migrate to go modules

7 files changed, 0 insertions, 1302 deletions

diff --git a/vendor/golang.org/x/text/AUTHORS b/vendor/golang.org/x/text/AUTHORS
deleted file mode 100644
index 15167cd7..00000000
--- a/vendor/golang.org/x/text/AUTHORS
+++ /dev/null
@@ -1,3 +0,0 @@
-# This source code refers to The Go Authors for copyright purposes.
-# The master list of authors is in the main Go distribution,
-# visible at http://tip.golang.org/AUTHORS.
diff --git a/vendor/golang.org/x/text/CONTRIBUTORS b/vendor/golang.org/x/text/CONTRIBUTORS
deleted file mode 100644
index 1c4577e9..00000000
--- a/vendor/golang.org/x/text/CONTRIBUTORS
+++ /dev/null
@@ -1,3 +0,0 @@
-# This source code was written by the Go contributors.
-# The master list of contributors is in the main Go distribution,
-# visible at http://tip.golang.org/CONTRIBUTORS.
diff --git a/vendor/golang.org/x/text/LICENSE b/vendor/golang.org/x/text/LICENSE
deleted file mode 100644
index 6a66aea5..00000000
--- a/vendor/golang.org/x/text/LICENSE
+++ /dev/null
@@ -1,27 +0,0 @@
-Copyright (c) 2009 The Go Authors. All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are
-met:
-
-   * Redistributions of source code must retain the above copyright
-notice, this list of conditions and the following disclaimer.
-   * Redistributions in binary form must reproduce the above
-copyright notice, this list of conditions and the following disclaimer
-in the documentation and/or other materials provided with the
-distribution.
-   * Neither the name of Google Inc. nor the names of its
-contributors may be used to endorse or promote products derived from
-this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/golang.org/x/text/PATENTS b/vendor/golang.org/x/text/PATENTS
deleted file mode 100644
index 73309904..00000000
--- a/vendor/golang.org/x/text/PATENTS
+++ /dev/null
@@ -1,22 +0,0 @@
-Additional IP Rights Grant (Patents)
-
-"This implementation" means the copyrightable works distributed by
-Google as part of the Go project.
-
-Google hereby grants to You a perpetual, worldwide, non-exclusive,
-no-charge, royalty-free, irrevocable (except as stated in this section)
-patent license to make, have made, use, offer to sell, sell, import,
-transfer and otherwise run, modify and propagate the contents of this
-implementation of Go, where such license applies only to those patent
-claims, both currently owned or controlled by Google and acquired in
-the future, licensable by Google that are necessarily infringed by this
-implementation of Go.  This grant does not include claims that would be
-infringed only as a consequence of further modification of this
-implementation.  If you or your agent or exclusive licensee institute or
-order or agree to the institution of patent litigation against any
-entity (including a cross-claim or counterclaim in a lawsuit) alleging
-that this implementation of Go or any code incorporated within this
-implementation of Go constitutes direct or contributory patent
-infringement, or inducement of patent infringement, then any patent
-rights granted to you under this License for this implementation of Go
-shall terminate as of the date such litigation is filed.
diff --git a/vendor/golang.org/x/text/runes/cond.go b/vendor/golang.org/x/text/runes/cond.go
deleted file mode 100644
index df7aa02d..00000000
--- a/vendor/golang.org/x/text/runes/cond.go
+++ /dev/null
@@ -1,187 +0,0 @@
-// 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
-}
diff --git a/vendor/golang.org/x/text/runes/runes.go b/vendor/golang.org/x/text/runes/runes.go
deleted file mode 100644
index 71933696..00000000
--- a/vendor/golang.org/x/text/runes/runes.go
+++ /dev/null
@@ -1,355 +0,0 @@
-// Copyright 2014 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 provide transforms for UTF-8 encoded text.
-package runes // import "golang.org/x/text/runes"
-
-import (
-	"unicode"
-	"unicode/utf8"
-
-	"golang.org/x/text/transform"
-)
-
-// A Set is a collection of runes.
-type Set interface {
-	// Contains returns true if r is contained in the set.
-	Contains(r rune) bool
-}
-
-type setFunc func(rune) bool
-
-func (s setFunc) Contains(r rune) bool {
-	return s(r)
-}
-
-// Note: using funcs here instead of wrapping types result in cleaner
-// documentation and a smaller API.
-
-// In creates a Set with a Contains method that returns true for all runes in
-// the given RangeTable.
-func In(rt *unicode.RangeTable) Set {
-	return setFunc(func(r rune) bool { return unicode.Is(rt, r) })
-}
-
-// In creates a Set with a Contains method that returns true for all runes not
-// in the given RangeTable.
-func NotIn(rt *unicode.RangeTable) Set {
-	return setFunc(func(r rune) bool { return !unicode.Is(rt, r) })
-}
-
-// Predicate creates a Set with a Contains method that returns f(r).
