func()

in html/token.go [950:1066]

• 102 lines of code
• 30 McCabe index (conditional complexity)

func (z *Tokenizer) Next() TokenType {
	z.raw.start = z.raw.end
	z.data.start = z.raw.end
	z.data.end = z.raw.end
	if z.err != nil {
		z.tt = ErrorToken
		return z.tt
	}
	if z.rawTag != "" {
		if z.rawTag == "plaintext" {
			// Read everything up to EOF.
			for z.err == nil {
				z.readByte()
			}
			z.data.end = z.raw.end
			z.textIsRaw = true
		} else {
			z.readRawOrRCDATA()
		}
		if z.data.end > z.data.start {
			z.tt = TextToken
			z.convertNUL = true
			return z.tt
		}
	}
	z.textIsRaw = false
	z.convertNUL = false

loop:
	for {
		c := z.readByte()
		if z.err != nil {
			break loop
		}
		if c != '<' {
			continue loop
		}

		// Check if the '<' we have just read is part of a tag, comment
		// or doctype. If not, it's part of the accumulated text token.
		c = z.readByte()
		if z.err != nil {
			break loop
		}
		var tokenType TokenType
		switch {
		case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z':
			tokenType = StartTagToken
		case c == '/':
			tokenType = EndTagToken
		case c == '!' || c == '?':
			// We use CommentToken to mean any of "<!--actual comments-->",
			// "<!DOCTYPE declarations>" and "<?xml processing instructions?>".
			tokenType = CommentToken
		default:
			// Reconsume the current character.
			z.raw.end--
			continue
		}

		// We have a non-text token, but we might have accumulated some text
		// before that. If so, we return the text first, and return the non-
		// text token on the subsequent call to Next.
		if x := z.raw.end - len("<a"); z.raw.start < x {
			z.raw.end = x
			z.data.end = x
			z.tt = TextToken
			return z.tt
		}
		switch tokenType {
		case StartTagToken:
			z.tt = z.readStartTag()
			return z.tt
		case EndTagToken:
			c = z.readByte()
			if z.err != nil {
				break loop
			}
			if c == '>' {
				// "</>" does not generate a token at all. Generate an empty comment
				// to allow passthrough clients to pick up the data using Raw.
				// Reset the tokenizer state and start again.
				z.tt = CommentToken
				return z.tt
			}
			if 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' {
				z.readTag(false)
				if z.err != nil {
					z.tt = ErrorToken
				} else {
					z.tt = EndTagToken
				}
				return z.tt
			}
			z.raw.end--
			z.readUntilCloseAngle()
			z.tt = CommentToken
			return z.tt
		case CommentToken:
			if c == '!' {
				z.tt = z.readMarkupDeclaration()
				return z.tt
			}
			z.raw.end--
			z.readUntilCloseAngle()
			z.tt = CommentToken
			return z.tt
		}
	}
	if z.raw.start < z.raw.end {
		z.data.end = z.raw.end
		z.tt = TextToken
		return z.tt
	}
	z.tt = ErrorToken
	return z.tt
}