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nixpkgs/lib/generators.nix
Profpatsch 26eb10e771 lib: add generator functions for toJSON & toYAML
They both reference the toJSON builtin, so we get semantic identifiers
that express the intent of the generation.
Both should be able to map each nix value (minus functions) to the
destination config files.

Includes two invocation unit tests.
2016-11-17 23:16:24 +01:00

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Nix

/* Functions that generate widespread config file
* formats from nix data structures.
* Tests can be found in ./tests.nix
*/
with import ./trivial.nix;
let
libStr = import ./strings.nix;
libAttr = import ./attrsets.nix;
flipMapAttrs = flip libAttr.mapAttrs;
in
rec {
/* Generates an INI-style config file from an
* attrset of sections to an attrset of key-value pairs.
*
* generators.toINI {} {
* foo = { hi = "${pkgs.hello}"; ciao = "bar"; };
* baz = { "also, integers" = 42; };
* }
*
*> [baz]
*> also, integers=42
*>
*> [foo]
*> ciao=bar
*> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10
*
* The mk* configuration attributes can generically change
* the way sections and key-value strings are generated.
*
* For more examples see the test cases in ./tests.nix.
*/
toINI = {
# apply transformations (e.g. escapes) to section names
mkSectionName ? (name: libStr.escape [ "[" "]" ] name),
# format a setting line from key and value
mkKeyValue ? (k: v: "${libStr.escape ["="] k}=${toString v}")
}: attrsOfAttrs:
let
# map function to string for each key val
mapAttrsToStringsSep = sep: mapFn: attrs:
libStr.concatStringsSep sep
(libAttr.mapAttrsToList mapFn attrs);
mkLine = k: v: mkKeyValue k v + "\n";
mkSection = sectName: sectValues: ''
[${mkSectionName sectName}]
'' + libStr.concatStrings (libAttr.mapAttrsToList mkLine sectValues);
in
# map input to ini sections
mapAttrsToStringsSep "\n" mkSection attrsOfAttrs;
/* Generates JSON from an arbitrary (non-function) value.
* For more information see the documentation of the builtin.
*/
toJSON = {}: builtins.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 = {}@args: toJSON args;
}