| 1 | ---
|
| 2 | title: Builtin Functions (Oils Reference)
|
| 3 | all_docs_url: ..
|
| 4 | body_css_class: width40
|
| 5 | default_highlighter: oils-sh
|
| 6 | preserve_anchor_case: yes
|
| 7 | ---
|
| 8 |
|
| 9 | <div class="doc-ref-header">
|
| 10 |
|
| 11 | [Oils Reference](index.html) —
|
| 12 | Chapter **Builtin Functions**
|
| 13 |
|
| 14 | </div>
|
| 15 |
|
| 16 | This chapter describes builtin functions (as opposed to [builtin
|
| 17 | commands](chap-builtin-cmd.html).)
|
| 18 |
|
| 19 | <span class="in-progress">(in progress)</span>
|
| 20 |
|
| 21 | <div id="dense-toc">
|
| 22 | </div>
|
| 23 |
|
| 24 | ## Values
|
| 25 |
|
| 26 | ### len()
|
| 27 |
|
| 28 | Returns the
|
| 29 |
|
| 30 | - number of entries in a `List`
|
| 31 | - number of pairs in a `Dict`
|
| 32 | - number of bytes in a `Str`
|
| 33 | - TODO: `countRunes()` can return the number of UTF-8 encoded code points.
|
| 34 |
|
| 35 | ### func/type()
|
| 36 |
|
| 37 | Given an arbitrary value, returns a string representing the value's runtime
|
| 38 | type.
|
| 39 |
|
| 40 | For example:
|
| 41 |
|
| 42 | var d = {'foo': 'bar'}
|
| 43 | var n = 1337
|
| 44 |
|
| 45 | $ = type(d)
|
| 46 | (Str) 'Dict'
|
| 47 |
|
| 48 | $ = type(n)
|
| 49 | (Str) 'Int'
|
| 50 |
|
| 51 | Similar names: [type][]
|
| 52 |
|
| 53 | [type]: chap-index.html#type
|
| 54 |
|
| 55 | ### repeat()
|
| 56 |
|
| 57 | TODO:
|
| 58 |
|
| 59 | = repeat('a', 3)
|
| 60 | (Str) 'aaa'
|
| 61 |
|
| 62 | = repeat(['a'], 3)
|
| 63 | (List) ['a', 'a', 'a']
|
| 64 |
|
| 65 | Note that list elements are NOT copied. They are repeated by reference, which
|
| 66 | means the List can have aliases.
|
| 67 |
|
| 68 | = repeat([[42]], 3)
|
| 69 | (List) [[42], [42], [42]]
|
| 70 |
|
| 71 | Modeled after these Python expressions:
|
| 72 |
|
| 73 | >>> 'a' * 3
|
| 74 | 'aaa'
|
| 75 | >>> ['a'] * 3
|
| 76 | ['a', 'a', 'a']
|
| 77 |
|
| 78 |
|
| 79 | ## Conversions
|
| 80 |
|
| 81 | ### bool()
|
| 82 |
|
| 83 | Returns the truth value of its argument. Similar to `bool()` in python, it
|
| 84 | returns `false` for:
|
| 85 |
|
| 86 | - `false`, `0`, `0.0`, `''`, `{}`, `[]`, and `null`.
|
| 87 |
|
| 88 | Returns `true` for all other values.
|
| 89 |
|
| 90 | ### int()
|
| 91 |
|
| 92 | Given a float, returns the largest integer that is less than its argument (i.e. `floor()`).
|
| 93 |
|
| 94 | $ = int(1.99)
|
| 95 | (Int) 1
|
| 96 |
|
| 97 | Given a string, `Int()` will attempt to convert the string to a base-10
|
| 98 | integer. The base can be overriden by calling with a second argument.
