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elinks/contrib/guile/hooks.scm
2018-02-24 15:08:17 -05:00

81 lines
1.9 KiB
Scheme

;;; Bare interface to C code
(define-module (elinks internal)
:export (goto-url-hooks
follow-url-hooks
pre-format-html-hooks
get-proxy-hooks
quit-hooks))
;;; GOTO-URL-HOOKS: Each hook is called in turn with a single argument
;;; (a URL string). Each may return one of:
;;;
;;; a string to visit the returned url
;;; () to go nowhere
;;; #f to continue with the next hook
;;;
;;; If no hooks return a string or empty list, the default action is
;;; to visit the original URL passed.
(define goto-url-hooks (make-hook 1))
(define (%goto-url-hook url)
(%call-hooks-until-truish goto-url-hooks
(lambda (h) (h url))
url))
;;; FOLLOW-URL-HOOKS: Each hook is called in turn with a single
;;; argument (a URL string). Each may return one of:
;;;
;;; a string to visit the returned url
;;; () to go nowhere
;;; #f to continue with the next hook
;;;
;;; If no hooks return a string or empty list, the default action is
;;; to visit the original URL passed.
(define follow-url-hooks (make-hook 1))
(define (%follow-url-hook url)
(%call-hooks-until-truish follow-url-hooks
(lambda (h) (h url))
url))
;;; PRE-FORMAT-HTML-HOOKS:
(define pre-format-html-hooks (make-hook 2))
(define (%pre-format-html-hook url html)
(%call-hooks-until-truish pre-format-html-hooks
(lambda (h) (h url html))
#f))
;;; GET-PROXY-HOOKS:
(define get-proxy-hooks (make-hook 1))
(define (%get-proxy-hook url)
(%call-hooks-until-truish get-proxy-hooks
(lambda (h) (h url))
#f))
;;; QUIT-HOOKS: ...
(define quit-hooks (make-hook))
(define (%quit-hook)
(run-hook quit-hooks))
;;; Helper: calls hooks one at a time until one of them returns
;;; non-#f.
(define (%call-hooks-until-truish hooks caller default)
(let lp ((hs (hook->list hooks)))
(if (null? hs)
default
(or (caller (car hs))
(lp (cdr hs))))))