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Expose limiting for * and + in Xeger.xeger() #37

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Expose limiting for * and + in Xeger.xeger() #37

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4b684bf
Expose limiting the amount of repeats for * and + metacharacters in X…
crackhead-koala Nov 24, 2024
ebefebd
Remove unnecessary import
crackhead-koala Nov 24, 2024
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28 changes: 17 additions & 11 deletions rstr/xeger.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,15 +15,6 @@
import sre_parse


# The * and + characters in a regular expression
# match up to any number of repeats in theory,
# (and actually 65535 repeats in python) but you
# probably don't want that many repeats in your
# generated strings. This sets an upper-bound on
# repeats generated from + and * characters.
STAR_PLUS_LIMIT = 100


class Xeger(RstrBase):
'''Inspired by the Java library Xeger: http://code.google.com/p/xeger/
This class adds functionality to Rstr allowing users to generate a
Expand Down Expand Up @@ -61,12 +52,27 @@ def __init__(
'negate': lambda x: [False],
}

def xeger(self, string_or_regex: Union[str, Pattern[str]]) -> str:
def xeger(
self,
string_or_regex: Union[str, Pattern[str]],
star_plus_limit: int = 100
) -> str:
'''Generate a random string from a regular expression

By default, * and + metacharacters will generate a maximum of 100
repetitions of the character or group of characters that they modify
for each occurance in the regular expression. You can provide a second
argument to change this limit (note that the maximum amount of repeats
in Python is 65535).

'''
try:
pattern = typing.cast(Pattern[str], string_or_regex).pattern
except AttributeError:
pattern = typing.cast(str, string_or_regex)

self.star_plus_limit = star_plus_limit

parsed = sre_parse.parse(pattern)
result = self._build_string(parsed)
self._cache.clear()
Expand Down Expand Up @@ -99,7 +105,7 @@ def _handle_in(self, value: Any) -> Any:

def _handle_repeat(self, start_range: int, end_range: int, value: str) -> str:
result = []
end_range = min((end_range, STAR_PLUS_LIMIT))
end_range = min((end_range, self.star_plus_limit))
times = self._random.randint(start_range, end_range)
for i in range(times):
result.append(''.join(self._handle_state(i) for i in value))
Expand Down