The ABNF to REGEX library is a pair of PHP functions that validate standard ABNF (RFC 5234) input and generate POSIX and Perl-compatible regular expressions for use in schema and applications.

I provide an online form front-end for these functions at:

http://abnf.msweet.org/

The file "example.php" shows how to implement your own web form.

This function parses the ABNF contained in the supplied string. On success, it returns an array of rules that can be passed to the "abnf_regex" function.

FALSE is returned on failure, with the following global variables describing the issue:

• "abnf_error" contains a string describing the issue.
• "abnf_errorline" contains the line number in the string where the issue occurred.
• "abnf_errorcol" contains the column number in the string where the issue occurred.

This function generates a regular expression for the named rule. If the named rule does not exist, an empty string is returned.

The "mode" parameter can be any of the following constants:

• ABNF_INSENSITIVE : Generates a case-insensitive regular expression.
• ABNF_SENSITIVE : Generates a case-sensitive regular expression.
• ABNF_LOWERCASE : Generates a case-sensitive regular expression with all string literals converted to uppercase.
• ABNF_UPPERCASE : Generates a case-sensitive regular expression with all string literals converted to lowercase.

Copyright (c) 2013-2017 Michael R Sweet

This software is provided under the terms of the MIT license, which is provided in the file "LICENSE.md".