-func Predicate(f func(rune) bool) Set {
-	return setFunc(f)
-}
-
-// Transformer implements the transform.Transformer interface.
-type Transformer struct {
-	t transform.SpanningTransformer
-}
-
-func (t Transformer) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
-	return t.t.Transform(dst, src, atEOF)
-}
-
-func (t Transformer) Span(b []byte, atEOF bool) (n int, err error) {
-	return t.t.Span(b, atEOF)
-}
-
-func (t Transformer) Reset() { t.t.Reset() }
-
-// Bytes returns a new byte slice with the result of converting b using t.  It
-// calls Reset on t. It returns nil if any error was found. This can only happen
-// if an error-producing Transformer is passed to If.
-func (t Transformer) Bytes(b []byte) []byte {
-	b, _, err := transform.Bytes(t, b)
-	if err != nil {
-		return nil
-	}
-	return b
-}
-
-// String returns a string with the result of converting s using t. It calls
-// Reset on t. It returns the empty string if any error was found. This can only
-// happen if an error-producing Transformer is passed to If.
-func (t Transformer) String(s string) string {
-	s, _, err := transform.String(t, s)
-	if err != nil {
-		return ""
-	}
-	return s
-}
-
-// TODO:
-// - Copy: copying strings and bytes in whole-rune units.
-// - Validation (maybe)
-// - Well-formed-ness (maybe)
-
-const runeErrorString = string(utf8.RuneError)
-
-// Remove returns a Transformer that removes runes r for which s.Contains(r).
-// Illegal input bytes are replaced by RuneError before being passed to f.
-func Remove(s Set) Transformer {
-	if f, ok := s.(setFunc); ok {
-		// This little trick cuts the running time of BenchmarkRemove for sets
-		// created by Predicate roughly in half.
-		// TODO: special-case RangeTables as well.
-		return Transformer{remove(f)}
-	}
-	return Transformer{remove(s.Contains)}
-}
-
-// TODO: remove transform.RemoveFunc.
-
-type remove func(r rune) bool
-
-func (remove) Reset() {}
-
-// Span implements transform.Spanner.
-func (t remove) Span(src []byte, atEOF bool) (n int, err error) {
-	for r, size := rune(0), 0; n < len(src); {
-		if r = rune(src[n]); r < utf8.RuneSelf {
-			size = 1
-		} else if r, size = utf8.DecodeRune(src[n:]); size == 1 {
-			// Invalid rune.
-			if !atEOF && !utf8.FullRune(src[n:]) {
-				err = transform.ErrShortSrc
-			} else {
-				err = transform.ErrEndOfSpan
-			}
-			break
-		}
-		if t(r) {
-			err = transform.ErrEndOfSpan
-			break
-		}
-		n += size
-	}
-	return
-}
-
-// Transform implements transform.Transformer.
-func (t remove) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
-	for r, size := rune(0), 0; nSrc < len(src); {
-		if r = rune(src[nSrc]); r < utf8.RuneSelf {
-			size = 1
-		} else if r, size = utf8.DecodeRune(src[nSrc:]); size == 1 {
-			// Invalid rune.
-			if !atEOF && !utf8.FullRune(src[nSrc:]) {
-				err = transform.ErrShortSrc
-				break
-			}
-			// We replace illegal bytes with RuneError. Not doing so might
-			// otherwise turn a sequence of invalid UTF-8 into valid UTF-8.
-			// The resulting byte sequence may subsequently contain runes
-			// for which t(r) is true that were passed unnoticed.
-			if !t(utf8.RuneError) {
-				if nDst+3 > len(dst) {
-					err = transform.ErrShortDst
-					break
-				}
-				dst[nDst+0] = runeErrorString[0]
-				dst[nDst+1] = runeErrorString[1]
-				dst[nDst+2] = runeErrorString[2]
-				nDst += 3
-			}
-			nSrc++
-			continue
-		}
-		if t(r) {
-			nSrc += size
-			continue
-		}
-		if nDst+size > len(dst) {
-			err = transform.ErrShortDst
-			break
-		}
-		for i := 0; i < size; i++ {
-			dst[nDst] = src[nSrc]
-			nDst++
-			nSrc++
-		}
-	}
-	return
-}
-
-// Map returns a Transformer that maps the runes in the input using the given
-// mapping. Illegal bytes in the input are converted to utf8.RuneError before
-// being passed to the mapping func.
-func Map(mapping func(rune) rune) Transformer {
-	return Transformer{mapper(mapping)}
-}
-
-type mapper func(rune) rune
-
-func (mapper) Reset() {}
-
-// Span implements transform.Spanner.
-func (t mapper) Span(src []byte, atEOF bool) (n int, err error) {
-	for r, size := rune(0), 0; n < len(src); n += size {
-		if r = rune(src[n]); r < utf8.RuneSelf {
-			size = 1
-		} else if r, size = utf8.DecodeRune(src[n:]); size == 1 {
-			// Invalid rune.
