/usr/share/gocode/src/golang.org/x/text/runes/cond.go is in golang-golang-x-text-dev 0.0~git20170627.0.6353ef0-1ubuntu2.
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The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 | // 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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