+++ /dev/null
-// 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 runes
-
-import (
- "unicode/utf8"
-
- "golang.org/x/text/transform"
-)
-
-// Note: below we pass invalid UTF-8 to the tIn and tNotIn transformers as is.
-// This is done for various reasons:
-// - To retain the semantics of the Nop transformer: if input is passed to a Nop
-// one would expect it to be unchanged.
-// - It would be very expensive to pass a converted RuneError to a transformer:
-// a transformer might need more source bytes after RuneError, meaning that
-// the only way to pass it safely is to create a new buffer and manage the
-// intermingling of RuneErrors and normal input.
-// - Many transformers leave ill-formed UTF-8 as is, so this is not
-// inconsistent. Generally ill-formed UTF-8 is only replaced if it is a
-// logical consequence of the operation (as for Map) or if it otherwise would
-// pose security concerns (as for Remove).
-// - An alternative would be to return an error on ill-formed UTF-8, but this
-// would be inconsistent with other operations.
-
-// If returns a transformer that applies tIn to consecutive runes for which
-// s.Contains(r) and tNotIn to consecutive runes for which !s.Contains(r). Reset
-// is called on tIn and tNotIn at the start of each run. A Nop transformer will
-// substitute a nil value passed to tIn or tNotIn. Invalid UTF-8 is translated
-// to RuneError to determine which transformer to apply, but is passed as is to
-// the respective transformer.
-func If(s Set, tIn, tNotIn transform.Transformer) Transformer {
- if tIn == nil && tNotIn == nil {
- return Transformer{transform.Nop}
- }
- if tIn == nil {
- tIn = transform.Nop
- }
- if tNotIn == nil {
- tNotIn = transform.Nop
- }
- sIn, ok := tIn.(transform.SpanningTransformer)
- if !ok {
- sIn = dummySpan{tIn}
- }
- sNotIn, ok := tNotIn.(transform.SpanningTransformer)
- if !ok {
- sNotIn = dummySpan{tNotIn}
- }
-
- a := &cond{
- tIn: sIn,
- tNotIn: sNotIn,
- f: s.Contains,
- }
- a.Reset()
- return Transformer{a}
-}
-
-type dummySpan struct{ transform.Transformer }
-
-func (d dummySpan) Span(src []byte, atEOF bool) (n int, err error) {
- return 0, transform.ErrEndOfSpan
-}
-
-type cond struct {
- tIn, tNotIn transform.SpanningTransformer
- f func(rune) bool
- check func(rune) bool // current check to perform
- t transform.SpanningTransformer // current transformer to use
-}
-
-// Reset implements transform.Transformer.
-func (t *cond) Reset() {
- t.check = t.is
- t.t = t.tIn
- t.t.Reset() // notIn will be reset on first usage.
-}
-
-func (t *cond) is(r rune) bool {
- if t.f(r) {
- return true
- }
- t.check = t.isNot
- t.t = t.tNotIn
- t.tNotIn.Reset()
- return false
-}
-
-func (t *cond) isNot(r rune) bool {
- if !t.f(r) {
- return true
- }
- t.check = t.is
- t.t = t.tIn
- t.tIn.Reset()
- return false
-}
-
-// This implementation of Span doesn't help all too much, but it needs to be
-// there to satisfy this package's Transformer interface.
-// TODO: there are certainly room for improvements, though. For example, if
-// t.t == transform.Nop (which will a common occurrence) it will save a bundle
-// to special-case that loop.
-func (t *cond) Span(src []byte, atEOF bool) (n int, err error) {
- p := 0
- for n < len(src) && err == nil {
- // Don't process too much at a time as the Spanner that will be
- // called on this block may terminate early.
- const maxChunk = 4096
- max := len(src)
- if v := n + maxChunk; v < max {
- max = v
- }
- atEnd := false
- size := 0
- current := t.t
- for ; p < max; p += size {
- r := rune(src[p])
- if r < utf8.RuneSelf {
- size = 1
- } else if r, size = utf8.DecodeRune(src[p:]); size == 1 {
- if !atEOF && !utf8.FullRune(src[p:]) {
- err = transform.ErrShortSrc
- break
- }
- }
- if !t.check(r) {
- // The next rune will be the start of a new run.
- atEnd = true
- break
- }
- }
- n2, err2 := current.Span(src[n:p], atEnd || (atEOF && p == len(src)))
- n += n2
- if err2 != nil {
- return n, err2
- }
- // At this point either err != nil or t.check will pass for the rune at p.
- p = n + size
- }
- return n, err
-}
-
-func (t *cond) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
- p := 0
- for nSrc < len(src) && err == nil {
- // Don't process too much at a time, as the work might be wasted if the
- // destination buffer isn't large enough to hold the result or a
- // transform returns an error early.
- const maxChunk = 4096
- max := len(src)
- if n := nSrc + maxChunk; n < len(src) {
- max = n
- }
- atEnd := false
- size := 0
- current := t.t
- for ; p < max; p += size {
- r := rune(src[p])
- if r < utf8.RuneSelf {
- size = 1
- } else if r, size = utf8.DecodeRune(src[p:]); size == 1 {
- if !atEOF && !utf8.FullRune(src[p:]) {
- err = transform.ErrShortSrc
- break
- }
- }
- if !t.check(r) {
- // The next rune will be the start of a new run.
- atEnd = true
- break
- }
- }
- nDst2, nSrc2, err2 := current.Transform(dst[nDst:], src[nSrc:p], atEnd || (atEOF && p == len(src)))
- nDst += nDst2
- nSrc += nSrc2
- if err2 != nil {
- return nDst, nSrc, err2
- }
- // At this point either err != nil or t.check will pass for the rune at p.
- p = nSrc + size
- }
- return nDst, nSrc, err
-}
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