Regular expressions

 This editor has extended regular expression support as in UNIX egrep(1).

      <character>  matches <character>
      \<character> matches <character> (escaping special meaning).
      .            matches any single character.
      [<class>]    matches any character in <class>.
      [^<class>]   matches any character not in <class>.
      <re>?        matches zero or one occurance of <re>.
      <re>+        matches one or more occurances of <re>.
      <re>*        matches zero or more occurances of <re>.
      <re><re>     2 regular expressions catenated form a <re>.
      <re>|<re>    matches one <re> or the other <re>.
      ^            matches the left most position (left-anchor).
      $            matches the right most position (right-anchor).

 Use of regular expressions in language recognition

 In the AE.INI file you will see a list of language_create commands.
 Here is one of them :-

      language_create "lisp" ";..." "" ".*\\.lsp" no yes yes 2 "_:"

 The highlighted part is an extended regular expression that is used for
 matching filenames.

 When AE encounters the file fred.lsp it finds that ".*\.lsp" matches
 "fred.lsp" exactly and so fred.lsp is deemed to be a Lisp file.