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