about summary refs log tree commit diff
path: root/lib/generators.nix
blob: 5f42a98de70988d1579e33c44802f62de2dba048 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
/* Functions that generate widespread file
 * formats from nix data structures.
 *
 * They all follow a similar interface:
 * generator { config-attrs } data
 *
 * `config-attrs` are “holes” in the generators
 * with sensible default implementations that
 * can be overwritten. The default implementations
 * are mostly generators themselves, called with
 * their respective default values; they can be reused.
 *
 * Tests can be found in ./tests/misc.nix
 * Documentation in the manual, #sec-generators
 */
{ lib }:

let
  inherit (lib)
    addErrorContext
    assertMsg
    attrNames
    concatLists
    concatMapStringsSep
    concatStrings
    concatStringsSep
    const
    elem
    escape
    filter
    flatten
    foldl
    functionArgs  # Note: not the builtin; considers `__functor` in attrsets.
    gvariant
    hasInfix
    head
    id
    init
    isAttrs
    isBool
    isDerivation
    isFloat
    isFunction    # Note: not the builtin; considers `__functor` in attrsets.
    isInt
    isList
    isPath
    isString
    last
    length
    mapAttrs
    mapAttrsToList
    optionals
    recursiveUpdate
    replaceStrings
    reverseList
    splitString
    tail
    toList
    ;

  inherit (lib.strings)
    escapeNixIdentifier
    floatToString
    match
    split
    toJSON
    typeOf
    ;

  ## -- HELPER FUNCTIONS & DEFAULTS --

  /* Convert a value to a sensible default string representation.
   * The builtin `toString` function has some strange defaults,
   * suitable for bash scripts but not much else.
   */
  mkValueStringDefault = {}: v:
    let err = t: v: abort
          ("generators.mkValueStringDefault: " +
           "${t} not supported: ${toPretty {} v}");
    in   if isInt      v then toString v
    # convert derivations to store paths
    else if isDerivation v then toString v
    # we default to not quoting strings
    else if isString   v then v
    # isString returns "1", which is not a good default
    else if true  ==   v then "true"
    # here it returns to "", which is even less of a good default
    else if false ==   v then "false"
    else if null  ==   v then "null"
    # if you have lists you probably want to replace this
    else if isList     v then err "lists" v
    # same as for lists, might want to replace
    else if isAttrs    v then err "attrsets" v
    # functions can’t be printed of course
    else if isFunction v then err "functions" v
    # Floats currently can't be converted to precise strings,
    # condition warning on nix version once this isn't a problem anymore
    # See https://github.com/NixOS/nix/pull/3480
    else if isFloat    v then floatToString v
    else err "this value is" (toString v);


  /* Generate a line of key k and value v, separated by
   * character sep. If sep appears in k, it is escaped.
   * Helper for synaxes with different separators.
   *
   * mkValueString specifies how values should be formatted.
   *
   * mkKeyValueDefault {} ":" "f:oo" "bar"
   * > "f\:oo:bar"
   */
  mkKeyValueDefault = {
    mkValueString ? mkValueStringDefault {}
  }: sep: k: v:
    "${escape [sep] k}${sep}${mkValueString v}";


  ## -- FILE FORMAT GENERATORS --


  /* Generate a key-value-style config file from an attrset.
   *
   * mkKeyValue is the same as in toINI.
   */
  toKeyValue = {
    mkKeyValue ? mkKeyValueDefault {} "=",
    listsAsDuplicateKeys ? false,
    indent ? ""
  }:
  let mkLine = k: v: indent + mkKeyValue k v + "\n";
      mkLines = if listsAsDuplicateKeys
        then k: v: map (mkLine k) (if isList v then v else [v])
        else k: v: [ (mkLine k v) ];
  in attrs: concatStrings (concatLists (mapAttrsToList mkLines attrs));


