File: nn.go 1 /* 2 The MIT License (MIT) 3 4 Copyright © 2024 pacman64 5 6 Permission is hereby granted, free of charge, to any person obtaining a copy of 7 this software and associated documentation files (the “Software”), to deal 8 in the Software without restriction, including without limitation the rights to 9 use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies 10 of the Software, and to permit persons to whom the Software is furnished to do 11 so, subject to the following conditions: 12 13 The above copyright notice and this permission notice shall be included in all 14 copies or substantial portions of the Software. 15 16 THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 SOFTWARE. 23 */ 24 25 /* 26 Single-file source-code for nn: this version has no http(s) support. Even 27 the unit-tests from the original nn are omitted. 28 29 To compile a smaller-sized command-line app, you can use the `go` command as 30 follows: 31 32 go build -ldflags "-s -w" -trimpath nn.go 33 */ 34 35 package main 36 37 import ( 38 "bufio" 39 "errors" 40 "io" 41 "os" 42 "strings" 43 ) 44 45 // Note: the code is avoiding using the fmt package to save hundreds of 46 // kilobytes on the resulting executable, which is a noticeable difference. 47 48 const info = ` 49 nn [options...] [file...] 50 51 52 Nice Numbers is an app which renders the UTF-8 text it's given to make long 53 numbers much easier to read. It does so by alternating 3-digit groups which 54 are colored using ANSI-codes with plain/unstyled 3-digit groups. 55 56 Unlike the common practice of inserting commas between 3-digit groups, this 57 trick doesn't widen the original text, keeping alignments across lines the 58 same. 59 60 Input is assumed to be UTF-8, and all CRLF byte-pairs are turned into line 61 feeds. 62 63 All (optional) leading options start with either single or double-dash, 64 and most of them change the style/color used. Some of the options are, 65 shown in their single-dash form: 66 67 -h show this help message 68 -help show this help message 69 70 -b use a blue color 71 -blue use a blue color 72 -bold bold-style digits 73 -g use a green color 74 -gray use a gray color (default) 75 -green use a green color 76 -hi use a highlighting/inverse style 77 -m use a magenta color 78 -magenta use a magenta color 79 -o use an orange color 80 -orange use an orange color 81 -r use a red color 82 -red use a red color 83 -u underline digits 84 -underline underline digits 85 ` 86 87 const errorStyle = "\x1b[31m" 88 89 // errNoMoreOutput is a dummy error, whose message is ignored, and which 90 // causes the app to quit immediately and successfully 91 var errNoMoreOutput = errors.New(`no more output`) 92 93 func main() { 94 if len(os.Args) > 1 { 95 switch os.Args[1] { 96 case `-h`, `--h`, `-help`, `--help`: 97 os.Stderr.WriteString(info[1:]) 98 return 99 } 100 } 101 102 args := os.Args[1:] 103 style, _ := lookupStyle(`gray`) 104 105 // if the first argument is 1 or 2 dashes followed by a supported 106 // style-name, change the style used 107 if len(args) > 0 && strings.HasPrefix(args[0], `-`) { 108 name := args[0] 109 name = strings.TrimPrefix(name, `-`) 110 name = strings.TrimPrefix(name, `-`) 111 112 // check if the `dedashed` argument is a supported style-name 113 if s, ok := lookupStyle(name); ok { 114 style = s 115 } else { 116 os.Stderr.WriteString(errorStyle + "invalid style name ") 117 os.Stderr.WriteString(name) 118 os.Stderr.WriteString("\x1b[0m\n") 119 os.Exit(1) 120 } 121 } 122 123 if len(os.Args) > 2 { 124 const