html/wrap.go

package html

import (
	"bytes"
	"unicode"
)

func words(buf *bytes.Buffer) []string {
	var (
		words       []string
		currentWord []rune
		inTag       bool
	)

	for {
		r, _, err := buf.ReadRune()
		if err != nil {
			break
		}

		if r == unicode.ReplacementChar {
			continue
		}

		if !inTag && unicode.IsSpace(r) {
			if len(currentWord) > 0 {
				words, currentWord = append(words, string(currentWord)), nil
			}

			continue
		}

		currentWord = append(currentWord, r)
		inTag = inTag && r != '>' || r == '<'
	}

	if len(currentWord) > 0 {
		words = append(words, string(currentWord))
	}

	return words
}

func wrap(buf *bytes.Buffer, pwidth int, indent string) *bytes.Buffer {
	var (
		lines       [][]string
		currentLine []string
		currentLen  int
	)

	words := words(buf)
	for _, w := range words {
		if currentLen != 0 {
			currentLen++
		}

		currentLen += len(w)
		if currentLen > pwidth && len(currentLine) > 0 {
			lines = append(lines, currentLine)
			currentLine = []string{w}
			currentLen = len(w)
			continue
		}

		currentLine = append(currentLine, w)
	}

	if len(currentLine) > 0 {
		lines = append(lines, currentLine)
	}

	ret := bytes.NewBuffer(nil)
	for i, l := range lines {
		if i > 0 {
			ret.WriteRune('\n')
		}

		ret.WriteString(indent)
		for j, w := range l {
			if j > 0 {
				ret.WriteRune(' ')
			}

			ret.WriteString(w)
		}
	}

	return ret
}