-			if !atEOF && !utf8.FullRune(src[n:]) {
-				err = transform.ErrShortSrc
-			} else {
-				err = transform.ErrEndOfSpan
-			}
-			break
-		}
-		if t(r) != r {
-			err = transform.ErrEndOfSpan
-			break
-		}
-	}
-	return n, err
-}
-
-// Transform implements transform.Transformer.
-func (t mapper) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
-	var replacement rune
-	var b [utf8.UTFMax]byte
-
-	for r, size := rune(0), 0; nSrc < len(src); {
-		if r = rune(src[nSrc]); r < utf8.RuneSelf {
-			if replacement = t(r); replacement < utf8.RuneSelf {
-				if nDst == len(dst) {
-					err = transform.ErrShortDst
-					break
-				}
-				dst[nDst] = byte(replacement)
-				nDst++
-				nSrc++
-				continue
-			}
-			size = 1
-		} else if r, size = utf8.DecodeRune(src[nSrc:]); size == 1 {
-			// Invalid rune.
-			if !atEOF && !utf8.FullRune(src[nSrc:]) {
-				err = transform.ErrShortSrc
-				break
-			}
-
-			if replacement = t(utf8.RuneError); replacement == utf8.RuneError {
-				if nDst+3 > len(dst) {
-					err = transform.ErrShortDst
-					break
-				}
-				dst[nDst+0] = runeErrorString[0]
-				dst[nDst+1] = runeErrorString[1]
-				dst[nDst+2] = runeErrorString[2]
-				nDst += 3
-				nSrc++
-				continue
-			}
-		} else if replacement = t(r); replacement == r {
-			if nDst+size > len(dst) {
-				err = transform.ErrShortDst
-				break
-			}
-			for i := 0; i < size; i++ {
-				dst[nDst] = src[nSrc]
-				nDst++
-				nSrc++
-			}
-			continue
-		}
-
-		n := utf8.EncodeRune(b[:], replacement)
-
-		if nDst+n > len(dst) {
-			err = transform.ErrShortDst
-			break
-		}
-		for i := 0; i < n; i++ {
-			dst[nDst] = b[i]
-			nDst++
-		}
-		nSrc += size
-	}
-	return
-}
-
-// ReplaceIllFormed returns a transformer that replaces all input bytes that are
-// not part of a well-formed UTF-8 code sequence with utf8.RuneError.
-func ReplaceIllFormed() Transformer {
-	return Transformer{&replaceIllFormed{}}
-}
-
-type replaceIllFormed struct{ transform.NopResetter }
-
-func (t replaceIllFormed) Span(src []byte, atEOF bool) (n int, err error) {
-	for n < len(src) {
-		// ASCII fast path.
-		if src[n] < utf8.RuneSelf {
-			n++
-			continue
-		}
-
-		r, size := utf8.DecodeRune(src[n:])
-
-		// Look for a valid non-ASCII rune.
-		if r != utf8.RuneError || size != 1 {
-			n += size
-			continue
-		}
-
-		// Look for short source data.
-		if !atEOF && !utf8.FullRune(src[n:]) {
-			err = transform.ErrShortSrc
-			break
-		}
-
-		// We have an invalid rune.
-		err = transform.ErrEndOfSpan
-		break
-	}
-	return n, err
-}
-
-func (t replaceIllFormed) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
-	for nSrc < len(src) {
-		// ASCII fast path.
-		if r := src[nSrc]; r < utf8.RuneSelf {
-			if nDst == len(dst) {
-				err = transform.ErrShortDst
-				break
-			}
-			dst[nDst] = r
-			nDst++
-			nSrc++
-			continue
-		}
-
-		// Look for a valid non-ASCII rune.
-		if _, size := utf8.DecodeRune(src[nSrc:]); size != 1 {
-			if size != copy(dst[nDst:], src[nSrc:nSrc+size]) {
-				err = transform.ErrShortDst
-				break
-			}
-			nDst += size
-			nSrc += size
-			continue
-		}
-
-		// Look for short source data.
-		if !atEOF && !utf8.FullRune(src[nSrc:]) {
-			err = transform.ErrShortSrc
-			break
-		}
-
-		// We have an invalid rune.
-		if nDst+3 > len(dst) {
-			err = transform.ErrShortDst
-			break
-		}
-		dst[nDst+0] = runeErrorString[0]
-		dst[nDst+1] = runeErrorString[1]
-		dst[nDst+2] = runeErrorString[2]
-		nDst += 3
-		nSrc++
-	}
-	return nDst, nSrc, err
-}
diff --git a/vendor/golang.org/x/text/transform/transform.go b/vendor/golang.org/x/text/transform/transform.go
deleted file mode 100644
index 520b9ada..00000000
--- a/vendor/golang.org/x/text/transform/transform.go
+++ /dev/null
@@ -1,705 +0,0 @@
-// Copyright 2013 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 transform provides reader and writer wrappers that transform the
-// bytes passing through as well as various transformations. Example
-// transformations provided by other packages include normalization and
-// conversion between character sets.