  /* Generate an INI-style config file from an
   * attrset of sections to an attrset of key-value pairs.
   *
   * generators.toINI {} {
   *   foo = { hi = "${pkgs.hello}"; ciao = "bar"; };
   *   baz = { "also, integers" = 42; };
   * }
   *
   *> [baz]
   *> also, integers=42
   *>
   *> [foo]
   *> ciao=bar
   *> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10
   *
   * The mk* configuration attributes can generically change
   * the way sections and key-value strings are generated.
   *
   * For more examples see the test cases in ./tests/misc.nix.
   */
  toINI = {
    # apply transformations (e.g. escapes) to section names
    mkSectionName ? (name: escape [ "[" "]" ] name),
    # format a setting line from key and value
    mkKeyValue    ? mkKeyValueDefault {} "=",
    # allow lists as values for duplicate keys
    listsAsDuplicateKeys ? false
  }: attrsOfAttrs:
    let
        # map function to string for each key val
        mapAttrsToStringsSep = sep: mapFn: attrs:
          concatStringsSep sep
            (mapAttrsToList mapFn attrs);
        mkSection = sectName: sectValues: ''
          [${mkSectionName sectName}]
        '' + toKeyValue { inherit mkKeyValue listsAsDuplicateKeys; } sectValues;
    in
      # map input to ini sections
      mapAttrsToStringsSep "\n" mkSection attrsOfAttrs;

  /* Generate an INI-style config file from an attrset
   * specifying the global section (no header), and an
   * attrset of sections to an attrset of key-value pairs.
   *
   * generators.toINIWithGlobalSection {} {
   *   globalSection = {
   *     someGlobalKey = "hi";
   *   };
   *   sections = {
   *     foo = { hi = "${pkgs.hello}"; ciao = "bar"; };
   *     baz = { "also, integers" = 42; };
   * }
   *
   *> someGlobalKey=hi
   *>
   *> [baz]
   *> also, integers=42
   *>
   *> [foo]
   *> ciao=bar
   *> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10
   *
   * The mk* configuration attributes can generically change
   * the way sections and key-value strings are generated.
   *
   * For more examples see the test cases in ./tests/misc.nix.
   *
   * If you don’t need a global section, you can also use
   * `generators.toINI` directly, which only takes
   * the part in `sections`.
   */
  toINIWithGlobalSection = {
    # apply transformations (e.g. escapes) to section names
    mkSectionName ? (name: escape [ "[" "]" ] name),
    # format a setting line from key and value
    mkKeyValue    ? mkKeyValueDefault {} "=",
    # allow lists as values for duplicate keys
    listsAsDuplicateKeys ? false
  }: { globalSection, sections ? {} }:
    ( if globalSection == {}
      then ""
      else (toKeyValue { inherit mkKeyValue listsAsDuplicateKeys; } globalSection)
           + "\n")
    + (toINI { inherit mkSectionName mkKeyValue listsAsDuplicateKeys; } sections);

  /* Generate a git-config file from an attrset.
   *
   * It has two major differences from the regular INI format:
   *
   * 1. values are indented with tabs
   * 2. sections can have sub-sections
   *
   * generators.toGitINI {
   *   url."ssh://git@github.com/".insteadOf = "https://github.com";
   *   user.name = "edolstra";
   * }
   *
   *> [url "ssh://git@github.com/"]
   *>   insteadOf = "https://github.com"
   *>
   *> [user]
   *>   name = "edolstra"
   */
  toGitINI = attrs:
    let
      mkSectionName = name:
        let
          containsQuote = hasInfix ''"'' name;
          sections = splitString "." name;
          section = head sections;
          subsections = tail sections;
          subsection = concatStringsSep "." subsections;
        in if containsQuote || subsections == [ ] then
          name
        else
          ''${section} "${subsection}"'';

      mkValueString = v:
        let
          escapedV = ''
            "${
              replaceStrings [ "\n" "	" ''"'' "\\" ] [ "\\n" "\\t" ''\"'' "\\\\" ] v
            }"'';
        in mkValueStringDefault { } (if isString v then escapedV else v);