|
| 99 |
|
| 100 | $ = int('10')
|
| 101 | (Int) 10
|
| 102 |
|
| 103 | $ = int('10', 2)
|
| 104 | (Int) 2
|
| 105 |
|
| 106 | ysh$ = Int('foo')
|
| 107 | # fails with an expression error
|
| 108 |
|
| 109 | ### float()
|
| 110 |
|
| 111 | Given an integer, returns the corressponding flaoting point representation.
|
| 112 |
|
| 113 | $ = float(1)
|
| 114 | (Float) 1.0
|
| 115 |
|
| 116 | Given a string, `Float()` will attempt to convert the string to float.
|
| 117 |
|
| 118 | $ = float('1.23')
|
| 119 | (Float) 1.23
|
| 120 |
|
| 121 | ysh$ = float('bar')
|
| 122 | # fails with an expression error
|
| 123 |
|
| 124 | ### str()
|
| 125 |
|
| 126 | Converts a `Float` or `Int` to a string.
|
| 127 |
|
| 128 | ### list()
|
| 129 |
|
| 130 | Given a list, returns a shallow copy of the original.
|
| 131 |
|
| 132 | Given an iterable value (e.g. a range or dictionary), returns a list containing
|
| 133 | one element for each item in the original collection.
|
| 134 |
|
| 135 | $ = list({'a': 1, 'b': 2})
|
| 136 | (List) ['a', 'b']
|
| 137 |
|
| 138 | $ = list(1:5)
|
| 139 | (List) [1, 2, 3, 4, 5]
|
| 140 |
|
| 141 | ### dict()
|
| 142 |
|
| 143 | Given a dictionary, returns a shallow copy of the original.
|
| 144 |
|
| 145 | ### runes()
|
| 146 |
|
| 147 | TODO
|
| 148 |
|
| 149 | Given a string, decodes UTF-8 into a List of integer "runes" (aka code points).
|
| 150 |
|
| 151 | Each rune is in the range `U+0` to `U+110000`, and **excludes** the surrogate
|
| 152 | range.
|
| 153 |
|
| 154 | runes(s, start=-1, end=-1)
|
| 155 |
|
| 156 | TODO: How do we signal errors?
|
| 157 |
|
| 158 | (`runes()` can be used to implement implemented Python's `ord()`.)
|
| 159 |
|
| 160 | ### encodeRunes()
|
| 161 |
|
| 162 | TODO
|
| 163 |
|
| 164 | Given a List of integer "runes" (aka code points), return a string.
|
| 165 |
|
| 166 | (`encodeRunes()` can be used to implement implemented Python's `chr()`.)
|
| 167 |
|
| 168 | ### bytes()
|
| 169 |
|
| 170 | TODO
|
| 171 |
|
| 172 | Given a string, return a List of integer byte values.
|
| 173 |
|
| 174 | Each byte is in the range 0 to 255.
|
| 175 |
|
| 176 | ### encodeBytes()
|
| 177 |
|
| 178 | TODO
|
| 179 |
|
| 180 | Given a List of integer byte values, return a string.
|
| 181 |
|
| 182 | ## Str
|
| 183 |
|
| 184 | ### strcmp()
|
| 185 |
|
| 186 | TODO
|
| 187 |
|
| 188 | ### split()
|
| 189 |
|
| 190 | TODO
|
| 191 |
|
| 192 | If no argument is passed, splits by whitespace
|
| 193 |
|
| 194 | <!-- respecting Unicode space? -->
|
| 195 |
|
| 196 | If a delimiter Str with a single byte is given, splits by that byte.
|
| 197 |
|
| 198 | Modes:
|
| 199 |
|
| 200 | - Python-like algorithm
|
| 201 | - Is awk any different?
|
| 202 | - Split by eggex
|
| 203 |
|
| 204 | ### shSplit()
|
| 205 |
|
| 206 | Split a string into a List of strings, using the shell algorithm that respects
|
| 207 | `$IFS`.
|
| 208 |
|
| 209 | Prefer `split()` to `shSplit()`.
