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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package precis
import (
"golang.org/x/text/cases"
"golang.org/x/text/language"
"golang.org/x/text/runes"
"golang.org/x/text/transform"
"golang.org/x/text/unicode/norm"
)
// An Option is used to define the behavior and rules of a Profile.
type Option func(*options)
type options struct {
// Preparation options
foldWidth bool
// Enforcement options
asciiLower bool
cases transform.SpanningTransformer
disallow runes.Set
norm transform.SpanningTransformer
additional []func() transform.SpanningTransformer
width transform.SpanningTransformer
disallowEmpty bool
bidiRule bool
repeat bool
// Comparison options
ignorecase bool
}
func getOpts(o ...Option) (res options) {
for _, f := range o {
f(&res)
}
// Using a SpanningTransformer, instead of norm.Form prevents an allocation
// down the road.
if res.norm == nil {
res.norm = norm.NFC
}
return
}
var (
// The IgnoreCase option causes the profile to perform a case insensitive
// comparison during the PRECIS comparison step.
IgnoreCase Option = ignoreCase
// The FoldWidth option causes the profile to map non-canonical wide and
// narrow variants to their decomposition mapping. This is useful for
// profiles that are based on the identifier class which would otherwise
// disallow such characters.
FoldWidth Option = foldWidth
// The DisallowEmpty option causes the enforcement step to return an error if
// the resulting string would be empty.
DisallowEmpty Option = disallowEmpty
// The BidiRule option causes the Bidi Rule defined in RFC 5893 to be
// applied.
BidiRule Option = bidiRule
)
var (
ignoreCase = func(o *options) {
o.ignorecase = true
}
foldWidth = func(o *options) {
o.foldWidth = true
}
disallowEmpty = func(o *options) {
o.disallowEmpty = true
}
bidiRule = func(o *options) {
o.bidiRule = true
}
repeat = func(o *options) {
o.repeat = true
}
)
// TODO: move this logic to package transform
type spanWrap struct{ transform.Transformer }
func (s spanWrap) Span(src []byte, atEOF bool) (n int, err error) {
return 0, transform.ErrEndOfSpan
}
// TODO: allow different types? For instance:
// func() transform.Transformer
// func() transform.SpanningTransformer
// func([]byte) bool // validation only
//
// Also, would be great if we could detect if a transformer is reentrant.
// The AdditionalMapping option defines the additional mapping rule for the
// Profile by applying Transformer's in sequence.
func AdditionalMapping(t ...func() transform.Transformer) Option {
return func(o *options) {
for _, f := range t {
sf := func() transform.SpanningTransformer {
return f().(transform.SpanningTransformer)
}
if _, ok := f().(transform.SpanningTransformer); !ok {
sf = func() transform.SpanningTransformer {
return spanWrap{f()}
}
}
o.additional = append(o.additional, sf)
}
}
}
// The Norm option defines a Profile's normalization rule. Defaults to NFC.
func Norm(f norm.Form) Option {
return func(o *options) {
o.norm = f
}
}
// The FoldCase option defines a Profile's case mapping rule. Options can be
// provided to determine the type of case folding used.
func FoldCase(opts ...cases.Option) Option {
return func(o *options) {
o.asciiLower = true
o.cases = cases.Fold(opts...)
}
}
// The LowerCase option defines a Profile's case mapping rule. Options can be
// provided to determine the type of case folding used.
func LowerCase(opts ...cases.Option) Option {
return func(o *options) {
o.asciiLower = true
if len(opts) == 0 {
o.cases = cases.Lower(language.Und, cases.HandleFinalSigma(false))
return
}
opts = append([]cases.Option{cases.HandleFinalSigma(false)}, opts...)
o.cases = cases.Lower(language.Und, opts...)
}
}
// The Disallow option further restricts a Profile's allowed characters beyond
// what is disallowed by the underlying string class.
func Disallow(set runes.Set) Option {
return func(o *options) {
o.disallow = set
}
}
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