      # generation for multiple ini values
      mkKeyValue = k: v:
        let mkKeyValue = mkKeyValueDefault { inherit mkValueString; } " = " k;
        in concatStringsSep "\n" (map (kv: "\t" + mkKeyValue kv) (toList v));

      # converts { a.b.c = 5; } to { "a.b".c = 5; } for toINI
      gitFlattenAttrs = let
        recurse = path: value:
          if isAttrs value && !isDerivation value then
            mapAttrsToList (name: value: recurse ([ name ] ++ path) value) value
          else if length path > 1 then {
            ${concatStringsSep "." (reverseList (tail path))}.${head path} = value;
          } else {
            ${head path} = value;
          };
      in attrs: foldl recursiveUpdate { } (flatten (recurse [ ] attrs));

      toINI_ = toINI { inherit mkKeyValue mkSectionName; };
    in
      toINI_ (gitFlattenAttrs attrs);

  # mkKeyValueDefault wrapper that handles dconf INI quirks.
  # The main differences of the format is that it requires strings to be quoted.
  mkDconfKeyValue = mkKeyValueDefault { mkValueString = v: toString (gvariant.mkValue v); } "=";

  # Generates INI in dconf keyfile style. See https://help.gnome.org/admin/system-admin-guide/stable/dconf-keyfiles.html.en
  # for details.
  toDconfINI = toINI { mkKeyValue = mkDconfKeyValue; };

  withRecursion =
    {
      /* If this option is not null, the given value will stop evaluating at a certain depth */
      depthLimit
      /* If this option is true, an error will be thrown, if a certain given depth is exceeded */
    , throwOnDepthLimit ? true
    }:
      assert isInt depthLimit;
      let
        specialAttrs = [
          "__functor"
          "__functionArgs"
          "__toString"
          "__pretty"
        ];
        stepIntoAttr = evalNext: name:
          if elem name specialAttrs
            then id
            else evalNext;
        transform = depth:
          if depthLimit != null && depth > depthLimit then
            if throwOnDepthLimit
              then throw "Exceeded maximum eval-depth limit of ${toString depthLimit} while trying to evaluate with `generators.withRecursion'!"
              else const "<unevaluated>"
          else id;
        mapAny = depth: v:
          let
            evalNext = x: mapAny (depth + 1) (transform (depth + 1) x);
          in
            if isAttrs v then mapAttrs (stepIntoAttr evalNext) v
            else if isList v then map evalNext v
            else transform (depth + 1) v;
      in
        mapAny 0;

