[PATCH] D68054: Regex: Add static convenience functions for "match" and "sub"

[Thomas Preud'homme via Phabricator via llvm-commits]

thopre added a comment.

How about the following commit message:

There are many cases where a Regex object is used only once: It is created,
used in a single call to match() or sub(), then thrown away. This was
done in various places in LLVM using the following idiom:

Regex(Pattern).match(String)

The problem with this idiom is that invalid patterns result in a match
failure, which can lead to unexpected behavior if the return value of
match() is used as a condition for an if statement. To force developers
to be mindful of this aspect, an assert is added to match() to check
that the regex is valid and an new idiom is created as follows for
cases where the pattern is known to be valid:

Regex::match(Pattern, String)

This new idiom is documented as returning false when the pattern is invalid.
Code using the old idiom is thus updated to use the new idiom.

A similar static convenience function was added for sub(). The constructor of Regex
was also extended to be able to return an error without requiring a subsequent
call to isValid(), for the sake of convenience and code reuse.


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https://reviews.llvm.org/D68054