Regex

This chapter forms an integral part of "The Regex Module" - should this module be implemneted, this chapter along with any chapter constituting part of "The Regex Module" must be implemented in their entirity.

[RegExp: bre_comp(regex, cflags) | ere_comp(regex, cflags)] := {
  // An opaque object representing a compiled regular expression.
  method split(subject);
  method match(subject);
  method capture(subject);
  method replace(subject, replacement, limit);
};

The bre_comp() and ere_comp() functions compiles a regular expression based on the "Basic Regular Expression" and "Extended Regular Expression" syntax specified by POSIX. Under the C/POSIX locale, all regex features up to POSIX-2017 are mandatory.

The cflags are expressed as radix-64 digits, whose correspondence with POSIX compile flag constants are as follow:

• 0\i: REG_ICASE - regex is executed without regard to case.
• 0\n: REG_NEWLINE - the lines (delimited by the LINE-FEED character) in the subject string is considered individually.

The split() method splits the subject string into a 0-base-indexed array of strings. The match() method determines whether the subject string can be matched by the regular expression.

The capture() method matches the subject string, putting matched subexpressions in array (starting from the index 1), the (entire) matched portion of the subject string in the 0th element of the said array, then return the array.

The replace() method replaces limit number of occurences of the substring matching the regex, with replacement. Each occurences of $<n> where <n> is a single decimal digit is replaced with the n-th subexpression in the regex. If <n> is 0, then it's replaced with the whole matched portion of the subject string. If limit is -1, then all occurences shall be replaced.