1package markdown
 2
 3import "strconv"
 4
 5type headingNumbering struct {
 6	levels [6]int
 7}
 8
 9// Observe register the event of a new level with the given depth and
10// adjust the numbering accordingly
11func (hn *headingNumbering) Observe(level int) {
12	if level <= 0 {
13		panic("level start at 1, ask blackfriday why")
14	}
15	if level > 6 {
16		panic("Markdown is limited to 6 levels of heading")
17	}
18
19	hn.levels[level-1]++
20	for i := level; i < 6; i++ {
21		hn.levels[i] = 0
22	}
23}
24
25// Render render the current headings numbering.
26func (hn *headingNumbering) Render() string {
27	slice := hn.levels[:]
28
29	// pop the last zero levels
30	for i := 5; i >= 0; i-- {
31		if hn.levels[i] != 0 {
32			break
33		}
34		slice = slice[:len(slice)-1]
35	}
36
37	var result string
38
39	for i := range slice {
40		if i > 0 {
41			result += "."
42		}
43		result += strconv.Itoa(slice[i])
44	}
45
46	return result
47}