|
| 210 |
|
| 211 |
|
| 212 | ## List
|
| 213 |
|
| 214 | ### join()
|
| 215 |
|
| 216 | Given a List, stringify its items, and join them by a separator. The default
|
| 217 | separator is the empty string.
|
| 218 |
|
| 219 | var x = ['a', 'b', 'c']
|
| 220 |
|
| 221 | $ echo $[join(x)]
|
| 222 | abc
|
| 223 |
|
| 224 | $ echo $[join(x, ' ')] # optional separator
|
| 225 | a b c
|
| 226 |
|
| 227 |
|
| 228 | It's also often called with the `=>` chaining operator:
|
| 229 |
|
| 230 | var items = [1, 2, 3]
|
| 231 |
|
| 232 | json write (items => join()) # => "123"
|
| 233 | json write (items => join(' ')) # => "1 2 3"
|
| 234 | json write (items => join(', ')) # => "1, 2, 3"
|
| 235 |
|
| 236 | ## Word
|
| 237 |
|
| 238 | ### glob()
|
| 239 |
|
| 240 | See `glob-pat` topic for syntax.
|
| 241 |
|
| 242 | ### maybe()
|
| 243 |
|
| 244 | ## Serialize
|
| 245 |
|
| 246 | ### toJson()
|
| 247 |
|
| 248 | Convert an object in memory to JSON text:
|
| 249 |
|
| 250 | $ = toJson({name: "alice"})
|
| 251 | (Str) '{"name":"alice"}'
|
| 252 |
|
| 253 | Add indentation by passing the `space` param:
|
| 254 |
|
| 255 | $ = toJson([42], space=2)
|
| 256 | (Str) "[\n 42\n]"
|
| 257 |
|
| 258 | Similar to `json write (x)`, except the default value of `space` is 0.
|
| 259 |
|
| 260 | See [err-json-encode][] for errors.
|
| 261 |
|
| 262 | [err-json-encode]: chap-errors.html#err-json-encode
|
| 263 |
|
| 264 | ### fromJson()
|
| 265 |
|
| 266 | Convert JSON text to an object in memory:
|
| 267 |
|
| 268 | = fromJson('{"name":"alice"}')
|
| 269 | (Dict) {"name": "alice"}
|
| 270 |
|
| 271 | Similar to `json read <<< '{"name": "alice"}'`.
|
| 272 |
|
| 273 | See [err-json-decode][] for errors.
|
| 274 |
|
| 275 | [err-json-decode]: chap-errors.html#err-json-decode
|
| 276 |
|
| 277 | ### toJson8()
|
| 278 |
|
| 279 | Like `toJson()`, but it also converts binary data (non-Unicode strings) to
|
| 280 | J8-style `b'foo \yff'` strings.
|
| 281 |
|
| 282 | In contrast, `toJson()` will do a lossy conversion with the Unicode replacement
|
| 283 | character.
|
| 284 |
|
| 285 | See [err-json8-encode][] for errors.
|
| 286 |
|
| 287 | [err-json8-encode]: chap-errors.html#err-json8-encode
|
| 288 |
|
| 289 | ### fromJson8()
|
| 290 |
|
| 291 | Like `fromJson()`, but it also accepts binary data denoted by J8-style `b'foo
|
| 292 | \yff'` strings.
|
| 293 |
|
| 294 | See [err-json8-decode][] for errors.
