// NewTransformer creates a new transform.Transformer that performs the PRECIS
// preparation and enforcement steps on the given UTF-8 encoded bytes.
func (p *Profile) NewTransformer() *Transformer {
var ts []transform.Transformer
// These transforms are applied in the order defined in
// https://tools.ietf.org/html/rfc7564#section-7
if p.options.foldWidth {
ts = append(ts, width.Fold)
}
for _, f := range p.options.additional {
ts = append(ts, f())
}
if p.options.cases != nil {
ts = append(ts, p.options.cases)
}
ts = append(ts, p.options.norm)
if p.options.bidiRule {
ts = append(ts, bidirule.New())
}
ts = append(ts, &checker{p: p, allowed: p.Allowed()})
// TODO: Add the disallow empty rule with a dummy transformer?
return &Transformer{transform.Chain(ts...)}
}
func (b *buffers) enforce(p *Profile, src []byte) (str []byte, err error) {
b.src = src
// These transforms are applied in the order defined in
// https://tools.ietf.org/html/rfc7564#section-7
// TODO: allow different width transforms options.
if p.options.foldWidth {
// TODO: use Span, once available.
if err = b.apply(width.Fold); err != nil {
return nil, err
}
}
for _, f := range p.options.additional {
if err = b.apply(f()); err != nil {
return nil, err
}
}
if p.options.cases != nil {
if err = b.apply(p.options.cases); err != nil {
return nil, err
}
}
if n := p.norm.QuickSpan(b.src); n < len(b.src) {
x := b.next & 1
n = copy(b.buf[x], b.src[:n])
b.src, _, err = transform.Append(p.norm, b.buf[x][:n], b.src[n:])
b.buf[x] = b.src
b.next++
if err != nil {
return nil, err
}
}
if p.options.bidiRule {
if err := b.apply(bidirule.New()); err != nil {
return nil, err
}
}
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
}
}
// TODO: Add the disallow empty rule with a dummy transformer?
if p.options.disallowEmpty && len(b.src) == 0 {
return nil, errEmptyString
}
return b.src, nil
}