Extract Fields from org-roam template

extract-fields.el

(defun org-roam-template-extract-fields (template)
  "return a list with the names of the fields used
in the given template"
  (let (
        (result '())
        (pos 0)
        )

    (while (string-match "\\${\\([^}]+\\)}" template pos)
      ;; position should be saved first, since
      ;; we use another string match inside
      ;; and it is not reentrant
      (setq pos (match-end 0))
      (setq result (cons
                    ;; concat current field
                    ;; up to :
                    (let (
                          (st (match-string 1 template))
                          )
                      (substring st 0 (string-match ":" st))
                      )
                    result))
      )
    (reverse result)))