  /* Pretty print a value, akin to `builtins.trace`.
   * Should probably be a builtin as well.
   * The pretty-printed string should be suitable for rendering default values
   * in the NixOS manual. In particular, it should be as close to a valid Nix expression
   * as possible.
   */
  toPretty = {
    /* If this option is true, attrsets like { __pretty = fn; val = …; }
       will use fn to convert val to a pretty printed representation.
       (This means fn is type Val -> String.) */
    allowPrettyValues ? false,
    /* If this option is true, the output is indented with newlines for attribute sets and lists */
    multiline ? true,
    /* Initial indentation level */
    indent ? ""
  }:
    let
    go = indent: v:
    let     introSpace = if multiline then "\n${indent}  " else " ";
            outroSpace = if multiline then "\n${indent}" else " ";
    in if   isInt      v then toString v
    # toString loses precision on floats, so we use toJSON instead. This isn't perfect
    # as the resulting string may not parse back as a float (e.g. 42, 1e-06), but for
    # pretty-printing purposes this is acceptable.
    else if isFloat    v then builtins.toJSON v
    else if isString   v then
      let
        lines = filter (v: ! isList v) (split "\n" v);
        escapeSingleline = escape [ "\\" "\"" "\${" ];
        escapeMultiline = replaceStrings [ "\${" "''" ] [ "''\${" "'''" ];
        singlelineResult = "\"" + concatStringsSep "\\n" (map escapeSingleline lines) + "\"";
        multilineResult = let
          escapedLines = map escapeMultiline lines;
          # The last line gets a special treatment: if it's empty, '' is on its own line at the "outer"
          # indentation level. Otherwise, '' is appended to the last line.
          lastLine = last escapedLines;
        in "''" + introSpace + concatStringsSep introSpace (init escapedLines)
                + (if lastLine == "" then outroSpace else introSpace + lastLine) + "''";
      in
        if multiline && length lines > 1 then multilineResult else singlelineResult
    else if true  ==   v then "true"
    else if false ==   v then "false"
    else if null  ==   v then "null"
    else if isPath     v then toString v
    else if isList     v then
      if v == [] then "[ ]"
      else "[" + introSpace
        + concatMapStringsSep introSpace (go (indent + "  ")) v
        + outroSpace + "]"
    else if isFunction v then
      let fna = functionArgs v;
          showFnas = concatStringsSep ", " (mapAttrsToList
                       (name: hasDefVal: if hasDefVal then name + "?" else name)
                       fna);
      in if fna == {}    then "<function>"
                         else "<function, args: {${showFnas}}>"
    else if isAttrs    v then
      # apply pretty values if allowed
      if allowPrettyValues && v ? __pretty && v ? val
         then v.__pretty v.val
      else if v == {} then "{ }"
      else if v ? type && v.type == "derivation" then
        "<derivation ${v.name or "???"}>"
      else "{" + introSpace
          + concatStringsSep introSpace (mapAttrsToList
              (name: value:
                "${escapeNixIdentifier name} = ${
                  addErrorContext "while evaluating an attribute `${name}`"
                    (go (indent + "  ") value)
                };") v)
        + outroSpace + "}"
    else abort "generators.toPretty: should never happen (v = ${v})";
  in go indent;

  # PLIST handling
  toPlist = {}: v: let
    expr = ind: x:
      if x == null  then "" else
      if isBool x   then bool ind x else
      if isInt x    then int ind x else
      if isString x then str ind x else
      if isList x   then list ind x else
      if isAttrs x  then attrs ind x else
      if isPath x   then str ind (toString x) else
      if isFloat x  then float ind x else
      abort "generators.toPlist: should never happen (v = ${v})";

    literal = ind: x: ind + x;

    bool = ind: x: literal ind  (if x then "<true/>" else "<false/>");
    int = ind: x: literal ind "<integer>${toString x}</integer>";
    str = ind: x: literal ind "<string>${x}</string>";
    key = ind: x: literal ind "<key>${x}</key>";
    float = ind: x: literal ind "<real>${toString x}</real>";

    indent = ind: expr "\t${ind}";

    item = ind: concatMapStringsSep "\n" (indent ind);

    list = ind: x: concatStringsSep "\n" [
      (literal ind "<array>")
      (item ind x)
      (literal ind "</array>")
    ];

    attrs = ind: x: concatStringsSep "\n" [
      (literal ind "<dict>")
      (attr ind x)
      (literal ind "</dict>")
    ];

    attr = let attrFilter = name: value: name != "_module" && value != null;
    in ind: x: concatStringsSep "\n" (flatten (mapAttrsToList
      (name: value: optionals (attrFilter name value) [
      (key "\t${ind}" name)
      (expr "\t${ind}" value)
    ]) x));

  in ''<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
${expr "" v}
</plist>'';

  /* Translate a simple Nix expression to Dhall notation.
   * Note that integers are translated to Integer and never
   * the Natural type.
  */
  toDhall = { }@args: v:
    let concatItems = concatStringsSep ", ";
    in if isAttrs v then
      "{ ${
        concatItems (mapAttrsToList
          (key: value: "${key} = ${toDhall args value}") v)
      } }"
    else if isList v then
      "[ ${concatItems (map (toDhall args) v)} ]"
    else if isInt v then
      "${if v < 0 then "" else "+"}${toString v}"
    else if isBool v then
      (if v then "True" else "False")
    else if isFunction v then
      abort "generators.toDhall: cannot convert a function to Dhall"
    else if v == null then
      abort "generators.toDhall: cannot convert a null to Dhall"
    else
      toJSON v;

  /*
   Translate a simple Nix expression to Lua representation with occasional
   Lua-inlines that can be constructed by mkLuaInline function.

