re-submatch

Arguments: regexp string indexes selector &key (type :string)

This is a convenience function to extract a specified submatch information from the value returned by match-re.

regexp should be a compiled regexp, and indexes should be a list of (start . end) index pairs returned by match-re. selector should be an integer that specifies a captured submatch (or 0 for the whole match), or a string or a symbol that names a named submatch.

Alternatively, you can pass the opaque 'match' object returned by match-re with :return :match argument, as regexp. The match object knows the information about the match results, so you don't need string and indexes; just pass nil to them.

The type argument may be :string, :after, :before or :index. It specifies the return value. If it is :string (the default), the substring of the specified submatch is returned. If it is :after or :before, the substring after or before the specified submatch is returned, respectively. If it is :index, a pair of (start . end) indexes are returned.

If the specified submatch isn't included in indexes, nil is returned.

A typical usage pattern of this function is like this:

(let ((r (multiple-value-list (match-re regexp string :return :index))))
  (re-submatch regexp string (cdr r) 3)))

Or, if you use the match object, like this:

(let ((match (match-re regexp string :return :match)))
  (re-submatch match nil nil 3))

Additional examples

cl-user(25): (let* ((s "abCDEfg")
                    (x (compile-re "[A-Z]([A-Z]+)"))
                    (r (cdr (multiple-value-list
                             (match-re x s :return :index)))))
               (list
                (re-submatch x s r 0)
                (re-submatch x s r 1)
                (re-submatch x s r 0 :type :before)
                (re-submatch x s r 1 :type :before)
                (re-submatch x s r 0 :type :after)
                (re-submatch x s r 1 :type :after)))
("CDE" "DE" "ab" "abC" "fg" "fg")
cl-user(26): 

The symbol naming this operator is also exported from the regexp package.

See The new regexp2 module in regexp.htm for further information on this function and the regexp2 module.

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This page has had moderate revisions compared to the 8.1 page.
Created 2016.6.21.