== Why is this an issue?

include::../description.adoc[]

=== Noncompliant code example
[source,php]
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preg_match("/Jack|Peter|/", "John"); // Noncompliant - returns 1
preg_match("/Jack||Peter/", "John"); // Noncompliant - returns 1
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=== Compliant solution
[source,php]
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preg_match("/Jack|Peter/", "John"); // returns 0
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=== Exceptions

One could use an empty alternation to make a regular expression group optional. Note that the empty alternation should be the first or the last within the group, or else the rule will still report.

[source,php]
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preg_match("/mandatory(|-optional)/", "mandatory"); // returns 1
preg_match("/mandatory(-optional|)/", "mandatory-optional"); // returns 1
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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,php]
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preg_match("/mandatory(-optional|)?/", "mandatory-optional"); // Noncompliant - using both `|` inside the group and `?` for the group.
----

include::../implementation.adoc[]