   Configuration:
     * multiline - by default is true which results in indented block-like view.
     * indent - initial indent.
     * asBindings - by default generate single value, but with this use attrset to set global vars.

   Attention:
     Regardless of multiline parameter there is no trailing newline.

   Example:
     generators.toLua {}
       {
         cmd = [ "typescript-language-server" "--stdio" ];
         settings.workspace.library = mkLuaInline ''vim.api.nvim_get_runtime_file("", true)'';
       }
     ->
      {
        ["cmd"] = {
          "typescript-language-server",
          "--stdio"
        },
        ["settings"] = {
          ["workspace"] = {
            ["library"] = (vim.api.nvim_get_runtime_file("", true))
          }
        }
      }

   Type:
     toLua :: AttrSet -> Any -> String
  */
  toLua = {
    /* If this option is true, the output is indented with newlines for attribute sets and lists */
    multiline ? true,
    /* Initial indentation level */
    indent ? "",
    /* Interpret as variable bindings */
    asBindings ? false,
  }@args: v:
    let
      innerIndent = "${indent}  ";
      introSpace = if multiline then "\n${innerIndent}" else " ";
      outroSpace = if multiline then "\n${indent}" else " ";
      innerArgs = args // {
        indent = if asBindings then indent else innerIndent;
        asBindings = false;
      };
      concatItems = concatStringsSep ",${introSpace}";
      isLuaInline = { _type ? null, ... }: _type == "lua-inline";

      generatedBindings =
          assert assertMsg (badVarNames == []) "Bad Lua var names: ${toPretty {} badVarNames}";
          concatStrings (
            mapAttrsToList (key: value: "${indent}${key} = ${toLua innerArgs value}\n") v
            );

      # https://en.wikibooks.org/wiki/Lua_Programming/variable#Variable_names
      matchVarName = match "[[:alpha:]_][[:alnum:]_]*(\\.[[:alpha:]_][[:alnum:]_]*)*";
      badVarNames = filter (name: matchVarName name == null) (attrNames v);
    in
    if asBindings then
      generatedBindings
    else if v == null then
      "nil"
    else if isInt v || isFloat v || isString v || isBool v then
      toJSON v
    else if isList v then
      (if v == [ ] then "{}" else
      "{${introSpace}${concatItems (map (value: "${toLua innerArgs value}") v)}${outroSpace}}")
    else if isAttrs v then
      (
        if isLuaInline v then
          "(${v.expr})"
        else if v == { } then
          "{}"
        else if isDerivation v then
          ''"${toString v}"''
        else
          "{${introSpace}${concatItems (
            mapAttrsToList (key: value: "[${toJSON key}] = ${toLua innerArgs value}") v
            )}${outroSpace}}"
      )
    else
      abort "generators.toLua: type ${typeOf v} is unsupported";

  /*
   Mark string as Lua expression to be inlined when processed by toLua.

   Type:
     mkLuaInline :: String -> AttrSet
  */
  mkLuaInline = expr: { _type = "lua-inline"; inherit expr; };

in

# Everything in this attrset is the public interface of the file.
{
  inherit
    mkDconfKeyValue
    mkKeyValueDefault
    mkLuaInline
    mkValueStringDefault
    toDconfINI
    toDhall
    toGitINI
    toINI
    toINIWithGlobalSection
    toKeyValue
    toLua
    toPlist
    toPretty
    withRecursion
    ;

  /* Generates JSON from an arbitrary (non-function) value.
    * For more information see the documentation of the builtin.
    */
  toJSON = {}: toJSON;

  /* YAML has been a strict superset of JSON since 1.2, so we
    * use toJSON. Before it only had a few differences referring
    * to implicit typing rules, so it should work with older
    * parsers as well.
    */
  toYAML = {}: toJSON;
}