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cursive_re - readable regular expressions for Python 3

 6 years ago
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cursive_re

Readable regular expressions for Python 3.6 and up.

Installation

pip install cursive_re

Examples

>>> from cursive_re import *

>>> hash = text('#')
>>> hexdigit = any_of(in_range('0', '9') + in_range('a-f') + in_range('A-F'))
>>> hexcolor = (
...     beginning_of_line() + hash +
...     group(repeated(hexdigit, exactly=6) | repeated(hexdigit, exactly=3)) +
...     end_of_line()
... )
>>> str(hexcolor)
'^\\#([a-f0-9]{6}|[a-f0-9]{3})$'

>>> hexcolor_re = compile(hexcolor)
re.compile('^\\#([a-f0-9]{6}|[a-f0-9]{3})$')

>>> hexcolor_re.match('#fff')
<re.Match object; span=(0, 4), match='#fff'>

>>> hexcolor_re.match('#ffff') is None
True

>>> hexcolor_re.match('#ffffff')
<re.Match object; span=(0, 7), match='#ffffff'>

>>> domain_name = one_or_more(any_of(in_range('a', 'z') + in_range('0', '9') + text('-')))
>>> domain = domain_name + zero_or_more(text('.') + domain_name)
>>> path_segment = zero_or_more(none_of('/'))
>>> path = zero_or_more(text('/') + path_segment)
>>> url = (
...     group(one_or_more(any_of(in_range('a', 'z'))), name='scheme') + text('://') +
...     group(domain, name='domain') +
...     group(path, name='path')
... )
>>> str(url)
'(?P<scheme>[a-z]+)://(?P<domain>[a-z0-9\-]+(?:\.[a-z0-9\-]+)*)(?P<path>(?:/[^/]*)*)'

Reference

cursive_re.compile

Compile a cursive_re expression to a real regular expression.

cursive_re.beginning_of_line

Matches the beginning of a line.

Examples:

>>> str(beginning_of_line())
'^'

cursive_re.end_of_line

Matches the end of a line.

Examples:

>>> str(end_of_line())
'$'

cursive_re.anything

Matches any character.

Examples:

>>> str(anything())
'.'

cursive_re.literal

Inserts a literal regular expression.

Examples:

>>> str(literal(r"\A\w"))
'\\A\\w'

cursive_re.text

Matches the given string exactly, escaping any special characters.

Examples:

>>> str(text("abc"))
'abc'

cursive_re.any_of

Matches any of the given characters.

Examples:

>>> str(any_of("ab"))
'[ab]'

>>> str(any_of(text("ab")))
'[ab]'

>>> str(any_of(text("[]")))
'[\\[\\]]'

cursive_re.none_of

Matches none of the given characters.

Examples:

>>> str(none_of("ab"))
'[^ab]'

>>> str(none_of(text("ab")))
'[^ab]'

>>> str(none_of(text("[]")))
'[^\\[\\]]'

cursive_re.in_range

Matches a character in the given range.

Examples:

>>> str(in_range("a", "z"))
'a-z'

cursive_re.zero_or_more

Matches zero or more of the given expr.

Examples:

>>> str(zero_or_more("a"))
'(?:a)*'

>>> str(zero_or_more(text("a")))
'(?:a)*'

>>> str(zero_or_more(text("abc")))
'(?:abc)*'

>>> str(zero_or_more(group(text("abc"))))
'(abc)*'

cursive_re.one_or_more

Matches one or more of the given expr.

Examples:

>>> str(one_or_more("a"))
'(?:a)+'

>>> str(one_or_more(text("a")))
'(?:a)+'

>>> str(one_or_more(group(text("abc"))))
'(abc)+'

cursive_re.maybe

Matches an expr if present.

Examples:

>>> str(maybe("abc"))
'(?:abc)?'

>>> str(maybe(text("abc")))
'(?:abc)?'

>>> str(maybe(group(text("abc"))))
'(abc)?'

>>> str(maybe(any_of("abc")))
'[abc]?'

cursive_re.repeated

Matches an expr repeated an exact number of times.

Examples:

>>> str(repeated("a", exactly=5))
'(?:a){5}'

>>> str(repeated(text("a"), exactly=5))
'(?:a){5}'

>>> str(repeated(text("a"), at_least=1))
'(?:a){1,}'

>>> str(repeated(text("a"), at_most=5))
'(?:a){0,5}'

>>> str(repeated(text("a"), at_least=2, at_most=5, greedy=False))
'(?:a){2,5}?'

cursive_re.group

Denotes a group whose contents can be retrieved after a match is performed.

Examples:

>>> str(group(text("a")))
'(a)'

>>> str(group(any_of("abc"), name="chars"))
'(?P<chars>[abc])'

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