func()

in secure/precis/profile.go [148:237]

• 83 lines of code
• 39 McCabe index (conditional complexity)

func (b *buffers) enforce(p *Profile, src []byte, comparing bool) (str []byte, err error) {
	b.src = src

	ascii := true
	for _, c := range src {
		if c >= utf8.RuneSelf {
			ascii = false
			break
		}
	}
	// ASCII fast path.
	if ascii {
		for _, f := range p.options.additional {
			if err = b.apply(f()); err != nil {
				return nil, err
			}
		}
		switch {
		case p.options.asciiLower || (comparing && p.options.ignorecase):
			for i, c := range b.src {
				if 'A' <= c && c <= 'Z' {
					b.src[i] = c ^ 1<<5
				}
			}
		case p.options.cases != nil:
			b.apply(p.options.cases)
		}
		c := checker{p: p}
		if _, err := c.span(b.src, true); err != nil {
			return nil, err
		}
		if p.disallow != nil {
			for _, c := range b.src {
				if p.disallow.Contains(rune(c)) {
					return nil, errDisallowedRune
				}
			}
		}
		if p.options.disallowEmpty && len(b.src) == 0 {
			return nil, errEmptyString
		}
		return b.src, nil
	}

	// These transforms are applied in the order defined in
	// https://tools.ietf.org/html/rfc8264#section-7

	r := 1
	if p.options.repeat {
		r = 4
	}
	for ; r > 0; r-- {
		// TODO: allow different width transforms options.
		if p.options.foldWidth || (p.options.ignorecase && comparing) {
			b.apply(foldWidthT)
		}
		for _, f := range p.options.additional {
			if err = b.apply(f()); err != nil {
				return nil, err
			}
		}
		if p.options.cases != nil {
			b.apply(p.options.cases)
		}
		if comparing && p.options.ignorecase {
			b.apply(lowerCaseT)
		}
		b.apply(p.norm)
		if p.options.bidiRule && !bidirule.Valid(b.src) {
			return nil, bidirule.ErrInvalid
		}
		c := checker{p: p}
		if _, err := c.span(b.src, true); err != nil {
			return nil, err
		}
		if p.disallow != nil {
			for i := 0; i < len(b.src); {
				r, size := utf8.DecodeRune(b.src[i:])
				if p.disallow.Contains(r) {
					return nil, errDisallowedRune
				}
				i += size
			}
		}
		if p.options.disallowEmpty && len(b.src) == 0 {
			return nil, errEmptyString
		}
	}
	return b.src, nil
}