backreference

backreference

See also: back-reference

English

Alternative forms

• back-reference

Etymology

From back +‎ reference

Noun

backreference (plural backreferences)

1. (regular expressions) An item in a regular expression equivalent to the text matched by an earlier pattern in the expression.
   • 2003, Rob Brooks-Bilson, Programming ColdFusion MX

     The third part of the regular expression, \\1, is the backreference and tells ColdFusion to refer back to the first subexpression […]

   • 2005, Ivan Ristic, Apache security

     Path traversal occurs when directory backreferences are used in a path to gain access to the parent folder of a subfolder.

Verb

backreference (third-person singular simple present backreferences, present participle backreferencing, simple past and past participle backreferenced)

1. (regular expressions, transitive) To access (the text matched by an earlier pattern in a regular expression).
   • 2009, Larry Ullman, Ruby: Visual QuickStart Guide, page 237:

     By wrapping it in parentheses, the attributes can be reused by backreferencing this part of the pattern […]

   • 2012, Tom Christiansen, brian d foy^[sic], Larry Wall, Programming Perl (page 46)

     It doesn't change what the part matches, so /\\d+/ and /(\\d+)/ will still match as many digits as possible, but in the latter case they will be remembered in a special variable to be backreferenced later.