+(defvar notmuch-id-regexp
+ (concat
+ ;; Match the id: prefix only if it begins a word (to disallow, for
+ ;; example, matching cid:).
+ "\\<id:\\("
+ ;; If the term starts with a ", then parse Xapian's quoted boolean
+ ;; term syntax, which allows for anything as long as embedded
+ ;; double quotes escaped by doubling them. We also disallow
+ ;; newlines (which Xapian allows) to prevent runaway terms.
+ "\"\\([^\"\n]\\|\"\"\\)*\""
+ ;; Otherwise, parse Xapian's unquoted syntax, which goes up to the
+ ;; next space or ). We disallow [.,;] as the last character
+ ;; because these are probably part of the surrounding text, and not
+ ;; part of the id. This doesn't match single character ids; meh.
+ "\\|[^\"[:space:])][^[:space:])]*[^])[:space:].,:;?!]"
+ "\\)")
+ "The regexp used to match id: links in messages.")
+