-package transform // import "golang.org/x/text/transform"
-
-import (
-	"bytes"
-	"errors"
-	"io"
-	"unicode/utf8"
-)
-
-var (
-	// ErrShortDst means that the destination buffer was too short to
-	// receive all of the transformed bytes.
-	ErrShortDst = errors.New("transform: short destination buffer")
-
-	// ErrShortSrc means that the source buffer has insufficient data to
-	// complete the transformation.
-	ErrShortSrc = errors.New("transform: short source buffer")
-
-	// ErrEndOfSpan means that the input and output (the transformed input)
-	// are not identical.
-	ErrEndOfSpan = errors.New("transform: input and output are not identical")
-
-	// errInconsistentByteCount means that Transform returned success (nil
-	// error) but also returned nSrc inconsistent with the src argument.
-	errInconsistentByteCount = errors.New("transform: inconsistent byte count returned")
-
-	// errShortInternal means that an internal buffer is not large enough
-	// to make progress and the Transform operation must be aborted.
-	errShortInternal = errors.New("transform: short internal buffer")
-)
-
-// Transformer transforms bytes.
-type Transformer interface {
-	// Transform writes to dst the transformed bytes read from src, and
-	// returns the number of dst bytes written and src bytes read. The
-	// atEOF argument tells whether src represents the last bytes of the
-	// input.
-	//
-	// Callers should always process the nDst bytes produced and account
-	// for the nSrc bytes consumed before considering the error err.
-	//
-	// A nil error means that all of the transformed bytes (whether freshly
-	// transformed from src or left over from previous Transform calls)
-	// were written to dst. A nil error can be returned regardless of
-	// whether atEOF is true. If err is nil then nSrc must equal len(src);
-	// the converse is not necessarily true.
-	//
-	// ErrShortDst means that dst was too short to receive all of the
-	// transformed bytes. ErrShortSrc means that src had insufficient data
-	// to complete the transformation. If both conditions apply, then
-	// either error may be returned. Other than the error conditions listed
-	// here, implementations are free to report other errors that arise.
-	Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error)
-
-	// Reset resets the state and allows a Transformer to be reused.
-	Reset()
-}
-
-// SpanningTransformer extends the Transformer interface with a Span method
-// that determines how much of the input already conforms to the Transformer.
-type SpanningTransformer interface {
-	Transformer
-
-	// Span returns a position in src such that transforming src[:n] results in
-	// identical output src[:n] for these bytes. It does not necessarily return
-	// the largest such n. The atEOF argument tells whether src represents the
-	// last bytes of the input.
-	//
-	// Callers should always account for the n bytes consumed before
-	// considering the error err.
-	//
-	// A nil error means that all input bytes are known to be identical to the
-	// output produced by the Transformer. A nil error can be returned
-	// regardless of whether atEOF is true. If err is nil, then n must
-	// equal len(src); the converse is not necessarily true.
-	//
-	// ErrEndOfSpan means that the Transformer output may differ from the
-	// input after n bytes. Note that n may be len(src), meaning that the output
-	// would contain additional bytes after otherwise identical output.
-	// ErrShortSrc means that src had insufficient data to determine whether the
-	// remaining bytes would change. Other than the error conditions listed
-	// here, implementations are free to report other errors that arise.
-	//
-	// Calling Span can modify the Transformer state as a side effect. In
-	// effect, it does the transformation just as calling Transform would, only
-	// without copying to a destination buffer and only up to a point it can
-	// determine the input and output bytes are the same. This is obviously more
-	// limited than calling Transform, but can be more efficient in terms of
-	// copying and allocating buffers. Calls to Span and Transform may be
-	// interleaved.
-	Span(src []byte, atEOF bool) (n int, err error)
-}
-
-// NopResetter can be embedded by implementations of Transformer to add a nop
-// Reset method.
-type NopResetter struct{}
-
-// Reset implements the Reset method of the Transformer interface.
-func (NopResetter) Reset() {}
-
-// Reader wraps another io.Reader by transforming the bytes read.
-type Reader struct {
-	r   io.Reader
-	t   Transformer
-	err error
-
-	// dst[dst0:dst1] contains bytes that have been transformed by t but
-	// not yet copied out via Read.
-	dst        []byte
-	dst0, dst1 int
-
-	// src[src0:src1] contains bytes that have been read from r but not
-	// yet transformed through t.
-	src        []byte
-	src0, src1 int
-
-	// transformComplete is whether the transformation is complete,
-	// regardless of whether or not it was successful.
-	transformComplete bool
-}
-
-const defaultBufSize = 4096
-
-// NewReader returns a new Reader that wraps r by transforming the bytes read
-// via t. It calls Reset on t.
-func NewReader(r io.Reader, t Transformer) *Reader {
-	t.Reset()
-	return &Reader{
-		r:   r,
-		t:   t,
-		dst: make([]byte, defaultBufSize),
-		src: make([]byte, defaultBufSize),
-	}
-}
-
-// Read implements the io.Reader interface.
