David K. Bainbridge | e05cf0c | 2021-08-19 03:16:50 +0000 | [diff] [blame] | 1 | // Copyright 2018 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package text |
| 6 | |
| 7 | import ( |
| 8 | "math" |
| 9 | "math/bits" |
| 10 | "strconv" |
| 11 | "strings" |
| 12 | "unicode/utf8" |
| 13 | |
| 14 | "google.golang.org/protobuf/internal/detrand" |
| 15 | "google.golang.org/protobuf/internal/errors" |
| 16 | ) |
| 17 | |
| 18 | // encType represents an encoding type. |
| 19 | type encType uint8 |
| 20 | |
| 21 | const ( |
| 22 | _ encType = (1 << iota) / 2 |
| 23 | name |
| 24 | scalar |
| 25 | messageOpen |
| 26 | messageClose |
| 27 | ) |
| 28 | |
| 29 | // Encoder provides methods to write out textproto constructs and values. The user is |
| 30 | // responsible for producing valid sequences of constructs and values. |
| 31 | type Encoder struct { |
| 32 | encoderState |
| 33 | |
| 34 | indent string |
| 35 | delims [2]byte |
| 36 | outputASCII bool |
| 37 | } |
| 38 | |
| 39 | type encoderState struct { |
| 40 | lastType encType |
| 41 | indents []byte |
| 42 | out []byte |
| 43 | } |
| 44 | |
| 45 | // NewEncoder returns an Encoder. |
| 46 | // |
| 47 | // If indent is a non-empty string, it causes every entry in a List or Message |
| 48 | // to be preceded by the indent and trailed by a newline. |
| 49 | // |
| 50 | // If delims is not the zero value, it controls the delimiter characters used |
| 51 | // for messages (e.g., "{}" vs "<>"). |
| 52 | // |
| 53 | // If outputASCII is true, strings will be serialized in such a way that |
| 54 | // multi-byte UTF-8 sequences are escaped. This property ensures that the |
| 55 | // overall output is ASCII (as opposed to UTF-8). |
| 56 | func NewEncoder(indent string, delims [2]byte, outputASCII bool) (*Encoder, error) { |
| 57 | e := &Encoder{} |
| 58 | if len(indent) > 0 { |
| 59 | if strings.Trim(indent, " \t") != "" { |
| 60 | return nil, errors.New("indent may only be composed of space and tab characters") |
| 61 | } |
| 62 | e.indent = indent |
| 63 | } |
| 64 | switch delims { |
| 65 | case [2]byte{0, 0}: |
| 66 | e.delims = [2]byte{'{', '}'} |
| 67 | case [2]byte{'{', '}'}, [2]byte{'<', '>'}: |
| 68 | e.delims = delims |
| 69 | default: |
| 70 | return nil, errors.New("delimiters may only be \"{}\" or \"<>\"") |
| 71 | } |
| 72 | e.outputASCII = outputASCII |
| 73 | |
| 74 | return e, nil |
| 75 | } |
| 76 | |
| 77 | // Bytes returns the content of the written bytes. |
| 78 | func (e *Encoder) Bytes() []byte { |
| 79 | return e.out |
| 80 | } |
| 81 | |
| 82 | // StartMessage writes out the '{' or '<' symbol. |
| 83 | func (e *Encoder) StartMessage() { |
| 84 | e.prepareNext(messageOpen) |
| 85 | e.out = append(e.out, e.delims[0]) |
| 86 | } |
| 87 | |
| 88 | // EndMessage writes out the '}' or '>' symbol. |
| 89 | func (e *Encoder) EndMessage() { |
| 90 | e.prepareNext(messageClose) |
| 91 | e.out = append(e.out, e.delims[1]) |
| 92 | } |
| 93 | |
| 94 | // WriteName writes out the field name and the separator ':'. |
| 95 | func (e *Encoder) WriteName(s string) { |
| 96 | e.prepareNext(name) |
| 97 | e.out = append(e.out, s...) |
