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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
+ }
+}