-func (r *Reader) Read(p []byte) (int, error) {
-	n, err := 0, error(nil)
-	for {
-		// Copy out any transformed bytes and return the final error if we are done.
-		if r.dst0 != r.dst1 {
-			n = copy(p, r.dst[r.dst0:r.dst1])
-			r.dst0 += n
-			if r.dst0 == r.dst1 && r.transformComplete {
-				return n, r.err
-			}
-			return n, nil
-		} else if r.transformComplete {
-			return 0, r.err
-		}
-
-		// Try to transform some source bytes, or to flush the transformer if we
-		// are out of source bytes. We do this even if r.r.Read returned an error.
-		// As the io.Reader documentation says, "process the n > 0 bytes returned
-		// before considering the error".
-		if r.src0 != r.src1 || r.err != nil {
-			r.dst0 = 0
-			r.dst1, n, err = r.t.Transform(r.dst, r.src[r.src0:r.src1], r.err == io.EOF)
-			r.src0 += n
-
-			switch {
-			case err == nil:
-				if r.src0 != r.src1 {
-					r.err = errInconsistentByteCount
-				}
-				// The Transform call was successful; we are complete if we
-				// cannot read more bytes into src.
-				r.transformComplete = r.err != nil
-				continue
-			case err == ErrShortDst && (r.dst1 != 0 || n != 0):
-				// Make room in dst by copying out, and try again.
-				continue
-			case err == ErrShortSrc && r.src1-r.src0 != len(r.src) && r.err == nil:
-				// Read more bytes into src via the code below, and try again.
-			default:
-				r.transformComplete = true
-				// The reader error (r.err) takes precedence over the
-				// transformer error (err) unless r.err is nil or io.EOF.
-				if r.err == nil || r.err == io.EOF {
-					r.err = err
-				}
-				continue
-			}
-		}
-
-		// Move any untransformed source bytes to the start of the buffer
-		// and read more bytes.
-		if r.src0 != 0 {
-			r.src0, r.src1 = 0, copy(r.src, r.src[r.src0:r.src1])
-		}
-		n, r.err = r.r.Read(r.src[r.src1:])
-		r.src1 += n
-	}
-}
-
-// TODO: implement ReadByte (and ReadRune??).
-
-// Writer wraps another io.Writer by transforming the bytes read.
-// The user needs to call Close to flush unwritten bytes that may
-// be buffered.
-type Writer struct {
-	w   io.Writer
-	t   Transformer
-	dst []byte
-
-	// src[:n] contains bytes that have not yet passed through t.
-	src []byte
-	n   int
-}
-
-// NewWriter returns a new Writer that wraps w by transforming the bytes written
-// via t. It calls Reset on t.
-func NewWriter(w io.Writer, t Transformer) *Writer {
-	t.Reset()
-	return &Writer{
-		w:   w,
-		t:   t,
-		dst: make([]byte, defaultBufSize),
-		src: make([]byte, defaultBufSize),
-	}
-}
-
-// Write implements the io.Writer interface. If there are not enough
-// bytes available to complete a Transform, the bytes will be buffered
-// for the next write. Call Close to convert the remaining bytes.
-func (w *Writer) Write(data []byte) (n int, err error) {
-	src := data
-	if w.n > 0 {
-		// Append bytes from data to the last remainder.
-		// TODO: limit the amount copied on first try.
-		n = copy(w.src[w.n:], data)
-		w.n += n
-		src = w.src[:w.n]
-	}
-	for {
-		nDst, nSrc, err := w.t.Transform(w.dst, src, false)
-		if _, werr := w.w.Write(w.dst[:nDst]); werr != nil {
-			return n, werr
-		}
-		src = src[nSrc:]
-		if w.n == 0 {
-			n += nSrc
-		} else if len(src) <= n {
-			// Enough bytes from w.src have been consumed. We make src point
-			// to data instead to reduce the copying.
-			w.n = 0
-			n -= len(src)
-			src = data[n:]
-			if n < len(data) && (err == nil || err == ErrShortSrc) {
-				continue
-			}
-		}
-		switch err {
-		case ErrShortDst:
-			// This error is okay as long as we are making progress.
-			if nDst > 0 || nSrc > 0 {
-				continue
-			}
-		case ErrShortSrc:
-			if len(src) < len(w.src) {
-				m := copy(w.src, src)
-				// If w.n > 0, bytes from data were already copied to w.src and n
-				// was already set to the number of bytes consumed.
-				if w.n == 0 {
-					n += m
-				}
-				w.n = m
-				err = nil
-			} else if nDst > 0 || nSrc > 0 {
-				// Not enough buffer to store the remainder. Keep processing as
-				// long as there is progress. Without this case, transforms that
-				// require a lookahead larger than the buffer may result in an
-				// error. This is not something one may expect to be common in
-				// practice, but it may occur when buffers are set to small
-				// sizes during testing.