msg = `only 1 (optional) named input is supported` 125 os.Stderr.WriteString(errorStyle + msg + "\x1b[0m\n") 126 os.Exit(1) 127 } 128 129 name := `-` 130 if len(os.Args) > 1 { 131 name = os.Args[1] 132 } 133 134 if err := run(os.Stdout, name, style); isActualError(err) { 135 os.Stderr.WriteString(errorStyle) 136 os.Stderr.WriteString(err.Error()) 137 os.Stderr.WriteString("\x1b[0m\n") 138 os.Exit(1) 139 } 140 } 141 142 func run(w io.Writer, name string, style []byte) error { 143 if name == `` || name == `-` { 144 return restyle(w, os.Stdin, style) 145 } 146 147 f, err := os.Open(name) 148 if err != nil { 149 return errors.New(`can't read from file named "` + name + `"`) 150 } 151 defer f.Close() 152 153 return restyle(w, f, style) 154 } 155 156 // isActualError is to figure out whether not to ignore an error, and thus 157 // show it as an error message 158 func isActualError(err error) bool { 159 return err != nil && err != io.EOF && err != errNoMoreOutput 160 } 161 162 func restyle(w io.Writer, r io.Reader, style []byte) error { 163 bw := bufio.NewWriter(w) 164 defer bw.Flush() 165 166 const gb = 1024 * 1024 * 1024 167 sc := bufio.NewScanner(r) 168 sc.Buffer(nil, 8*gb) 169 170 for sc.Scan() { 171 restyleLine(bw, sc.Bytes(), style) 172 if err := bw.WriteByte('\n'); err != nil { 173 // a write error may be the consequence of stdout being closed, 174 // perhaps by another app along a pipe 175 return errNoMoreOutput 176 } 177 } 178 return sc.Err() 179 } 180 181 func lookupStyle(name string) (style []byte, ok bool) { 182 if alias, ok := styleAliases[name]; ok { 183 name = alias 184 } 185 186 style, ok = styles[name] 187 return style, ok 188 } 189 190 var styleAliases = map[string]string{ 191 `b`: `blue`, 192 `g`: `green`, 193 `m`: `magenta`, 194 `o`: `orange`, 195 `p`: `purple`, 196 `r`: `red`, 197 `u`: `underline`, 198 199 `bolded`: `bold`, 200 `h`: `inverse`, 201 `hi`: `inverse`, 202 `highlight`: `inverse`, 203 `highlighted`: `inverse`, 204 `hilite`: `inverse`, 205 `hilited`: `inverse`, 206 `inv`: `inverse`, 207 `invert`: `inverse`, 208 `inverted`: `inverse`, 209 `underlined`: `underline`, 210 211 `bb`: `blueback`, 212 `bg`: `greenback`, 213 `bm`: `magentaback`, 214 `bo`: `orangeback`, 215 `bp`: `purpleback`, 216 `br`: `redback`, 217 218 `gb`: `greenback`, 219 `mb`: `magentaback`, 220 `ob`: `orangeback`, 221 `pb`: `purpleback`, 222 `rb`: `redback`, 223 224 `bblue`: `blueback`, 225 `bgray`: `grayback`, 226 `bgreen`: `greenback`, 227 `bmagenta`: `magentaback`, 228 `borange`: `orangeback`, 229 `bpurple`: `purpleback`, 230 `bred`: `redback`, 231 232 `backblue`: `blueback`, 233 `backgray`: `grayback`, 234 `backgreen`: `greenback`, 235 `backmagenta`: `magentaback`, 236 `backorange`: `orangeback`, 237 `backpurple`: `purpleback`, 238 `backred`: `redback`, 239 } 240 241 // styles turns style-names into the ANSI-code sequences used for the 242 // alternate groups of digits 243 var styles = map[string][]byte{ 244 `blue`: []byte("\x1b[38;2;0;95;215m"), 245 `bold`: []byte("\x1b[1m"), 246 `gray`: []byte("\x1b[38;2;168;168;168m"), 247 `green`: []byte("\x1b[38;2;0;135;95m"), 248 `inverse`: []byte("\x1b[7m"), 249 `magenta`: []byte("\x1b[38;2;215;0;255m"), 250 `orange`: []byte("\x1b[38;2;215;95;0m"), 251 `plain`: []byte("\x1b[0m"), 252 `red`: []byte("\x1b[38;2;204;0;0m"), 253 `underline`: []byte("\x1b[4m"), 254 255 // `blue`: []byte("\x1b[38;5;26m"), 256 // `bold`: []byte("\x1b[1m"), 257 // `gray`: []byte("\x1b[38;5;248m"), 258 // `green`: []byte("\x1b[38;5;29m"), 259 // `inverse`: []byte("\x1b[7m"), 