Elia Battiston | be9edc1 | 2022-03-09 11:35:58 +0100 | [diff] [blame^] | 1 | // Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT. |
| 2 | |
| 3 | // Copyright 2016 The Go Authors. All rights reserved. |
| 4 | // Use of this source code is governed by a BSD-style |
| 5 | // license that can be found in the LICENSE file. |
| 6 | |
| 7 | package idna |
| 8 | |
| 9 | // This file implements the Punycode algorithm from RFC 3492. |
| 10 | |
| 11 | import ( |
| 12 | "math" |
| 13 | "strings" |
| 14 | "unicode/utf8" |
| 15 | ) |
| 16 | |
| 17 | // These parameter values are specified in section 5. |
| 18 | // |
| 19 | // All computation is done with int32s, so that overflow behavior is identical |
| 20 | // regardless of whether int is 32-bit or 64-bit. |
| 21 | const ( |
| 22 | base int32 = 36 |
| 23 | damp int32 = 700 |
| 24 | initialBias int32 = 72 |
| 25 | initialN int32 = 128 |
| 26 | skew int32 = 38 |
| 27 | tmax int32 = 26 |
| 28 | tmin int32 = 1 |
| 29 | ) |
| 30 | |
| 31 | func punyError(s string) error { return &labelError{s, "A3"} } |
| 32 | |
| 33 | // decode decodes a string as specified in section 6.2. |
| 34 | func decode(encoded string) (string, error) { |
| 35 | if encoded == "" { |
| 36 | return "", nil |
| 37 | } |
| 38 | pos := 1 + strings.LastIndex(encoded, "-") |
| 39 | if pos == 1 { |
| 40 | return "", punyError(encoded) |
| 41 | } |
| 42 | if pos == len(encoded) { |
| 43 | return encoded[:len(encoded)-1], nil |
| 44 | } |
| 45 | output := make([]rune, 0, len(encoded)) |
| 46 | if pos != 0 { |
| 47 | for _, r := range encoded[:pos-1] { |
| 48 | output = append(output, r) |
| 49 | } |
| 50 | } |
| 51 | i, n, bias := int32(0), initialN, initialBias |
| 52 | for pos < len(encoded) { |
| 53 | oldI, w := i, int32(1) |
| 54 | for k := base; ; k += base { |
| 55 | if pos == len(encoded) { |
| 56 | return "", punyError(encoded) |
| 57 | } |
| 58 | digit, ok := decodeDigit(encoded[pos]) |
| 59 | if !ok { |
| 60 | return "", punyError(encoded) |
| 61 | } |
| 62 | pos++ |
| 63 | i += digit * w |
| 64 | if i < 0 { |
| 65 | return "", punyError(encoded) |
| 66 | } |
| 67 | t := k - bias |
| 68 | if t < tmin { |
| 69 | t = tmin |
| 70 | } else if t > tmax { |
| 71 | t = tmax |
| 72 | } |
| 73 | if digit < t { |
| 74 | break |
| 75 | } |
| 76 | w *= base - t |
| 77 | if w >= math.MaxInt32/base { |
| 78 | return "", punyError(encoded) |
| 79 | } |
| 80 | } |
| 81 | x := int32(len(output) + 1) |
| 82 | bias = adapt(i-oldI, x, oldI == 0) |
| 83 | n += i / x |
| 84 | i %= x |
| 85 | if n > utf8.MaxRune || len(output) >= 1024 { |
| 86 | return "", punyError(encoded) |
| 87 | } |
| 88 | output = append(output, 0) |
| 89 | copy(output[i+1:], output[i:]) |
| 90 | output[i] = n |
| 91 | i++ |
| 92 | } |
| 93 | return string(output), nil |
| 94 | } |
| 95 | |
| 96 | // encode encodes a string as specified in section 6.3 and prepends prefix to |
| 97 | // the result. |
| 98 | // |
