html/wrap.go

package html

import (
	"code.squareroundforest.org/arpio/textedit"
	"io"
	"unicode"
)

type wrapState struct {
	line, word                            []rune
	inWord, inTag, inSingleQuote, inQuote bool
	lastSpace, started                    bool
}

type wrapper struct {
	indent *textedit.Writer
	wrap   *textedit.Writer
}

func wrapFeed(width int, s wrapState) ([]rune, wrapState) {
	var ret []rune
	withSpace := s.lastSpace && len(s.line) > 0
	l := len(s.line) + len(s.word)
	if withSpace && len(s.word) > 0 {
		l++
	}

	feedLine := l > width && len(s.line) > 0
	if feedLine {
		if s.started {
			ret = append(ret, '\n')
		}

		ret = append(ret, s.line...)
		s.line = nil
		s.started = true
	}

	if !feedLine && withSpace {
		s.line = append(s.line, ' ')
	}

	s.line = append(s.line, s.word...)
	s.word = nil
	return ret, s
}

func wrapEdit(width int) func(rune, wrapState) ([]rune, wrapState) {
	return func(r rune, s wrapState) ([]rune, wrapState) {
		var ret []rune
		if s.inSingleQuote {
			s.inSingleQuote = r != '\''
			s.word = append(s.word, r)
			return ret, s
		}

		if s.inQuote {
			s.inQuote = r != '"'
			s.word = append(s.word, r)
			return ret, s
		}

		if s.inTag {
			s.inSingleQuote = r == '\''
			s.inQuote = r == '"'
			s.inTag = r != '>'
			s.inWord = !s.inTag && !unicode.IsSpace(r)
			if s.inTag || !unicode.IsSpace(r) {
				s.word = append(s.word, r)
			}

			if !s.inTag {
				ret, s = wrapFeed(width, s)
				s.lastSpace = unicode.IsSpace(r)
			}

			return ret, s
		}

		if s.inWord {
			s.inTag = r == '<'
			s.inWord = !s.inTag && !unicode.IsSpace(r)
			if !s.inWord {
				ret, s = wrapFeed(width, s)
				s.lastSpace = unicode.IsSpace(r)
			}

			if s.inWord || s.inTag {
				s.word = append(s.word, r)
			}

			return ret, s
		}

		if unicode.IsSpace(r) {
			s.lastSpace = true
			return ret, s
		}

		s.word = append(s.word, r)
		s.inTag = r == '<'
		s.inWord = !s.inTag
		return ret, s
	}
}

func wrapReleaseState(width int) func(wrapState) []rune {
	return func(s wrapState) []rune {
		var ret []rune
		if s.inTag || s.inWord {
			ret, s = wrapFeed(width, s)
		}

		ret1, _ := wrapFeed(0, s)
		return append(ret, ret1...)
	}
}

func newWrapper(out io.Writer, width int, indent string) *wrapper {
	indentWriter := newIndentWriter(out, indent)
	return &wrapper{
		indent: indentWriter,
		wrap: textedit.New(
			indentWriter,
			textedit.Func(
				wrapEdit(width),
				wrapReleaseState(width),
			),
		),
	}
}

func (w *wrapper) Write(p []byte) (int, error) {
	return w.wrap.Write(p)
}

func (w *wrapper) Flush() error {
	if err := w.wrap.Flush(); err != nil {
		return err
	}

	if err := w.indent.Flush(); err != nil {
		return err
	}

	return nil
}