260 // `magenta`: []byte("\x1b[38;5;99m"), 261 // `orange`: []byte("\x1b[38;5;166m"), 262 // `plain`: []byte("\x1b[0m"), 263 // `red`: []byte("\x1b[31m"), 264 // `underline`: []byte("\x1b[4m"), 265 266 `blueback`: []byte("\x1b[48;2;0;95;215m\x1b[38;2;238;238;238m"), 267 `grayback`: []byte("\x1b[48;2;168;168;168m\x1b[38;2;238;238;238m"), 268 `greenback`: []byte("\x1b[48;2;0;135;95m\x1b[38;2;238;238;238m"), 269 `magentaback`: []byte("\x1b[48;2;215;0;255m\x1b[38;2;238;238;238m"), 270 `orangeback`: []byte("\x1b[48;2;215;95;0m\x1b[38;2;238;238;238m"), 271 `purpleback`: []byte("\x1b[48;2;135;95;255m\x1b[38;2;238;238;238m"), 272 `redback`: []byte("\x1b[48;2;204;0;0m\x1b[38;2;238;238;238m"), 273 } 274 275 // restyleLine renders the line given, using ANSI-styles to make any long 276 // numbers in it more legible; this func doesn't emit a line-feed, which 277 // is up to its caller 278 func restyleLine(w *bufio.Writer, line []byte, style []byte) { 279 for len(line) > 0 { 280 i := indexDigit(line) 281 if i < 0 { 282 // no (more) digits to style for sure 283 w.Write(line) 284 return 285 } 286 287 // emit line before current digit-run 288 w.Write(line[:i]) 289 // advance to the start of the current digit-run 290 line = line[i:] 291 292 // see where the digit-run ends 293 j := indexNonDigit(line) 294 if j < 0 { 295 // the digit-run goes until the end 296 restyleDigits(w, line, style) 297 return 298 } 299 300 // emit styled digit-run 301 restyleDigits(w, line[:j], style) 302 // skip right past the end of the digit-run 303 line = line[j:] 304 } 305 } 306 307 // indexDigit finds the index of the first digit in a string, or -1 when the 308 // string has no decimal digits 309 func indexDigit(s []byte) int { 310 for i := 0; i < len(s); i++ { 311 switch s[i] { 312 case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': 313 return i 314 } 315 } 316 317 // empty slice, or a slice without any digits 318 return -1 319 } 320 321 // indexNonDigit finds the index of the first non-digit in a string, or -1 322 // when the string is all decimal digits 323 func indexNonDigit(s []byte) int { 324 for i := 0; i < len(s); i++ { 325 switch s[i] { 326 case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': 327 continue 328 default: 329 return i 330 } 331 } 332 333 // empty slice, or a slice which only has digits 334 return -1 335 } 336 337 // restyleDigits renders a run of digits as alternating styled/unstyled runs 338 // of 3 digits, which greatly improves readability, and is the only purpose 339 // of this app; string is assumed to be all decimal digits 340 func restyleDigits(w *bufio.Writer, digits []byte, altStyle []byte) { 341 if len(digits) < 4 { 342 // digit sequence is short, so emit it as is 343 w.Write(digits) 344 return 345 } 346 347 // separate leading 0..2 digits which don't align with the 3-digit groups 348 i := len(digits) % 3 349 // emit leading digits unstyled, if there are any 350 w.Write(digits[:i]) 351 // the rest is guaranteed to have a length which is a multiple of 3 352 digits = digits[i:] 353 354 // start by styling, unless there were no leading digits 355 style := i != 0 356 357 for len(digits) > 0 { 358 if style { 359 w.Write(altStyle) 360 w.Write(digits[:3]) 361 w.Write([]byte{'\x1b', '[', '0', 'm'}) 362 } else { 363 w.Write(digits[:3]) 364 } 365 366 // advance to the next triple: the start of this func is supposed 367 // to guarantee this step always works 368 digits = digits[3:] 369 370 // alternate between styled and unstyled 3-digit groups 371 style = !style 372 } 373 }