This is especially true of SQL interfaces to databases, where the ANSI standard for pattern matching is so pathetic that most databases support some extension. Indeed for MariaDB 10 (when finally GA) will include PCRE with Unicode as standard.Īs can be seen there is great variability in regular expressions support. ‡ MySQL/MariaDB do have options to incorporate PCRE rather than POSIX ERE. † The PCRE library can compiled with Unicode support, but is not always. This may result in some loss of functionality, but is necessary to avoid confusing users.
SQLITE REGEX CHECK CONSTRAINTS CODE
In the event that an external tool supports regular expression syntax that is not compatible with Perl, the calling code must defuse the regex feature that is not perl compatible. ( and \(.ĭevelopers working with regular expressions must take great care, when exposing features of non-Perl regular expressions to end users, that they don't use features which are sparsely supported. Note also that Foswiki internal regexes may use meta-syntax that might need to be escaped/modified for different regex flavours e.g. This won't necessarily make Foswiki unusable, but should be borne in mind.
Loss of one or more of the features in this column will affect Foswiki (or one or more important extensions) functionality in some way. For example, when searching for topic references, the core code assembles a regex and then uses the search engine to look for it. The Required by Foswiki column documents regex features used by the core code when using the search engine. The features are chosen from those described in. The following table lists the features of Perl regular expressions that are understood to be supported by a number of common third-party tools. However, because Foswiki has to interface with third party tools and libraries, it is not always possible to support all the features of Perl regular expressions in all places.Īny developer who implements an interface to such a third-party tool must make every effort to map all the functionality of Perl regular expressions to the tool.
Foswiki strives to support the rich Perl regular expression syntax for end users, for example in searching.
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