-				continue
-			}
-		case nil:
-			if w.n > 0 {
-				err = errInconsistentByteCount
-			}
-		}
-		return n, err
-	}
-}
-
-// Close implements the io.Closer interface.
-func (w *Writer) Close() error {
-	src := w.src[:w.n]
-	for {
-		nDst, nSrc, err := w.t.Transform(w.dst, src, true)
-		if _, werr := w.w.Write(w.dst[:nDst]); werr != nil {
-			return werr
-		}
-		if err != ErrShortDst {
-			return err
-		}
-		src = src[nSrc:]
-	}
-}
-
-type nop struct{ NopResetter }
-
-func (nop) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
-	n := copy(dst, src)
-	if n < len(src) {
-		err = ErrShortDst
-	}
-	return n, n, err
-}
-
-func (nop) Span(src []byte, atEOF bool) (n int, err error) {
-	return len(src), nil
-}
-
-type discard struct{ NopResetter }
-
-func (discard) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
-	return 0, len(src), nil
-}
-
-var (
-	// Discard is a Transformer for which all Transform calls succeed
-	// by consuming all bytes and writing nothing.
-	Discard Transformer = discard{}
-
-	// Nop is a SpanningTransformer that copies src to dst.
-	Nop SpanningTransformer = nop{}
-)
-
-// chain is a sequence of links. A chain with N Transformers has N+1 links and
-// N+1 buffers. Of those N+1 buffers, the first and last are the src and dst
-// buffers given to chain.Transform and the middle N-1 buffers are intermediate
-// buffers owned by the chain. The i'th link transforms bytes from the i'th
-// buffer chain.link[i].b at read offset chain.link[i].p to the i+1'th buffer
-// chain.link[i+1].b at write offset chain.link[i+1].n, for i in [0, N).
-type chain struct {
-	link []link
-	err  error
-	// errStart is the index at which the error occurred plus 1. Processing
-	// errStart at this level at the next call to Transform. As long as
-	// errStart > 0, chain will not consume any more source bytes.
-	errStart int
-}
-
-func (c *chain) fatalError(errIndex int, err error) {
-	if i := errIndex + 1; i > c.errStart {
-		c.errStart = i
-		c.err = err
-	}
-}
-
-type link struct {
-	t Transformer
-	// b[p:n] holds the bytes to be transformed by t.
-	b []byte
-	p int
-	n int
-}
-
-func (l *link) src() []byte {
-	return l.b[l.p:l.n]
-}
-
-func (l *link) dst() []byte {
-	return l.b[l.n:]
-}
-
-// Chain returns a Transformer that applies t in sequence.
-func Chain(t ...Transformer) Transformer {
-	if len(t) == 0 {
-		return nop{}
-	}
-	c := &chain{link: make([]link, len(t)+1)}
-	for i, tt := range t {
-		c.link[i].t = tt
-	}
-	// Allocate intermediate buffers.
-	b := make([][defaultBufSize]byte, len(t)-1)
-	for i := range b {
-		c.link[i+1].b = b[i][:]
-	}
-	return c
-}
-
-// Reset resets the state of Chain. It calls Reset on all the Transformers.
-func (c *chain) Reset() {
-	for i, l := range c.link {
-		if l.t != nil {
-			l.t.Reset()
-		}
-		c.link[i].p, c.link[i].n = 0, 0
-	}
-}
-
-// TODO: make chain use Span (is going to be fun to implement!)
-
-// Transform applies the transformers of c in sequence.
-func (c *chain) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
-	// Set up src and dst in the chain.
-	srcL := &c.link[0]
-	dstL := &c.link[len(c.link)-1]
-	srcL.b, srcL.p, srcL.n = src, 0, len(src)
-	dstL.b, dstL.n = dst, 0
-	var lastFull, needProgress bool // for detecting progress
-
-	// i is the index of the next Transformer to apply, for i in [low, high].
-	// low is the lowest index for which c.link[low] may still produce bytes.
-	// high is the highest index for which c.link[high] has a Transformer.
-	// The error returned by Transform determines whether to increase or
-	// decrease i. We try to completely fill a buffer before converting it.
-	for low, i, high := c.errStart, c.errStart, len(c.link)-2; low <= i && i <= high; {
-		in, out := &c.link[i], &c.link[i+1]
-		nDst, nSrc, err0 := in.t.Transform(out.dst(), in.src(), atEOF && low == i)
-		out.n += nDst
-		in.p += nSrc
-		if i > 0 && in.p == in.n {
-			in.p, in.n = 0, 0
-		}
-		needProgress, lastFull = lastFull, false
-		switch err0 {
-		case ErrShortDst:
-			// Process the destination buffer next. Return if we are already
-			// at the high index.