| 98 | e.out = append(e.out, ':') |
| 99 | } |
| 100 | |
| 101 | // WriteBool writes out the given boolean value. |
| 102 | func (e *Encoder) WriteBool(b bool) { |
| 103 | if b { |
| 104 | e.WriteLiteral("true") |
| 105 | } else { |
| 106 | e.WriteLiteral("false") |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | // WriteString writes out the given string value. |
| 111 | func (e *Encoder) WriteString(s string) { |
| 112 | e.prepareNext(scalar) |
| 113 | e.out = appendString(e.out, s, e.outputASCII) |
| 114 | } |
| 115 | |
| 116 | func appendString(out []byte, in string, outputASCII bool) []byte { |
| 117 | out = append(out, '"') |
| 118 | i := indexNeedEscapeInString(in) |
| 119 | in, out = in[i:], append(out, in[:i]...) |
| 120 | for len(in) > 0 { |
| 121 | switch r, n := utf8.DecodeRuneInString(in); { |
| 122 | case r == utf8.RuneError && n == 1: |
| 123 | // We do not report invalid UTF-8 because strings in the text format |
| 124 | // are used to represent both the proto string and bytes type. |
| 125 | r = rune(in[0]) |
| 126 | fallthrough |
| 127 | case r < ' ' || r == '"' || r == '\\' || r == 0x7f: |
| 128 | out = append(out, '\\') |
| 129 | switch r { |
| 130 | case '"', '\\': |
| 131 | out = append(out, byte(r)) |
| 132 | case '\n': |
| 133 | out = append(out, 'n') |
| 134 | case '\r': |
| 135 | out = append(out, 'r') |
| 136 | case '\t': |
| 137 | out = append(out, 't') |
| 138 | default: |
| 139 | out = append(out, 'x') |
| 140 | out = append(out, "00"[1+(bits.Len32(uint32(r))-1)/4:]...) |
| 141 | out = strconv.AppendUint(out, uint64(r), 16) |
| 142 | } |
| 143 | in = in[n:] |
| 144 | case r >= utf8.RuneSelf && (outputASCII || r <= 0x009f): |
| 145 | out = append(out, '\\') |
| 146 | if r <= math.MaxUint16 { |
| 147 | out = append(out, 'u') |
| 148 | out = append(out, "0000"[1+(bits.Len32(uint32(r))-1)/4:]...) |
| 149 | out = strconv.AppendUint(out, uint64(r), 16) |
| 150 | } else { |
| 151 | out = append(out, 'U') |
| 152 | out = append(out, "00000000"[1+(bits.Len32(uint32(r))-1)/4:]...) |
| 153 | out = strconv.AppendUint(out, uint64(r), 16) |
| 154 | } |
| 155 | in = in[n:] |
| 156 | default: |
| 157 | i := indexNeedEscapeInString(in[n:]) |
| 158 | in, out = in[n+i:], append(out, in[:n+i]...) |
| 159 | } |
| 160 | } |
| 161 | out = append(out, '"') |
| 162 | return out |
| 163 | } |
| 164 | |
| 165 | // indexNeedEscapeInString returns the index of the character that needs |
| 166 | // escaping. If no characters need escaping, this returns the input length. |
| 167 | func indexNeedEscapeInString(s string) int { |
| 168 | for i := 0; i < len(s); i++ { |
| 169 | if c := s[i]; c < ' ' || c == '"' || c == '\'' || c == '\\' || c >= 0x7f { |
| 170 | return i |
| 171 | } |
| 172 | } |
| 173 | return len(s) |
| 174 | } |
| 175 | |
| 176 | // WriteFloat writes out the given float value for given bitSize. |
| 177 | func (e *Encoder) WriteFloat(n float64, bitSize int) { |
| 178 | e.prepareNext(scalar) |
| 179 | e.out = appendFloat(e.out, n, bitSize) |
| 180 | } |
| 181 | |
| 182 | func appendFloat(out []byte, n float64, bitSize int) []byte { |
| 183 | switch { |
