core of opener.el

opener-core.el

(defun opener-open-url-in-buffer (url)
  ; let's do a GET request to the url 
  (request
   url
   :parser 'buffer-string
   ; get response as a string and pass it together with an appropriate
   ; "file"-name to our buffer function
   :complete (let ((buffer-name (opener-filename-for url)))
               (function*
                (lambda (&key data &allow-other-keys)
                  (opener-http-response-in-buffer buffer-name data))))))

(defun opener-http-response-in-buffer (buffer-name data)
  ; let's get a buffer, a storage solution that can be displayed inside
  ; of a window. Think of it like a virtual file.
  (let ((buffer (get-buffer-create buffer-name)))
    ; ensure that we can return to where we started from   
    (save-excursion
      ; claim our new buffer as the current one for all operations
      (with-current-buffer buffer
        ; clear our buffer (as might be necessary when we want to "refresh" a page)
        (erase-buffer)
        ; activate multi-byte character support (necessary for unzipping)
        (if enable-multibyte-characters (toggle-enable-multibyte-characters))
        ; write our HTTP response to the buffer
        (insert data)
        ; try to decompress gzipped content
        (zlib-decompress-region (point-min) (point-max))
        ; perform "file"-type like recognition in Emacs
        ; e.g. switches on syntax highlighting for json or XML
        (normal-mode)
        ; perform some private hooks the user might set up, e.g. pretty printing/unminifying
        (opener-perform-major-mode-hooks)))
    ; actually switch our current window display that new buffer
    (switch-to-buffer buffer)))