-			if i == high {
-				return dstL.n, srcL.p, ErrShortDst
-			}
-			if out.n != 0 {
-				i++
-				// If the Transformer at the next index is not able to process any
-				// source bytes there is nothing that can be done to make progress
-				// and the bytes will remain unprocessed. lastFull is used to
-				// detect this and break out of the loop with a fatal error.
-				lastFull = true
-				continue
-			}
-			// The destination buffer was too small, but is completely empty.
-			// Return a fatal error as this transformation can never complete.
-			c.fatalError(i, errShortInternal)
-		case ErrShortSrc:
-			if i == 0 {
-				// Save ErrShortSrc in err. All other errors take precedence.
-				err = ErrShortSrc
-				break
-			}
-			// Source bytes were depleted before filling up the destination buffer.
-			// Verify we made some progress, move the remaining bytes to the errStart
-			// and try to get more source bytes.
-			if needProgress && nSrc == 0 || in.n-in.p == len(in.b) {
-				// There were not enough source bytes to proceed while the source
-				// buffer cannot hold any more bytes. Return a fatal error as this
-				// transformation can never complete.
-				c.fatalError(i, errShortInternal)
-				break
-			}
-			// in.b is an internal buffer and we can make progress.
-			in.p, in.n = 0, copy(in.b, in.src())
-			fallthrough
-		case nil:
-			// if i == low, we have depleted the bytes at index i or any lower levels.
-			// In that case we increase low and i. In all other cases we decrease i to
-			// fetch more bytes before proceeding to the next index.
-			if i > low {
-				i--
-				continue
-			}
-		default:
-			c.fatalError(i, err0)
-		}
-		// Exhausted level low or fatal error: increase low and continue
-		// to process the bytes accepted so far.
-		i++
-		low = i
-	}
-
-	// If c.errStart > 0, this means we found a fatal error.  We will clear
-	// all upstream buffers. At this point, no more progress can be made
-	// downstream, as Transform would have bailed while handling ErrShortDst.
-	if c.errStart > 0 {
-		for i := 1; i < c.errStart; i++ {
-			c.link[i].p, c.link[i].n = 0, 0
-		}
-		err, c.errStart, c.err = c.err, 0, nil
-	}
-	return dstL.n, srcL.p, err
-}
-
-// Deprecated: Use runes.Remove instead.
-func RemoveFunc(f func(r rune) bool) Transformer {
-	return removeF(f)
-}
-
-type removeF func(r rune) bool
-
-func (removeF) Reset() {}
-
-// Transform implements the Transformer interface.
-func (t removeF) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
-	for r, sz := rune(0), 0; len(src) > 0; src = src[sz:] {
-
-		if r = rune(src[0]); r < utf8.RuneSelf {
-			sz = 1
-		} else {
-			r, sz = utf8.DecodeRune(src)
-
-			if sz == 1 {
-				// Invalid rune.
-				if !atEOF && !utf8.FullRune(src) {
-					err = ErrShortSrc
-					break
-				}
-				// We replace illegal bytes with RuneError. Not doing so might
-				// otherwise turn a sequence of invalid UTF-8 into valid UTF-8.
-				// The resulting byte sequence may subsequently contain runes
-				// for which t(r) is true that were passed unnoticed.
-				if !t(r) {
-					if nDst+3 > len(dst) {
-						err = ErrShortDst
-						break
-					}
-					nDst += copy(dst[nDst:], "\uFFFD")
-				}
-				nSrc++
-				continue
-			}
-		}
-
-		if !t(r) {
-			if nDst+sz > len(dst) {
-				err = ErrShortDst
-				break
-			}
-			nDst += copy(dst[nDst:], src[:sz])
-		}
-		nSrc += sz
-	}
-	return
-}
-
-// grow returns a new []byte that is longer than b, and copies the first n bytes
-// of b to the start of the new slice.
-func grow(b []byte, n int) []byte {
-	m := len(b)
-	if m <= 32 {
-		m = 64
-	} else if m <= 256 {
-		m *= 2
-	} else {
-		m += m >> 1
-	}
-	buf := make([]byte, m)
-	copy(buf, b[:n])
-	return buf
-}
-
-const initialBufSize = 128
-
-// String returns a string with the result of converting s[:n] using t, where
-// n <= len(s). If err == nil, n will be len(s). It calls Reset on t.
-func String(t Transformer, s string) (result string, n int, err error) {
-	t.Reset()
-	if s == "" {
-		// Fast path for the common case for empty input. Results in about a
-		// 86% reduction of running time for BenchmarkStringLowerEmpty.
-		if _, _, err := t.Transform(nil, nil, true); err == nil {
-			return "", 0, nil
-		}
-	}
-
-	// Allocate only once. Note that both dst and src escape when passed to
-	// Transform.
-	buf := [2 * initialBufSize]byte{}
-	dst := buf[:initialBufSize:initialBufSize]
-	src := buf[initialBufSize : 2*initialBufSize]
-
-	// The input string s is transformed in multiple chunks (starting with a
-	// chunk size of initialBufSize). nDst and nSrc are per-chunk (or
-	// per-Transform-call) indexes, pDst and pSrc are overall indexes.