| 184 | case math.IsNaN(n): |
| 185 | return append(out, "nan"...) |
| 186 | case math.IsInf(n, +1): |
| 187 | return append(out, "inf"...) |
| 188 | case math.IsInf(n, -1): |
| 189 | return append(out, "-inf"...) |
| 190 | default: |
| 191 | return strconv.AppendFloat(out, n, 'g', -1, bitSize) |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | // WriteInt writes out the given signed integer value. |
| 196 | func (e *Encoder) WriteInt(n int64) { |
| 197 | e.prepareNext(scalar) |
| 198 | e.out = append(e.out, strconv.FormatInt(n, 10)...) |
| 199 | } |
| 200 | |
| 201 | // WriteUint writes out the given unsigned integer value. |
| 202 | func (e *Encoder) WriteUint(n uint64) { |
| 203 | e.prepareNext(scalar) |
| 204 | e.out = append(e.out, strconv.FormatUint(n, 10)...) |
| 205 | } |
| 206 | |
| 207 | // WriteLiteral writes out the given string as a literal value without quotes. |
| 208 | // This is used for writing enum literal strings. |
| 209 | func (e *Encoder) WriteLiteral(s string) { |
| 210 | e.prepareNext(scalar) |
| 211 | e.out = append(e.out, s...) |
| 212 | } |
| 213 | |
| 214 | // prepareNext adds possible space and indentation for the next value based |
| 215 | // on last encType and indent option. It also updates e.lastType to next. |
| 216 | func (e *Encoder) prepareNext(next encType) { |
| 217 | defer func() { |
| 218 | e.lastType = next |
| 219 | }() |
| 220 | |
| 221 | // Single line. |
| 222 | if len(e.indent) == 0 { |
| 223 | // Add space after each field before the next one. |
| 224 | if e.lastType&(scalar|messageClose) != 0 && next == name { |
| 225 | e.out = append(e.out, ' ') |
| 226 | // Add a random extra space to make output unstable. |
| 227 | if detrand.Bool() { |
| 228 | e.out = append(e.out, ' ') |
| 229 | } |
| 230 | } |
| 231 | return |
| 232 | } |
| 233 | |
| 234 | // Multi-line. |
| 235 | switch { |
| 236 | case e.lastType == name: |
| 237 | e.out = append(e.out, ' ') |
| 238 | // Add a random extra space after name: to make output unstable. |
| 239 | if detrand.Bool() { |
| 240 | e.out = append(e.out, ' ') |
| 241 | } |
| 242 | |
| 243 | case e.lastType == messageOpen && next != messageClose: |
| 244 | e.indents = append(e.indents, e.indent...) |
| 245 | e.out = append(e.out, '\n') |
| 246 | e.out = append(e.out, e.indents...) |
| 247 | |
| 248 | case e.lastType&(scalar|messageClose) != 0: |
| 249 | if next == messageClose { |
| 250 | e.indents = e.indents[:len(e.indents)-len(e.indent)] |
| 251 | } |
| 252 | e.out = append(e.out, '\n') |
| 253 | e.out = append(e.out, e.indents...) |
| 254 | } |
| 255 | } |
| 256 | |
| 257 | // Snapshot returns the current snapshot for use in Reset. |
| 258 | func (e *Encoder) Snapshot() encoderState { |
| 259 | return e.encoderState |
| 260 | } |
| 261 | |
| 262 | // Reset resets the Encoder to the given encoderState from a Snapshot. |
| 263 | func (e *Encoder) Reset(es encoderState) { |
| 264 | e.encoderState = es |
| 265 | } |
| 266 | |
| 267 | // AppendString appends the escaped form of the input string to b. |
| 268 | func AppendString(b []byte, s string) []byte { |
| 269 | return appendString(b, s, false) |
| 270 | } |