361 lines
13 KiB
Nix
361 lines
13 KiB
Nix
/* Functions that generate widespread file
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* formats from nix data structures.
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*
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* They all follow a similar interface:
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* generator { config-attrs } data
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*
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* `config-attrs` are “holes” in the generators
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* with sensible default implementations that
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* can be overwritten. The default implementations
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* are mostly generators themselves, called with
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* their respective default values; they can be reused.
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*
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* Tests can be found in ./tests.nix
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* Documentation in the manual, #sec-generators
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*/
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{ lib }:
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with (lib).trivial;
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let
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libStr = lib.strings;
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libAttr = lib.attrsets;
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inherit (lib) isFunction;
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in
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rec {
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## -- HELPER FUNCTIONS & DEFAULTS --
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/* Convert a value to a sensible default string representation.
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* The builtin `toString` function has some strange defaults,
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* suitable for bash scripts but not much else.
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*/
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mkValueStringDefault = {}: v: with builtins;
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let err = t: v: abort
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("generators.mkValueStringDefault: " +
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"${t} not supported: ${toPretty {} v}");
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in if isInt v then toString v
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# convert derivations to store paths
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else if lib.isDerivation v then toString v
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# we default to not quoting strings
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else if isString v then v
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# isString returns "1", which is not a good default
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else if true == v then "true"
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# here it returns to "", which is even less of a good default
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else if false == v then "false"
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else if null == v then "null"
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# if you have lists you probably want to replace this
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else if isList v then err "lists" v
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# same as for lists, might want to replace
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else if isAttrs v then err "attrsets" v
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# functions can’t be printed of course
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else if isFunction v then err "functions" v
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# Floats currently can't be converted to precise strings,
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# condition warning on nix version once this isn't a problem anymore
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# See https://github.com/NixOS/nix/pull/3480
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else if isFloat v then libStr.floatToString v
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else err "this value is" (toString v);
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/* Generate a line of key k and value v, separated by
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* character sep. If sep appears in k, it is escaped.
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* Helper for synaxes with different separators.
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*
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* mkValueString specifies how values should be formatted.
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*
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* mkKeyValueDefault {} ":" "f:oo" "bar"
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* > "f\:oo:bar"
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*/
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mkKeyValueDefault = {
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mkValueString ? mkValueStringDefault {}
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}: sep: k: v:
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"${libStr.escape [sep] k}${sep}${mkValueString v}";
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## -- FILE FORMAT GENERATORS --
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/* Generate a key-value-style config file from an attrset.
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*
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* mkKeyValue is the same as in toINI.
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*/
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toKeyValue = {
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mkKeyValue ? mkKeyValueDefault {} "=",
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listsAsDuplicateKeys ? false
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}:
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let mkLine = k: v: mkKeyValue k v + "\n";
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mkLines = if listsAsDuplicateKeys
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then k: v: map (mkLine k) (if lib.isList v then v else [v])
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else k: v: [ (mkLine k v) ];
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in attrs: libStr.concatStrings (lib.concatLists (libAttr.mapAttrsToList mkLines attrs));
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/* Generate an INI-style config file from an
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* attrset of sections to an attrset of key-value pairs.
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*
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* generators.toINI {} {
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* foo = { hi = "${pkgs.hello}"; ciao = "bar"; };
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* baz = { "also, integers" = 42; };
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* }
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*
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*> [baz]
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*> also, integers=42
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*>
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*> [foo]
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*> ciao=bar
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*> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10
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*
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* The mk* configuration attributes can generically change
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* the way sections and key-value strings are generated.
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*
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* For more examples see the test cases in ./tests.nix.
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*/
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toINI = {
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# apply transformations (e.g. escapes) to section names
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mkSectionName ? (name: libStr.escape [ "[" "]" ] name),
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# format a setting line from key and value
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mkKeyValue ? mkKeyValueDefault {} "=",
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# allow lists as values for duplicate keys
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listsAsDuplicateKeys ? false
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}: attrsOfAttrs:
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let
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# map function to string for each key val
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mapAttrsToStringsSep = sep: mapFn: attrs:
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libStr.concatStringsSep sep
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(libAttr.mapAttrsToList mapFn attrs);
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mkSection = sectName: sectValues: ''
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[${mkSectionName sectName}]
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'' + toKeyValue { inherit mkKeyValue listsAsDuplicateKeys; } sectValues;
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in
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# map input to ini sections
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mapAttrsToStringsSep "\n" mkSection attrsOfAttrs;
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/* Generate a git-config file from an attrset.
