include::../description.adoc[]

== Noncompliant Code Example
[source,python]
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re.search(r"Jack|Peter|", "John") # Noncompliant - will match an empty string
re.search(r"Jack||Peter", "John") # Noncompliant - will match an empty string
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== Compliant Solution
[source,python]
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re.search(r"Jack|Peter", "John") # returns false
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== Exceptions

One could use an empty alternation to make a regular expression group optional. Rule will not report on such cases.

[source,python]
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re.search(r"mandatory(-optional|)", "mandatory")
re.search(r"mandatory(-optional|)", "mandatory-optional")
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However, if there is a quantifier after the group the issue will be reported as using both `|` and quantifier is redundant.

[source,python]
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re.search(r"mandatory(-optional|)?", "mandatory-optional") # Noncompliant - using both `|` inside the group and `?` for the group.
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include::../implementation.adoc[]