from pregex.core.classes import AnyUpperCaseLetter, AnyLowerCaseLetter, AnyDigit from pregex.core.quantifiers import AtLeast pattern = AnyUpperCaseLetter() + AtLeast(AnyLowerCaseLetter()) + AtLeast(AnyDigit()) 2. What is a "Safe Reset Code" in Pregex? A "safe reset code" is not a built-in Pregex function name. Instead, it refers to a design pattern where Pregex is used to generate regex that safely resets capturing groups, avoids catastrophic backtracking, and prevents runaway matches .
| Problem | Traditional Regex | Pregex Safe Reset | |--------|------------------|------------------| | Catastrophic backtracking | (a+)+b | Use AtMostOnce or Either with explicit bounds | | Accidental group capture | (?:...) needed everywhere | Pregex defaults to non-capturing; use .capture() explicitly | | Overlapping matches | Manual reset with \G | Use Pregex + .enclosed_by() to control boundaries | | Unintended partial resets | Nested groups | Use .then() chaining for clear sequence | Suppose you want to extract values after = but reset after each newline. pregex safe reset code
from pregex.core.classes import AnyDigit, AnyWordChar from pregex.core.operators import Either safe_reset = Either(AnyDigit(), AnyWordChar()) from pregex
This is because it doesn’t capture the lookbehind content, avoiding group pollution and side effects. 4. Why “Safe”? Avoiding Common Regex Pitfalls Using Pregex for resetting helps avoid: Instead, it refers to a design pattern where
Example:
from pregex.core.pregex import Pregex from pregex.core.classes import AnyDigit pattern = Pregex(AnyDigit()).skip(r"\s+") # Ignore spaces after a digit
