(defgroup elide-head nil
"Eliding copyright headers and the like in source files."
:version "21.1"
:prefix "elide-head"
:group 'tools)
(defcustom elide-head-headers-to-hide
'(("is free software; you can redistribute it" . "Boston, MA 02111-1307, USA\\.")
("The Regents of the University of California\\. All rights reserved\\." .
"SUCH DAMAGE\\.") ("Permission is hereby granted, free of charge" . "authorization from the X Consortium\\."))
"Alist of regexps defining start end end of text to elide.
The cars of elements of the list are searched for in order. Text is
elided with an invisible overlay from the end of the line where the
first match is found to the end of the match for the corresponding
cdr."
:group 'elide-head
:type '(alist :key-type (string :tag "Start regexp")
:value-type (string :tag "End regexp")))
(defvar elide-head-overlay nil)
(make-variable-buffer-local 'elide-head-overlay)
(defun elide-head (&optional arg)
"Hide header material in buffer according to `elide-head-headers-to-hide'.
The header is made invisible with an overlay. With a prefix arg, show
an elided material again.
This is suitable as an entry on `find-file-hooks' or appropriate mode hooks."
(interactive "P")
(if arg
(elide-head-show)
(save-excursion
(save-restriction
(let ((rest elide-head-headers-to-hide)
beg end)
(widen)
(goto-char (point-min))
(while rest
(save-excursion
(when (re-search-forward (caar rest) nil t)
(setq beg (point))
(when (re-search-forward (cdar rest) nil t)
(setq end (point-marker)
rest nil))))
(if rest (setq rest (cdr rest))))
(if (not (and beg end))
(if (interactive-p)
(error "No header found"))
(goto-char beg)
(end-of-line)
(if (overlayp elide-head-overlay)
(move-overlay elide-head-overlay (point-marker) end)
(setq elide-head-overlay (make-overlay (point-marker) end)))
(overlay-put elide-head-overlay 'invisible t)
(overlay-put elide-head-overlay 'intangible t)
(overlay-put elide-head-overlay 'evaporate t)
(overlay-put elide-head-overlay 'after-string "...")))))))
(defun elide-head-show ()
"Show a header elided current buffer by \\[elide-head]."
(interactive)
(if (and (overlayp elide-head-overlay)
(overlay-buffer elide-head-overlay))
(delete-overlay elide-head-overlay)
(if (interactive-p)
(error "No header hidden"))))
(provide 'elide-head)