|
| 295 |
|
| 296 | [err-json8-decode]: chap-errors.html#err-json8-decode
|
| 297 |
|
| 298 | ## Pattern
|
| 299 |
|
| 300 | ### `_group()`
|
| 301 |
|
| 302 | Like `Match => group()`, but accesses the global match created by `~`:
|
| 303 |
|
| 304 | if ('foo42' ~ / d+ /) {
|
| 305 | echo $[_group(0)] # => 42
|
| 306 | }
|
| 307 |
|
| 308 | ### `_start()`
|
| 309 |
|
| 310 | Like `Match => start()`, but accesses the global match created by `~`:
|
| 311 |
|
| 312 | if ('foo42' ~ / d+ /) {
|
| 313 | echo $[_start(0)] # => 3
|
| 314 | }
|
| 315 |
|
| 316 | ### `_end()`
|
| 317 |
|
| 318 | Like `Match => end()`, but accesses the global match created by `~`:
|
| 319 |
|
| 320 | if ('foo42' ~ / d+ /) {
|
| 321 | echo $[_end(0)] # => 5
|
| 322 | }
|
| 323 |
|
| 324 | ## Introspection
|
| 325 |
|
| 326 | ### `shvarGet()`
|
| 327 |
|
| 328 | Given a variable name, return its value. It uses the "dynamic scope" rule,
|
| 329 | which looks up the stack for a variable.
|
| 330 |
|
| 331 | It's meant to be used with `shvar`:
|
| 332 |
|
| 333 | proc proc1 {
|
| 334 | shvar PATH=/tmp { # temporarily set PATH in this stack frame
|
| 335 | my-proc
|
| 336 | }
|
| 337 |
|
| 338 | proc2
|
| 339 | }
|
| 340 |
|
| 341 | proc proc2 {
|
| 342 | proc3
|
| 343 | }
|
| 344 |
|
| 345 | proc proc3 {
|
| 346 | var path = shvarGet('PATH') # Look up the stack (dynamic scoping)
|
| 347 | echo $path # => /tmp
|
| 348 | }
|
| 349 |
|
| 350 | proc1
|
| 351 |
|
| 352 | Note that `shvar` is usually for string variables, and is analogous to `shopt`
|
| 353 | for "booleans".
|
| 354 |
|
| 355 | If the variable isn't defined, `shvarGet()` returns `null`. So there's no way
|
| 356 | to distinguish an undefined variable from one that's `null`.
|
| 357 |
|
| 358 | ### `getVar()`
|
| 359 |
|
| 360 | Given a variable name, return its value.
|
| 361 |
|
| 362 | $ var x = 42
|
| 363 | $ echo $[getVar('x')]
|
| 364 | 42
|
| 365 |
|
| 366 | The variable may be local or global. (Compare with `shvarGet()`.) the "dynamic
|
| 367 | scope" rule.)
|
| 368 |
|
| 369 | If the variable isn't defined, `getVar()` returns `null`. So there's no way to
|
| 370 | distinguish an undefined variable from one that's `null`.
|
| 371 |
|
| 372 | ### `evalExpr()`
|
| 373 |
|
| 374 | Given a an expression quotation, evaluate it and return its value:
|
| 375 |
|
| 376 | $ var expr = ^[1 + 2]
|
| 377 |
|
| 378 | $ = evalExpr(expr)
|
| 379 | 3
|
| 380 |
|
| 381 | ## Hay Config
|
| 382 |
|
| 383 | ### parseHay()
|
| 384 |
|
| 385 | ### evalHay()
|
| 386 |
|
| 387 |
|
| 388 | ## Hashing
|
| 389 |
|
| 390 | ### sha1dc()
|
| 391 |
|
| 392 | Git's algorithm.
|
| 393 |
|
| 394 | ### sha256()
|
| 395 |
|
| 396 |
|
| 397 | <!--
|
| 398 |
|
| 399 | ### Better Syntax
|
| 400 |
|
| 401 | These functions give better syntax to existing shell constructs.
|
| 402 |
|
| 403 | - `shQuote()` for `printf %q` and `${x@Q}`
|
| 404 | - `trimLeft()` for `${x#prefix}` and `${x##prefix}`
|
| 405 | - `trimRight()` for `${x%suffix}` and `${x%%suffix}`
|
| 406 | - `trimLeftGlob()` and `trimRightGlob()` for slow, legacy glob
|
| 407 | - `upper()` for `${x^^}`
|
| 408 | - `lower()` for `${x,,}`
|
| 409 | - `strftime()`: hidden in `printf`
|
| 410 |
|
| 411 | -->
|