podman

1
package text
2

3
import (
4
	"bytes"
5
	"math"
6
)
7

8
var (
9
	nl = []byte{'\n'}
10
	sp = []byte{' '}
11
)
12

13
const defaultPenalty = 1e5
14

15
// Wrap wraps s into a paragraph of lines of length lim, with minimal
16
// raggedness.
17
func Wrap(s string, lim int) string {
18
	return string(WrapBytes([]byte(s), lim))
19
}
20

21
// WrapBytes wraps b into a paragraph of lines of length lim, with minimal
22
// raggedness.
23
func WrapBytes(b []byte, lim int) []byte {
24
	words := bytes.Split(bytes.Replace(bytes.TrimSpace(b), nl, sp, -1), sp)
25
	var lines [][]byte
26
	for _, line := range WrapWords(words, 1, lim, defaultPenalty) {
27
		lines = append(lines, bytes.Join(line, sp))
28
	}
29
	return bytes.Join(lines, nl)
30
}
31

32
// WrapWords is the low-level line-breaking algorithm, useful if you need more
33
// control over the details of the text wrapping process. For most uses, either
34
// Wrap or WrapBytes will be sufficient and more convenient.
35
//
36
// WrapWords splits a list of words into lines with minimal "raggedness",
37
// treating each byte as one unit, accounting for spc units between adjacent
38
// words on each line, and attempting to limit lines to lim units. Raggedness
39
// is the total error over all lines, where error is the square of the
40
// difference of the length of the line and lim. Too-long lines (which only
41
// happen when a single word is longer than lim units) have pen penalty units
42
// added to the error.
43
func WrapWords(words [][]byte, spc, lim, pen int) [][][]byte {
44
	n := len(words)
45

46
	length := make([][]int, n)
47
	for i := 0; i < n; i++ {
48
		length[i] = make([]int, n)
49
		length[i][i] = len(words[i])
50
		for j := i + 1; j < n; j++ {
51
			length[i][j] = length[i][j-1] + spc + len(words[j])
52
		}
53
	}
54

55
	nbrk := make([]int, n)
56
	cost := make([]int, n)
57
	for i := range cost {
58
		cost[i] = math.MaxInt32
59
	}
60
	for i := n - 1; i >= 0; i-- {
61
		if length[i][n-1] <= lim || i == n-1 {
62
			cost[i] = 0
63
			nbrk[i] = n
64
		} else {
65
			for j := i + 1; j < n; j++ {
66
				d := lim - length[i][j-1]
67
				c := d*d + cost[j]
68
				if length[i][j-1] > lim {
69
					c += pen // too-long lines get a worse penalty
70
				}
71
				if c < cost[i] {
72
					cost[i] = c
73
					nbrk[i] = j
74
				}
75
			}
76
		}
77
	}
78

79
	var lines [][][]byte
80
	i := 0
81
	for i < n {
82
		lines = append(lines, words[i:nbrk[i]])
83
		i = nbrk[i]
84
	}
85
	return lines
86
}
87