--- /dev/null
+// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
+
+// Copyright 2016 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 idna
+
+// This file implements the Punycode algorithm from RFC 3492.
+
+import (
+ "math"
+ "strings"
+ "unicode/utf8"
+)
+
+// These parameter values are specified in section 5.
+//
+// All computation is done with int32s, so that overflow behavior is identical
+// regardless of whether int is 32-bit or 64-bit.
+const (
+ base int32 = 36
+ damp int32 = 700
+ initialBias int32 = 72
+ initialN int32 = 128
+ skew int32 = 38
+ tmax int32 = 26
+ tmin int32 = 1
+)
+
+func punyError(s string) error { return &labelError{s, "A3"} }
+
+// decode decodes a string as specified in section 6.2.
+func decode(encoded string) (string, error) {
+ if encoded == "" {
+ return "", nil
+ }
+ pos := 1 + strings.LastIndex(encoded, "-")
+ if pos == 1 {
+ return "", punyError(encoded)
+ }
+ if pos == len(encoded) {
+ return encoded[:len(encoded)-1], nil
+ }
+ output := make([]rune, 0, len(encoded))
+ if pos != 0 {
+ for _, r := range encoded[:pos-1] {
+ output = append(output, r)
+ }
+ }
+ i, n, bias := int32(0), initialN, initialBias
+ for pos < len(encoded) {
+ oldI, w := i, int32(1)
+ for k := base; ; k += base {
+ if pos == len(encoded) {
+ return "", punyError(encoded)
+ }
+ digit, ok := decodeDigit(encoded[pos])
+ if !ok {
+ return "", punyError(encoded)
+ }
+ pos++
+ i += digit * w
+ if i < 0 {
+ return "", punyError(encoded)
+ }
+ t := k - bias
+ if t < tmin {
+ t = tmin
+ } else if t > tmax {
+ t = tmax
+ }
+ if digit < t {
+ break
+ }
+ w *= base - t
+ if w >= math.MaxInt32/base {
+ return "", punyError(encoded)
+ }
+ }
+ x := int32(len(output) + 1)
+ bias = adapt(i-oldI, x, oldI == 0)
+ n += i / x
+ i %= x
+ if n > utf8.MaxRune || len(output) >= 1024 {
+ return "", punyError(encoded)
+ }
+ output = append(output, 0)
+ copy(output[i+1:], output[i:])
+ output[i] = n
+ i++
+ }
+ return string(output), nil
+}
+
+// encode encodes a string as specified in section 6.3 and prepends prefix to
+// the result.
+//
+// The "while h < length(input)" line in the specification becomes "for
+// remaining != 0" in the Go code, because len(s) in Go is in bytes, not runes.
+func encode(prefix, s string) (string, error) {
+ output := make([]byte, len(prefix), len(prefix)+1+2*len(s))
+ copy(output, prefix)
+ delta, n, bias := int32(0), initialN, initialBias
+ b, remaining := int32(0), int32(0)
+ for _, r := range s {
+ if r < 0x80 {
+ b++
+ output = append(output, byte(r))
+ } else {
+ remaining++
+ }
+ }
+ h := b
+ if b > 0 {
+ output = append(output, '-')
+ }
+ for remaining != 0 {
+ m := int32(0x7fffffff)
+ for _, r := range s {
+ if m > r && r >= n {
+ m = r
+ }
+ }
+ delta += (m - n) * (h + 1)
+ if delta < 0 {
+ return "", punyError(s)
+ }
+ n = m
+ for _, r := range s {
+ if r < n {
+ delta++
+ if delta < 0 {
+ return "", punyError(s)
+ }
+ continue
+ }
+ if r > n {
+ continue
+ }
+ q := delta
+ for k := base; ; k += base {
+ t := k - bias
+ if t < tmin {
+ t = tmin
+ } else if t > tmax {
+ t = tmax
+ }
+ if q < t {
+ break
+ }
+ output = append(output, encodeDigit(t+(q-t)%(base-t)))
+ q = (q - t) / (base - t)
+ }
+ output = append(output, encodeDigit(q))
+ bias = adapt(delta, h+1, h == b)
+ delta = 0
+ h++
+ remaining--
+ }
+ delta++
+ n++
+ }
+ return string(output), nil
+}
+
+func decodeDigit(x byte) (digit int32, ok bool) {
+ switch {
+ case '0' <= x && x <= '9':
+ return int32(x - ('0' - 26)), true
+ case 'A' <= x && x <= 'Z':
+ return int32(x - 'A'), true
+ case 'a' <= x && x <= 'z':
+ return int32(x - 'a'), true
+ }
+ return 0, false
+}
+
+func encodeDigit(digit int32) byte {
+ switch {
+ case 0 <= digit && digit < 26:
+ return byte(digit + 'a')
+ case 26 <= digit && digit < 36:
+ return byte(digit + ('0' - 26))
+ }
+ panic("idna: internal error in punycode encoding")
+}
+
+// adapt is the bias adaptation function specified in section 6.1.
+func adapt(delta, numPoints int32, firstTime bool) int32 {
+ if firstTime {
+ delta /= damp
+ } else {
+ delta /= 2
+ }
+ delta += delta / numPoints
+ k := int32(0)
+ for delta > ((base-tmin)*tmax)/2 {
+ delta /= base - tmin
+ k += base
+ }
+ return k + (base-tmin+1)*delta/(delta+skew)
+}
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