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*
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* It has two major differences from the regular INI format:
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*
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* 1. values are indented with tabs
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* 2. sections can have sub-sections
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*
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* generators.toGitINI {
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* url."ssh://git@github.com/".insteadOf = "https://github.com";
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* user.name = "edolstra";
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* }
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*
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*> [url "ssh://git@github.com/"]
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*> insteadOf = https://github.com/
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*>
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*> [user]
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*> name = edolstra
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*/
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toGitINI = attrs:
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with builtins;
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let
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mkSectionName = name:
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let
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containsQuote = libStr.hasInfix ''"'' name;
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sections = libStr.splitString "." name;
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section = head sections;
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subsections = tail sections;
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subsection = concatStringsSep "." subsections;
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in if containsQuote || subsections == [ ] then
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name
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else
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''${section} "${subsection}"'';
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# generation for multiple ini values
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mkKeyValue = k: v:
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let mkKeyValue = mkKeyValueDefault { } " = " k;
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in concatStringsSep "\n" (map (kv: "\t" + mkKeyValue kv) (lib.toList v));
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# converts { a.b.c = 5; } to { "a.b".c = 5; } for toINI
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gitFlattenAttrs = let
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recurse = path: value:
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if isAttrs value && !lib.isDerivation value then
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lib.mapAttrsToList (name: value: recurse ([ name ] ++ path) value) value
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else if length path > 1 then {
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${concatStringsSep "." (lib.reverseList (tail path))}.${head path} = value;
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} else {
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${head path} = value;
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};
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in attrs: lib.foldl lib.recursiveUpdate { } (lib.flatten (recurse [ ] attrs));
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toINI_ = toINI { inherit mkKeyValue mkSectionName; };
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in
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toINI_ (gitFlattenAttrs attrs);
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/* Generates JSON from an arbitrary (non-function) value.
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* For more information see the documentation of the builtin.
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*/
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toJSON = {}: builtins.toJSON;
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/* YAML has been a strict superset of JSON since 1.2, so we
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* use toJSON. Before it only had a few differences referring
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* to implicit typing rules, so it should work with older
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* parsers as well.
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*/
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toYAML = {}@args: toJSON args;
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withRecursion =
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args@{
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/* If this option is not null, the given value will stop evaluating at a certain depth */
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depthLimit
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/* If this option is true, an error will be thrown, if a certain given depth is exceeded */
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, throwOnDepthLimit ? true
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}:
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assert builtins.isInt depthLimit;
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let
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transform = depth:
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if depthLimit != null && depth > depthLimit then
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if throwOnDepthLimit
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then throw "Exceeded maximum eval-depth limit of ${toString depthLimit} while trying to evaluate with `generators.withRecursion'!"
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else const "<unevaluated>"
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else id;
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mapAny = with builtins; depth: v:
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let
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evalNext = x: mapAny (depth + 1) (transform (depth + 1) x);
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in
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if isAttrs v then mapAttrs (const evalNext) v
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else if isList v then map evalNext v
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else transform (depth + 1) v;
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in
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mapAny 0;
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/* Pretty print a value, akin to `builtins.trace`.
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* Should probably be a builtin as well.
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*/
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toPretty = {
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/* If this option is true, attrsets like { __pretty = fn; val = …; }
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will use fn to convert val to a pretty printed representation.
