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Diffstat (limited to 'Godeps/_workspace/src/golang.org/x/text/runes/cond.go')
-rw-r--r-- | Godeps/_workspace/src/golang.org/x/text/runes/cond.go | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/Godeps/_workspace/src/golang.org/x/text/runes/cond.go b/Godeps/_workspace/src/golang.org/x/text/runes/cond.go new file mode 100644 index 000000000..ae7a92158 --- /dev/null +++ b/Godeps/_workspace/src/golang.org/x/text/runes/cond.go @@ -0,0 +1,126 @@ +// 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 + } + a := &cond{ + tIn: tIn, + tNotIn: tNotIn, + f: s.Contains, + } + a.Reset() + return Transformer{a} +} + +type cond struct { + tIn, tNotIn transform.Transformer + f func(rune) bool + check func(rune) bool // current check to perform + t transform.Transformer // 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 +} + +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 { + var r rune + r, size = utf8.DecodeRune(src[p:]) + if r == utf8.RuneError && 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 +} |