| 99 | // The "while h < length(input)" line in the specification becomes "for |
| 100 | // remaining != 0" in the Go code, because len(s) in Go is in bytes, not runes. |
| 101 | func encode(prefix, s string) (string, error) { |
| 102 | output := make([]byte, len(prefix), len(prefix)+1+2*len(s)) |
| 103 | copy(output, prefix) |
| 104 | delta, n, bias := int32(0), initialN, initialBias |
| 105 | b, remaining := int32(0), int32(0) |
| 106 | for _, r := range s { |
| 107 | if r < 0x80 { |
| 108 | b++ |
| 109 | output = append(output, byte(r)) |
| 110 | } else { |
| 111 | remaining++ |
| 112 | } |
| 113 | } |
| 114 | h := b |
| 115 | if b > 0 { |
| 116 | output = append(output, '-') |
| 117 | } |
| 118 | for remaining != 0 { |
| 119 | m := int32(0x7fffffff) |
| 120 | for _, r := range s { |
| 121 | if m > r && r >= n { |
| 122 | m = r |
| 123 | } |
| 124 | } |
| 125 | delta += (m - n) * (h + 1) |
| 126 | if delta < 0 { |
| 127 | return "", punyError(s) |
| 128 | } |
| 129 | n = m |
| 130 | for _, r := range s { |
| 131 | if r < n { |
| 132 | delta++ |
| 133 | if delta < 0 { |
| 134 | return "", punyError(s) |
| 135 | } |
| 136 | continue |
| 137 | } |
| 138 | if r > n { |
| 139 | continue |
| 140 | } |
| 141 | q := delta |
| 142 | for k := base; ; k += base { |
| 143 | t := k - bias |
| 144 | if t < tmin { |
| 145 | t = tmin |
| 146 | } else if t > tmax { |
| 147 | t = tmax |
| 148 | } |
| 149 | if q < t { |
| 150 | break |
| 151 | } |
| 152 | output = append(output, encodeDigit(t+(q-t)%(base-t))) |
| 153 | q = (q - t) / (base - t) |
| 154 | } |
| 155 | output = append(output, encodeDigit(q)) |
| 156 | bias = adapt(delta, h+1, h == b) |
| 157 | delta = 0 |
| 158 | h++ |
| 159 | remaining-- |
| 160 | } |
| 161 | delta++ |
| 162 | n++ |
| 163 | } |
| 164 | return string(output), nil |
| 165 | } |
| 166 | |
| 167 | func decodeDigit(x byte) (digit int32, ok bool) { |
| 168 | switch { |
| 169 | case '0' <= x && x <= '9': |
| 170 | return int32(x - ('0' - 26)), true |
| 171 | case 'A' <= x && x <= 'Z': |
| 172 | return int32(x - 'A'), true |
| 173 | case 'a' <= x && x <= 'z': |
| 174 | return int32(x - 'a'), true |
| 175 | } |
| 176 | return 0, false |
| 177 | } |
| 178 | |
| 179 | func encodeDigit(digit int32) byte { |
| 180 | switch { |
| 181 | case 0 <= digit && digit < 26: |
| 182 | return byte(digit + 'a') |
| 183 | case 26 <= digit && digit < 36: |
| 184 | return byte(digit + ('0' - 26)) |
| 185 | } |
| 186 | panic("idna: internal error in punycode encoding") |
| 187 | } |
| 188 | |
| 189 | // adapt is the bias adaptation function specified in section 6.1. |
| 190 | func adapt(delta, numPoints int32, firstTime bool) int32 { |
| 191 | if firstTime { |
| 192 | delta /= damp |
| 193 | } else { |
| 194 | delta /= 2 |
| 195 | } |
| 196 | delta += delta / numPoints |
| 197 | k := int32(0) |
| 198 | for delta > ((base-tmin)*tmax)/2 { |
| 199 | delta /= base - tmin |
| 200 | k += base |
| 201 | } |
| 202 | return k + (base-tmin+1)*delta/(delta+skew) |
| 203 | } |