-	nDst, nSrc := 0, 0
-	pDst, pSrc := 0, 0
-
-	// pPrefix is the length of a common prefix: the first pPrefix bytes of the
-	// result will equal the first pPrefix bytes of s. It is not guaranteed to
-	// be the largest such value, but if pPrefix, len(result) and len(s) are
-	// all equal after the final transform (i.e. calling Transform with atEOF
-	// being true returned nil error) then we don't need to allocate a new
-	// result string.
-	pPrefix := 0
-	for {
-		// Invariant: pDst == pPrefix && pSrc == pPrefix.
-
-		n := copy(src, s[pSrc:])
-		nDst, nSrc, err = t.Transform(dst, src[:n], pSrc+n == len(s))
-		pDst += nDst
-		pSrc += nSrc
-
-		// TODO:  let transformers implement an optional Spanner interface, akin
-		// to norm's QuickSpan. This would even allow us to avoid any allocation.
-		if !bytes.Equal(dst[:nDst], src[:nSrc]) {
-			break
-		}
-		pPrefix = pSrc
-		if err == ErrShortDst {
-			// A buffer can only be short if a transformer modifies its input.
-			break
-		} else if err == ErrShortSrc {
-			if nSrc == 0 {
-				// No progress was made.
-				break
-			}
-			// Equal so far and !atEOF, so continue checking.
-		} else if err != nil || pPrefix == len(s) {
-			return string(s[:pPrefix]), pPrefix, err
-		}
-	}
-	// Post-condition: pDst == pPrefix + nDst && pSrc == pPrefix + nSrc.
-
-	// We have transformed the first pSrc bytes of the input s to become pDst
-	// transformed bytes. Those transformed bytes are discontiguous: the first
-	// pPrefix of them equal s[:pPrefix] and the last nDst of them equal
-	// dst[:nDst]. We copy them around, into a new dst buffer if necessary, so
-	// that they become one contiguous slice: dst[:pDst].
-	if pPrefix != 0 {
-		newDst := dst
-		if pDst > len(newDst) {
-			newDst = make([]byte, len(s)+nDst-nSrc)
-		}
-		copy(newDst[pPrefix:pDst], dst[:nDst])
-		copy(newDst[:pPrefix], s[:pPrefix])
-		dst = newDst
-	}
-
-	// Prevent duplicate Transform calls with atEOF being true at the end of
-	// the input. Also return if we have an unrecoverable error.
-	if (err == nil && pSrc == len(s)) ||
-		(err != nil && err != ErrShortDst && err != ErrShortSrc) {
-		return string(dst[:pDst]), pSrc, err
-	}
-
-	// Transform the remaining input, growing dst and src buffers as necessary.
-	for {
-		n := copy(src, s[pSrc:])
-		nDst, nSrc, err := t.Transform(dst[pDst:], src[:n], pSrc+n == len(s))
-		pDst += nDst
-		pSrc += nSrc
-
-		// If we got ErrShortDst or ErrShortSrc, do not grow as long as we can
-		// make progress. This may avoid excessive allocations.
-		if err == ErrShortDst {
-			if nDst == 0 {
-				dst = grow(dst, pDst)
-			}
-		} else if err == ErrShortSrc {
-			if nSrc == 0 {
-				src = grow(src, 0)
-			}
-		} else if err != nil || pSrc == len(s) {
-			return string(dst[:pDst]), pSrc, err
-		}
-	}
-}
-
-// Bytes returns a new byte slice with the result of converting b[:n] using t,
-// where n <= len(b). If err == nil, n will be len(b). It calls Reset on t.
-func Bytes(t Transformer, b []byte) (result []byte, n int, err error) {
-	return doAppend(t, 0, make([]byte, len(b)), b)
-}
-
-// Append appends the result of converting src[:n] using t to dst, where
-// n <= len(src), If err == nil, n will be len(src). It calls Reset on t.
-func Append(t Transformer, dst, src []byte) (result []byte, n int, err error) {
-	if len(dst) == cap(dst) {
-		n := len(src) + len(dst) // It is okay for this to be 0.
-		b := make([]byte, n)
-		dst = b[:copy(b, dst)]
-	}
-	return doAppend(t, len(dst), dst[:cap(dst)], src)
-}
-
-func doAppend(t Transformer, pDst int, dst, src []byte) (result []byte, n int, err error) {
-	t.Reset()
-	pSrc := 0
-	for {
-		nDst, nSrc, err := t.Transform(dst[pDst:], src[pSrc:], true)
-		pDst += nDst
-		pSrc += nSrc
-		if err != ErrShortDst {
-			return dst[:pDst], pSrc, err
-		}
-
-		// Grow the destination buffer, but do not grow as long as we can make
-		// progress. This may avoid excessive allocations.
-		if nDst == 0 {
-			dst = grow(dst, pDst)
-		}
-	}
-}