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nixpkgs/lib/generators.nix
Profpatsch 61311665cb lib: add ini configuration generator
Many configurations are INI-style files. Attribute sets can be mapped
rather painlessly to the INI format.
This adds a function toINI inside a new generators library section.
Also, unit tests for the default values are provided.
2016-11-17 19:46:41 +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
{
/* 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;
}