How to parse org-mode by org-element elegantly

Question

org-element is a new module for org-mode, I think it is good for parse org file, and don't want to parse it by old way with match-string. but after play with it for some hours, I have to admit I don't have enough experience with org-mode, so could masters give me some clues, thanks very much!

My requirement is simple, I want to get all headlines and content.

* headline

:PROPERTIES

** subheadline

content1

** subheadline

content2

Answer 1

based on @YoungFrog's prompt:

• get all headlines:

  (let ((parsetree (org-element-parse-buffer 'headline))) 
    (org-element-map parsetree 'headline 
                     (lambda (hl) (org-element-property :title hl)))) 
  

• get all contents:

  (let ((parsetree (org-element-parse-buffer 'paragraph)))
    (org-element-map parsetree 'paragraph 
                     (lambda (hl) (org-element-interpret-data hl))))