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(This means fn is type Val -> String.) */
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allowPrettyValues ? false,
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/* If this option is true, the output is indented with newlines for attribute sets and lists */
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multiline ? true
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}@args:
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let
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go = indent: v: with builtins;
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let isPath = v: typeOf v == "path";
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introSpace = if multiline then "\n${indent} " else " ";
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outroSpace = if multiline then "\n${indent}" else " ";
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in if isInt v then toString v
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else if isFloat v then "~${toString v}"
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else if isString v then
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let
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# Separate a string into its lines
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newlineSplits = filter (v: ! isList v) (builtins.split "\n" v);
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# For a '' string terminated by a \n, which happens when the closing '' is on a new line
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multilineResult = "''" + introSpace + concatStringsSep introSpace (lib.init newlineSplits) + outroSpace + "''";
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# For a '' string not terminated by a \n, which happens when the closing '' is not on a new line
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multilineResult' = "''" + introSpace + concatStringsSep introSpace newlineSplits + "''";
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# For single lines, replace all newlines with their escaped representation
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singlelineResult = "\"" + libStr.escape [ "\"" ] (concatStringsSep "\\n" newlineSplits) + "\"";
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in if multiline && length newlineSplits > 1 then
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if lib.last newlineSplits == "" then multilineResult else multilineResult'
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else singlelineResult
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else if true == v then "true"
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else if false == v then "false"
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else if null == v then "null"
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else if isPath v then toString v
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else if isList v then
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if v == [] then "[ ]"
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else "[" + introSpace
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+ libStr.concatMapStringsSep introSpace (go (indent + " ")) v
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+ outroSpace + "]"
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else if isFunction v then
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let fna = lib.functionArgs v;
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showFnas = concatStringsSep ", " (libAttr.mapAttrsToList
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(name: hasDefVal: if hasDefVal then name + "?" else name)
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fna);
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in if fna == {} then "<function>"
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else "<function, args: {${showFnas}}>"
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else if isAttrs v then
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# apply pretty values if allowed
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if attrNames v == [ "__pretty" "val" ] && allowPrettyValues
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then v.__pretty v.val
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else if v == {} then "{ }"
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else if v ? type && v.type == "derivation" then
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"<derivation ${v.drvPath or "???"}>"
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else "{" + introSpace
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+ libStr.concatStringsSep introSpace (libAttr.mapAttrsToList
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(name: value:
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"${libStr.escapeNixIdentifier name} = ${go (indent + " ") value};") v)
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+ outroSpace + "}"
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else abort "generators.toPretty: should never happen (v = ${v})";
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in go "";
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# PLIST handling
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toPlist = {}: v: let
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isFloat = builtins.isFloat or (x: false);
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expr = ind: x: with builtins;
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if x == null then "" else
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if isBool x then bool ind x else
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if isInt x then int ind x else
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if isString x then str ind x else
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if isList x then list ind x else
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if isAttrs x then attrs ind x else
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if isFloat x then float ind x else
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abort "generators.toPlist: should never happen (v = ${v})";
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literal = ind: x: ind + x;
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bool = ind: x: literal ind (if x then "<true/>" else "<false/>");
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int = ind: x: literal ind "<integer>${toString x}</integer>";
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str = ind: x: literal ind "<string>${x}</string>";
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key = ind: x: literal ind "<key>${x}</key>";
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float = ind: x: literal ind "<real>${toString x}</real>";
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indent = ind: expr "\t${ind}";
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item = ind: libStr.concatMapStringsSep "\n" (indent ind);
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list = ind: x: libStr.concatStringsSep "\n" [
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(literal ind "<array>")
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(item ind x)
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(literal ind "</array>")
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];
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attrs = ind: x: libStr.concatStringsSep "\n" [
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(literal ind "<dict>")
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(attr ind x)
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(literal ind "</dict>")
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];
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attr = let attrFilter = name: value: name != "_module" && value != null;
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in ind: x: libStr.concatStringsSep "\n" (lib.flatten (lib.mapAttrsToList
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(name: value: lib.optional (attrFilter name value) [
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(key "\t${ind}" name)
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(expr "\t${ind}" value)
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]) x));
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in ''<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
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<plist version="1.0">
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${expr "" v}
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</plist>'';
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/* Translate a simple Nix expression to Dhall notation.
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* Note that integers are translated to Integer and never
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* the Natural type.
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*/
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toDhall = { }@args: v:
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with builtins;
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let concatItems = lib.strings.concatStringsSep ", ";
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in if isAttrs v then
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"{ ${
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concatItems (lib.attrsets.mapAttrsToList
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(key: value: "${key} = ${toDhall args value}") v)
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} }"
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else if isList v then
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"[ ${concatItems (map (toDhall args) v)} ]"
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else if isInt v then
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"${if v < 0 then "" else "+"}${toString v}"
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else if isBool v then
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(if v then "True" else "False")
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else if isFunction v then
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abort "generators.toDhall: cannot convert a function to Dhall"
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else if isNull v then
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abort "generators.toDhall: cannot convert a null to Dhall"
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else
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builtins.toJSON v;
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}
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