"""The result of a parse() or search() if no results are generated.
This class is only used to expose internal used regex match objects
to the user and use them for external Parser.evaluate_result calls.
"""
def __init__(self, parser, match):
self.parser = parser
self.match = match
def evaluate_result(self):
'''Generate results for this Match'''
return self.parser.evaluate_result(self.match)
class ResultIterator(object):
"""The result of a findall() operation.
Each element is a Result instance.
"""
def __init__(self, parser, string, pos, endpos, evaluate_result=True):
self.parser = parser
self.string = string
self.pos = pos
self.endpos = endpos
self.evaluate_result = evaluate_result
def __iter__(self):
return self
def __next__(self):
m = self.parser._search_re.search(self.string, self.pos, self.endpos)
if m is None:
raise StopIteration()
self.pos = m.end()
if self.evaluate_result:
return self.parser.evaluate_result(m)
else:
return Match(self.parser, m)
# pre-py3k compat
next = __next__
def parse(format, string, extra_types=None, evaluate_result=True, case_sensitive=False):
"""Using "format" attempt to pull values from "string".
The format must match the string contents exactly. If the value
you're looking for is instead just a part of the string use
search().
If ``evaluate_result`` is True the return value will be an Result instance with two attributes:
.fixed - tuple of fixed-position values from the string
.named - dict of named values from the string
If ``evaluate_result`` is False the return value will be a Match instance with one method:
.evaluate_result() - This will return a Result instance like you would get
with ``evaluate_result`` set to True
The default behaviour is to match strings case insensitively. You may match with
case by specifying case_sensitive=True.
If the format is invalid a ValueError will be raised.
See the module documentation for the use of "extra_types".
In the case there is no match parse() will return None.
"""
p = Parser(format, extra_types=extra_types, case_sensitive=case_sensitive)
return p.parse(string, evaluate_result=evaluate_result)
def search(
format,
string,
pos=0,
endpos=None,
extra_types=None,
evaluate_result=True,
case_sensitive=False,
):
"""Search "string" for the first occurrence of "format".
The format may occur anywhere within the string. If
instead you wish for the format to exactly match the string
use parse().
Optionally start the search at "pos" character index and limit the search
to a maximum index of endpos - equivalent to search(string[:endpos]).
If ``evaluate_result`` is True the return value will be an Result instance with two attributes:
.fixed - tuple of fixed-position values from the string
.named - dict of named values from the string
If ``evaluate_result`` is False the return value will be a Match instance with one method:
.evaluate_result() - This will return a Result instance like you would get
with ``evaluate_result`` set to True
The default behaviour is to match strings case insensitively. You may match with
case by specifying case_sensitive=True.
If the format is invalid a ValueError will be raised.
See the module documentation for the use of "extra_types".
In the case there is no match parse() will return None.
"""
p = Parser(format, extra_types=extra_types, case_sensitive=case_sensitive)
return p.search(string, pos, endpos, evaluate_result=evaluate_result)
def findall(
format,
string,
pos=0,
endpos=None,
extra_types=None,
evaluate_result=True,
case_sensitive=False,
):
"""Search "string" for all occurrences of "format".
You will be returned an iterator that holds Result instances
for each format match found.
Optionally start the search at "pos" character index and limit the search
to a maximum index of endpos - equivalent to search(string[:endpos]).
If ``evaluate_result`` is True each returned Result instance has two attributes:
.fixed - tuple of fixed-position values from the string
.named - dict of named values from the string
If ``evaluate_result`` is False each returned value is a Match instance with one method:
.evaluate_result() - This will return a Result instance like you would get
with ``evaluate_result`` set to True
The default behaviour is to match strings case insensitively. You may match with
case by specifying case_sensitive=True.
If the format is invalid a ValueError will be raised.
See the module documentation for the use of "extra_types".
"""
p = Parser(format, extra_types=extra_types, case_sensitive=case_sensitive)
return p.findall(string, pos, endpos, evaluate_result=evaluate_result)
def compile(format, extra_types=None, case_sensitive=False):
"""Create a Parser instance to parse "format".
The resultant Parser has a method .parse(string) which
behaves in the same manner as parse(format, string).
The default behaviour is to match strings case insensitively. You may match with
case by specifying case_sensitive=True.
Use this function if you intend to parse many strings
with the same format.
See the module documentation for the use of "extra_types".
Returns a Parser instance.
"""
return Parser(format, extra_types=extra_types, case_sensitive=case_sensitive)
# Copyright (c) 2012-2020 Richard Jones <richard@python.org>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
# vim: set filetype=python ts=4 sw=4 et si tw=75
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