use ivy to jump to a PDF outline entry

for use with pdftools.

(defun counsel-pdf-outline-action (entry)
  (let ((line (cdr entry)))
    (with-current-buffer (ivy-state-buffer ivy-last)
      (save-excursion
        (goto-line (1+ line)) ;; was starting from 0
        (call-interactively #'pdf-outline-follow-link)))))

(defun counsel-pdf-outline ()
  (interactive)
  (let* ((buffer (pdf-outline-noselect nil))
         entries)
    (with-current-buffer buffer
      (setq entries
            (split-string
             (buffer-substring-no-properties
              (point-min) (point-max))
             "\n"))

      (ivy-read "Title: "
                (-zip entries
                      (number-sequence 0 (length entries)))
                :action #'counsel-pdf-outline-action
                :caller 'counsel-pdf-outline))))